Nutrients for Prevention: Negative Trials Send Researchers Back to Drawing Board

Extract

The dream of preventing cancer with a vitamin pill is rapidly evaporating. Over the past few months, results from clinical trials and observational studies report no benefit—and in a few cases, possible harm—from supplementation with several micronutrients, including vitamins C, D, and E; selenium; calcium; and folate.

The findings have sobered investigators in the field of chemoprevention and led to a wholesale reevaluation of the methods used to assess possible benefits of vitamins and minerals and to prioritize them for definitive testing.

“I think there is a lot of disappointment,” said Peter Gann, M.D., Sc.D., a physician–epidemiologist at the University of Illinois at Chicago who studies nutrition and cancer. “When these expensive trials were being designed, there was a lot of hope. Some pretty heavy bets were being placed on those interventions.”

In light of the results, investigators anticipate more laboratory work and smaller, exploratory human studies designed to probe exactly how vitamins and minerals affect tumor formation and growth. They also foresee more research geared toward determining whether certain subpopulations—say, those with a certain genetic profile—might still benefit from supplementation.