Basic Sea Vegetables Information

Sea vegetables are wild ocean plants, or marine algae, enjoyed daily as staple and healing foods in many coastal parts of the world. Small amounts of sea veggies add a rich flavor and enhance the nutritional value of most dishes. These exceptionally vital plants inhabit the fertile, energetic region where ocean meets land; from the very exposed high tide mark to the constantly immersed bottom just below low tide. They inhabit all the world's oceans.

Technically speaking, not all sea vegetables are plants, even though we refer to them that way.  Macroalgae are classified by three color groups: red (6,000 species), brown (2,000 species), and green (1,200 species).  The red and green groups (Rhodophytes and Ulvophytes) are classified on the same fork of the tree of life as plants, though different side branches.  The brown algae (Phaeophytes) are placed on a different fork unrelated to plants or the other macroalgae species.

While there are many species of marine algae, only about 145 of them have a history as human food. Popular American sea vegetables from the east coast are dulse, kelp, Alaria, and laver, and sea palm from the west coast. Asian varieties include nori, hijiki, arame, kombu and wakame. We offer dulsesugar kelp, Alaria, laverIrish moss, sea lettuce, rockweed, and bladderwrack. 

Sea vegetables have many culinary uses and they add distinctive flavor and trace ocean nutrients to our diet.  They are also very nutritious.  Sea vegetables are rich in minerals and iodine, high in fiber, and contain high quality protein.  They also contain unique polysaccharides that have been linked to a long list of health benefits, including absorbing and removing radioactive elements and heavy metals from the body; inhibiting tumor cells, pathogenic bacteria, and viruses; and acting as prebiotics for healthy gut bacteria.  Sea vegetables have even been linked to good mental health.  Our Medicinal Botanical FAQs address these benefits in more detail.

If flavor and healthy nutrition aren’t enough, consider the environmental benefits.  Sea vegetables require no fresh water, valuable agricultural land, pesticides, or fertilizers.  Whether wild or farmed, seaweed removes CO2 and is considered a carbon negative crop with a high potential for mitigating climate change.  Our wild sea vegetables are sustainably harvested to allow regrowth; some of the beds have been harvested for 40+ years! 

For those with a botanical bent, following are the scientific names of the sea veggies we harvest and sell:

Dulse - Palmaria palmata
Laver - Porphyra umbilicalis
Sushi Nori - Porphyra yezoensis
Irish Moss - Chondrus crispus

Alaria - Alaria esculenta
Bladderwrack - Fucus vesiculosus
Kelp, whole leaf - Saccharina latissima (formerly known as Laminaria longicruris)
Rockweed - Ascophyllum nodosum

Sea Lettuce - Ulva spp (probably Ulva fenestra) 

Dried sea vegetables last a very long time when they’re properly stored in airtight containers, out of direct sunlight, and not exposed to long stretches of hot temperatures.  Nutrients such as minerals, iodine, and fiber are likely to remain wholly intact in dried sea vegetables for many years, although no one has ever shown this scientifically. The flavor and texture are also likely to be unaffected. However, it’s possible that some of the plant’s vitamins and lipids may deteriorate after many years’ storage.

Generally speaking, we label our sea vegetables with a “best before” date of 3-5 years from harvest.  This date can be found on a white "BEST BEFORE" sticker adhered to the package.  However, just because your sea vegetables are past this date (or the sticker is missing) doesn’t mean they’re bad and should be thrown away.  We’ve had customers report that dried kelp purchased over 10 years ago was still as good as the day they bought it.  Ultimately, you’re the judge.

Dried seaweed is rich in mineral salts and contains very little available moisture.  This combination inhibits growth of bacteria, yeast, and molds, and ensures a prolonged shelf life of at least 3-5 years if the seaweed is kept properly stored. Recommended storage containers are our re-sealable bags or, for bulk amounts, glass jars with screw top lids. Refrigeration is not necessary or desirable, because it can contribute odors and moisture to dried seaweed.  Room temperature storage in a closed cupboard or on the counter but away from direct sunlight is fine.

Sea veggies exposed to moisture or excessive heat may show signs of mold or deterioration. This will be readily visible as discoloration, and the seaweed may have an off-odor similar to mushrooms or seafood past their prime. The whitish powder that sometimes appears on sea vegetables consists of precipitated salts and sugars.  These add flavor and saltiness to the seaweed and it remains safe to eat. You can rinse or use as is. It is not a good idea to rinse sea veggies and store unless you're going to use in 24-48 hours or refrigerate.

If your sea veggies get too dry and crispy, they can be rehydrated by adding a piece of lettuce, slice of apple or damp paper towel to the container for a day or two. Brittle kelp or Alaria can be lightly sprinkled or soaked until rehydrated to your preference.

Our sea vegetables are sometimes rinsed or soaked in fresh water before use, but often this is unnecessary. Dulse, for instance, is eaten right out of the bag as a healthy, "salty" snack. Kelp is often lightly soaked and rehydrated (it expands!) to be cut into attractive shapes and sizes. In any case, a light rinse before use lessens sea vegetables' salty taste. You will lose some sodium and potassium salts, but very little if any calcium, iron, magnesium, etc. You can save the rinse water for cooking.  It is not a good idea to rinse sea veggies and then store them, unless you're going to use within 24-48 hours or refrigerate.

You may want to inspect the plants for tiny shells (periwinkles) before use. We do our best but sometimes they hide in the folds. Simply dip the plants in water long enough to unfold them and release any shells.

Some people find the distinctive aroma of sea vegetables to be strong or off-putting. One reason that it smells so strong is because it's a highly concentrated, dehydrated food.  As long as there is no mold or other signs of deterioration (usually from being stored under damp and/or overly warm conditions) the product is fine to eat. Storing sea vegetables in a tightly sealed glass or plastic jar helps keep the odor from permeating the kitchen or pantry.

A whitish powder sometimes occurs on some of our sea vegetables, most often on sugar kelp and Alaria, and less often on dulse.  The product may arrive in this condition or it may develop during storage.  This is nothing to worry about!  People sometimes mistake this powder for mold, but it probably is not. To learn more about whether mold occurs on dried seaweed, click on this link "Moldy Seaweed" for a downloadable PDF on the topic, complete with photos.

As sea vegetables dry, salts and sugars often precipitate to the surface from the internal tissues. These salts and sugars are easily rinsed off, but they can also be safely eaten as is.  In kelp, the principle sugar is mannitol and the salts are predominantly potassium and sodium. Mannitol is less sweet than most other sugars, but it still adds a subtle flavor quality. Along with kelps’ high mineral content and naturally occurring glutamate, mannitol is why kelp makes beans taste so great, cook so quickly and digest so easily!

While we are more skilled than ever at handling all our sea veggies from harvest to packaging, they are not ultra-processed to the point of total control. This is actually one of their unique selling points: minimally processed whole foods, enzymes intact. 

In many Asian nations, beautiful healthy hair, skin, and nails are attributed to the regular use of seaweed in food, soap and shampoo. It’s thought that a combination of factors including an abundance of organic colloidal minerals, particularly calcium, silica, iron and phosphorous;  emulsifying alginates (fibers that become mucilaginous when moistened) that cleanse surface toxins, emulsify oils and de-acidify; and the abundance of iodine, amino acids, active enzymes, beta carotenes, and B-vitamins all contribute to this effect.

If you want to experiment, try mixing 1 tsp. of our powdered rockweed (Ascophyllum nodosum) with 3/4 cup of warm water, wait about 30 minutes until the alginate gels fully develop, and then strain out any remaining particles. The remaining viscous liquid can be used as a shampoo or simple hand soap for cleansing and moisturizing. Or, add some whole kelp (or alaria, bladderwrack, or irish moss) to your bath. A cheesecloth bag keeps the seaweed from clogging the drain but still allow it to release the mucilaginous polysaccharides and minerals that are so beneficial for skin and hair.

For more detailed information, please read our cookbook and resource guide Sea Vegetable Celebration, pp 35-38.

Most domesticated animals are far from the diets of their wild ancestors, and in need of broad-based mineral support just as we humans are.  Sea vegetables can provide chelated, colloidal trace elements to the diet of your special animals, as opposed to the inorganic mineral salts that supplement many commercial animal feeds and leave free metal ions in the digestive tract.  We receive numerous reports from customers who have successfully fed our sea vegetables to their dogs, cats, fish, hamsters, iguanas, etc. Dog and cat owners claim not only healthier animals but also healthier, fuller coats.

