Vegetarians are more likely to produce equol--a substance that may play a role in cancer prevention.

People differ in how they metabolize soy products. Between 20 and 35 percent of Western adults are able to produce a substance called equol when they consume soyfoods. Bacteria in the intestines produce equol. Equol production is higher in those living in Asian countries, where 50 to 55 percent of adults are equol producers. There may be health advantages to producing equol, although research in this area is preliminary. Equol may play a role in preventing some cancers and may function as an antioxidant.

Do vegetarians have an edge when it comes to equol production? Apparently, they do. A group of 41 adults, 29 of whom said they were vegetarian, was given a soymilk drink twice daily for three days. Equol production was measured. Vegetarians were more than four times as likely to produce equol compared to non-vegetarians. Close to 60 percent of vegetarians produced equol. Diets of study participants were not assessed, so we cannot know if dietary differences in carbohydrate, protein, or fat were associated with the results. Although the vegetarians were more likely to have used soy products before this study, other studies have found no link between long-term soy food use and the ability to produce equol.

By Reed Mangels, PhD, RD, FADA 

Setchell KDR, Cole SJ. 2006. Method of defining equol-producer status and its frequency among vegetarians. J Nutr 136:2188-93.