What Is Kelp Extract (Laminaria japonica) Kelp extract (Laminaria japonica) is a large brown algae seaweed in the Laminariales family that grows in underwater kelp forests in shallow oceans. They can grow as quickly as half a meter a day and can reach 260 ft in height. Sea kelp extract is often used in cosmetics to promote healthy skin. Kelp Extract (Laminaria japonica) Benefits Kelp extract (Laminaria japonica) may aid in maintaining healthy glucose levels and weight in already healthy individuals when taken in conjunction with a healthy diet and exercise.* It supports the cardiovascular system and heart.* Sea kelp extract is also rich in iodine and may help contribute to healthy, younger-looking skin.*