Milled kelp (kelp meal) has been fed to cattle, sheep, chickens, and other barnyard animals for decades. If you wish to purchase seaweed-based feed supplements especially formulated for domesticated animals, and for feeding suggestions, please visit and For a more detailed discussion of this general topic, please read our cookbook and resource guide Sea Vegetable Celebration, pp 32-33.

Seaweed has been used for centuries by coastal people worldwide to nourish plants and gardens. Besides contributing a broad spectrum of abundant minerals, the brown varieties such as kelp and rockweed contain plant biostimulants such as cytokinins, natural plant hormones that stimulate growth and flowering, intensify color, and increase yield.  Seaweed can also improve soil microbial ecology and tilth.  Rockweed (Ascophyllum nodosum) in particular is widely utilized as a sustainable alternative to chemical fertilizers and pesticides. Numerous scientific studies show that rockweed extracts can improve not just plant health and vigor, but also the nutritional quality of a variety of vegetable and fruit crops (1).  Maine supports a small but important rockweed fishery for production of plant biostimulants.  The Maine Seaweed Council website has links to Maine companies that sell seaweed-based agricultural products, as well as other products.

If you have access to fresh seaweed gathered from the shore, it can be tilled directly into the garden, composted with grass clippings, hay, or manure, or used on top of the soil as mulch. Our landbound customers can also use seaweed by adding small amounts of dried seaweed to water for regular watering of healthy plants or by making a seaweed 'tea' to help sickly plants recover.  Steep some dried seaweed (any of the Browns' is most common) overnight in enough water to cover and then pour the tea on the roots the following day or apply as a foliar spray. A more detailed discussion of growing plants with sea vegetables can be found in our cookbook and resource guide Sea Vegetable Celebration, pp 34-35.

#1 Shukla et al., “Ascophyllum nodosum-Based Biostimulants: Sustainable Applications in Agriculture for the Stimulation of Plant Growth, Stress Tolerance, and Disease Management”, Frontiers in Plant Science 2019 10:65 doi: 10.3389/fpls.2019.00655

Culinary Questions

If you’re new to sea vegetables you might be wondering about their texture and flavor. Some dried whole leaf sea vegetables, such as kelp and Alaria, can be crunchy or even brittle right out of the bag. Others, such as dulse, are softer and more pliable. In any event, most sea vegetables can be eaten right from the bag, and they will soften and become chewy when eaten as is or soaked in liquid. 

In general, most sea vegetables have a strong, briny, minerally and umami flavor.  They shouldn’t taste fishy, although some say the ocean flavor reminds them of fish. The brown seaweeds (kelp, rockweed, bladderwrack and Alaria) have more umami flavor than the reds (dulse, laver, nori, and Irish moss) or greens (sea lettuce).  Dulse is often described as having a smoky essence and some people say fried dulse reminds them of bacon.  Laver and nori have a slightly sweet and nutty taste.  Sea lettuce has a certain bitterness and is best used in recipes.

Whole sea vegetables can all be eaten as a raw snack straight from the bag, but most people prefer adding them in small amounts to other foods. Sea Seasonings or any milled form are a convenient way to add see vegetables to food, and a great introduction as well. Recipes can be found on the Recipes page of this website or in our cookbook Sea Vegetable Celebration.  We offer sample sizes of most of our products or if you want to jump right in we also offer a Sea Starter Kit with an introductory selection of products.

It's really quite easy!  Whole leaf can be cut into bite sized pieces and added to  soups, salads, sandwiches and stir-fries. Milled products (flakes, granules, and powder) can be added by the spoonful to smoothies, soups and many recipes. Our shaker products can be used as a salt substitute or simply to add flavor to all sorts of dishes. Each Maine Coast package comes with instructions and recipe suggestions. To get started cooking with sea vegetables, go to the Recipes section and read Basic Prep section for each sea veggie.

Sea vegetables' strong taste and odor surprise some people. Remember that dried sea vegetables are a highly vital wild food and provide highly concentrated nutrition — a little goes a long way, and most easy Maine Coast recipes use less than one quarter ounce per serving! Sea vegetables are sometimes rinsed or soaked in fresh water before use, but often this is unnecessary. We suggest eating a variety of sea vegetables for maximum nutrition and taste.

It certainly is, and using sea vegetables instead of salt may be one of the easiest ways to incorporate them into your diet!  Our sea vegetables contain only between 1% to 4% sodium on a dry weight basis but they taste saltier than they actually are due to the presence of other minerals such as potassium and calcium. Glutamate, a naturally occurring amino acid found in seaweed, adds additional umami flavor.  Add 1-2 teaspoons of any of our dried, milled seaweeds to recipes to reduce the salt content while boosting the flavor.  They’re great in scrambled eggs, salads, noodles, and even a bloody mary! Our line of Sea Seasonings, specially made for this purpose, comes in convenient shakers or in bulk for those who want to fill their own shakers.

Gluten is a group of proteins found in certain grains, such as wheat, rye, and barley.  Sea vegetables are naturally gluten free because they don’t contain these proteins.  This led some food scientists to develop and evaluate a gluten free pasta made from seaweed (1)!  Consumers who tested the seaweed pasta said it tasted good and that it had less of the characteristic seaweed aroma after cooking.  Since we don’t process any gluten containing products at our facility, there’s also no chance for cross contamination.


#1 Fradinho et al, “Edible Brown Seaweed in Gluten-Free Pasta: Technological and Nutritional Evaluation.” Foods (2019)8; doi:10.3390/foods8120622

Sea vegetables are great for any vegetarian or vegan diet.  The red and green species are related to plants and the brown species, even though they're technically not a plant, are definitely not an animal either.  Nothing is added...they come straight to you from the sea, minimally processed.

Sea vegetables contribute important nutrients to a vegetarian or vegan diet that may otherwise be difficult to obtain from a diet based solely on land plants.  They have balanced amino acid profiles, are mineral rich, and it's thought that some species (especially laver) can even be a source of vitamin B12.

Sometimes there may be tiny animals (or pebbles!) hidden in the fronds, such as mussels, barnacles, or even an occasional fish.  These happened to be attached to the sea vegetable at the time of harvest or accidentally included.  This sort of accidental inclusion is common to all organic vegetable crops, and the FDA even sets standards. A single serving of canned or frozen spinach, for example, is allowed to have 50 thrips, aphids, and/or mites, or possibly the larvae of spinach worms — or even eight entire leaf miner bugs!

The consensus among Jewish scholars is that seaweed, per se, is a kosher food, although not everyone agrees.  It’s probably best to get the opinion of your rabbi if this is a concern.  In order for most foods to bear the hechsher “seal of approval”, the food and the manufacturing facility must be certified by a kosher certification agency.  Also, be aware that sea vegetables, since they come from the sea, may sometimes hold tiny dried shellfish such as snails, periwinkles, and mussels within their fronds. 

All Maine Coast sea vegetables are sun or air dried at mild temperatures that never exceed 100 degrees F.  This means they remain a raw food with all of their minerals, enzymes, vitamins, proteins, lipids, and marine phytochemicals still fully intact. This can’t be said of all sea vegetables; our understanding is that the Japanese sea vegetables arame, hijiki, and wakame are heat processed  and may even sometimes be boiled or blanched. 

All of our sea vegetables can be eaten uncooked, right out of the bag, but some may find them too dry or chewy eaten that way.  Soaking or marinating whole sea vegetables in vinegar or citrus juice makes them moist and more tender, while still preserving their raw food goodness. Or skip right to flakes, granules or powdered options for ease of use!

Seaweed is said to add umami flavor to dishes, but what is umami?  Umami is a Japanese word that roughly translates as "delicious essence", and it's often described as being a savory meaty or brothy flavor.  Scientists have confirmed that umami is the fifth flavor with its own taste receptors on the tongue that are neither salty, sweet, sour, nor bitter.  Most of umami’s flavor comes from glutamate, a naturally occurring amino acid found in abundance in such foods as ham, mushrooms, cheese, and seaweed.  Monosodium glutamate (MSG) is a synthetic form of glutamate made by fermenting starches and combining the resulting glutamic acid with sodium.  Including seaweed in recipes is a great way to add umami flavor without using MSG. The quintessential umami dish is Japanese dashi broth made with kombu.  Kombu is the name for a group of large brown seaweeds from the family Laminareacea.  Our own sugar kelp (Wild Atlantic Kombu) is a member of this family, and Alaria (Wild Atlantic Wakame) comes from a closely related group.  All of our seaweeds add umami to recipes, but the brown seaweeds are especially rich in it!

