Kelp is a generic name for many species of seaweed, which grow in shallow regions of the ocean in forests supporting many other forms of marine life. It is thought to be up to 23 million years old, and California's channel islanders have been harvesting it for 12,000 years! As a human food, kelp has long formed part of the Japanese, Chinese and Korean diet, and it's coming now into greater prominence as a dietary supplement.
Because of its growth in seawater, brown kelp is an extremely rich source of iodine, and has been used since the middle ages in treating thyroid problems, which in turn are responsible for changes in the metabolism and can affect body weight. It has also been identified as a natural, inorganic antioxidant which can have a beneficial effect in fighting free radicals in the immune system.
Kelp is also an excellent source of vitamins and minerals, particularly sodium and calcium. It has substantially more calcium content than milk, so it is a very good supplement in non-dairy diets. It can be used as a substitute for kale in smoothies or miso soup, wrapped round your sushi rolls, or as a crispy vegetable snack.