Use of Coke to Kill Sperm Prompts Tests : Medical Team Says Drinks Ineffective

Times Staff Writer

Ever since they made a marketing blunder of Edsel magnitude, it hasn’t been easy for the makers of Coca-Cola.

Now, as if the company didn’t already have enough problems with the ill-fated new formula for its flagship soft drink, researchers at no less than Harvard Medical School find New Coke fails in yet another respect--sperm-killing ability when used (foolishly) as a contraceptive douche.

And though this is not the sort of thing that could lead to a new version of the Pepsi Challenge, the researchers said they found marked differences in the ability of four different Coca-Cola formulations to act as a spermicide. At the same time, they warned against the use of soft drinks of any kind as douches after intercourse to prevent pregnancy. While there are differences among soft drinks, all fail as effective contraceptives, the researchers noted.


Rating of Beverages

Their measurements, though, said the members of the Harvard team, led them to conclude--in ways Coca-Cola may never have intended in its advertising--that of the two most widely sold forms of the drink, Classic Coke “is it.”

The variations in the Cokes’ spermicidal capabilities apparently have to do, the team reported, with some hidden nuance of the secret formula for what is now called Old Coke. The formula has been guarded jealously for decades.

The improbable conclusion about Coke--reached by three researchers who admitted they undertook the study as much because they thought the premise funny as anything else--is being published today in, of all places, the New England Journal of Medicine. “This is not Nobel Prize-winning work,” confided Dr. Sharee Umpierre, a Harvard research fellow in obstetrics and gynecology who headed the three-person team that included one other fellowship holder and a full professor.

Brought Guffaws

The new study brought guffaws from reproductive health experts across the country who agreed soda pop douches are not widely employed among young American women. But the same experts were divided on the extent to which such a belief has existed in medical folklore in the United States though unanimous in their opinion that douching to prevent pregnancy is totally ineffective.

“They must have strange people on the East Coast,” observed Dr. Larrian Gillespie, a Los Angeles urologist. “And they think California people are kinky. No way.”

But Dr. Gerald Bernstein, a USC expert, said he remembers the Coca-Cola douche as a fixture of Southern California teen-age life in the 1960s when, as a young intern and resident physician, he was aware soda pop was widely used as a contraceptive. “It was the thing you did on the beach,” Bernstein said.


A contraceptive technology expert at the federal government’s Centers for Disease Control in Atlanta issued a strong caution that even examining the question in jest could induce some American teen-agers to believe soda douches can avert pregnancy.

“I grew up in Texas and I never heard of this,” said the government expert, Dr. Nancy Lee. “My fear is that teen-agers and people who are not particularly well read may actually believe this.” There is one consistent reality about douches as contraceptives, agreed Lee and other experts: They simply don’t--in fact, can’t--work.

The Harvard team, which included Umpierre, Dr. Joseph Hill and Deborah Anderson, took up the question, they said in a brief report published as a letter to the editor, because they had become aware that in some underdeveloped countries--and, perhaps, even in certain U.S. population groups--a belief persists in the value of the Coca-Cola douche.

The entire study took less than an afternoon, Umpierre said. “We did not spend months thinking this up,” she recalled.

Test Tubes Prepared

To test the sperm-killing abilities of various Coca-Cola products, the three researchers prepared test tubes containing small samples of carefully preserved sperm and poured in small amounts of Diet Coke, New Coke, caffeine-free New Coke and Classic Coke--carefully repeating the test three times for each soda.

All of them killed some sperm, but New Coke turned out to be least effective, with Diet Coke having the most pronounced effect overall and Classic Coke recording a five times greater sperm-killing rate than its upstart rival. “Coca-Cola products do appear to have a spermicidal effect,” the study deadpanned. “Furthermore, our data indicate that, at least in the area of spermicidal effect, ‘Classic Coke’ ‘is it.’ ”


Despite these results, however, both the Harvard doctors and other experts questioned about the new study agreed that the serious medical purpose of such humor should be to call attention to the ineffectiveness of trying to douche for birth control after the fact. Even with Coke’s effectiveness as a spermicide established, the problem is that no douche can be administered quickly enough to prevent at least some sperm from migrating from the vagina to the uterus--some sperm have completed that journey within 90 seconds after intercourse.

Remarkable Resilience

No only that, but using Coke as a douche can’t ensure that--whatever the formula--the soda will reach all sperm that may remain in a woman’s reproductive system. Sperm not killed by any douche have a remarkable resilience and can remain alive and healthy for hours. There is also the fact that the force of introducing any douche is easily capable of pushing live sperm even closer to the uterus than they were.

Douching with a solution of vinegar and water has been relied on by some American women in the past for birth control purposes, Lee said, but the practice has all but faded from most popular use, she said, “thank goodness.”

Coca-Cola saw little humor in the Harvard project. A spokesman said the company hadn’t seen the new report, but “our position is we do not promote any of our products for any medical use.”

As for the Harvard researchers, Umpierre professed consternation when contacted by a reporter.

“Oh, my God,” she exclaimed, “I hope my mother doesn’t read this!”