Grapefruit seed extract
Extract derived from grapefruit seeds

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, and glycerin blended together.[1] GSE is sold as a dietary supplement and is used in cosmetics.[2]

Grapefruit history

The grapefruit is a subtropical citrus tree grown for its fruit which was originally named the "forbidden fruit" of Barbados.[3] The fruit was first documented in 1750 by Rev. Griffith Hughes when describing specimens from Barbados.[4] All parts of the fruit can be used. The fruit is mainly consumed for its tangy juice.[5] The peel can be processed into aromatherapy oils[6] and is also a source of dietary fiber.[7] The seed and pulp, as byproducts of the juice industry, are retrieved for GSE processing[8] or sold as cattle feed.[9]

Efficacy

Despite claims that GSE has antimicrobial effects,[10] there is no scientific evidence that GSE has such properties.[11][8] Some evidence indicates that the suspected antimicrobial activity of GSE was due to the contamination or adulteration of commercial GSE preparations with synthetic antimicrobials or preservatives.[1][2][12] These chemicals were not present in grapefruit seed extracts prepared in the laboratory, and GSE preparations without the contaminants were found to possess no detectable antimicrobial effect.[1] Although citrus seed extract is sold in health food markets,[12] there is no good evidence for any antimicrobial activity.[1]

Phytochemicals

Analysis shows the phytochemicals of the seed extract and pulp are flavonoids,[13][14] ascorbic acid (vitamin C), tocopherols, citric acid, limonoids,[15][16] sterols, and minerals.[17]

Preparations

GSE is prepared by grinding the grapefruit seed and juiceless pulp, then mixing with glycerin.[1] Commercially available GSE is made from the seed, pulp, glycerin, and synthetic preservatives all blended together.[1]

Health claims and safety concerns

Although various health claims for using GSE are marketed in the dietary supplement industry, there is no scientific evidence from high-quality clinical research that it has any health effects, as of 2018.[8][11] Phytochemicals in grapefruit seeds, particularly furanocoumarins and flavonoids, may cause adverse effects on health resulting from grapefruit–drug interactions that influence the intended therapeutic effects of some 85 prescription drugs.[11][18] The main safety concern about GSE is inhibition of the liver enzyme, cytochrome P450, which controls liver metabolism of drugs; consequently, its inhibition by GSE unpredictably increases the blood concentrations of prescribed drugs.[18]

References

  1. ^ a b c d e f g h von Woedtke T, Schlüter B, Pflegel P, Lindequist U, Jülich WD (June 1999). "Aspects of the antimicrobial efficacy of grapefruit seed extract and its relation to preservative substances contained". Pharmazie. 54 (6): 452–6. PMID 10399191.
  2. ^ a b Ganzera M, Aberham A, Stuppner H (May 2006). "Development and validation of an HPLC/UV/MS method for simultaneous determination of 18 preservatives in grapefruit seed extract". J. Agric. Food Chem. 54 (11): 3768–72. doi:10.1021/jf060543d. PMID 16719494.
  3. ^ Dowling, Curtis F.; Morton, Julia Frances (1987). Fruits of warm climates. Miami, Fla: J.F. Morton. pp. 152–8. ISBN 978-0-9610184-1-2.
  4. ^ Michael Quinion. World Wide Words: Questions & Answers; Grapefruit. 2009.
  5. ^ Fellers PJ, Nikdel S, Lee HS (August 1990). "Nutrient content and nutrition labeling of several processed Florida citrus juice products". J Am Diet Assoc. 90 (8): 1079–84. doi:10.1016/S0002-8223(21)01704-1. PMID 2380455. S2CID 25833812.
  6. ^ Worwood, Valerie Ann (1991). The complete book of essential oils and aromatherapy. Novato, Calif: New World Library. ISBN 978-0-931432-82-8.
  7. ^ Cerda JJ, Robbins FL, Burgin CW, Baumgartner TG, Rice RW (September 1988). "The effects of grapefruit pectin on patients at risk for coronary heart disease without altering diet or lifestyle". Clin Cardiol. 11 (9): 589–94. doi:10.1002/clc.4960110902. PMID 3229016. S2CID 45520617.
  8. ^ a b c Scott Gravura (10 March 2016). "Not natural, not safe: Grapefruit seed extract". Science-based Medicine. Retrieved 17 November 2018.
  9. ^ Arthington JD, Kunkle WE, Martin AM (July 2002). "Citrus pulp for cattle". Vet. Clin. North Am. Food Anim. Pract. 18 (2): 317–26, vii. doi:10.1016/S0749-0720(02)00023-3. PMID 12235663.
  10. ^ Cvetnić Z, Vladimir-Knezević S (September 2004). "Antimicrobial activity of grapefruit seed and pulp ethanolic extract". Acta Pharm. 54 (3): 243–50. PMID 15610620.
  11. ^ a b c "Grapefruit". Drugs.com. 15 January 2018. Retrieved 17 November 2018.
  12. ^ a b Takeoka GR, Dao LT, Wong RY, Harden LA (September 2005). "Identification of benzalkonium chloride in commercial grapefruit seed extracts". J. Agric. Food Chem. 53 (19): 7630–6. doi:10.1021/jf0514064. PMID 16159196.
  13. ^ Drewnowski A, Gomez-Carneors C (2000). "Bitter taste, phytonutrients, and consumer: a review". Am. J. Clin. Nutr. 72 (6): 1424–35. doi:10.1093/ajcn/72.6.1424. PMID 11101467.
  14. ^ Tirillini B (2000). "Grapefruit: the last decade acquisitions". Fitoterapia. 71: 29–37. doi:10.1016/S0367-326X(00)00176-3. PMID 10930710.
  15. ^ Bennett RD, Hasegava S, Herman Z (1989). "Glucosides of acidic limonoids in citrus". Phytochemistry. 28 (10): 2777–81. Bibcode:1989PChem..28.2777B. doi:10.1016/S0031-9422(00)98087-7.
  16. ^ Ohta H, Fong CH, Berhow M, Hesegawa (1993). "Thin-layer and high-performance liquid chromatographic analyses of limonoids and limonoid glucosides in citrus seeds". J. Chromatogr. 639 (2): 295–302. doi:10.1016/0021-9673(93)80266-B.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ^ Tushiswili LS, Durmishidze SV, Sulaberidze KV (1983). "Sterols of grapefruit, orange, mandarin pulps (Citrus paradisi, Citrus sinensis, Citrus unshiu)". Chemistry of Natural Compounds. 18: 445–7. doi:10.1007/BF00579640. S2CID 4814220.
  18. ^ a b Bailey, D. G.; Dresser, G.; Arnold, J. M. O. (2012). "Grapefruit-medication interactions: Forbidden fruit or avoidable consequences?". Canadian Medical Association Journal. 185 (4): 309–316. doi:10.1503/cmaj.120951. PMC 3589309. PMID 23184849.
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