From www.microbicide.org/publications/index.html.

Alliance for microbicide Development News Digest
Volume 7, Number 14, 07 April 2006 (pdf)

New data suggest safety concerns regarding use of lemon and lime juice

New data regarding the potential impact of using lemon or lime juice vaginally was presented at a special panel convened as part of the Alliance for Microbicide Development’s annual meeting on March 28, 2006. Carol Lackman-Smith presented the results of a pre-clinical study conducted by Southern Research Institute (US); research that was previously presented at the Conference on Retroviruses and Opportunistic Infections in Denver in February[i].

Lackman-Smith and her colleagues conducted pre-clinical research to compare the cytotoxicity (cell-damaging effect) and anti-HIV activity of lemon and lime juice to that of the spermicide Nonoxynol-9 (N-9). When tested on cervical explant tissue (cells obtained from routine hysterectomies that have been kept alive in lab cultures), results indicated that the lemon and lime juices caused damage to cells comparable to that of N-9. Additional results showed that the concentration of lemon or lime juice that induced cell damage was equivalent to the concentration needed to inhibit HIV replication. Thus, when the concentration was reduced to a point where no cell damage occurred, there was little or no effect on HIV replication. Finally, the authors noted that even a 20% concentration of either lemon or lime juice had the effect of inhibiting Lactobacilli, naturally-occurring bacteria that help keep the vagina healthy.

These findings suggest that we should be concerned about whether lemon or lime juice is safe for use as a vaginal microbicide. Since N-9 has already been ruled out as a candidate microbicide because of its tendency to cause cell damage with repeated use, it seems unlikely that a product causing even more irritation than N-9 would be a good candidate. In a separate study, Dr. Robin Shattock of St. George’s Hospital, London, has shown that lemon and lime juice may well be irritating to cells in the penis and male urethra[ii].

This concern about safety is further supported by preliminary findings presented by Christine Mauck of CONRAD in Arlington, Virginia (US). Dr. Mauck and colleagues have just concluded a clinical trial in which 48 sexually abstinent women volunteers used lime juice vaginally. Divided into four treatment groups, they used 100%, 50% and 25% concentration of juice, and one group used plain water as a control. Each group inserted their assigned test fluid twice daily for six consecutive days during two menstrual cycles. In one cycle, it was inserted via a douche and, in the other, via a modified tampon soaked in the fluid.

The results of this safety trial are still being analyzed and will be presented at the Microbicides 2006 conference in Cape Town, South Africa at the end of April. Dr. Mauck reported, however, that the preliminary findings suggest a dose-dependent effect on the vaginal epithelium (cells lining the vagina) – meaning that the level of vaginal irritation and damage noted among the women using the 50% and 100% concentrations of lime juice was higher than that experienced by the women using the 25% concentration or plain water.

The studies performed at Southern Research Institute showed that juice concentrations less than 50% could result in the death of cells in culture. In addition, the preliminary clinical safety data suggest that the 50% and 100% juice concentrations may damage vaginal tissues. Taken together the laboratory and human testing data suggest the need for caution in the assumption or use of these juices as microbicides to prevent HIV transmission until a complete presentation of the analysis of the human testing is available. We will provide a more complete report of the CONRAD study after Microbicides 2006. Stay tuned!

[1] Carol Lackman-Smith*1, B Snyder1, K Luckenbaugh1, et al. “In vitro assessment of efficacy and cytotoxicity of natural substances proposed as vaginal microbicides against sexual transmission of HIV”. Poster presented at 13th Conference on Retroviruses and Opportunistic Infections, Paper 894, February 6, 2006.

[1] Robin Shattock, L Fischetti., P Fletcher P., et al. “Development of a human penile tissue explant model to evaluate safety and efficacy of Microbicide candidates”. Poster presented at IAS Conference on HIV Pathenogenesis and Treatment, Abstract no. MoPp0104, July 25, 2005