8 Nutritionally Important Minerals Found in Kelp and Other Seaweed Superfoods - Maine Coast Sea Vegetables

Disclaimer: Although the information presented in this article is accurate and factual, it should not be used as basis for diagnosis or treatment. The signs and symptoms described here are not unique to mineral deficiency and can indicate other serious health concerns. Consult a qualified health care practitioner if you experience any of the symptoms described in this article, or any symptom for that matter!  Likewise, seaweed should not be used to treat any condition, including mineral deficiency. Although we at Maine Coast Sea Vegetables wholeheartedly believe in the nutritional and health-giving properties of sea vegetables, we are not medical experts. Statements made here about seaweed consumption and health have not been verified by the FDA. Sea vegetables are wild marine plants and their nutritional composition naturally fluctuates with season, tides, weather, and other variables. The following information regarding the mineral content of various seaweeds is based on composite averages, and levels of any particular mineral may vary from what’s presented.

Sea vegetables offer multiple impressive health and nutritional benefits, but they truly excel when it comes to minerals. Gram for gram, seaweed packs a greater variety and abundance of minerals than almost any other food. The mineral content of sea vegetables is often 10 to 100 times higher than that of land vegetables. Since we must get all our essential minerals from food, this is reason enough to eat sea vegetables several times per week, if not every day.

Mineral deficiency is not uncommon, especially among athletes, who have higher mineral requirements than non-athletes; children; pregnant and lactating women; and among older people, who may not absorb nutrients as effectively as when they were younger. Underlying health conditions can also cause mineral deficiency. It’s often thought that eating a healthy diet or taking mineral supplements will prevent deficiency, but this isn’t always true. Vegetables grown in mineral deficient soils will lack certain minerals, and supplements may consist of inorganic mineral salts that are poorly absorbed by some. 

Signs of mineral deficiency are varied and sometimes subtle. Unexplained fatigue can be caused by deficiency of magnesium, iodine, calcium, or iron. White spots on finger or toe nails can indicate a zinc deficiency, and slow healing of skin wounds or thinning hair are other signs. Iron deficiency, said to be one of the most common mineral deficiencies in the world, causes anemia with symptoms such as fatigue, pale skin, and decreased libido. Magnesium deficiency is also common, with symptoms that can include constipation, tremor, and nystagamus (twitchy eyes). Magnesium deficiency is often accompanied by low potassium. Signs of inadequate potassium intake include irregular heartbeat, muscle cramps, and high blood pressure. 

What are minerals?

Geologically speaking, minerals are inorganic, naturally occurring solids with a definite chemical composition and unique atomic structure. Minerals may consist of one or more elements, such as sodium chloride or calcium carbonate.  Nutritional minerals are a subset of minerals that naturally occur in soil and food and are required by our bodies for appropriate development and function. Since minerals are inorganic substances, they can’t be made by either plants or animals. Plants get them from soil or water and animals get them from eating plants or other animals.

Most medical authorities list about 18 essential minerals for human health, while the FDA provides Reference Daily Values for 14 minerals. Essential minerals can be either macro-minerals (major), or micro-minerals (minor or trace), depending on how much of each mineral is required and/or how much is stored in the body.  Minor minerals are just as important and essential as major minerals; they’re just required at smaller levels. In addition, another 14 or so ultra-trace minerals might also be essential to human health, including elements like arsenic and cadmium that we don’t usually associate with health. All told, the human body is known to contain at least 56 elemental minerals, but some of these likely aren’t needed for human health, and some, like uranium, are dangerous. These non-essential minerals wind up in our bodies not by design, but as a consequence of living.

Why is seaweed so mineral rich?

The ocean contains much more than sodium salt; about 84 elements have been detected in ordinary seawater. Seaweed spends its entire life cycle immersed in this mineral rich bath absorbing all the nutrients it needs to live, grow, and reproduce.  After just a few months of growth, seaweed contains much higher mineral levels than found in the ocean. Sugar kelp, for example, contains about 71,500ppm (parts per million) potassium, compared to just 380ppm in seawater…this is a bioaccumulation factor of 188. Dulse contains about 370ppm iron (0.37mg/g), compared to a background level of 0.02ppm in seawater, for a bioaccumulation factor of 18,500. The most extraordinary bioaccumulation factor is seen with iodine. All seaweed species magnify this trace ocean element, but sugar kelp is especially proficient. Iodine levels in sugar kelp are often about 13,600ppm, compared to 0.05ppm in seawater, or 272,000 times higher! No other land or sea plant comes close to this level.

