Seaweed grows in or near salty waters. There are several types, and they generally contain many minerals that are easy for the body to break down. Adding seaweed to the diet may help with thyroid function, digestive health, and weight loss.

Types of seaweed include:

  • nori
  • kelp
  • wakame
  • kombu
  • dulse
  • blue-green algae, such as spirulina and chlorella

This variety can make it easy for people to incorporate seaweed into different recipes. However, it is possible to eat too much seaweed, and some individuals should avoid it.

Keep reading to learn more about the health benefits of seaweed, potential side effects and risks, and some frequently asked questions.

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The following are the best health benefits of seaweed:

1. It is highly nutritious

Each type of seaweed may contain slightly different nutrients and minerals.

Eating marine alga may be a simple way to boost a person’s intake of vitamins and minerals without adding many calories.

As a study in Marine Drugs notes, seaweed is generally a good supply of:

A study in the Journal of Applied Phycology notes that various types of seaweed contain helpful nutrients, including:

Seaweed also contains antioxidants, which may protect the body from oxidative stress and reduce inflammation at the cellular level.

2. It may help with thyroid function

The thyroid gland controls and releases hormones for energy production, growth, and cellular repair. The thyroid needs iodine to function correctly, but the amount that a person requires depends on the health of the thyroid.

The type of seaweed and the location in which it was grown can alter the iodine contents, which can make it an unreliable source of iodine.

According to research from 2021, the consumption of several whole food seaweed or food products containing seaweed can cause excess iodine intake. Some seaweed dietary supplements may not provide adequate iodine, while others offer more than the Daily Value.

Iodine deficiency is one cause of hypothyroidism, an underactive thyroid that can cause symptoms such as fatigue, cold intolerance, and sore muscles and joints. It can also cause a goiter, which is a visible enlargement of the thyroid gland.

However, excessive iodine intake may worsen a person’s symptoms of hyperthyroidism. This occurs when an overactive thyroid gland produces excessive amounts of hormones.

3. It may help with diabetes

Fiber-rich foods may help with diabetes. This is because high amounts of fiber help regulate blood sugar levels and insulin levels. Adding seaweed to the diet may help boost a person’s fiber intake without a large increase in calories.

A 2018 study in rats found that compounds in one type of seaweed may directly reduce markers of type 2 diabetes, such as high blood sugar.

Compounds in seaweed may also reduce diabetes risk factors, such as inflammation, high fat levels, and insulin sensitivity. Further research in humans may help provide stronger evidence for using these compounds.

4. It may support gut health

Bacteria in the intestines play an important role in breaking down food and supporting digestion and overall health.

Algae may be an ideal food for the gut. Authors of a study in the Journal of Applied Phycology report that algae tend to contain high amounts of fiber, which may make up 23–64% of the algae’s dry weight.

This fiber can help feed the gut’s bacteria. Intestinal bacteria break fiber into compounds that improve gut health and the health of the immune system.

Adding algae to the diet may be a simple way to provide plenty of gut-healthy prebiotic fiber, which can help people experiencing issues such as constipation or diarrhea.

5. It may help with weight loss

The fiber in seaweed may benefit individuals who are trying to lose weight. This is because fiber is low in calories and helps a person feel full.

According to the study in Marine Drugs, a high amount of dietary fiber delays stomach emptying. As a result, the stomach may delay sending signals of hunger to the brain, which may help prevent overeating.

6. It may protect the heart

As the same study notes, high-fiber foods such as algae may also reduce cholesterol levels. These soluble fibers bind to bile acids or salts in the body.

The body then uses cholesterol to replace these elements, which may decrease a person’s total cholesterol by up to 18%.

Plus, the high antioxidant content of many types of algae may support heart health over time.

There are several factors a person should be aware of when adding seaweed to their diet, including:

Excess iodine

Most seaweed contains high levels of iodine, and a person may consume too much if they eat a lot of seaweed over an extended period.

While many people can handle high levels of iodine, some are more vulnerable to its effects, which can include hyperthyroidism. This condition may cause weight changes or swelling and tightness around the neck.

Anyone experiencing these symptoms should stop consuming iodine and consult their doctor for a full evaluation.

Heavy metals

Another common concern involves heavy metals since seaweed absorbs minerals and nutrients from the sea.

A study in Chemosphere found that in edible seaweed, levels of the toxic metals aluminum, cadmium, and lead are generally very low.

A study in Scientific Reports investigating 10 potentially dangerous metals in seaweed came to a similar conclusion, though the authors called for more research into other metals.

While levels may be low, toxic metals may build up over time in a person who eats seaweed daily. Though the general risk is low, it may be a good idea to ensure that seaweed is organic and comes from a high-quality source.

People can add seaweed to their diet in many ways. These include:

  • Substituting tortillas, bread, and wraps with dried nori sheets used in sushi.
  • Flavoring bean soups with kombu. This can reduce the risk of gas due to kombu’s healthful enzymes.
  • Roasting seaweed with a small amount of oil and salt to satisfy a salty craving.
  • Using toasted seaweed or seaweed flakes as a topping on grains, such as rice or quinoa. This may help reduce the amount of salt or soy sauce a person uses.
  • Adding seaweed to vegetable soup. This is a good option for people who do not enjoy the flavor of seaweed.

Some frequently asked questions about seaweed include:

Does seaweed make you poop?

Seaweed contains prebiotic fiber, which may cause people to poop and help to alleviate constipation. Research from 2020 suggests that the high-fiber content of seaweed causes it to act as a natural laxative. It can also enhance gut health and improve digestion.

It is also important to note that insoluble fiber is more associated with alleviating constipation. Algae contain both insoluble fiber but most are soluble.

Is seaweed good for the skin?

Using cosmetics containing seaweed may be beneficial for a person’s skin. The anti-inflammatory effects of seaweed plus its high antioxidant and bioactive compound content may help to improve skin health.

A 2019 review suggests that using seaweed in cosmetics may have a moisturizing and protective effect on the skin, which may help to reduce acne, even out skin tone, and slow the signs of aging.

Can you eat too much seaweed?

It is possible to eat too much seaweed, especially if it contains large amounts of iodine, which can affect thyroid health. A small 2020 study suggests that consuming seaweed may cause high iodine exposure, which can lead to a thyroid condition.

A 2019 review notes that seaweed may also contain heavy metals. Though the amounts are usually not toxic, consuming seaweed in large quantities can cause arsenic bioaccumulation.

Therefore, it is important for people to eat seaweed in moderation, especially since some products may not list accurate iodine and heavy metal content.

Seaweed is a welcome addition to most people’s diets. The flavor can boost various recipes, the nutrient content can support a healthy diet, and seaweed blends can replace salt.

However, some individuals may need to avoid seaweed. Anyone taking thyroid medications should consult their doctor before adding seaweed to the diet.