Recipe suggestions are found on the back of our retail sea veggie packaging, and a more extensive selection of recipes can be found on the Recipes page of this website. We also offer an excellent seaweed cookbook on our Online Store: Sea Vegetable Celebration is a cookbook and reference book by Shep Erhart, MCSV founder, and noted organic chef Leslie Cerier, containing over 100 vegetarian recipes, plus 40 pages of biological, nutritional and practical info on all your favorite sea vegetables, American and Asian. 

Seaweed Nutritional Information

We get this question a lot! Most of our products come with a “Nutrition Facts” panel on the package showing levels of essential nutrients found in a usual or “normal” serving size.  Essential nutrients are ones required by the FDA to be on the Nutrition Facts label, but other equally important minerals and vitamins are also found in sea vegetables. In addition, some of our bulk packaging may lack the “Nutrition Facts”panel and/or some people consume their sea vegetables in “unusual” serving sizes.

Fortunately, the levels of many various nutrients found in a specific serving size can be easily calculated using information presented on our website’s “Seaweed Nutritional Facts” page and some simple math.  For the most accuracy, you’ll need a good scale to get a weight (grams) of your usual serving size or daily portion.  If you don’t have a scale you can at least get a good approximation using common measures such as ½ cup, tbsp, etc.  In this case, you can use the Typical Serving Size table at the bottom of the “Seaweed Nutritional Facts” page to get the weight in grams for common measures of various sea vegetables.

Once you have an idea of how much your serving weighs, the next step is to look for the nutrient of interest in the Nutritional Composition Tables near the top of the “Seaweed Nutritional Facts” page.  These tables show how much of a particular nutrient there is in 100 grams for various seaweed species and products, and you’ll have to divide this number by 100 to get how much there is in one gram. The tables include data for several important minerals and vitamins that aren’t required for the FDA Nutrition Facts label.  If the nutrient you’re interested in isn’t listed in these tables, it probably means we don’t have enough information to give the level with any confidence.  However, it never hurts to ask our Customer Service <>

Once you know how much your serving weighs and how much of the nutrient is present in one gram, the next step is to simply multiply the two together.  Here’s an example of how the process works.  Let’s say you want to know how much zinc you’re getting in 2 tsp of dulse powder added to a smoothie.  The Nutritional Composition Table says there’s 3mg of zinc in 100g of dulse, so 1g of dulse would contain 0.03mg of zinc (3÷100).  The Typical Serving Size Table says that 1tsp of dulse powder weighs 4g, so 2 tsp would weigh 8g.  8g of dulse powder X 0.03mg of zinc per gram =0.24mg of zinc.  Incidentally, humans require about 11mg of zinc per day, so 2 tsp of dulse powder meets about 2% of the recommended daily intake for zinc.

It’s important to remember, though, that it’s not possible to know with certainty the exact level of a nutrient present in a serving. This is because seaweed is a wild marine plant and its nutritional profile varies depending on season, age, location and other variables. The nutrient levels provided on our labels and in our tables are based on composite averages using the best available data, but each particular batch may contain more or less of a particular nutrient.

This question is usually in regards to a specific nutrient. For example, people often ask how much of a product do they need to eat in order to get the RDI of iodine or some other amount of a mineral.

The answer is complicated by the question of bioavailability. There are very few foods where 100% of the nutrients they contain are fully assimilated during digestion. We know, for example, that less than 100% of the iodine found in seaweed is fully absorbed by humans. The percentage varies depending on all sorts of variables, not the least of which is individual metabolism. This makes the issue of bioavailabilty almost impossible to address with precision for any one person.

So, let's leave the bioavailability issue out of it and assume the nutrient of interest is 100% available. The answer now becomes similar to the one for the FAQ just before this one ("How do I calculate nutrient content in a serving?").

First, of course, you'll need to know how much of a particular nutrient you want to get every day, week, or whatever. The next step is to go to the nutritional tables found on our Nutrition page to find how much of the nutrient is present in 100 grams. Divide this number by 100 to get how much is present in one gram. From there, it's a simple matter of dividing the amount you want to get by the amount that's in one gram. The answer tells you how many grams you need to eat to get the nutrient.

Example: Let's say you want to know how much of our Kelp Blend Granules you need to eat to get the RDI of iodine. The RDI for iodine is 150 mcg per day. Our nutrition tables tell us that there are 54,600 mcg of iodine in 100 grams...which means there are 546 mcg in one gram. 150 divided by 546 = 0.27 grams. In other words, a very small amount of kelp blend granules, really just a sprinkle, will in theory provide the full RDI of iodine (1/4 tsp of kelp granules is about 0.8g).

This example shows why people call seaweed a super food...especially when it comes to iodine!

It’s well known that sea vegetables are a good source of iodine. Iodine is naturally present in seawater and almost every seaweed species bioconcentrates it, sometimes to extraordinary levels.  Brown seaweeds (such as kelp species) tend to contain more iodine than red or green seaweeds.  The “Seaweed Nutritional Facts” page has tables showing how much iodine is present in 100g of each species we sell, as well as how much is found in common serving sizes.  If you wish to determine how much iodine you’re getting in a serving size not in our tables, please consult the FAQ “How do I calculate nutrient content in a serving?” Please remember that nutrient contents presented in the tables, including those for iodine, are based on composite averages and it’s not possible to know with any certainty exactly how much iodine a serving may contain.

Iodine is an essential nutrient for thyroid health and it affects many aspects of our physiology, especially metabolism.  Iodine is critically important for proper prenatal brain important that insufficient dietary iodine is considered the worlds' leading cause of childhood intellectual deficiency. This is mostly a problem in undeveloped countries with iodine poor soils and little access to seafood. A diet that regularly includes sea vegetables helps ensure your thyroid always maintains adequate levels of healthy iodine.

The iodine found in seaweed can also protect the thyroid from harmful radioactive iodine released during nuclear accidents.  Many people who are aware of this fact take special care to eat sea vegetables whenever a nuclear accident occurs, most recently following the Fukushima disaster.

The Reference Daily Intake (RDI) of iodine for adult humans is considered to be 150 micrograms (mcg or µg) per day, but most people safely tolerate up to 1,100 µg per day.  It’s easy to get the RDI by consuming just a small portion of sea vegetables every day.  For example, just ½ tsp of bladderwrack powder contains about 1,164 µg of iodine. Most people safely “spill” excess iodine from their bodies, but some sensitive individuals may experience adverse symptoms similar to those experienced with iodine deficiency. In most cases the symptoms abate with reduced iodine intake.  Please consult with your health care practitioner if you have any questions about your consumption of iodine. The “Seaweed Science Resources” page has links to more in depth information about iodine.

Sea vegetables provide all of the 20 or so minerals and trace elements required for your body's physiological functions, often in quantities greatly exceeding those of land plants.  Sea vegetables present these essential nutrients to your body in a chelated, colloidal bio-available form that helps them be readily absorbed and utilized by the body.

Some Examples

Iron - A 7g serving of dulse (about 1/3 cup) contains almost 3mg of iron, about the same amount as is found in a 100g serving of spinach, and more than kidney beans, apricots, and peas

Potassium - a 7g serving of Alaria contains as much potassium as a 100g serving of raw kale. Gram for gram, Alaria contains nearly 13 times more potassium than bananas (45.5 mg/g vs 3.6mg/g)!

Calcium - 7g of sea lettuce contains nearly as much calcium (214mg) as one cup of milk (305mg).

Magnesium - Sea vegetables are a good source of magnesium.  7g of laver contains nearly as much magnesium (38mg) as one cup of cooked collard greens (40mg).

Finally, consider this somewhat poetic image: we evolved from simple unicellular creatures in the briny, mineral laden Mother Ocean. Now, billions of years later, our "inner ocean" — the saline fluids around and in our cells and organs — recreates the primal birthing environment, with a similar range and balance of minerals. Sea vegetables concentrate this mineral matrix. When you eat sea veggies, your cells recognize this natural, harmonious, health giving balance.  