It’s not well understood why seaweed absorbs and bioaccumulates ocean minerals to such magnitude, but it certainly makes them nutritious for humans. Regularly including sea vegetables in your diet can go a long way towards preventing mineral deficiencies.  

Dulse mold minerals
Mineral deposits found on dulse (It's not mold!)
Kelp Mold Minerals

Mineral deposits found on kelp (It's not mold!)

1 - Calcium

Calcium is the most abundant mineral in the body and the main structural component of bone and teeth. There is also a small ‘pool’ of ionized calcium in the circulatory system, various tissues, and extracellular fluid that mediates blood vessel contraction and dilation, muscle and blood function, nerve transmission, and hormonal secretion. The bones act as a reservoir to replenish and maintain this calcium pool at the proper level.

Healthy adults need between 1,000 to 1,300 mg of calcium per day, depending on age. Younger and older people require more calcium than people between 19 and 50 years. Pregnant or lactating women also need the higher amount. Although calcium is found in many foods, especially dairy, a surprising number of people are estimated to not take in enough. A recent National Health and Nutrition Examination Survey (NHANES) found that 49% of children aged 4–18 years and 39% of all individuals aged 4 and older consume less calcium than they should. Calcium absorption varies between people and foods, depending on things such as vitamin D intake, which helps people absorb calcium, and levels of certain plant compounds, such as oxalic or phytic acid, which decrease absorption.

Seaweed contains more calcium than just about any other food, including whole milk. The red sea vegetables (dulse, laver, Irish moss) generally contain less than the browns (sugar kelp, Alaria, rockweed, and bladderwrack). Sea lettuce contains the most calcium, averaging about 23mg per gram. A 5-gram serving of dried sea lettuce (about 2 TBS of flakes) contains 9% of the daily requirement for a teenager or pregnant or lactating woman.

2 - Potassium

Potassium is the most abundant intracellular (within cells) cation (positive charge) found in people, and the third most abundant mineral overall.  It plays essential roles to maintain intracellular fluid volume and electrochemical gradients.  Potassium also helps muscles contract and supports normal blood pressure. It is sometimes referred to as an electrolyte because of its small positive electrical charge, which helps activates various cell and nerve functions. 

As an electrolyte, potassium counterbalances sodium, the body’s other important electrolyte. Where sodium increases blood pressure, potassium decreases it, and the two electrolytes need to be in balance for optimum cardiovascular health. Our ancestors had a sodium to potassium ratio of about 1:16, meaning they took in 16 times more potassium than sodium due to their plant rich diet and lack of table salt. Today, we modern humans get more sodium than potassium, which may be a major contributor to high blood pressure and other cardiovascular disorders. One way to help correct that imbalance is to substitute Sea Seasonings for salt in dishes and at the table. Much of the salty flavor imparted by Sea Seasonings actually comes from potassium, not sodium.

Humans need more daily potassium than any other mineral; the Recommended Dietary Allowance (RDA), which is the average daily intake level sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people, is 4,700mg.  Males require more than females, and since potassium is lost through sweat, athletes may actually require more than 4,700mg during periods of strenuous activity. Potassium is found in a large variety of foods, with fruits and vegetables being especially good sources. Generally, it appears to be well absorbed from most foods.

Despite this, dietary surveys consistently show that people consume less potassium than recommended. People who eat mostly meat can be deficient in potassium because fruits, nuts and vegetables are main sources (along with seaweed, of course!). Although including small amounts of sea vegetables in your diet may not completely make up for the deficit, they can certainly help. On average, sugar kelp contains more potassium than any other sea vegetable we sell, about 71mg per gram. A 5-gram serving of whole leaf sugar kelp meets 8% of our potassium RDA; not bad for such a small amount. 

3 - Magnesium

Magnesium is a cofactor in over 300 enzyme systems that regulate a diversity of biochemical reactions essential for bodily performance and health. Among other processes, magnesium plays an essential role in building proteins and strong bones, muscle and nerve function, regulating blood pressure, and regulating blood glucose levels. Magnesium also acts as an electrical conductor that contracts muscles and makes the heart beat steadily.

