4 Benefits of Seaweed: Health, Nutrition, & Safety

Seaweed is currently gaining major attention due to the benefits they provide for human health. Recent studies have demonstrated that seaweed is rich in a variety of nutrients, especially minerals. …

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Written by: Daniel Powers, MS
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Seaweed is currently gaining major attention due to the benefits they provide for human health.

Recent studies have demonstrated that seaweed is rich in a variety of nutrients, especially minerals. Additionally, various seaweeds are known for specialty bioactive compounds, including carrageenan and fucoidans.

In this article, we will look at the health benefits of seaweed, its safety, and its history.

the benefits of seaweed

What is Seaweed?

Seaweed is a type of macroalgae. The word “seaweed” includes a variety of different types of algae, including Rhodophyta (red), Phaeophyceae (brown), and Chlorophyta (green) macroalgae.

Seaweed is a plant-like organism that attaches itself to rocks underwater. They belong to the algae family. These specialized forms of algae have been useful to humankind mainly as food, industrial products, medicinal uses, and even fertilizers.

Seaweed is rich in various vitamins, minerals, and fiber. Traditionally, seaweed was a major foodstuff. It is still commonly used as a food – including in sushi.

Types of Seaweed:

Seaweed can be classified within a number of different groups depending on its color. The three main groups are red, green, and brown seaweed.

Brown Seaweed (Phaeophyceae)

This type of seaweed is widely distributed in cold temperature zones and is absent from tropical waters. This category of seaweed includes the kelp family. The kelps are among the largest types of seaweed; certain species of kelp can grow over 100 feet in length. 

Common types of brown seaweed include:

Kelp (Laminariales spp.)

Bladderwrack (Fucus vesiculosus)

Red Seaweed (Rhodophyta)

Red seaweed comprises one of the largest phyla of algae, containing over 7,000 currently cataloged species. Red algae are typically found in saltwater environments. This family of algae has a long history of traditional use as a food source, as well as for medicine. Various species of red seaweed carpet the shoreline along the rocky coastline of the Atlantic.

Common types of red seaweed include:

Dulse (Palmaria palmata)

Irish sea moss (Chondrus crispus)

•Nori (Pyropia spp.)

Green Seaweed (Chlorophyta)

Green seaweed is the smallest group of algae. This type of algae grows in both saltwater and freshwater, although some can be found growing on the land. There are 30+ species of edible seaweed, which are naturally rich in a variety of different minerals. Edible types of green algae include sea lettuce, sea palm, and sea grapes.

Common types of green seaweed include:

•Sea Lettuce, also known as green Nori (Ulva spp.)

•Sea Grapes (Caulerpa lentillifera)

As you can see, there are many different types of seaweed, all of which provide different health benefits.

Health Benefits of Seaweed:

Seaweed benefits the human body in a variety of different ways. We’ll look at the top research-backed health benefits of seaweed below.

1. Rich in Minerals

Seaweeds are considered to be nutrient-rich as they are a good source of vitamins (A, B1, B2, B9, B12, C, D, E, and K), minerals (calcium, iron, iodine, magnesium, phosphorus, potassium, zinc, copper, manganese, selenium, and fluoride), dietary fiber, and essential amino acids.

In fact, seaweeds are thought to be some of the best magnesium rich herbs.

Seaweeds typically have low fat content. This makes them even more attractive, as they are healthy, nutritive, and low-calorie.

From a mineral perspective, seaweed tends to be rich in iodine, an essential mineral for human health. It is necessary for the proper function of the thyroid gland. Thyroid hormones play a role in regulating metabolism and growth.


Seaweed has been found to be very nutritious due to its large amount of vitamins, minerals, dietary fiber, and amino acids.

2. May Support Heart Health

Seaweeds are some of the best natural herbs for heart health.

A study involving 40 individuals with heart disease found that supplementation with carrageenan, the main compound in Irish sea moss, led to decreases in total cholesterol, LDL cholesterol, and the atherosclerotic index. Moreover, the carrageenan group showed lower levels of inflammatory markers compared to the placebo group.

Additionally, another study on sea moss showed that it has high levels of omega-3 fatty acids, which are known to decrease inflammation and protect against cardiovascular disease. 

In an animal study, researchers found that both the protein hydrolysate and specific tridecapeptide from dulse led to significant reductions in blood pressure in hypertensive rats. In fact, the blood pressure drop was over 30mmHg, a significant decrease.

