The use of lubricants may make anal sex more comfortable, but they may also increase the risk of spreading sexually transmitted infections, including HIV, researchers said Tuesday. Many experts have been concerned about the potential effects of such lubricants, but there have previously been virtually no studies about how they affect disease.
In the United States, as many as 90% of gay men practice anal sex, according to International Rectal Microbicides Advocates, a group that has been lobbying for the development of microbicides — chemical agents that can kill HIV during sexual acts. Estimates in the U.S. also suggest that as many as 35% of women have participated in anal sex at least once. The majority of both sexes are thought to use lubricants to ease penetration.
Epidemiologist Pamina H. Gorbach of UCLA's Geffen School of Medicine and her colleagues studied 879 men and women between October 2006 and December 2008. The participants were tested for gonorrhea and chlamydia and queried about their sexual behavior in private, computer-based interviews, which have been shown to elicit more truthful answers than face-to-face interviews. Of the 879 participants, 229 men and 192 women reported having receptive anal intercourse in the past year, and about half said they used lubricants. When the team analyzed the data, Gorbach told a Pittsburgh microbicides meeting, they found that those who used lubricants were three times as likely to have contracted a rectal infection.
A partial explanation for the increased risk may have been provided by Charlene Dezzutti, a reproductive science specialist at the University of Pittsburgh, and her colleagues. They studied the effects of six of the most popular lubricants on rectal cells and tissues in laboratory dishes.They found that many of the products had high concentrations of dissolved salts and sugars that draw water out of cells, weakening and even killing the cells. Some of them even stripped away significant portions of the surface epithelial cells on the rectal tissue, the layer of cells that serves as a protective barrier. They also studied the effect of the lubricants on beneficial bacteria in the rectum.
Two of the six lubricants, PRE and Wet Platinum, were shown to be safest for the cells, while Astroglide was the most toxic to cells and tissue. KY Jelly had the worst effect on rectal bacteria, essentially wiping out the entire colony. ID Glide and Elbow Grease had intermediate effects, the team found. None of the lubricants was found to have measurable anti-HIV activity.
The team now plans to investigate the effect of the lubricants on HIV infections.
-- Thomas H. Maugh II