About half of the body’s magnesium reserves are stored in bones, with the rest distributed throughout various body tissues. The current RDA for adult men is 420mg and for women 320mg. The demands of pregnancy up the RDA to 360mg. Magnesium is found in plant foods like legumes, leafy greens, nuts & seeds, whole grains, and fortified cereals. It is also in fish, poultry, and beef. Like seen with other minerals, sea vegetables contain more magnesium per gram than just about any other food, with Irish moss and sea lettuce being especially good sources. A 5-gram serving of sea lettuce flakes meets over 25% of the RDA for men. The high magnesium content of Irish moss may be one of the reasons why the Irish found this red seaweed so useful as medicine. Magnesium can help relieve constipation and other intestinal disorders.

4 - Iron

Iron is an essential component of hemoglobin, an erythrocyte (red blood cell) protein that transfers oxygen from the lungs to the tissues. It’s also a component of myoglobin, another oxygen carrying protein that helps support muscle metabolism. Iron is important in children for healthy brain development and growth, and in everyone for the normal production and function of various cells and hormones.

Iron deficiency is said to be the most common nutritional deficiency in the world.  Insufficient iron intake results in a lack of enough red blood cells to transport oxygen, a condition known as anemia. Fatigue is a common symptom. This is often accompanied by other deficits such as gastrointestinal disorders, weakness, and difficulty concentrating. Infants and children, menstruating or pregnant women, frequent blood donors, and patients with colon cancer are among those most likely to suffer from inadequate iron.

Iron is found in animal products as heme iron and in plant sources as nonheme iron. The name “heme iron” comes from the heme protein that’s attached to a lone iron atom. Heme iron is easier for our bodies to absorb, but for many people the majority of the iron we consume is nonheme iron from plant sources. Absorption of nonheme iron is only about 2% to 20%, as compared to 15% to 30% absorption of heme iron from animal sources. This means vegetarians, vegans, and those who eat hardly any meat must consume about twice as much iron as people who are mainly carnivores.

The adult RDA for iron is just 18mg, but because it is so poorly absorbed and because so many other factors affect uptake and retention, iron deficiency is not at all uncommon. Beef liver and shellfish such as oysters are considered to be good sources, but sea vegetables far surpass them in iron content and sea lettuce is especially high. A 5-gram serving of sea lettuce contributes a whopping 30% RDI. By now, you may have detected the theme that sea lettuce is an especially good source of various minerals, even when compared to other sea vegetables.  However, a 5-gram serving of a sea vegetable such as dulse contributes 10% of the RDA. This means that including even small amounts of sea vegetables in your daily diet can help reduce the risk of iron deficiency.

5 - Manganese

Manganese is a cofactor in many enzymes and because of this it’s involved in various metabolic processes, bone formation, reproduction, and immune response. Manganese is found in the pancreas, where it’s involved in insulin production and thus helps stabilize blood sugar levels. Manganese also works in conjunction with vitamin K, which plays a key role in blood clotting, to reduce blood loss from injury. One of the body’s most important antioxidant enzymes that protects and defends your cells owes its existence to manganese.

The RDA for manganese is 2.3mg for adult males and 1.8mg for adult females.  Manganese is found in a wide variety of foods, especially cereals and vegetables, and even though only about 5% of dietary manganese is absorbed, deficiency is thought to be rare. Including seaweed in your diet is a good way to ensure this remains the case, as most popular sea vegetables contain manganese.  Bladderwrack (Fucus), for instance, averages about 0.08mg per gram and a 5-gram serving contains 0.42mg, or 18% of the RDA. Interestingly, Fucus has also been shown to contain vitamin K; yet another example of how the whole is greater than the sum of the parts.

6 - Iodine

Iodine doesn’t always jump to mind when people think about dietary minerals, but iodine is by definition a mineral, and one that’s highly important for thyroid function.  Because the thyroid makes hormones that regulate many of your body’s functions, iodine deficiency can cause a cascade of problems. Deficiency, though relatively uncommon in affluent societies, remains an important global health problem.

Seaweed iodine content far surpasses that of any other food source. Much has been written about iodine and seaweed, including previously in our blog post “Should I eat seaweed to get iodine?”, so we won’t rehash that information here.  Suffice it to say that even a serving size as small as 1-gram of most sea vegetables can meet 100% or more of the RDA. Beyond the iodine, of course, you’re also getting other minerals, which isn’t the case with most iodine supplements.