They may taste salty, but most sea vegetables contain far less sodium per serving than a ¼ tsp of table salt. Rockweed (Ascophyllum), our “saltiest” sea vegetable, only contains about 40 mg of sodium per gram, which means a 5-gram serving contains about 200 mg of sodium. A ¼ tsp of iodized table salt contains 590 mg of sodium!  The salty flavor but relatively low sodium content of our Sea Seasonings and other milled products makes them a healthy salt substitute.

Much of the salty flavor of sea vegetables comes from their high potassium,calcium, and magnesium levels. Although these minerals are also known as salts, they don't raise blood pressure like sodium does, and they offer a healthy counter-balance to our modern, sodium rich diet. The diet of our Paleolithic hunter/gatherer ancestors had a sodium to potassium ratio of about 1 to 16.  Modern humans run into trouble when our "civilized" diet reverses the natural availability of sodium and potassium — potassium is leached out of processed foods, and sodium is used extravagantly as a flavor enhancer and preservative. Our bodies tend to retain sodium as an evolutionary adaptation to its scarcity in our natural diet. Potassium, on the other hand, was plentiful in our natural diet of vegetables, nuts, seeds, and fruits, and so our bodies evolved to not retain it. This imbalance — along with the lack of magnesium and calcium — is implicated in high blood pressure, giving the sodium in table salt a bad rap. Sea vegetables help correct this imbalance with a sodium to potassium ratio of about 1:2. 

Susan Asanovic, M.S., R.D., states unequivocally, "Almost everyone, except renal, severely hypertensive and CHF (congestive heart failure) patients, can enjoy organic Maine Coast Sea Vegetables in varying amounts. Even patients on modified clinical diets can healthfully incorporate moderate to liberal amounts of sea vegetables into their diets; just remind them to limit shoyu, tamari, miso and processed foods. For patients on a no-added-salt diet (about 2500 mg), sea vegetables can give just the right saltiness, and are far better in nutrition and taste than commercial 'lite' salts. Used in moderation, they can be enjoyed in a typical serving of 5 to 10 grams (about 1/4 oz.)."

If you have questions about your sodium intake, please consult your health care provider and or dietary counselor. In any case, a light rinse of whole sea vegetables before use reduces the content of sodium and potassium without affecting other minerals such as calcium or iron. If you're specifically interested in sea veggies as salt substitute, check out our Sea Seasonings, milled sea vegetables in convenient shakers. 

Sea vegetables generally contain decent levels of vitamins, especially the B vitamins. Multiple studies show that a 7g serving of most sea vegetables (for example 1/3 cup dulse leaf) contains between 1% to 10% of the RDI for vitamins B1 (Thiamine), B2 (riboflavin), and B6.  Red seaweeds (dulse and laver) can also contain up to 10% of the RDI for vitamin C. Check out our Nutritional Charts for a more detailed accounting.

Japanese researchers have found evidence that Pyropia species (purple laver) found in nori sheets contain high levels of Vitamin B12. This may also be true of Enteromorpha, a close relative of our Ulva sea lettuce.

However, it's unwise to rely on sea vegetables as a sole source of Vitamin B12. Tieraona Low Dog, MD, author of Fortify Your Life: Your Guide to Vitamins, Minerals, and More, writes “No matter what you might read, you cannot get vitamin B12 by eating non-fortified grains, nutritional yeast, algae, or seaweed.”

Tieraona Low Dog isn't the only expert with this opinion. It's also shared by the Academy of Nutrition and Dietetics and other authorities. There simply isn't enough scientific evidence to support the view that seaweed is a good source of non-animal origin B12.

The difficulty lies in the fact that B12 comes in a bioavailable form known as cobalamin and in non-bioavailable forms known as pseudocobalamin (also called analogues). The difference lies in the fact that the B12 found in seaweed is actually made by bacteria associated with the plant, and different bacteria make different forms of B12. Older research that found B12 in purple laver used an analytical method that couldn't detect the difference between the two forms.

However, many scientists suspect that up to half of all seaweed species actually could contain bioavailable B12. Unfortunately, there's not been enough up-to-date research using more precise analytical methods to confirm this suspicion.

Vitamin B12 is essential for human health and the RDI is 2.4 mcg/day. Since humans are unable to make their own vitamin B12, they must get it through their diet. Usual sources include animal meats and some seafood such as clams and sardines, but not vegetables, fruits, grains or nuts. This makes it challenging for vegetarians, and especially vegans, to ensure they get enough B12 every day.

Although we believe low temperature dried, minimally processed sea vegetables could be a source of Vitamin B12, you, of course, must decide for yourself. Please consult with your health care practitioner if you have any questions about whether your body is getting sufficient levels of B12.

The protein content of most sea vegetables ranges from 9% to 15%, but laver is especially rich in it, containing up to 40% protein.  Food scientists consider the protein found in seaweed to be high quality because it typically contains all or most of the essential amino acids (including the ones our bodies can't produce). An important amino acid found especially in brown seaweeds such as Alaria and sugar kelp is glutamic acid, the basis for synthetic MSG. This amino acid naturally enhances flavors and is responsible for adding umami, the fifth taste. Glutamic acid helps tenderize high protein foods like beans, while also making them more digestible. It's also been shown to improve mental and nervous system activity; provide energy, and is thought to help control alcoholism, schizophrenia and sugar cravings.

Check out our Nutritional Charts for a more detailed accounting of protein in sea vegetables.

Sea vegetables are good for people managing their weight. Not only are they very low in unsaturated fat (<2%), their high iodine levels can stimulate the thyroid to increase metabolism and burn calories. Further, sea vegetable fiber aids digestion and improves gut health.

We've had our brown sea vegetables tested for Omega-6 and Omega-3 essential fatty acids, and while they are present in only small amounts, they occur in a favorable ratio of between 1.5 and 2 to 1 (the NIH suggests an optimal ratio of between 2 and 3 to 1). As importantly, sea veggies contribute all the minerals, vitamins, and trace elements needed for optimum utilization of omega 3's and 6's. 

Fiber is a carbohydrate that remains essentially undigested by the time it reaches the large intestine. Even though we don't digest fiber, it's extremely important for our health and nutrition!  A high fiber diet  promotes the growth of healthy gut microbes and is thought to help prevent certain types of cancer. It also helps slow glucose metabolism, especially important for diabetics. Sea vegetables are high in fiber and they contain unique fibers not found in land plants. Known as sulfated polysaccharides, they've been shown to provide a broad range of potential health benefits.  Read the Medicinal Botanical FAQs to learn more about these benefits.

Dulse, kelp, Alaria, and laver each contain about 30% total fiber, about half of which is soluble and half insoluble. For comparison, dulse contains as much fiber as oat bran. Of course, because you usually eat a larger serving size of oat bran than of sea vegetables, you'll get more fiber per serving from the oat bran. But every time you eat sea vegetables, you're getting a very special and high quality fiber.

Harvest and Sourcing Practices

Most of our wild sea vegetables are hand harvested from the Gulf of Maine, including coastal islands across the Bay of Fundy and on up to Nova Scotia. Some species (notably our Icelandic Kelp Blend) are harvested further north in Iceland. 

Sea vegetables are harvested following the tides, from small boats or by scrambling along rocky beaches at low tide. Some intrepid souls even don wet suits and wade into the cold Atlantic water to harvest! The plants are cut to leave the holdfast behind for regrowth, and many of the same beds have been sustainably harvested in this fashion for 40+ years.  The freshly harvested sea veggies are taken to drying facilities to be solar or air-dried at warm, mild temperatures.  The dried sea vegetables are then shipped to our processing plant, where they’re graded for quality and stored to await final packaging. 

Harvesting, drying, and processing are all done in accordance with National Organic Program (NOP) Standards. Please see The Harvest for more information on harvesting.

Most of our dulse is selectively hand-harvested from remote rocky beaches in the Bay of Fundy. Since dulse is a wild food, we are limited in how much we can sustainably harvest every year. Dulse's popularity means we often have to ration our sales so that more customers can share in the harvest. Luckily we sell dulse in 3 milled and 3 whole leaf forms, so you should always be able to get some form of dulse! Please read our blog post on the topic to learn more.

