Can Coca-Cola be used as a contraceptive?

Dear Cecil: I heard a weird radio news report a while back about some college medical researchers who had done a study on Coca-Cola being used as a contraceptive. Can this be? The researchers claimed that several third world countries use it and it works. Also, they did a study of the various Cokes out on the market and found that new Coke was not as effective as old Coke and Diet Coke was better than both. Is this true? What college did the research, and how do you go about using Coke as a contraceptive? Illinois Smith, Chicago

Cecil replies:

A lot of research on contraceptive techniques is done at colleges, Smitty. Some of it is even done in the labs.

The Coke bulletin was issued by three researchers at the distinguished Harvard Medical School, and published last November in the equally distinguished New England Journal of Medicine, surrounded by articles on such topics as “Retinoic Acid Embryopathy” and “Aldosterone-Receptor Deficiency in Pseudohypoaldosteronism.” It consists of four paragraphs plus a table. From these we may glean the following: “Postcoital douching with household substances was a popular form of contraception at the beginning of this century, and Coca-Cola is still said to be used in developing countries for this purpose.” The Fugs, if I remember correctly, did a song on this subject once. Great group, the Fugs. Gave new meaning to the expression “seminal influence.”

Our authors go on: “There has recently been controversy over the attributes of old-formula (“Classic’) Coke and those of “New Coke.’ We therefore compared the effect of various modern formulations of Coca-Cola on sperm motility.” (Motility basically means the sperm’s swimming ability.) The results were dramatic. “All samples of Coca-Cola markedly reduced sperm motility, whereas [a saltwater control solution] had no spermicidal effect.” Old Coke was five times as potent as new Coke, and Diet Coke was the most potent of all, annihilating all in its path. That may give you pause next time you’re tempted to chug down a frosty one.

The Harvard folks conclude, “The effectiveness of Coca-Cola as a spermicidal agent in vaginal douching has been attributed to its acidic pH.” However, since the various types of Coke had similar acidity, some other factor must be at work to account for the observed differences. The researchers don’t speculate on what this might be. I blame the NutraSweet.

I should point out that the experiments were conducted in test tubes, rather than in vivo, if you follow me. Postcoital contraceptive douching in general isn’t especially effective because the sperm travel pretty fast. Still, I suppose if you were a woman waking up after a particularly rambunctious evening to find the Incredible Hulk snoring beside you … well, any port in a storm.

I should also underscore the preliminary nature of the study. The researchers didn’t test the effectiveness of common beverages such as Mr. Pibb, Mello Yello, or Cherry-Ola Cola, which limits the usefulness of their work. You wouldn’t want to be condemned to an unwanted pregnancy simply because of an unfortunate choice of soft drink.

Nonetheless, Harvard has opened up some interesting possibilities here. One can envision the day when the contraceptive properties of a brand might become an integral part of its marketing strategy, e.g.:

CONTRA-COLA

Kills Sperm by the Million on Contact

… and tastes great too

The potential, clearly, is huge.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.