It's the Salsa, Stupid

With all the hullabaloo about the E.coli at Taco Bell, we’re reminded of a piece we ran in September 2002 that first appeared in New Scientist magazine. It bears repeating now.

If you want to know why you’re getting Montezuma’s revenge when you travel to Mexico and elsewhere, the answer is at Carlos and Charlie’s in the salsa, jalapeno sauce and guacamole.

Researchers from the University of Texas found E. coli in two-thirds of the condiments they tested from Mexico. The levels of contamination averaged one thousand times more than what they measured in restaurants in Houston.

The bugs come from human feces via unwashed hands and hand-picked, unwashed vegetables from the field, says Herbert DuPont, chief of internal medicine at St. Luke’s Episcopal Hospital in Houston. “Most people think it’s the water, but it’s not.” He has found that bad food is responsible for about 90 percent of traveler’s diarrhea.

DuPont’s team collected samples of 71 sauces from 36 restaurants in Guadalajara and compared them with 25 sauces served in 12 Mexican-style restaurants in Houston. E. coli was present in 66 percent of the sauces from Guadalajara and 40 percent of those collected in Houston. While none of the Houston samples contained dangerous strains of E. coli, sauces from Mexico commonly contained two that wreak havoc in the gut. One, found in 9 percent of the samples, releases a toxin, and the other, found in 44 percent, causes inflammation.

The Mexican restaurants in Houston are probably safer because they serve their condiments either freshly made or from the refrigerator. In Mexico, the same sauces sit on the table all day. Not only are they unrefrigerated, but many diners stick their fingers in them while dipping their chips, says DuPont.