Grapefruit Seed Extract
In case you’re not part of the “dirty hippy vegan” club as Kurt calls it, GSE or Grapefruit Seed Extract is this wildly popular “natural” do it all medication/supplement, household cleaner, fruit and vegetable wash, and food and cosmetic preservative. Does that sound odd and maybe a little scary to anyone else?
I discovered GSE though researching parrot diet and nutrition. One thing that kept coming up in bird forums, books, and web sites was using GSE for sprouting to reduce risk of mold and for cleaning their cage because birds are very sensitive to the chemical products many use. I’ve noticed GSE all over the place since my initial search, and because of what I’ve found out about it, that makes me twitch. Some brands of GSE apparently are truly Grapefruit Seed Extract, and they do none of the above listed tasks any better than water. Other brands however, are not what they seem. I’m not saying that ingesting them will kill or maim. It might not even make people sick if used in the diluted amounts recommended by manufacturers as a vegetable wash, but if your goal is to reduce your exposure to chemicals, I’m afraid you may have been duped. Just to be on the safe side I would not add GSE to pet foods, take it as a pregnant woman nor feed it to an infant, but that’s just me.
From the National Center for Biotechnology Information’s site, 1999 tests that revealed preservatives:
Institute of Pharmacy, Ernst Moritz Arndt University, Greifswald, Germany.
The antimicrobial efficacy as well as the content of preservative agents of six commercially available grapefruit seed extracts were examined. Five of the six extracts showed a high growth inhibiting activity against the test germs Bacillus subtilis SBUG 14, Micrococcus flavus SBUG 16, Staphylococcus aureus SBUG 11, Serratia marcescens SBUG 9, Escherichia coli SBUG 17, Proteus mirabilis SBUG 47, and Candida maltosa SBUG 700. In all of the antimicrobial active grapefruit seed extracts, the preservative benzethonium chloride was detected by thin layer chromatography. Additionally, three extracts contained the preserving substances triclosan and methyl parabene. In only one of the grapefruit seed extracts tested no preservative agent was found. However, with this extract as well as with several self-made extracts from seed and juiceless pulp of grapefruits (Citrus paradisi) no antimicrobial activity could be detected (standard serial broth dilution assay, agar diffusion test). Thus, it is concluded that the potent as well as nearly universal antimicrobial activity being attributed to grapefruit seed extract is merely due to the synthetic preservative agents contained within. Natural products with antimicrobial activity do not appear to be present.
From the United States Department of Agriculture’s site (bold text is my emphasis):
Identification of Benzalkonium Chloride in Commercial Grapefruit Seed ExtractsSubmitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Date: August 12, 2005
Citation: Takeoka, G.R., Dao, L.T., Wong, R.Y., Harden, L.A. 2005. Identification of Benzalkonium Chloride in Commercial Grapefruit Seed Extracts. Journal of Agricultural and Food Chemistry. 53:7630-7636.“In this study we identified a new synthetic adulterant, benzalkonium chloride, in commercial GSE samples. This ingredient is a synthetic antimicrobial agent that is widely used in cleaning and disinfection agents. The presence of benzalkonium chloride in a commercial product designated for internal and external use by humans is troubling in light of its toxicity and allergenicity.”
From the Food and Drug Administration’s site (bold text is my emphasis):
Chapter VI
Microbiological Safety of Controlled and Modified Atmosphere Packaging of Fresh and Fresh-Cut Produce
“Antimicrobial compounds have also been used with traditional films such as low-density polyethylene (LDPE); for example, the fungicide Imazalil (IM) and the antimicrobial grapefruit seed extract (GFSE) have recently been used with bell peppers and lettuce, respectively (Miller and others 1984; Han 2000)…”
“…Lee and others (1998) investigated the ability of GFSE with LDPE films to inhibit growth of E. coli, Staphylocuccus aureus, molds, yeasts, and lactic acid bacteria, using the plate disk test. Films containing 1.0% GFSE in LDPE film inhibited E. coli and S. aureus as demonstrated by a clear zone; however, molds, yeasts and lactic acid bacteria were unaffected…”
“…Grapefruit seed extract is reported to be inhibitory to a number of human pathogens. There has been evidence, however, that any antibacterial activity of commercial preparations is due to the various preservative agents (triclosan, methyl parabene, benzethonium chloride) contained within the product. Researchers have found that products not containing any preservatives and several self-made preparations had no antimicrobial activity (Woedtke and others 1999). In the aforementioned study by Lee and others (1998), the composition of the GFSE incorporated in the film was not discussed or examined. It is obvious that if pure GFSE is to be used, its antimicrobial properties will have to be fully investigated. If the active antimicrobial ingredients in commercial GFSE preparations are preserving agents, they may be better targets for investigation.”
From the National Center for Biotechnology Information’s site, 2006 tests that again revealed preservatives:
Institute of Pharmacy, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria. markus.ganzera@uibk.ac.at
Grapefruit seed extracts are used in cosmetics, food supplements, and pesticides because of their antimicrobial properties, but suspicions about the true nature of the active compounds arose when synthetic disinfectants such as benzethonium or benzalkonium chloride were found in commercial products. The HPLC method presented herein allows the quality assessment (qualitative and quantitative) of these products for the first time. On the basis of a standard mixture of 18 preservatives most relevant for food and grapefruit products, a method was developed allowing the baseline separation of all compounds within 40 min. Optimum results were obtained with a C-8 stationary phase and a solvent system comprising aqueous trifluoroacetic acid, acetonitrile, and 2-propanol. The assay was fully validated and shown to be sensitive (LOD < or= 12.1 ng on-column), accurate (recovery rates > or = 96.1%), repeatable (sigma(rel) < or = 3.5%), precise (intra-day variation < or = 4.5%, interday variation < or = 4.1%), and rugged. Without any modifications the method could be adopted for LC-MS experiments, where the compounds of interest were directly assignable in positive ESI mode. The quantitative results of several products for ecofarming confirmed previous studies, as seven out of nine specimens were adulterated with preservatives in varying composition. The samples either contained benzethonium chloride (2.5-176.9 mg/mL) or benzalkonium chloride (138.2-236.3 mg/mL), together with smaller amounts of 4-hydroxybenzoic acid esters, benzoic acid, and salicylic acid.
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