Anyone for algae?

UNESCO Courier, July-August, 1998 by Sophie Boukhari

It's great for your health and easy to farm. Whether you like it or not, there may be seaweed on your plate.

Seaweed-or algae-is everywhere in our food nowadays. Chunks of it float around in Korean soups, paper-thin sheets of it are wrapped around Japanese rice balls, and it lies hidden in the alginates and carrageenans in hamburgers, yoghurt and strawberry ice cream. "Seaweed-based food additives are now so commonly used in prepared and fast food that virtually everybody in Europe and North America eats some processed seaweed every day," says Michael Guiry of the National University of Ireland, where marine algae are also used as a fertilizer and food supplement for livestock. In other parts of the world, especially the Far East and the Pacific, seaweed is a traditional part of the staple diet.

There are three categories of seaweed: red (4,500 species), green (900 species), and brown (1,000 species). Red seaweeds are the most numerous, green the most widespread and brown the largest. Some species of kelp off the Californian coast can grow to be 50 metres long, in "forests" that are just as vast and complex as those on land. Every year 140,000 tonnes of kelp are harvested for the extraction of food additives. Most of the edible green and red seaweeds are eaten unprocessed.

The most valuable seaweed species are known by their Japanese names: nori (Porphyra), kombu (Laminaria) and wakame (Undaria). They are so easy to digest and so rich in vitamins, mineral salts and oligo-elements that they deserve to be called "the vegetables of the sea". Wakame, for example, has a very high calcium content, and nori contains 50 per cent more vitamin C than oranges.

In some parts of Asia, seaweed provides the poor with good, cheap nutrition, and in the rich countries it helps people lose weight. "It seems that Westerners, unlike Asians, are unable to assimilate seaweed, and that's why we consider it to be a low calorie food," says Guiry. The total seaweed market is worth over $5 billion, with food additives alone accounting for $600 million. Kazutosi Nisizawa, former President of the Japanese Phycological Society, says "the world's total yearly harvest is 8.4 million tonnes of green seaweed, 2.8 million tonnes of brown seaweed and 1.2 million tonnes of red seaweed." China is the leader, producing 3.5 million tonnes of kombu yearly - the world's biggest harvest. This is even more impressive when we know that from the fifth century on China imported dried seaweed from Japan, until it began to farm its own in the 1950s, growing the plants on long ropes stretched under the water. The Chinese now hold the title of the world's biggest seaweed consumers.

Meanwhile, the Japanese harvest of nori is the world's biggest in value, worth a total of almost $1.3 billion. The Japanese seaweed industry employs some 35,000 people. Japan is also the world's leading seaweed exporter, ringing up sales of $170 million in 1995, according to FAO. Seaweed, of course, is a historic staple of the Japanese diet. "The Japanese currently eat some twenty different species, and they have been using six of them since as far back as the eighth century," reports Guiry. "Seaweed accounts for about 10 per cent of the modern Japanese diet." Even the Japanese gods love seaweed, it seems. "In a book dating back to 701," recounts Nisizawa, "it is written that several varieties of edible seaweed were used as offerings in the temples." Even today, there are towns in Japan where the meal served at the betrothal ceremony must include Laminaria, which is believed to bring good luck and happiness. In many countries, seaweed has long been part of the traditional pharmacopeia, and scientists today hope to see it as an ingredient of tomorrow's medicines. Researchers are currently trying to isolate substances in seaweed which could be used to treat high blood pressure, cholesterol, cancerous tumours and other ailments.