Kelp (Fucus vesiculosus) is a type of brown sea-weed, moderate in size, that grows in regions with cold coastlines, including those of the northwestern United States and northern Europe.

There are several varieties of kelp: true kelp, which thrives in cool seas; giant kelp, and bladder kelp, which grow in the North Pacific. Giant kelp is so named because it grows to 213 ft (65 m). Kelp anchors itself to rocky surfaces via tentacle-like roots. From these roots grows a slender stalk with long, leaf-like blades.

Kelp belongs to the Fucaceae family. Other names for Fucus vesiculosus are kelpware, black-tang, bladderfucus, cutweed, and bladderwrack. The main constituents of kelp include phenolic compounds, mucopolysaccharides, algin, polar lipids, and glycosyl ester diglycerides. Kelp also contains protein, carbohydrates, and essential fatty acids.

Kelp contains approximately 30 minerals. It is a rich source of iodine, calcium, sulfur, and silicon. Other minerals include phosphorus, iron, sodium, potassium, magnesium, chloride, copper, zinc, manganese, barium, boron, chromium, lithium, nickel, silver, titanium, vanadium, aluminum, strontium, bismuth, chlorine, cobalt, gallium, tin, and zirconium. Kelp also contains vitamins C, E, D, K, and B complex.

The highest concentrations of these vitamins and minerals are found in the tissues of kelp. Since kelp is such a valuable source of nutrients, it is often recommended as a dietary supplement, particularly for people with mineral deficiencies.


Kelp forest
Kelp forest

Different kinds of kelp have been eaten for nutritional value for over a thousand years. The Chinese used kelp and other types of seaweed as medicine as far back as 3,000 B.C.

The Greeks used kelp to feed their cattle around the first century B.C. Kelp has been a staple food of Icelanders for centuries, and ancient Hawaiian nobles grew gardens of edible seaweed. Kelp was also used in Europe and Great Britain as fertilizer to nourish soil and assist plant growth.

The largest consumer of kelp, however, has been Japan. The Japanese have incorporated kelp and seaweed into their diets for 1,500 years. During the seventh to ninth centuries, only the Japanese nobility consumed seaweed.

In the seventeenth century, Japan began farming seaweed. The Japanese and other Asian cultures used kelp to treat uterine problems, genital tract disorders, and kidney, bladder, and prostate ailments.

Kelp is still an integral part of the Japanese diet. The Japanese include kelp in almost every meal, using it in salads or as a garnish, or cooking it in soups, sauces, and cakes. Noodles made from kelp are a staple of the Japanese diet.

Until recently, kelp was eaten almost exclusively by the Japanese. Now the Western population is beginning to take note of this nutrient-rich seaweed. However, Fucus vesiculosus is not the kind of kelp that is eaten.

Eating dietary kelp may be responsible for the low rate of breast cancer among Japanese women, and also for the low rate of heart disease, respiratory disease, rheumatism, arthritis, high blood pressure, and gastrointestinal ailments. The occurrence of thyroid disease is also low in Japan.

General use

Many herbalist and naturopathic physicians recommend Fucus vesiculosus to treat thyroid disorders, arthritis, rheumatism, constipation, colds, high blood pressure, colitis, eczema, goiter, obesity, low vitality, poor digestion, nervous disorders, menstrual irregularities, glandular disorders, and water retention.

Fucus vesiculosus has a therapeutic effect on many systems of the body. It strengthens immune system function and increases resistance to infection and fever. Kelp is also beneficial to the nervous and endocrine systems. It enhances the function of the adrenal, thyroid, and pituitary glands, and supports brain health and function.

One of the main therapeutic uses of Fucus vesiculosus is for thyroid conditions such as hypothyroidism and goiter. Partly due to its high iodine content, this kind of kelp assists in the production of thyroid hormones, which help regulate the thyroid gland.

People who don’t eat dairy products, seafood, and salt may develop an iodine deficiency, which may result in low thyroid function. Kelp is a good source of iodine for those who may be deficient.

Thyroid hormones are also necessary to maintain a normal metabolism. Fucus vesiculosus helps boost metabolism, which helps to sustain normal weight (especially in people who are overweight because of a thyroid condition).

This type of kelp is also used to rid the body of and keep it from absorbing harmful chemicals, toxins, carcinogens, and such heavy metal pollutants as barium and cadmium.

Algin, a fiber-like extract of kelp, helps prevent the body from assimilating these elements. Algin is used industrially in the production of tires and as an agent that prevents ice cream from crystallizing.

Kelp also helps to prevent the body from absorbing radioactive elements such as strontium 90, a dangerous radioactive substance created by nuclear power plants. However, since Fucus vesiculosus absorbs toxic chemicals, it must be harvested from clean waters or it may contain toxins.

Kelp also reduces cholesterol levels by inhibiting bile acid absorption. The diuretic effect of kelp is beneficial to an irritated or infected bladder since it helps to flush out harmful bacteria.

Kelp helps reduce inflammation in injured tissues and ease painful joints in rheumatism and rheumatoid arthritis. Kelp may also reduce an enlarged prostate in men, and is also used to strengthen fingernails, prevent hair loss, and regenerate hair if the follicle is still alive.

In addition to its medicinal uses, kelp contains natural antioxidants that make it useful to the food industry in retarding spoilage. The cosmetics industry is also studying the effects of a gel derived from kelp in improving the elasticity of human skin.


The kelp used medicinally in modern times is generally harvested in kelp farms. These farms help preserve the natural balance of the sea, which is disrupted when large amounts of naturally growing seaweed are removed.

Farming kelp also helps to ensure that the kelp retains its nutritional value. Kelp loses valuable nutrients when it is washed ashore. When kelp is harvested, it is cut, dried, then ground into powder. It is this powder that is encapsulated or pressed into tablets.

Kelp is available in bulk form either dried or as a ground powder. It is also sold as granules, capsules, tablets, or tinctures. Granulated or powdered kelp can be added to food as a salt substitute.

The recommended daily dose for adults is 10–15 mg. Kelp can also be made into a tea. To create an infusion, 1 cup of boiling water is poured over 2-3 tsp of dried or powdered kelp. The tea is steeped for 10 minutes, and can be drunk three times daily.


People should not gather wild kelp because it may contain contaminants absorbed from the sea.

People with high blood pressure or a history of thyroid problems should consult their healthcare practitioner before using kelp. The high sodium content of Fucus vesiculosus may make high blood pressure worse. Kelp isn’t recommended for people on a low-sodium diet.

Excessive consumption of kelp can provide the body with too much iodine and interfere with thyroid function. Consumers should use it only as directed.

Side effects

There are no known side effects, but some people may be sensitive or allergic to kelp. Common allergic symptoms include mild stomachache.


Fucus vesiculosus shouldn’t be taken with thyroid medications.