Kombu

Known by some as the "king of seaweeds," Kombu is a brown type of kelp that grows in long narrow blades (up to 6 feet long), in dense forests below the tide. A rich source of iodine, Kombu has been used to treat thyroid dysfunction. It contains concentrated amounts of calcium, potassium, magnesium, trace minerals (including copper and zinc), as well as chromium.

Incredibly low in calories, high in fiber, and delicious, Kombu has been a staple the Japanese diet for centuries.