Grapefruit seed extract is marketed as a natural preservative and dietary supplement. While the name suggests this product is natural, it really isn't. In fact, the majority of grapefruit seed extract preparations are actually synthesized by chemical catalyst and high pressure or heat using pulp discarded as a byproduct of grapefruit juice production. If you use grapefruit seed extract, you should be aware of some potential dangers.
Chemical Processing
The production of grapefruit seed extract begins with the dried and powdered pulp and seed, which is then dissolved in purified water and distilled to remove impurities. The resulting slurry is slowly dried using low heat to form a concentrated powder and then combined with glycerin and subjected to heat once more. At this point, natural grapefruit extract is achieved. However, in commercial production, the active phenol compounds undergo further catalytic conversion with ammonium chloride and hydrochloric acid to form quaternary ammonium chlorides. In short, the "natural" product you see on the market is actually an artificial chemical compound created in a laboratory that may present health risks.
Benzethonium Chloride Contamination
In a 2001 analysis of commercial grapefruit seed extracts conducted by the U.S. Department of Agriculture, benzethonium chloride was found in some liquid samples in a concentration of more than 8 percent, with even higher concentrations in powdered samples. In the Interpretive Summary of this study, the authors state that benzethonium chloride is a synthetic antimicrobial agent that is approved only for topical use and that its inclusion in products designed for internal use is "troubling in light of its toxicity and allergenicity."
Other Questionable Ingredients
The U.S. Department of Agriculture study, led by researcher Gary Takeoka, cites additional compounds commonly found in commercial grapefruit seed extracts that are added as preservatives, such as methyl paraben. Like other parabens, methyl paraben is associated with an increased risk of certain cancers. For instance, in the July 26, 2008 issue of Chemical Research in Toxicology, a team of Japanese researchers published the results of a study that indicates that topically applied methyl paraben may react with ultraviolet radiation from the sun to promote skin aging and DNA damage in skin cells.
Drug Interactions
A team of Swedish researchers led by Helena Brandin found that grapefruit seed extracts that contain benzethonium chloride inhibit the activity of two kinds of digestive enzymes. The team, who published their findings in the European Journal of Clinical Pharmacology, subsequently concluded that this effect is responsible for an increased rate of absorption of certain medications, most notably the anticoagulant drug warfarin.
References
- Institute for Traditional Medicine: Grapefruit Seed Extract Products
- U.S. National Library of Medicine: Identification of Benzethonium Chloride in Commercial Grapefruit Seed Extracts.
- USDA Agricultural Research Service: Identification of Benzalkonium Chloride in Commercial Grapefruit Seed Extracts.
- ACS Publications: Combined Activation of Methyl Paraben by Light Irradiation and Esterase Metabolism toward Oxidative DNA Damage.
- SpringerLink: Adverse Effects by Artificial Grapefruit Seed Extract Products in Patients on Warfarin Therapy.
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