We mainly sell wild harvested, non-cultivated sea vegetables, though the rise of seaweed aquaculture in Maine means we may someday sell farmed sea vegetables as well. We're one of the few companies in the world to mostly sell wild harvested seaweed. 

Globally, over 97% of the seaweed that people eat is farm raised.  Seaweed aquaculture is often known as mariculture and it may be one of the world's most environmentally sustainable ways to produce food.  No fresh water, herbicides, pesticides, fertilizers, or precious crop land are required.  Seaweed farming is regarded as a carbon negative crop, with a high potential for climate change mitigation. Most seaweed mariculture occurs in Asia, Indonesia, and the Philippines, but in recent years many new farms have started in Europe and elsewhere, including Maine. 

As of 2018 Maine had 16 seaweed farms, mostly growing sugar kelp.  As a company we've supported these new farmers with advice and advocacy, and as the supply of locally farmed seaweed grows, we anticipate offering it as a group of products.  When that day occurs, we will always differentiate between wild harvested and farm raised sea vegetables.

It's true that compared to land plants we have little control over the growing conditions of our wild marine plants. But we do have choices about how, when, where, and how much we harvest as well as how the plants are transported, dried, stored and packaged. The NOP (National Organic Program) Standards address all these areas and help ensure sustainability. NOP Standards give clear and uniform direction to all responsible parties for harvesting and handling these precious plants on their way to your table. Definitely worth the trouble!

Harvest Standards: These ensure that the seaweed is harvested at sustainable levels, in particular that the harvest bed or area remains healthy and productive (very much in our own best interest, of course!). Beds are inspected annually. Further, post-harvest handling and transport procedures are designed to ensure that no chemical contamination of the harvest occurs.  See The Harvest for a map and slide show.

Processing and Packaging Standards: These maintain the integrity and purity of the sea veggies from the harvester to the packaged product at our certified facility.  Lot numbers are documented at every step so that each bag of finished product can be traced back to the source.

Testing Standard: Certification agencies randomly test our products for pesticide and herbicide residues.  We also voluntarily test most of our products for these residues as well as for other chemical contaminants and microbiological concerns.

Sustainability is the fundamental operating principle of this company. It's based on our belief that these gifts from the sea come with the responsibility to maintain sustainable practices in harvesting, processing and merchandising...leaving more than we harvest, producing more than we consume, and giving back more than we take. Our wild sea vegetables are harvested from the Gulf of Maine by hand: a simple and ancient technology that encourages mindful practice. The beds are lightly harvested to ensure regeneration; some of the same beds have been tended by harvesters for over 30 years. At times, market demand for some of our sea vegetables, such as dulse, exceeds the amount that's been harvested.  When that happens, we prefer rationing our sales as opposed to putting more pressure on the resource.  See the FAQ "Where's the dulse" for more on this topic.

Each year it seems there are more reasons for concern about the health of our oceans, and each year we receive more inquiries about the purity of our seaweed products. Fortunately, the northern Gulf of Maine, where most of our sea vegetables are sourced, has very little industrial activity and no major metropolis.  Northern Maine is covered by a vast 3.5-million-acre forest known as the North Maine Woods, and with a population density of less than 25 people per square mile it’s the least populated region east of the Mississippi.   Organic certification further ensures our sea vegetables are harvested away from marinas, aquaculture pens, and other sources of contamination, and that they’re handled and processed without the use of chemicals.  As a final precaution, every year 3rd party labs analyze our seaweed for heavy metals and other contaminants.  The results are posted here on the Product Testing page. 

To educate ourselves, we have investigated possible changes in contaminant levels over time in the waters where our seaweeds are harvested. Our research indicates that the levels of heavy metals such as cadmium and lead in the Gulf of Maine have remained unchanged for at least the past 25-30 years. The Gulfwatch Contaminants Monitoring Program, organized and administered by the Gulf of Maine Council on the Marine Environment, has monitored pollution in the waters where we harvest since 1993.  Their annual reports and other information can be found here at Gulfwatch.

Information about our retail bags packaging can be found on our packaging page.

Medicinal Botanical Properties of Sea Vegetables

Sea vegetables have been used for centuries in traditional Japanese and Chinese medicine to treat cancer. Recent scientific research has begun to verify and validate this tradition.  Dr. Jane Teas, affiliated with the Harvard School of Public Health, first suggested a link in 1981 between seaweed consumption and the lower rate of breast cancer found in postmenopausal women in Japan, which she attributed to seaweed iodine. Subsequent research provided further evidence that iodine plays a role in maintaining healthy breast tissue and could even slow or prevent the development of breast cancer (1).  

In addition to iodine, macroalgae are rich in sulfated polysaccharides known as fucoidans, which are shown in lab studies to slow or stop the proliferation of cancer cells (2). These compounds, which are extracted from brown seaweeds, induced apoptosis (cell death) in a range of cancer cell lines without harming normal cells.

Algae also contain abundant levels of carotenoids, compounds responsible for pigmentation and known to be powerful anti-oxidants. One of these is fucoxanthin, an orange-colored pigment found in brown seaweeds.  Fucoxanthin has remarkable biological properties, including inhibition of several kinds of cancer cells (3).  Its ability to scavenge free radicals, a trait shared by most carotenoids, is thought to play a key role in cancer prevention.

So far, the evidence that eating seaweed reduces cancer risk is circumstantial but compelling.  Among other clues, researchers note a lower incidence of breast and colon cancers in Asian cultures where seaweed is an important part of the diet. New findings continue to emerge showing the potential of seaweed bioactive compounds for cancer prevention and therapy.


#1 Aceves et al.  “Antineoplastic effect of iodine in mammary cancer: participation of 6-iodolactone (6-IL) and peroxisome proliferator-activated receptors (PPAR).” Molecular Cancer (2009) 8(33).    

#2 Murphy et al. “The potential of seaweed as a source of drugs for use in cancer chemotherapy.” Journal of Applied Phycology (2014) 26:2211–2264.

#3 Peng et al.  “Fucoxanthin, a Marine Carotenoid Present in Brown Seaweeds and Diatoms: Metabolism and Bioactivities Relevant to Human Health.”  Marine Drugs (2011) 9(10):1806-1828. 

Oriental medicine has long held that eating seaweed is good for the heart.  Modern medicine has found clues as to why (1).  An unbalanced diet is an important root cause of cardiovascular disease (CVD), but a balanced diet that includes seaweed on a daily basis may help prevent CVD. For one thing, seaweed is rich in soluble dietary fibers such as alginates, carrageenan, and agar.  Soluble dietary fiber is known to help lower cholesterol, reduce blood pressure, and decrease the risk of type II diabetes. 

Sea vegetables may taste salty, but only some of this is due to sodium. Seaweed is rich in sea salts, such as potassium and calcium, that help reduce hypertension.  These salts exist in seaweed in a healthy ratio with sodium, so even if you’re trying to reduce sodium intake it may not be necessary (or wise) to avoid seaweed.  A 5g serving of sugar kelp has about 168mg of sodium (7% RDI) and 357mg potassium (8% RDI), for a sodium to potassium ratio of about 1:2.  This favorable ratio makes our milled seaweeds or Sea Seasonings® great salt substitutes.

Finally, it’s worth mentioning seaweed’s lipid profile.  Although seaweed generally has <3% fat, these fats consist mostly of heart (and brain) healthy polyunsaturated fatty acids.


#1 Cornish et al. "A role for dietary macroalgae in the amelioration of certain risk factors associated with cardiovascular disease."  Phycologia (2015) 54(6):649-666.

The effectiveness of sea vegetables for treating radiation poisoning has been investigated worldwide. Strontium-90 is a poisonous radioactive isotope released in nuclear accidents and bomb testing.  If ingested in contaminated food it accumulates in bone with adverse long-term consequences.  In the 1960's researchers at McGill University in Canada found that alginic acid (also called alginate), a polysaccharide found in brown algae like kelp and Alaria, could reduce the amount of strontium-90 absorbed through the intestinal wall (1).  Other studies by researchers in Japan and elsewhere confirmed these important findings (2).

