6 Benefits of Sea Kelp: Dosage & Safety

The ocean is an abundant source of nutrient-rich foods, not the least of which are seaweeds. Among these seaweeds, sea kelp is very intriguing due to its wide range of …

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Written by: Jack Cincotta, MS
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Medical Review by: Daniel Powers, MS
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The ocean is an abundant source of nutrient-rich foods, not the least of which are seaweeds.

Among these seaweeds, sea kelp is very intriguing due to its wide range of potential benefits and applications in food and medicine.

In this article, we will look at the health benefits of kelp, its safety, its history, and how to incorporate it into the diet. 

sea kelp and its benefits

What is Kelp?

Sea kelp is a general term referring to many different types of brown seaweeds that make up the order Laminariales

Some of the top varietals of sea kelp include:

  • Laminaria japonica (Kombu)
  • Laminaria digitata (Oarweed)
  • Laminaria saccharina (Sugar Kelp)
  • Macrocystis pyrifera (Giant Kelp)
  • Nereocystis luetkeana (Bull-Head Kelp)

Kelp generally thrives in colder-to-temperate waters (42-72 degrees F) and can usually be found in shallow areas close to shore. They are abundant along the Pacific coast from Alaska all the way down to southern California, but can also be found on the Atlantic coastline.

Like other seaweeds, varieties of sea kelp are rich in numerous nutrients, including fiber, vitamins, minerals, and antioxidants.

Some of the specific nutrients found in sea kelp include:

  • Soluble fibers, such as alginates, laminarin, and fucoidan
  • Fucoxanthin and fucosterol
  • Magnesium
  • Omega-3 fatty acids
  • Iron
  • Iodine
  • Calcium
  • Zinc
  • Vitamins A, B (B1, B2, B6, B9, B12), and  K

Health Benefits of Kelp:

Due to its nutrient content, there are a number of potential health benefits of sea kelp.

Additionally, sea kelp varieties appear to have some of the most clinical research behind them, which makes them more applicable to human health.

All in all, sea kelp benefits the following aspects of human health.

1. May Help with Weight Loss

In this day and age, weight loss is a top priority for many people. Intriguingly, sea kelp benefits weight loss through a number of effects on metabolism, gut health, and other factors. 

One study looked into the effects of Laminaria japonica extract supplementation in 22 female college students. After 8 weeks, they found that supplementation led to improved body composition, nutrient intake, and quality of life.

In another study, supplementation with iodine-reduced kelp powder in 50 overweight men led to significant reductions in body fat, body weight, and body mass index (BMI).

Another human study found that supplementing with fucoxanthin extract from kelp led to reductions in body weight, BMI, and abdominal fat. Fucoxanthin is a carotenoid compound, a type of antioxidant, found in a number of brown seaweeds The researchers concluded that fucoxanthin was able to decrease both visceral and subcutaneous body fat. 

Finally, one study done on mice found that a polysaccharide-rich Laminaria japonica extract led to significant reductions in weight gain and fat accumulation. Moreover, this extract improved serum lipid profiles, decreased intestinal damage, and had favorable effects on fat metabolism.


Studies indicate that sea kelp may be beneficial in reducing body weight.

2. May Help With Blood Sugar Stabilization

Emerging evidence shows that sea kelp benefits insulin activity and metabolic health, which could have implications for diabetes and other metabolic disorders.

In a placebo-controlled clinical study involving 25 overweight individuals, supplementing with fucoidan extract from sea kelp led to significantly lower LDL cholesterol and blood pressure compared to placebo.

Also, in a 3-way, blinded, crossover human clinical trial, supplementing with brown seaweed was associated with lower glucose, insulin, and C-peptide response compared to placebo. The seaweed groups also showed better appetite control compared to the placebo.

In another study in high-fat-diet-fed mice, a sea kelp extract was associated with reductions in insulin resistance, inflammation, gut permeability, and gut dysbiosis. Overall, the beneficial metabolic effects were attributed to improved gut health.


Sea kelp has been shown to have properties that assist in improving insulin activity and metabolism.

3. Antioxidant Properties

Another potential health benefit of sea kelp is its antioxidant and anti-inflammatory properties. 

In a placebo-controlled clinical study, researchers looked into the effects of a fermented sea kelp extract on antioxidant levels in 48 people with high gamma-glutamyl transferase (GGT) (a marker of possible liver damage). They found that supplementing with this extract led to a significant reduction in GGT alongside significant increases in superoxide dismutase and other antioxidants compared to placebo.

Another study discovered that fucoidan extracted from brown seaweed possesses significant antioxidant and anticoagulant properties, and thus may play a role in cardiovascular health as well.

An additional study done in mice found that an extract from Laminaria digitata had protective effects against certain markers of aging. Specifically, compared to controls, mice who received the extract had lower levels of inflammation (e.g. IL-6) in the brain and liver, higher skin collagen content, and lower fat levels, suggesting antioxidant and anti-aging effects.

Lastly, another study looked into the protective effects of an extract from Laminaria digitata after inducing skin cancer in mice. It was found that, compared to controls, mice fed the sea kelp extract had healthier levels of keratin, better skin health, and better liver and heart function.


Several studies show that sea kelp has the ability to increase antioxidant levels in the body.

4. May Improve Gut Health

It is also likely that sea kelp benefits gut health due to its many gut-supportive compounds, including alginate and fucoidan, among others.

