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Hijiki is a black fibrous seaweed that grows along the coast of Korea, China, and Japan. This seaweed is most commonly used in Japanese dishes, and is a traditional part of the diet in this country. The seaweed is used in vegetable and fish dishes, stir fries, salads, and sushi.
Hijiki usually comes dried. It must be soaked in water and rinsed before it can be used. During the reconstitution process, the seaweed increases in size up to five times. After this soaking, the leaves resemble slippery black noodles more than they do a plant.
The high fiber content of hikiji gives it a distinct texture. The flavor of the seaweed is relatively mild. It is often chopped very fine and mixed into items such as sushi rice, dips and dressings, and grains. This type of seaweed is not used to wrap sushi, as other seaweeds often are.
This seaweed is believed by the Japanese to have a wide variety of healing benefits. It is thought to nourish hair, nails, and skin, strengthen teeth and bones, and generally detoxify the body. It may be used to treat high blood pressure, congestion, and intestinal problems. Anxiety-related issues may be treated by the seaweed’s high calcium content and the iron in hijiki is good for anemia.
Despite these benefits, hijiki is considered by many to be dangerous for consumption due to high levels of inorganic arsenic naturally present in the seaweed. The Canadian Food Inspection Agency issued a warning about the arsenic in this food in 2001. The Food Standards Agency in Britain followed this with a similar warning in 2004. Other agencies to issue warnings about the seaweed include the New Zealand Food Safety Authority and the Food and Environmental Hygiene Department in Hong Kong.
Inorganic arsenic can be linked to cancer, liver damage, and gastrointestinal problems. The levels of arsenic in hijiki are considered to be toxic. However, Japan’s Ministry of Health, Labour and Welfare has pointed out that the average daily intake of this seaweed for those in Japan is minimal and therefore unlikely to cause serious damage.
Overall, those interested in using hijiki in their foods will need to make their own judgment call on the safety of the item. It should always be used in small amounts. One to two tablespoons per serving is usually more than enough to add texture to a dish.
@Soulfox -- good advice because Hijiki does contain an unusually high number of beneficial vitamins and minerals. Chief among them are calcium and fiber, but it also has magnesium and iron.
By the way, the danger of this stuff may not be as great as some health agencies make out. Consider this -- this food has been a staple for Japanese diets for centuries and it has been shown that eating very large amounts of it can lead to the arsenic problem you mentioned. It would seem that a little moderation is in order.
If you do decide to consume Hijiki, make sure to see how it is processed. The traditional method involves picking it, steaming it, letting it air dry and then packaging it. Any methods that speed up that process tend to sacrifice the very minerals that people claim are so healthful.
The question of arsenic will remain regardless of what you buy, but Hijiki contains a high concentration of vitamins and minerals and you certainly don't want to lose those. The good stuff will cost a bit more than the rapidly processed Hijiki, but the added price may well be worth it.