Additionally, a placebo-controlled trial found that taking dulse capsules (2g/day) for 8 weeks led to decreased triglycerides in women, although there weren’t any significant improvements in glycemic control or other metabolic markers compared to controls. 


Certain types of red seaweed show evidence of protecting the body against cardiovascular disease and inflammation.

3. May Aid Weight Management

Weight loss is a common goal, as many individuals struggle with being overweight.  Fortunately, it appears that natural seaweeds may help to prevent or reduce obesity. 

In a study, overweight participants were given a supplement called Gdue, which is a combination of bladderwrack and rockweed (Ascophyllum nodosum). After 6 months, they found that supplementation led to significant reductions in waist circumference as well as other markers of metabolic syndrome, including insulin sensitivity. 

A clinical study involving 500 patients with metabolic syndrome found that supplementation with Gude (bladderwrack and rockweed combo) over 6 months led to an average weight loss of 15lbs per person and a reduction in waist circumference on average of about 3 in.

Additionally, a placebo-controlled trial found that dulse had the ability to decrease the level of triglycerides in women taking dulse capsules (2g/day) for 8 weeks, however, there were no significant improvements in glycemic control or other metabolic markers when compared to controls.


Various studies demonstrate that certain seaweeds may be useful in managing and losing weight.

4. Rich in Antioxidants

Seaweed is well known for its antioxidant activity.

Antioxidants are molecules that help neutralize harmful free radicals in our bodies. This is thought to aid in better overall health in addition to having an anti-aging effect.

A study found that Irish sea moss extract significantly reduced free radicals and increase total antioxidant capacity. It was also shown to inhibit inflammation. This study also showed that sea moss’s antioxidant effects may be beneficial against cancer cells due to their cytotoxic effects. 

A study found that a dulse extract had significant free-radical scavenging activity, while also reducing lipid peroxidation. Dulse extract was also found to have potential anti-cancer effects.

Another study looking at dulse extract found that eicosapentaenoic acid (EPA) was the most abundant fatty acid in dulse. EPA is known to have significant antioxidant and free radical-inhibiting activity.


Several types of red seaweed have naturally high level of antioxidants, making them ideal for neutralizing harmful free radicals in the body.

History of Seaweed:

For several centuries, seaweed has been used as food in China, Japan, and Korea, as well as in certain Latin American countries, such as Mexico.

The migration of the people from these countries around the world has meant that this custom has moved with them, so today, there are many more countries where seaweed consumption is becoming more commonplace.

In fact, seaweed has gained more acceptance in US regions such as California and Hawaii, which have large Japanese populations. The taste for seaweed is spreading to the surrounding population as it is found in restaurant dishes and on supermarket menus.

Is Seaweed Safe To Eat?

Seaweed is generally safe to consume for most individuals. However, it’s possible to eat too much seaweed due to the fact that it contains high amounts of iodine, a mineral known to affect thyroid health.

Depending on the source, seaweed can also be high in heavy metals (including cadmium). Buying from a trusted, organic source that screens for heavy metals is the best bet.

Best Ways To Add Seaweed To Your Diet:

Seaweed can be taken either as a dietary supplement or as whole food.

Fresh seaweed is commonly used in Asian cooking. It adds a briny, vegetal flavor. 

Dried seaweed can typically be found in powdered or encapsulated form. Capsules can be easily swallowed. Dried seaweed powder can be added to food as a flavor additive, or added to smoothies as an extra nutrient booster.

Seaweed consumption worldwide has declined in the past 30 years. World collection of wild seaweed fell from 1.33 million tons in 1990 to 1.08 million tons in 2019. This decline was found across all three major types of seaweed (red, brown, and green).


Seaweed is beneficial for human health.

Research shows that seaweed may be beneficial for its nutrient content, for heart health, for its antioxidant content, as well as for weight management.

From a safety standpoint, it appears that seaweed is generally safe for most individuals.

It’s worth looking into adding seaweed to your diet if you are needing support in any of these areas. As always, make sure to consult your doctor before making any changes to your diet or adding a new supplement.

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About Daniel Powers, MS

Daniel has a master's degree in herbal science from the Maryland University of Integrative Health. He has a passion for herbal medicine and how it can be used to support everyday health & wellness.

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