Fucus vesiculosus, Ascophyllum nodosum, and various Laminaria (e.g., Laminaria digitata and Laminaria japonica), Macrocystis, and Nereocystis species.

What Is Kelp?

For the most part, these flat, ribbonlike organisms grow attached to rocks by means of holdfasts, and have a salty and fishy taste and a mucilaginous consistency. They are found primarily in the cold waters of the Atlantic and Pacific oceans. The brown alga known as bladderwrack (Fucus vesiculosus) is a particularly common source of kelp. The entire plant body is used medicinally and for other purposes.

What it Is Used For:

Forms Available Include:

Kelp has long served as a standard part of the Japanese diet and appears on any basic sushi menu. For decades in early America, iodide-rich kelp was valued highly for preventing goiter, an often unsightly enlargement of the thyroid gland caused by a deficiency in iodine. It was also popular as an antiseptic for wounds. A tincture was billed as a treatment for ailments ranging from syphilis to vaginal discharge, menstrual cramps, liver disorders, ovarian tumors, gallstones, bronchitis and asthma, ulcers, and testicle enlargement. Today, kelp tablets containing dried seaweed are still sold as sources of iodide as well as energy boosters, antiobesity agents, and weight loss ("slimming") aids. Some sources claim they can protect the consumer from arteriosclerosis and heart disease and from the harmful effects of exposure to radiation and toxic heavy metals. Forms Available Include: Capsule, infused oil, infusion, liquid extract, powder, raw (including granulated or powdered), tablet, tea (instant, often in herbal blends), tincture. The mineral concentrations (including iodine) of various seaweeds used to make kelp preparations vary depending on such factors as the species used, the time it was harvested, and the age of the plant. Select a preparation with a standardized amount of the mineral desired. To avoid ingesting contaminants, do not collect your own kelp; buy it from a commercial source.

Dosage Commonly Reported:

An infusion is made using 2 to 3 teaspoons of dried powdered frond per cup of water and is drunk up to three times a day. Follow package instructions for dosage of commercial preparations.

Will it Work for You? What the Studies Say:

Some sources argue that the sodium alginate in kelp can help prevent absorption of heavy metals such as barium, plutonium, cesium, and radioactive strontium 90, a by-product of nuclear power and weapons plants and nuclear explosions.[1] Strontium 90 builds up in the body and has been linked to the development of leukemia, Hodgkin's disease, and other cancers. Studies have shown that sodium alginate can reduce the absorption of radioactive strontium in both animals and humans.[2] But several sources have questioned the need for this type of routine prevention in a society not experiencing major radioactive leaks or explosions.[3] Investigators are examining a possible role for laminaria in explaining the relatively low breast cancer rates in Japan [4] and have looked at potential antitumor-promoting properties in various models.[5] They have also examined anti- HIV components in bladderwrack.[6]

1. M. Castleman, The Healing Herbs: The Ultimate Guide to the Curative Power of Nature's Medicines (New York: Bantam Books, 1995).

2. Y.F. Gong et al., Biomedical & Environmental Sciences, 4(3) (1991): 273-82.

3. V.E. Tyler, The Honest Herbal (Binghamton, NY: Haworth Press/Pharmaceutical Products Press, 1993).

4. J. Teas, Nutrition & Cancer, 4(3) (1983): 217-22.

5. H. Ohigashi et al., Bioscience, Biotechnology & Biochemistry, 56(5) (1992): 994-95.

6. A. Beress et al., Journal of Natural Products, 56(4) (1993): 478-88.