Grapefruit seed extract (GSE), also known as citrus seed extract, is a liquid extract derived from the seeds, pulp, and white membranes of grapefruit.[1] GSE is prepared by grinding the grapefruit seed and juiceless pulp, then mixing with glycerin.[1] Commercially available GSEs sold to consumers are made from the seed, pulp, glycerin blended together.[1] GSE is sold as a dietary supplement and is used in cosmetics.[2] Laboratory tests have found that GSE has no antimicrobial or other anti-disease attributes.[3][4]