Natural Products from the Sea: Ethnopharmacology, Nutrition and Conservation

Townsend Letter for Doctors and Patients,  Feb, 2001  by Tim Batchelder

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Sea vegetables such as kelp have also been used topically as a folk remedy for minor burns, by moistening the strips in cool water and applying them to the skin. Alginates may help to promote the healing of burns and wounds. Alginate fibers in surgical gauze and bandages can help stop bleeding.

Sea vegetables such as kelp, along with green beans and common rue, contains substances that have a direct effect on the cardiovascular system and may be helpful in lowering blood pressure. (Chiu 1997)

Sea vegetables such as kelp are a source of mucilage, which can have a soothing effect on mucous membranes. Kelp may help to prevent or treat digestive disorders and bronchial congestion. Polysaccharide alginates found in kelp and other brown seaweeds have been widely used by the cosmetic and food industries for decades as emulsifiers, suspending agents, and stabilizers.

Sea vegetables can be eaten fresh or dried. Some people consume them as a side dish while they can also be used to flavor soups, stews, and salads. Sea vegetables are available in tablets, capsules, and liquids. The quality of sea vegetable products varies widely. Commercially available extracts are often deficient in the active compounds found in sea vegetables so they are best consumed in their whole state. Tinctures extract only 5% of the active compounds in Fucus, for example (Ryan Drum PhD, personal communication 1999). Drying does not damage sea vegetables (they are naturally dried every day on the beach.) Many cultures, particularly in Asia, have used sea vegetables both as food and medicine for much of history. Social science researchers have documented fluctuations in the harvest quantity and quality of sea vegetables in various cultures and pointed out ways to maintain sustainable usage patterns. From example, in the kombu harvest in Japan, this can include regulating harvesting by communal laws de termined by the harvesters themselves, which often works better than bureaucratic regulation by government agencies. (Lida: 1998).

Toxicity of sea vegetables is low. However, long-term consumption of large doses of kelp may deliver excess levels of iodine to the thyroid, resulting in hyperthyroidism (over-active thyroid). Check labels of kelp supplements for iodine content since it can vary considerably depending upon species, growing conditions, and other factors. Kelp can also be high in sodium and may need to be taken with caution by anyone following a salt-restricted diet.

Chitin

Chitin and chitosan are fibers derived from marine animals. Chitin is a polysaccharide, a string of sugar molecules, that naturally occurs in the hard outer shell of insects, shellfish such as crab, lobster, and shrimp, and marine coral. Chitin is chemically similar to cellulose and starch, the abundant plant fibers. It is used to make various other substances, including chitosan, which is derived from chitin by heating it with a chemical solution. Chitosan, has the advantage of being more soluble in water compared to chitin. Scientists have intensively investigated the properties and uses of chitin, chitosan, and their derivatives. Collectively they are the subjects of approximately 1,000 scientific studies and hundreds of patents. Most of this attention originated in Asia but in recent decades Westerners have begun to take chitin and chitosan as nutritional supplements and major corporations have jumped on the research bandwagon.