Iodine-131 is another poisonous radioactive isotope released from nuclear accidents.  Here again, seaweed plays an important role in preventing radiation sickness.  Iodine-131 can be taken up by the thyroid, where it causes harm to the organ or even cancer.  Seaweed is rich in natural iodine-127, the form normally used by the thyroid.  If the thyroid's iodine receptors are filled with healthy iodine-127 molecules, the thyroid won't absorb the radioactive form. So, it serves us well to keep our thyroids full of natural iodine, and sea vegetables are the best food source for it. All sea vegetables contain iodine but kelp tends to be one of the most significant sources.

After the Chernobyl nuclear disaster in Russia we noticed an increase in our sales of kelp, and we joined with other small producers in sending a kelp care package to survivors. We saw a similar sales increase following the 2011 nuclear disaster at Fukushima, Japan.  Although iodine-131 has a very short half-life of just 8 days, other forms of radiation, such as strontium-90, can persist for much longer. Dr. Ryan Drum tells us "… we are regularly taking in radioactive isotopes from the total world contamination by continual radioactive fallout from all nuclear power plants, weapons facilities and past nuclear tests."  Another good reason to regularly eat seaweed! For iodine levels in our sea vegetables please refer to our Nutritional Chart


#1 Skoryna et al., "Studies on Inhibition of Intestinal Absorption of Radioactive Strontium: I. Prevention of Absorption from Ligated Intestinal Fragments," Canadian Medical Association Journal (1964) vol. 91.

#2 Tanaka et al, "Studies on Inhibition of Intestinal Absorption of Radioactive Strontium: VII. Relationship of Biological Activity to Chemical Composition of Alginates Obtained from North American Seaweeds" Canadian Medical Association Journal (1968) vol. 99.

Inflammation can be either acute, as a result of wound or infection, or chronic, persisting long after the precipitating event.  Traditional uses of sea vegetables, especially in Asia, have shown they provide some therapeutic effect on the inflammatory response, particularly in tissue wounds. Ryan Drum, Ph.D., herbalist and seaweed specialist, asserts that fucoidan is the bio-active compound in brown seaweed responsible for lessening the inflammatory response. This view is supported by recent scientific research showing how various fucoidan extracts from brown seaweeds modulate the body’s inflammatory response (1, 2). Fucoidan is a water-soluble compound that can be easily extracted by boiling/simmering a quart of water with an ounce (about 1½ cups) of dried brown sea vegetable for 20 to 40 minutes. Either pre-surgically or after tissue wounding has occurred Dr. Drum recommends drinking this fucoidan extract daily for 1 to 2 weeks (3).


#1 Fitton, Jane Helen, “Therapies from Fucoidan; Multifunctional Marine Polymers.”  Marine Drugs (2011) 9:1731-1760 doi:10.3390/md9101731

#2 Luthuli et al, “Therapeutic Effects of Fucoidan: A Review on Recent Studies.”  Marine Drugs (2019) 17, 487 doi:10.3390/md17090487

#3 Drum, R., “Medicinal Uses of Seaweed.” (2008)

Laboratory studies show that sulfated seaweed polysaccharides (SSPs) have high antiviral activity against enveloped viruses such as HIV, herpes simplex virus, dengue virus, and coronaviruses (1).

SSPs include agarins and carrageenans from red seaweeds and fucoidans from the browns.  As their name implies, sulfated seaweed polysaccharides are carbohydrates with sulfate molecules (sulfur + oxygen) attached to them, and found only in seaweeds. In addition to their antiviral properties SSPs are being widely investigated for a range of other medicinal properties, including the ability to modulate the immune response. It's important to know that, so far, their anti-viral properties have only been demonstrated in vitro (in a culture dish or tube and outside the human body). Because SSPs are a type of dietary fiber they are not readily digested by humans and thus not absorbed. Scientists continue to work on developing a useful antiviral medication from SSPs. In the meantime, SSPs offer a number of other health benefits, described further in the FAQs for intestinal health, mental health, cardiovascular disease, and cancer.


#1 Damonte et al, Sulfated "Seaweed Polysaccharides as Antiviral Agents,' Current Medicinal Chemistry (2004) 11:2399-2419.

The widespread prevalence of heavy metals such as lead, mercury, and cadmium in the environment and in our food and water raises concern that these metals can accumulate in the body with adverse health effects. Heavy metal detoxification diets have become increasingly popular to address this concern, and several foods have been proposed for their cleansing abilities, including sea vegetables. Anthony William, a New York Times bestselling author known as the “Medical Medium”, promotes dulse flakes for this purpose.  Dr. Ryan Drum (aka Fucus man), an expert in herbal medicine, advocates eating brown seaweeds for heavy metal detox due to their high levels of fucoidans.  Fucoidan was first extracted in 1913 from bladderwrack Fucus vesiculosus.  In addition to its possible role as a chelator of heavy metals, fucoidan is being extensively studied for anti-cancer, anti-viral, and anti-inflammatory properties (reference #1).

Is there scientific evidence to support eating sea vegetable for detox?  Unfortunately, at this time such evidence is lacking.  In part, this may be because scientists haven’t really addressed the topic, which also means we can’t say for certain that sea vegetables don’t detoxify heavy metals.  There is evidence, though, that seaweed carbohydrates such as fucoidans and alginates readily bind to and absorb metals and other contaminants. Phycoremediation (removal of contaminants with algae) has been extensively studied and used for wastewater treatment for decades (references 2 & 3). 

If seaweed can trap and remove contaminants from the environment, it’s reasonable to think it can do the same in humans.  We do know that fucoidans, alginates, and other seaweed dietary fibers pass through the intestine mostly undigested and excreted. Anything bound within these dietary fibers, such as heavy metals, would also be excreted.  It seems plausible to speculate that as seaweed fiber passes through the intestine it can “sponge up” any heavy metals it encounters that may be present from the other food and drink we ingest.  However, for now this remains speculation, because to our knowledge there’s been no research demonstrating this occurs.  The ability of dietary seaweed to detoxify heavy metals from internal human tissue, organs, and bone is even more difficult to evaluate. No plausible mechanism has been proposed in the scientific literature to explain how dulse or other seaweeds could remove heavy metals or other toxins from organs and bone.  Since fucoidans and alginates are poorly digested, they’re not likely to occur at significant levels in our blood circulation.

This lack of empirical evidence makes it difficult to evaluate claims that sea vegetables can detoxify humans of heavy metals or other contaminants. For this reason, we can neither recommend nor disapprove of the practice.  Anyone concerned about their bodily burden of heavy metals should discuss the matter with their health care practitioner. We discuss this topic in greater detail in our FAQ “Do sea vegetables contain heavy metals?”


#1 Janet Helen Fitton "Therapies from Fucoidan; Multifunctional Marine Polymers." Marine Drugs (2011)9: pp. 1731-1760; doi:10.3390/md9101731


#2 Brinzaet al., “Marine micro and macro algal species as biosorbents for heavy metals.”Environmental Engineering and Management Journal (2007)6(3):237-251

#3 Davisa et al, "A review of the biochemistry of heavy metal biosorption by brown algae." Water Research (2003) 37: pp. 4311–4330

Besides being good for the body sea vegetables are also good for the brain!  Seaweed is rich in iodine, an essential nutrient for proper brain development in fetuses and infants.  Iodine deficiency in pregnant and lactating woman is regarded as the world’s leading cause of mental deficiency in children; a problem with long-term consequences.  The US National Institutes of Health advises that pregnant women get 220mcg per day of iodine and lactating women up to 290mcg.  Modest amounts of seaweed included in the diet are a great way to get more iodine, but it’s important not to overdo it.  Pregnant and lactating women should always consult a health care professional before supplementing their diet with iodine!

In adults, eating seaweed may benefit the brain through its positive effects on another important organ – our gut!  In 2019 Chinese researchers got approval for a new Alzheimer’s treatment developed from a seaweed polysaccharide.  The polysaccharide – sodium oligomannate – was found to suppress intestinal dysbiosis and the resulting accumulation of phenylalanine/isoleucine, with reduced neuroinflammation and a measurable improvement in cognitive abilities. This finding adds further evidence that diet affects mental health through the gut brain axis (1).  The complex sulfated polysaccharides found only in seaweed are believed to exert a profound positive effect on the composition of our gut microbiota, as described in our FAQ Intestinal Health.  Another recent study showed that a seaweed extract eaten before lunch helped healthy volunteers perform better on cognitive tests after lunch (2).   Read our blog post “Seaweed and the Brain” to learn more about these exciting developments. 


