Grapefruit seed extract

Grapefruit seed extract (GSE) is a purported "all-natural" supplement sold in health food stores and over the Internet. It is supposedly a natural antimicrobial and antifungal product.

However, tests on actual grapefruit (Citrus × paradisi) seed extract show zero antimicrobial or antifungal properties, while tests on commercially available GSE do show such properties. The difference? Tests on commercial GSE products show they contain benzethonium chloride and triclosan, both antimicrobial and antifungal compounds also used in deodorants, disinfectant sprays, and antiseptic hand wipes. Neither of these compounds occur naturally in grapefruit seed extract, which indicates they were either added to "all-natural" grapefruit seed extract products as preservatives, or GSE products were adulterated with those compounds to give them their claimed benefits. Benzethonium chloride and triclosan, while effective, are approved and generally regarded as safe for external use only, but specifically disapproved for internal use.

Bottom line: GSE products sold in health food stores are not "all-natural". Their apparent active ingredients aren't listed on the label. The actual amount of benzethonium chloride and triclosan they contain could vary widely, making their effectiveness for any given application unclear. Given these unknowns and the unapproved status of these two compounds for internal use, it is probably a very bad idea to take GSE products internally.