7 - Selenium

Selenium is a constituent of more than two dozen selenoproteins that play critical roles in reproduction, DNA synthesis, protection from oxidative damage and infection, and thyroid hormone metabolism. The body stores selenium in muscle tissue, but the highest concentration is found in the thyroid gland, due to various selenoproteins that assist with thyroid function. Selenium has been studied for its possible role in cancer prevention, with mixed conclusions. One meta-analysis found a 31% reduced cancer risk in groups with the highest selenium, but another study detected no such relationship and instead found a higher incidence of Type 2 diabetes with long term use (7+ years) of selenium supplements.

This finding shows the dangers of too much of a good thing, and why it may be better to get nutrients from whole foods rather than supplements whenever possible. The RDA for selenium is 55mcg (microgram) for most adults, though pregnant or lactating women are advised to get a bit more (60 and 70 micrograms, respectively). Selenium deficiency is thought to be quite rare in the US, as it’s found in a variety of foods and most North American agricultural soils are rich in selenium.

Seaweed contains small levels of selenium; between 0.05 to 0.14 micrograms per gram on a dry weight basis. A 5-gram serving of most sea vegetables contributes about 1% to our daily requirement. We include it here as a seaweed mineral because of its importance for thyroid function. Sea vegetables are known for their high iodine content, which is absolutely essential for thyroid function. The presence of selenium along with the iodine may help strengthen the role sea vegetables play in thyroid health.

8 - Zinc

Zinc is required for the catalytic activity of about 100 enzymes the body produces and uses for a range of activities, including immune function, protein synthesis, wound healing, and cell division. Because of its important role in immune function, zinc is often included in cold lozenges and over-the-counter cold medications.  Zinc supports growth and development during pregnancy, childhood, and adolescence, and it’s also required for proper sense of taste and smell. However, excess zinc consumption could lead to loss of smell, which has been linked to the use of nasal sprays or gels containing zinc.

The body has no specialized zinc storage system, so a small amount is required every day in the diet to make up for what the body uses. People require an increasing level of zinc as they grow.  The RDA for infants is 2mg; for healthy adult males 11mg; and for women 8mg. Breast milk usually contains adequate zinc (2mg) for infants up to 7 months, but children who are fed exclusively or mostly breast milk beyond this age may be at risk of deficiency because older children require 3mg.

Zinc deficiency is uncommon for most adults in North America, but certain groups are at risk. Zinc is more bioavailable in meat than in vegetables, and phytates found in whole grains and legumes bind zinc and further limit bioavailability. For this reason, vegetarians may require as much as 50% more zinc than non-vegetarians. Heavy users of alcohol can also be zinc deficient because ethanol inhibits zinc absorption and increases zinc excretion through the urine. Elderly people have also been found to be at higher risk, despite having a lower RDA of 6.8mg for elderly women and 9.4mg for elderly men. In addition, some people like to take in extra zinc when they feel a cold or flu coming on because it may decrease symptoms and duration.

Oysters are said to contain more zinc per serving than any other food, but most North Americans get their zinc from red meat and poultry. Although seaweed isn’t especially rich in zinc, it can certainly be a good supplemental source. The sea vegetable species sold by MCSV contain between 0.02mg to 0.06mg of zinc per gram, with Irish moss containing the most. Irish doctors once prescribed Irish moss for respiratory ailments because of the therapeutic properties of carrageenan, but its zinc content may have helped as well!

In Conclusion

Sea vegetables contain minerals essential for human health at concentrations that often far exceed those found in most other foods. Including even small servings of sea vegetables in your diet on a regular basis helps you meet the RDA of these important nutrients, while adding savory, umami flavor to a variety of foods and recipes. We have always believed that in the case of sea vegetables, the whole is greater than the sum of the parts, due to synergies between the various minerals, other nutrients, and bioactive compounds they contain. 

We also believe that, whenever feasible, it’s better to get essential nutrients from whole foods, such as sea vegetables, rather than from supplements. This belief was nicely summarized in a 2001 research paper titled Plants as a natural source of concentrated mineral nutritional supplements (M.P. Elless et al, Food Chemistry 2001 V. 61 iss. 2). The authors state “While further studies involving human nutritional trials and in vitro cell culture are required to confirm the dietary benefits derived from trace elements supplied by plant tissue, the results presented here suggest that they may be more bioavailable than their current inorganic counterparts with the added benefits of other phytochemicals present in the plant tissue.”

Only you can determine what’s best for your health, but naturally, we hope you include sea vegetables as part of a balanced diet. If you do, we believe you can’t go wrong with sustainably wild harvested, certified organic North Atlantic seaweed from Maine Coast Sea Vegetables!

Nutrition & health

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