Grapefruit Seed Extract

What does it do? Grapefruit seed extract (GSE) has been shown to exert significant antibiotic effects in test tube studies.1 2 However, one study concluded that these effects were due to the chemical preservatives used to stabilize the grapefruit seed extract rather than to any particular compound found in the extract.3

Human research using grapefruit seed extract is very limited. In one study, 25 patients with symptoms associated with irritable bowel syndrome such as intermittent diarrhea, constipation, flatulence, bloating, and abdominal discomfort were treated with either 2 drops of a 0.5% oral solution of grapefruit seed extract twice daily or 150 mg of encapsulated grapefruit seed extract three times daily.4 After one month, symptoms had improved in 20% of those taking the liquid, while all of the patients taking capsules noted definite improvement of constipation, flatulence, abdominal discomfort, and night rest. These results need confirmation in double-blind studies.

Where is it found? Grapefruit seed extract is available in liquid concentrate and in capsules and tablets.

Grapefruit seed extract has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
1Star Irritable bowel syndrome
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? Grapefruit seed extract is not an essential nutrient and no deficiency states have been reported.

How much is usually taken? The typical recommendation for the liquid concentrate is 10–12 drops in 6–7 ounces of water one to three times daily. For capsules and tablets containing dried grapefruit seed extract, the usual recommendation is 100–200 mg one to three times daily.

Are there any side effects or interactions? No side effects are known. The effects of grapefruit seed extract during pregnancy and breast-feeding have not been sufficiently evaluated.

At the time of writing, there were no well-known drug interactions with grapefruit seed extract.

References:

1. Ionescu G, Kiehl R, Wichmann-Kunz F, et al. Oral citrus seed extract in atopic eczema: in vitro and in vivo studies on intestinal microflora. J Orthomol Med 1990;5:155–8.

2. Xiong H, Li Y, Slavik MF, Walker J. Spraying chicken skin with selected chemicals to reduce attached Salmonella typhimurium. J Food Prot 1998;61:272–5.

3. von Woedtke T, Schluter B, Pflegel P, et al. Aspects of the antimicrobial efficacy of grapefruit seed extract and its relation to preservative substances contained. Pharmazie 1999;54:452–6.

4. Ionescu G, Kiehl R, Wichmann-Kunz F, et al. Oral citrus seed extract in atopic eczema: in vitro and in vivo studies on intestinal microflora. J Orthomol Med 1990;5:155–8.