Does Mountain Dew Kill Sperm?

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A shocking bit of misinformation has captured the hearts and minds of high school and college students of late — the notion that the popular caffeinated soft drink Mountain Dew can be used as a contraceptive.

If Internet chatter is any indication, it is widely believed among people that drinking Mountain Dew "kills sperm cells" or, at minimum, drastically lowers a male's sperm count. There are some who fear it may cause impotency, while others seem to view it as a cheap and easy method of birth control.

Analysis of the Myth: Does Mountain Dew Kill Sperm?

Lest you think we're joking, in 1999 the Wall Street Journal reported that in the fall of that year this factoid "boomeranged across the country from Oregon to Washington, D.C., and from Texas to Montana." Its currency continues to perplex health care officials, not to mention PepsiCo, the manufacturer of the allegedly spermicidal soft drink.

"This is an urban myth," says Jonathon Harris, a public affairs manager in the company. He likens it people believing Elvis is still alive and claiming to have bumped into him in a convenience store — i.e., not merely false, but, in Harris's words, "absurd, unfounded and ridiculous."

True believers attribute the soft drink's purported sperm-killing properties to its relatively high caffeine content (55 mg. per 12 oz. can, versus 45.6 mg. in Coke and 37.2 mg. in Pepsi) and/or the presence of a coloring agent named Yellow Dye No. 5, but there's nothing in the scientific literature to support either claim. The FDA determined long ago that Yellow Dye No. 5 poses no physiological threat to non-allergic people, and, as for caffeine, there's evidence to suggest it actually increases the motility and efficacy of sperm cells, not the opposite.

These misconceptions date back to the mid-1990s, if not further. Variations on the theme have included such claims as Mountain Dew "causes your testicles to shrink" or "shrivels your penis." Where these ideas came from is unclear, but they echo stories going even further back in time (a decade or more) to the effect that certain companies allegedly owned by the Ku Klux Klan or other racist organizations purposely add sterility-inducing ingredients to foods and beverages popular with African Americans.

Growth of the Rumor

The Dew rumor's current growth spurt may be partially due to a surge in the popularity of the product itself. According to figures compiled by Beverage Digest, as of this writing Mountain Dew is the fastest-growing soft drink in the U.S.

As we mentioned earlier, the spread of these tall tales among young people has some health care officials worried. The state of Wisconsin, to name one governmental authority, has warned parents that the notion that Mountain Dew functions as a spermicide could spark a rise in the number of unwanted pregnancies. Marjorie Saltzman, a longtime Planned Parenthood volunteer in Portland, Oregon, has lobbied PepsiCo to address the misinformation through advertising or special warning labels — so far without success, she says. For its part, the company claims it has never received a consumer inquiry or complaint in connection with the rumor.

To its credit, PepsiCo has responded forthrightly to questions from the press, but Pepsi's PR folks would do well to resist the temptation to adopt a dismissive attitude toward the urban legend. Granted, it's a "schoolyard tale" with no foundation in fact — comparable to Elvis sightings and the like — but bumping into a dead pop star at the neighborhood 7-11 has never, to my knowledge, resulted in an unwanted pregnancy.

Just because an idea is silly, that doesn't mean it's harmless.