What are the benefits of seaweed?

By | December 7, 2018
Seaweed grows in or near salty waters. There are several types, and they generally contain many healthful 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 to incorporate seaweed into different recipes. It is possible to eat too much seaweed, however, and some people should avoid it.

The benefits of seaweed

The following are the best health benefits of seaweed:

1. It is highly nutritious

Seaweed in a bowl over mat and next to chopsticks
Seaweed is a rich source of iron and iodine.

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

In general, however, eating this marine algae is 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 points out that the various types of seaweed contain helpful nutrients, including:

  • vitamin C
  • vitamin B
  • vitamin A
  • vitamin E
  • iron
  • iodine

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 state of the thyroid.

Iodine deficiency is one cause of hypothyroidism (underactive thyroid). It may result in the development of a goiter, a visible enlargement of the thyroid gland.

People may be able to prevent or improve hypothyroidism by ensuring that their diet contains sufficient iodine.

Hyperthyroidism occurs when the thyroid gland is overactive and produces excessive amounts of hormones. An excessive iodine intake may worsen symptoms of hyperthyroidism.

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Seaweed is very rich in iodine. According to a study in the Journal of Food and Drug Analysis, kombu is the richest source of iodine, followed by wakame and nori. Kelp powder is also a significant source.

The type of seaweed and location in which it was grown can alter the iodine contents.

3. It may help with diabetes

Nori seaweed sheets on wooden surface
Seaweed may help in the management of diabetes.

Fiber-rich foods may help with diabetes. This is because high amounts of fiber help regulate blood glucose levels and insulin levels. Adding seaweed to the diet may help increase 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 the use of 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 percent 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 the body with plenty of gut-healthy prebiotic fiber, which in turn can help with issues such as constipation or diarrhea.

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5. It may help with weight loss

The fiber in seaweed may benefit people who are trying to lose weight.

Fiber helps a person feel full, but it contains very few or no calories itself.

According to the study in Marine Drugs, a high amount of dietary fiber delays stomach emptying. As a result, the stomach may not send signals of hunger to the brain for a longer time, which may help prevent overeating.

6. May protect the heart

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

The body then uses cholesterol to replace these elements, which may result in a decrease of total cholesterol by up to 18 percent.

Many types of algae also have high levels of antioxidants, which may also support heart health over time.

Side effects and risks

There are a few things to be aware of when adding seaweed to the diet, including:

Excess iodine

Excess iodine can cause tightness around the neck.
Excess iodine consumption can cause tightness around the neck.

A primary concern is the risk of consuming too much iodine.

Most seaweed contains high levels, 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 thyroid dysfunction.

A resulting condition could cause symptoms such as weight gain or swelling and tightness around the neck.

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

Heavy metals

Another common concern involves heavy metals. Seaweed absorbs minerals and nutrients from the sea. If the surrounding water contains these metals, the seaweed will absorb them as well.

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

Also, a study in Scientific Reports investigated 10 potentially dangerous metals in seaweed and 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 every day. Though the general risk is low, it may be a good idea to ensure that seaweed is organic and derived from a high-quality source.

How to eat seaweed

Adding seaweed to the diet can be very simple. The big sheets of dried nori used in sushi also make a great substitution for tortillas or bread, and they can make delicious wraps.

Flavoring bean soups with kombu can reduce the risk of gas thanks to kombu’s healthful enzymes.

Also, many companies produce roasted seaweed with a little oil and salt, which can be a perfect way to satisfy a salty craving.

Toasted seaweed or seaweed flakes can be a great topping for grains such as rice or quinoa and may help reduce the amount of salt or soy sauce a person needs.

For those who are not fans of seaweed’s flavor, a person can slip it into a hearty vegetable soup.


Seaweed is a welcome addition to most diets. The flavor can boost a variety of recipes, the nutrient content can support a healthful diet, and people can often use seaweed blends in place of salt.

For some people, however, it is a good idea to avoid seaweed. Anyone taking thyroid medications should talk to their doctor before adding seaweed to the diet.

Nutrition / Diet News From Medical News Today