#1 Luna & Foster. “Gut brain axis: diet microbiota interactions and implications for modulation of anxiety and depression”. Current Opinion in Biotechnology (2015) 32:35-41.

#2 Haskell-Ramsay et al, "Acute Post-Prandial Cognitive Effects of Brown seaweed Extract in Humans" Nutrients (2018) 10, 85; doi 10.3390/nu10010085

Dietary fiber is essential for intestinal health and sea vegetables are an excellent source, containing from 25% to 50% dietary fiber.  What’s more, the fiber found in seaweed has unique complex carbohydrates known as sulfated polysaccharides that are being extensively researched for having a broad range of health promoting properties.  These sulfated seaweed polysaccharides – SSPs for short – differ between the red, brown, and green seaweeds, but they all possess similar properties that may positively impact our health on a broad range of fronts: cardiovascular, anticancer, anti-inflammatory, diabetes, and mental health (1).  Perhaps most importantly, there’s evidence that, in conjunction with other seaweed phytochemicals, SSPs act as prebiotics to promote a beneficial microbial community in our gut.  Known as the gut microbiome, these microbes outnumber our own body’s cells by about 10 to 1.  Given these numbers it should come as no surprise that they strongly affect our health. Everyone’s gut microbiome is unique and a function of their diet.  Diets that include a variety of foods (especially unprocessed, whole foods and fermented foods) and that are also high in fiber promote a greater diversity of gut microbes and a healthier gut microbiome. Read our blog post “Seaweed and the Brain” to learn about how seaweed can promote a healthy gut microbiome that improves mental function.  The health benefits of SSPs are also described in some of our other Medicinal Botanical FAQs.  

 #1 Cherry et al., “Prebiotics from Seaweeds: An Ocean of Opportunity?” Marine Drugs (2019) 17, 327; doi:10.3390/md17060327

Plato said "The sea cures all ailments of man".  In Greek mythology Thalassa was the primeval spirit of the sea, and since ancient times Thalassotherapy has been practiced for healing through restorative seawater baths.  Seaweed, with its concentrated ocean minerals, is often included in these baths.  Victorian English flocked to the seaweed baths to immerse themselves in hot water filled with Bladderwrack (Fucus sp.) or other mucilaginous and high iodine seaweeds to ease their aches and pains. Immersion in warm water allows the ocean minerals to pass through the skin. Thalassotherapy spas still exist, many of them quite luxurious. France is renowned for having some of the best Thalassotherapy spas in the world, but unfortunately the concept hasn't quite caught on in the US.  But no can enjoy a luxurious seaweed Thallasotherapy spa experience right at home using any of our bulk kelp products! Simply place some dried seaweed in something like a cheesecloth bag with fine enough mesh to keep the seaweed from clogging the drain and add it to your hot bath.

Environmental Concerns

We test our sea vegetables annually following each harvest season and throughout the year for microbial contamination, heavy metals, pesticides, petroleum residues, and radiation.  We also periodically test for nutrient composition. Annual test results are posted on our Product Testing page

Nutritional information is found on our Nutrition Page.

Humans have released radiation into the environment, whether intentionally or accidentally, ever since the US first tested atomic bombs in 1945. Because eating seaweed offers some protection from radiation, it’s important to ensure the seaweed itself is free of harmful radioactive isotopes. We began testing products for radioactivity in 2011 in response to the Fukushima, Japan nuclear catastrophe, and we’ve continued testing every year since.  On occasion, we've had customers contact us in alarm after testing their seaweed using a Geiger counter and finding "radiation". Please be assured that this finding was due to a harmless, naturally occurring isotope of potassium that's also found in bananas and other foods.  Our testing is done by 3rd party labs using sensitive methods that definitely don't involve a Geiger counter!  Please see our Product Testing page for more information.

Sea vegetables can often contain trace levels of the heavy metals arsenic, cadmium, and lead. These metals are widely distributed in the world’s oceans from both natural and human sources, and seaweed absorbs them just as it absorbs other minerals and elements. We annually test for these metals, as well as for mercury, and we report the results on our Product Testing page.

Heavy metals are present in many foods, not just sea vegetables.  They are of concern because exposure can lead to illness, impairment, and in high doses, death.  The risk doesn’t come from any one single food, but rather from eating many different foods containing heavy metals at low levels.  The FDA monitors and tests foods for heavy metals and sets standards. Go to this link “Metals and Your Food” to learn more about how the FDA regulates metals in food.

The significance of heavy metals in food varies from food to food.  We ourselves are not concerned about the trace levels found in our sea vegetables, for several reasons.  For one thing, sea vegetables are generally consumed in small portions, usually less than 7 grams per day.  For another, we have reason to believe that when heavy metals are present in seaweed, they have low bioavailability because they are bound within an indigestible matrix of dietary fiber.  Indeed, the ability of seaweed carbohydrates to trap and bind toxins has led some to propose the use of sea vegetables for cleansing and detoxifying the human body of heavy metals!  We cover this topic in more detail in the FAQ about heavy metal detoxing.  Finally, we believe that the nutritional and health promoting properties of sea vegetables far outweigh the presence of heavy metals.

Ultimately, of course, it’s up to each person to decide if they want to avoid all of the many foods and substances that contain heavy metals, including sea vegetables, or if they want to balance the risk against the benefit for each particular food.  The topic of heavy metals in sea vegetables and other foods is complicated, but if you want to take a deeper dive please continue reading.  Below, we discuss each of the four most common heavy metals found in sea vegetables in more detail.


Arsenic is the 22nd most abundant element in seawater and seaweed seems to have a particular affinity for it, accumulating arsenic at levels 1,000 to 50,000 times higher than in seawater. The reason this occurs isn’t clear, but what is known is that most seaweed species transform inorganic arsenic into organic arsenosugars, possibly to detoxify it. Arsenosugars are rapidly excreted by humans and considered harmless.  Of greater concern is inorganic arsenic (iAs), which is usually found at trace levels along with arsenosugars.  The US FDA has not established permissible iAs levels for any food other than apple juice and rice cereals for infants.  These two foods are regulated because they’re known to contain iAs and because infants and young children are especially vulnerable. Children three years and younger are most at risk because they eat 2-3 times more food per body weight compared to adults and they often have a limited diet, eating the same few foods day after day.  The FDA action level for iAs in apple juice is 0.01ppm and for rice cereal it’s 0.1ppm.  It’s important to understand that toxicity depends not just on the level in the food but also on serving size, frequency of consumption, and body size.  At 0.01ppm a 12-ounce glass of apple juice contains about 3.5µg (microgram) of iAs. By comparison, a 5g serving of dulse with 0.13ppm iAs contains a total of 0.65µg iAs.  In France the maximum allowable iAS level in seaweed is 3ppm; at this level a 5g serving contains 15µg iAs.  Hijiki seaweed, which has been eaten for centuries in Japan, contains 67-96 ppm iAs, one of the highest levels measured in edible seaweeds. This prompted European and North American government food safety agencies to advise against consuming hijiki.  Maine Coast Sea Vegetables has never offered hijiki for sale and it isn’t found anywhere in the North Atlantic.


Cadmium is readily absorbed by macroalgae, though it’s not believed to offer any nutritional or other value to the plant. Like other elements, cadmium is naturally present in seawater at very low concentrations, but mining and industrial products such as batteries and paint pigments contribute anthropogenic cadmium into the world’s oceans. Cadmium accumulates in the kidney and bones of humans with continuous long-term exposure, leading to toxicity and dysfunction. Cigarette smoke contains cadmium and smokers typically have twice as much cadmium in their bodies as non-smokers. Most cadmium exposure for non-smokers is through food, but the total amount of cadmium found in food is not absorbed into the body, only the bioavailable fraction. Cadmium bioavailability in seaweed may be low, because studies with other foods have found that copper, iron, and zinc inhibit cadmium retention (1, 2) and seaweed has relatively high levels of these micronutrients. The FDA has not yet established a Maximum Daily Intake (MDI) for cadmium in food, but other countries provide some guidance. The European Union recommends an upper limit in seaweed of 3ppm cadmium, but in France the limit is set at just 0.5ppm. The European Food Safety Authority advises a tolerable weekly intake (TWI) of 2.5 μg/kg body weight from all dietary sources.  An adult weighing 140 pounds would have to consume 75g per week of Alaria containing 2.1ppm cadmium before exceeding this level; or more than ten 7g servings.  These various thresholds differ because even though they’re based on the same science, they have different safety margins built in to them.


