Ascophyllum nodosum is a species of seaweed found around the globe. It is one of the many species of seaweed called kelp.
Ascophyllum nodosum contains compounds called phlorotannins, which are unique to seaweed and may be able to inhibit starch and lipid absorption. This effect is very unreliable, to the point where two human studies investigating carbohydrate absorption reported two opposite effects.
Ascophyllum nodosum also contains a compound called ascophyllan, which may have immunostimulatory properties. Ascophyllum nodosum extract has anti-inflammatory properties. Much more research is needed to determine the practical significance of Ascophyllum nodosum supplementation.
Though Ascophyllum nodosum is a healthy food, there is no evidence to support its usefulness as a supplement.