The Manao (Lime) Project - Update Report - August, 2004

The Lemon and the Lime (Lime is Manao in Thai) have always been synonymous with good health - hence the Latin name Citrus medica. In the 18th century James Lind, a Scottish doctor, showed that limes would prevent scurvy, thus saving the lives of hundreds of thousands of sailors, and earning the British the nickname "Limeys."

At about that time, women living around the Meditteranean discovered that lemon juice, soaked in a piece of sponge and put into the vagina before sex, was outstandingly successful as a contraceptive. Maybe lemon or lime juice (when there are no lemons available) would be useful for women in today's world, as a cheap and readily available contraceptive. Initial evidence also suggests that the juice might even act as a protection against sexually transmitted diseases, INCLUDING HIV.

As the HIV pandemic continues to spread, especially in developing countries, we are discovering that young women are becoming infected at a much higher rate than young men. Social circumstances often force them to have sex with older, infected men, and it may be impossible for them to insist on condom use. Therefore, they need their own personal protection, such as a microbicide that will kill HIV in the vagina before it has a chance to infect them. And it must be readily available, cheap and safe.

Could lemon or lime juice act as both a contraceptive, AND also as a microbicide?

The scientific evidence is beginning to look encouraging. The contraceptive effect of lemons and limes is due to the acidity of the juice, which very rapidly immobilizes the sperm, thus making it impossible for them to burrow into the egg and fertilize it. If ONE volume of the juice is added to FOUR volumes of semen, all the sperm are permanently immobilized in less than 30 seconds!

A number of sexually transmitted disease organisms, such as syphilis, gonorrhoea, chlamydia and HIV, are also known to be killed by acidity below a pHof 4, so there is the exciting possibility that intravaginal lemon or lime juice might also protect women against these infections.

The acidity of the juice is mainly due to its citric acid content. Citric acid is one of the body's natural metabolites, and is also present in human semen - although not in high enough concentrations to damage the sperm. Thus, citric acid is no stranger to the human body.

How safe would it be for a woman to use the juice in her vagina repeatedly?

We have carried out a controlled trial in a group of 6 macaque monkeys given undiluted lime juice intravaginally once a day for a month and then examined their reproductive tracts under the microscope; we could find no differences from the untreated control animals.

These reassuring negative findings suggest that it is safe to proceed with human clinical trials of intravaginal lemon juice.

Would the juice hurt?

Men and women who have applied undiluted lemon juice to the penis or vagina say that it usually causes no pain or discomfort. However, if lesions produced by some sexually transmitted diseases were present, it might be painful, giving a warning that you need to go to a doctor for treatment - a cheap diagnostic aid.

Are limes and lemons readily available and cheap?

They originated in India. China and S.E. Asia, and today are grown throughout the tropical and temperate regions of the world, but they will not withstand frost.

In South Africa you can buy 5 lemons for the cost of just one condom.

Since you probably only need 3 milliliters of juice (a teaspoonful) in the vagina per act of intercourse, one lemon can go a long way.

And lemon juice doesn't damage latex condoms.

How can we determine if the juice is an effective contraceptive?

The laboratory research, which has been carried out in Melbourne, Australia, is almost complete. Encouraged by the results, the Thai Ministry of Public Health and the Population and Community Development Association (PDA) have adopted the Manao Project as it's known, and are planning the human clinical trials of acceptability, safety and contraceptive efficacy to be carried out in Thailand.

How soon can we find out if the juice really does protect women from sexually transmitted diseases and HIV infection?

Here, we have had a stroke of good luck.

Nigerian doctors have discovered that in the cities of Kano and Jos, many female prostitutes have been using pre-or post-coital vaginal washes with lime or lemon juice for years, in the belief that it may protect them from pregnancy and sexually transmitted diseases.

By setting up properly controlled clinical trials in current users, this will give us some invaluable clues about efficacy, and make it much easier to design ethically acceptable microbicidal trials in Thailand.

So what next?