In a randomized clinical trial in 40 subjects, supplementing with Laminaria japonica alongside lactic acid bacteria led to significant increases in beneficial probiotic species in the gut. Additionally, Laminaria japonica alone and in combination with lactic acid bacteria led to improvements in bowel functions, overall gut health, and quality of life. 

In another in vitro study, Laminaria japonica water extracts appeared to be able to reduce markers of inflammation in the gut (e.g. IL-6), while also enhancing the function of tight-junction proteins, which are important for gut barrier function.

Thirdly, a study done in mice showed that supplementing with brown algae extract led to improved gut barrier function by increasing gut microbiota concentrations. They also found that these extracts appeared to improve amino acid and glucose metabolism, regulate blood glucose levels, improve body weight, and even offered antioxidant effects.


Research shows that sea kelp may be beneficial in improving overall gut health by reducing inflammation and enhancing gut function.

5. May Improve Cognitive Function

One of the more unique potential benefits of sea kelp is enhanced cognitive function, as there are several studies showing that sea kelp benefits brain health.

In a placebo-controlled study involving 40 elderly individuals, supplementing with Laminaria japonica led to significant improvements in brain function, such as working memory, compared to placebo. Additionally, the sea kelp group had higher levels of antioxidant activity and better neuromuscular function compared to controls. The researchers noted that certain compounds such as fucoidan and GABA are likely responsible for the antioxidant and neuroprotective effects.

Another study found that compounds in brown algae showed free radical scavenging and anti-inflammatory activities. Additionally, these compounds showed acetylcholinesterase inhibitory activities. Acetylcholinesterase is an enzyme that breaks down acetylcholine, inhibiting this enzyme leads to more available acetylcholine, an important neurotransmitter for memory, focus, and cognitive health.

A study done on mice with radiation-induced brain injury provided evidence that Laminaria japonica extracts may be able to provide neuroprotective effects. Specifically, this sea kelp extract was associated with decreased neurogenesis damage, lower inflammatory markers, and diminished collagen damage in the brain hippocampus.

Finally, another animal study found that sea kelp extract was able to offer protective effects against memory impairment, largely by increasing acetylcholine levels, inhibiting acetylcholinesterase, and improving neuroplasticity. 


Sea kelp has been found to improve brain function by aiding memory, focus, and cognitive health.

6. Nutrient-Rich Properties

Another benefit of sea kelp is simply its rich nutrient density. In particular, kelp is rich in various minerals. 

Kelp is high in the mineral iodine, but there is a large range of variability. Some of the more common varieties of kelp (e.g. Oarweed, Sugar Kelp, Kombu) can contain up to nearly 8,000mcg of iodine per gram. 

Kelp is also rich in numerous other minerals, including magnesium, phosphorus, potassium, iron, and zinc. 

Moreover, they contain B-complex vitamins, some of which are not found in land plants, and vitamins A, C, E, and K. 

Kelp is considered one of the best herbs high in magnesium.


Sea kelp is considered nutrient-rich because of its high levels of vitamins and minerals.

Sea Kelp Safety:

Generally, sea kelp is safe to take in normal amounts that occur in food.

However, sea kelp can absorb harmful metals, such as arsenic, cadmium, and lead.

Always look for certified organic sources of sea kelp and, if consuming a kelp supplement, ensure that the product has been tested for heavy metals.


One should be cautious with certain kelp supplements so as to not exceed the recommended dosage. It is not recommended to exceed more than 225 mcg of iodine per day unless otherwise instructed by a healthcare professional. 

In practice, this amounts to around 1 ounce of raw kelp or any derivative from that 1-ounce portion. However, different varieties have different iodine concentrations, so be sure to check the label if available.

How to Incorporate Sea Kelp into the Diet:

Sea kelp can be taken as a supplement, but it is likely better and safer to consume it in its natural form, whether that’s fresh (raw), dried, or some other variation. 

Dried kelp can be mixed into soups, stews, and other hot dishes. It can also be added to smoothies as an added nutrient booster.

One can even make kelp noodles from raw kelp and use them as a replacement for other noodle-based dishes.

Dried kelp flakes can be added to any number of foods as a spice or seasoning. 

Naming & Taxonomy:

Sea kelp is a common name for any of the large brown seaweeds that make up the order Laminariales. There are around 30 different genera of kelp. 

Kelp is identified by its slender stalk with long, flat, leaf-like blades. It is composed of three basic structural units:

  • Holdfast, which is a root-like structure anchoring the body to the sea floor
  • Stipe, which is sort of like a plant stalk
  • Fronds, which are the leaf-like structures attached to the stipe.

History & Traditional Use:

Historical usage of sea kelp dates back to at least the 5th century in China and Japan. 

It was used as a versatile culinary ingredient, with usage in soups, meat, and fish dishes, often with rice.

From a medical perspective, sea kelp was used in traditional cultures to treat goiters and other thyroid conditions, as well as to reduce symptoms of various gut problems. This is most likely due to its rich iodine content.


The many varieties of sea kelp are similar in that they are all nutritionally packed and have many potential health benefits. Consuming sea kelp may help with weight loss, antioxidant activities, gut health, cognitive function, and metabolic health. 

Additionally, sea kelp has an edge over some other seaweeds due to the greater number of clinical studies backing it.

As such, it is worthwhile to consider implementing sea kelp in the diet for possible health benefits.

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About Jack Cincotta, MS

Jack has a Master of Science degree in Psychology and is also an AADP® Board Certified Holistic Health Practitioner and AFPA® Certified Holistic Health Coach. His passion is to help people develop optimal levels of health, particularly mental health.

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