Lead has a wide range of known ill effects, but the brain is the organ most sensitive to lead poisoning.  Because of its long history as a paint and gasoline additive lead is widespread in the environment, and it is perhaps the most challenging heavy metal to regulate.  Scientists unanimously agree there is no safe level of lead exposure, particularly for children, while acknowledging it’s often found in food and drink.  The EPA action level for lead in drinking water is 15 parts per billion (ppb). At 10ppb someone drinking 8 glasses (about 2 liters) of water would ingest 20 µg of lead. The FDA established a much lower total dietary limit for adults of 12.5 µg/day to protect against fetal lead exposure in women who are unaware they are pregnant, and to reduce infant exposure during nursing. The FDA has also established lead thresholds for juice and candy, foods likely to be consumed by children. The acceptable juice level is 50 parts per billion and for candy it’s 0.1 ppm.  The FDA has not established a safe level for seaweed, but in France the acceptable level of lead in seaweed is <5ppm. The highest lead test result we’ve recently recorded in our sea vegetables was 0.69ppm (in bladderwrack, 2018).  One would have to eat about 18 g of bladderwrack to exceed the FDA total daily dietary lead limit of 12.5µg. The French seaweed standard is higher than the FDA candy standard in part because seaweed is generally eaten in small amounts, whereas children sometimes consume lots of candy.


Mercury is the heavy metal most often associated with seafood.  The FDA has found that swordfish can contain as much as 3.22ppm mercury, with an average of about 1ppm.  This occurs as organic methylmercury, which unlike organic arsenosugars is the more toxic form. Mercury accumulates in fish, other seafood, and humans as a consequence of bioaccumulation.  However, studies from around the world have found that sea vegetables contain only trace levels of mercury, if any.  This is borne out by our own lab testing, which usually finds that mercury can’t be detected, and when it is found it’s at just trace levels.  Mercury exposure does not seem to be an issue when eating sea vegetables, but of course we will continue to monitor.

The Bioavailability Question

In nutrition, bioavailability is a measure of how much of a particular nutrient, element, or other substance is digested and absorbed into the bloodstream. A portion of the heavy metals found in seaweed are not bioavailable because they are chemically bound to complex carbohydrates, such as fucoidans and alginates.  These polysaccharides are dietary fibers that passage through the intestine largely undigested, meaning anything they absorb and chemically bind is also excreted.  Although we know that a portion of the heavy metals found in seaweed aren’t bioavailable, we don’t yet have a good sense of how that percentage varies between metals, seaweed species, and variations in human digestion.  This is a complex research topic, and we will update this information as advances are made.


The above information is a summary of the best available guidance and evidence from regulatory agencies and the scientific literature as of 2020.  It is not intended and should not be used for diagnosis,treatment, or any other medical purpose, and we neither recommend nor disapprove of eating seaweed for heavy metal detoxification.  We advise anyone concerned about heavy metals and their health status to seek guidance from a trusted medical practitioner.  We believe sea vegetables are more than the sum of their parts, and that when included in a balanced diet they confer extraordinary nutrition and health.


#1 McLaughlin et al "Metals and micronutrients - food safety issues." Field Crops Research (1998)60 pp. 143-163

#2 Yanfang et al,  "Arsenic and cadmium in the marine macroalgae (Porphyra yezoensis and Laminaria japonica) — forms and concentrations." Chemical Speciation & Bioavailability, (2012) 24:3, 197-203, DOI:10.3184/095422912X13404690516133

Seaweed is very efficient at absorbing and concentrating minerals and various elements, including metals, from seawater.   Metals such as copper, iron, and zinc are considered essential minerals because they’re needed for health, but others such as arsenic, cadmium, lead, and mercury, known as heavy metals because of their high atomic mass, are toxic at high levels.  However, even essential minerals can be toxic if ingested at too high levels or out of balance with other minerals.

Metals occur naturally in the ocean due to weathering of the earth’s crust.  Unfortunately, over the past century anthropogenic (manmade) sources have elevated the levels of some heavy metals in the oceans.  These are widely distributed in all the world's oceans. This is why ‘where and how’ sea vegetables are harvested matters.  Some parts of the ocean contain more heavy metals and other contaminants than others, maybe because they receive industrial effluent or are located near a large metropolis. 

The northern Gulf of Maine, where most of our sea vegetables are sourced, has very little industrial activity and no major metropolis. Northern Maine is covered by a vast 3.5-million-acre forest known as the North Maine Woods, and with a population density of less than 25 people per square mile it’s the least populated region east of the Mississippi.  Organic certification further ensures our sea vegetables are harvested away from marinas, aquaculture pens, and other sources of contamination, and that they’re handled and processed without the use of chemicals.  As a final precaution, every year 3rd party labs analyze samples of our seaweed for heavy metals and other contaminants.  We post the results on our website for customers to see; we’re one of the few seaweed companies anywhere with this practice. 

Carrageenan is a generic name for a group of seaweed polysaccharides widely used in food and cosmetics for their gel-forming qualities as thickeners, emulsifiers, and stabilizers. Irish moss is especially rich in carageenan and it has a long history of being used as both food and medicine.  However, carageenan in processed food products has received some bad press recently about potentially negative health effects. We respond to many of those claims in this blog post.

Bromine is the seventh most abundant element in seawater and it's readily absorbed by seaweed. Some naturopaths and other healers have expressed concern that bromine, because it’s so closely related to iodine, competes with thyroid iodine receptors and potentially causes symptoms of iodine insufficiency and hypothyroidism.  Is bromide in sea vegetables something to be concerned about? Could the bromide found in seaweed adversely affect your thyroid? The short answer is we don't believe so. For a more comprehensive answer, read our bromine blog post on the topic

We've been hearing a lot about the sea of plastics polluting our oceans and how they eventually break down into barely visible or even microscopic microplastics. Customers sometimes ask if these microplastics pose a risk to sea vegetables or to those who eat them. So far, the evidence shows this isn't a concern. Read this blog post for a detailed answer.

Because they come from the sea, sea vegetables sometimes hold tiny dried shellfish such as snails, periwinkles, and mussels within their fronds. We do our best to remove these as we sort and package, but they occasionally get through anyways.

Seaweed itself is not considered to be an allergenic food. Case reports of allergic reactions after eating sea vegetables are exceedingly rare; we’re aware of just one report worldwide as of 2020! 

Our facility does not process any tree nuts, peanuts, dairy, eggs, wheat, crustacean shellfish, or other seafood, so there’s no danger of cross contamination from these common allergens during processing or packaging. 

Although in 40+ years we've never had a customer report an allergic reaction after eating sea vegetables, we recommend that each person evaluate the risk for themselves.

You may have noticed a label on our sea vegetables warning about lead and/or cadmium and referring to California’s Proposition 65. Why would a Certified Organic natural food with a reputation for being healthy have this label?

Seaweed is renowned for its capacity to absorb and accumulate minerals, metals, and other elements from seawater.  This includes essential nutrients such as iodine, calcium, manganese, and zinc, but also undesirable elements such as lead, cadmium and arsenic.  The California law known as Proposition 65 requires businesses selling products in California to give consumers a “clear and reasonable warning” when their products contain listed chemicals known to cause cancer, birth defects or reproductive harm.  Because the levels of cadmium and lead found in our sea vegetables sometimes exceed Prop 65 thresholds, many of the products we market in California must bear a Prop 65 exposure warning. However, none of our products exceed the Prop 65 threshold for inorganic arsenic.

The Proposition 65 website states “A Proposition 65 warning does not necessarily mean a product is in violation of any product-safety standards or requirements”.  It’s up to you, the customer, to decide whether to use the product or not, and our website includes additional information to help you make an informed choice.  The Harvest page and several of our FAQs address how and where we source our certified organic sea vegetables. The Product Testing page displays test results for heavy metals and other concerns for most of our products, which can be used to calculate dietary intake.  Our FAQ on “Heavy Metals” presents science-based information on the presence of heavy metals in sea vegetables and other foods. If you wish to learn more about Proposition 65 you can visit the Proposition 65 website or visit our  Prop 65 page.

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