Under the sea: superior nutrition from the ocean's depths

Better Nutrition, May, 2004 by Kim Schoenhals

Anyone who has been to a sushi restaurant is familiar with the endless menu of rolls (or maki-sushi), all of which are wrapped in a delicious--and healthful--vegetable that's harvested under the sea. Nori, the type of seaweed used for maki-sushi, is chock-full of vitamins, minerals and protein. Similarly, the entire category of sea vegetables is highly nutritious and can add flavor and flair to any number of recipes.

Sea vegetables comprise seaweeds, algae and kelp, although the terms "seaweed" and "algae" are often used interchangeably, and "kelp" describes any of the edible brown seaweeds, as opposed to the red and green varieties. Traditionally, sea vegetables have been more commonly eaten in Asian cultures. But edible seaweeds have gained a foothold in America and have steadily increased in popularity since the 1980s--no doubt in large part due to the rise in popularity of sushi restaurants.

Savory Seaweeds

This sushi bend is a healthful addition to the typical fat- and calorie-laden Western diet. According to a 2001 study published in the Asia Pacific Journal of Clinical Nutrition by researchers at Kyoto University in Japan, seaweed consumption may help prevent chronic disease, as demonstrated by a high intake among the exceptionally long-lived Okinawans.

"From a nutritional point of view, [seaweeds] are low-calorie foods with a high concentration of minerals, vitamins, proteins and indigestible carbohydrates and a low content of lipids," say researchers from the Universidad Complutense de Madrid, who published a study in the Archivos Latinoamericanos de Nutricion in June 1999. The Spanish researchers also suggest that the dietary fiber derived from sea vegetables has antimutagenic (the ability to prevent cellular mutations that are potential risk factors for cancer), anticoagulant (the ability to prevent blood clotting) and antioxidant effects.

The most popular type of seaweed utilized by American sushi chefs is nori, which is classified as red algae, even though it grows purple and appears dark green in its dried form. In addition to being used in sushi, nori can add a tangy-sweet flavor to salads and soups--as well as a healthful dollop of protein, calcium, iron and vitamins. Particularly, according to a 1999 study published in the Journal of Agricultural and Food Chemistry by researchers at Kochi Women's University in Japan, nori is "the most excellent source of vitamin [B.sub.12] among edible seaweeds, especially for strict vegetarians."

Another B-vitamin-laden seaweed, purple laver proved to elevate vitamin [B.sub.12] levels in deficient rats, as noted by researchers in Sakai, Japan, who published their findings in 2001 in the British Journal of Nutrition. They estimated purple laver contains five types of biologically active vitamin Bp compounds, as well as a whopping 54.5-58.6 micrograms (mcg) of vitamin [B.sub.12] per 100 grams of dry weight.

Other red algae known as dulse have been pinpointed as rich sources of protein and iron, although dulse may hot be easily digested. Because the protein from dulse was poorly digested in some studies, researchers at the Laboratory of Cellular and Molecular Pathology in Nutrition at Vandoeuvre les Nancy in France treated it with a fermentation process, learning that by degrading the plant's insoluble fibers, digestibility was improved. The researchers reported their findings in the October 2003 issue of the German food journal Die Nahrung. Aside from its digestibility, dulse is recognized for a strong briny flavor and is most commonly used in soups or as a condiment. When dried, dulse can also be used as a thickening agent in processed foods, including salad dressings and ice cream.

Edible Algae

In addition to red algae, brown algae are known for their healthful attributes, for example, brown seaweed containing 10 percent fiber was shown by researchers at Japan's Kyoto University to lower blood pressure and to reduce the risk of stroke in animals predisposed to cardiovascular problems. One study, featured in a 1986 supplemental issue office Journal of Hypertension, indicated alginic acid, a compound found in seaweed fiber, probably had something to do with the heart-healthy effects.

Two wholesome brown kelps that are popular among Japanese diners are kombu and arame. Kombu (sometimes konbu) is typically sun-dried and used as a flavoring in f soups and rice or it may be pickled n and used as a condiment. It can also be boiled and added to vegetable dishes, and it is a necessary component in a popular Japanese soup stock called dashi. Similarly, arame--known for its mild, almost sweet flavor--can be added to soups and salads, or it can be steamed or boiled and eaten plain.

Like arame, brown algae called hijiki are used as an ingredient in soups or other slowly cooked or simmered dishes, although it is characterized by a slightly bitter flavor. In terms of health, hijiki may improve bone strength due to its magnesium content. Hijiki was compared to wakame, a green seaweed, and both were used in a study that investigated the relative bioavailability of magnesium from sea vegetables.