Potentially contradictory findings on whether lemon and lime juice could safely protect women from HIV infection if they apply it to their vaginas will be presented at an international conference later this month.
Researchers from the CONRAD programme at the Eastern Virginia Medical School, United States are expected to present evidence that lemon or lime juice can damage the cells of the vagina.
Another US-based team, from the University of Berkeley, will suggest however that lime juice is safe if it is used in low concentrations.
Historical documents show that through the centuries, women have used acidic solutions such as vinegar as a contraceptive.
But in the past few decades, research has suggested that the acidic juice of lemons and limes could also function as a microbicide — a product that women apply to their vaginas to protect themselves from HIV infection.
Studies show that this practice is already common among sex workers in Nigeria, and anecdotal evidence suggests it also takes place in other African countries.
But the safety and efficacy of using lime juice has not yet been proven scientifically, and some researchers are concerned that women could begin using lemon and lime juice with potentially harmful effects.
In February, Carol Lackman-Smith of the Southern Research Institute, United States, presented data at a conference showing that 50 per cent solutions of the juices damaged the cells that line the vagina.
The CONRAD team is expected to confirm the finding at this month's Microbicides 2006 conference in Cape Town, South Africa.
According to the team's preliminary results, most women who applied pure or 50 per cent dilutions of lime juice to their vaginas later showed signs of damage to the vaginal tissues.
Lackman-Smith says there are grounds to be concerned about the safety of using lime or lemon juice.
However, Anke Hemmerling of the University of Berkeley will present results in Cape Town that suggest that weaker dilutions of 10-20 per cent cause little, if any, damage to the lining of the vagina.
Hemmerling says the difference could be because it is difficult to assess the extent of vaginal damage.
The prospect of using lemon or lime juice as a microbicide is also complicated by the fact that sperm reduces the overall acidity inside the vagina.Previous research by Robin Shattock of Imperial College in the United Kingdom shows that in the presence of sperm, anything weaker than a 50 per cent solution of juice does not efficiently inactivate HIV.