Ecklonia cava is a type of brown algae that is rich in phlorotannins, a type of antioxidant. It's used in food and supplements in Japan and Korea.

Ecklonia cava contains several chemicals that are thought to prevent damage to the body that can lead to cancer and other conditions. These chemicals might also have effects on swelling and the body's immune system.

People use Ecklonia cava for high cholesterol, cancer, osteoarthritis, athletic performance, diabetes, and many other conditions.

Don't confuse Ecklonia cava with other types of algae, including Ascophyllum nodosum, Fucus vesiculosus, and Laminaria. These are not the same.