Boston scientists are launching a major study to finally answer the question on the lips of many chocoholics: Do components of dark chocolate protect the heart?
Brigham and Women’s Hospital researchers will announce Monday that they will lead a $20 million industry-funded clinical trial to test whether cocoa flavanols can reduce heart attacks, strokes, and heart disease deaths in 18,000 healthy people across the country.
The five-year study will also be the first to try to determine whether women who take a typical multivitamin — containing the daily recommended amounts of more than 20 vitamins and minerals — develop fewer cancers than those who take placebos.
The only previous large trial to test multivitamins for cancer prevention, also conducted at the Brigham, involved just men. This time, the researchers said two-thirds of the participants would be women, in an effort to help plug a gap in women’s health research highlighted earlier this month in a report released by the hospital.
“We’ll be contacting women age 65 and older who participated in the Women’s Health Initiative trial,” Manson said.
Men age 60 and older will be recruited from a pool who volunteered for but were unable to join a trial of vitamin D and fish oil supplements, another study led by Manson that is underway.
Nutrition researchers not involved in the new trial reacted enthusiastically to the possibility of learning once and for all whether taking a daily multivitamin can help healthy people avoid cancer and whether cocoa flavanols would live up to the heart-protective promise seen in small clinical trials of short duration.
A 2012 analysis of 42 small clinical trials involving a total of nearly 1,300 patients found that eating cocoa flavanols in chocolate, cocoa, or supplements for a few weeks or months had beneficial effects on blood pressure, insulin, and cholesterol levels with no side effects.
“I’m 90 percent certain they’ll find something beneficial with cocoa flavanols,” said Eric Ding, a nutrition researcher at the Harvard School of Public Health. “For multivitamins, it’s really hard to say. I’m in the camp where I do think they have some benefit, but I’m not sure the study will be long enough to really see if cancers can be prevented.”
The earlier study of multivitamins in men found that those who took multivitamins for nearly 15 years had only a slightly lower risk of getting cancer compared with a placebo group. The benefits were larger for men over 70, who had an 18 percent lower risk of getting cancer, according to Manson, who helped conduct the research published two years ago in the Journal of the American Medical Association.
Based on that finding and a handful of smaller studies, a large government-sponsored task force concluded last month that there was insufficient evidence to recommend for or against taking multivitamins for cancer prevention. “I think it’s terrific and really exciting that this study will be done; it’s exactly the kind of research that we called for,” said Dr. Virginia Moyer, chairwoman of the group, which is called the US Preventive Services Task Force.
But some scientists expressed concern over the Brigham study’s funding source: mainly industry. Mars, Inc. will donate the cocoa extract capsules and funds to cover the researchers’ expenses, and a vitamin manufacturer, still to be determined, will donate the multivitamins.
Clinical trials with industry sponsorship are “more likely to report favorable results,” said Dr. Beatrice Golomb, a professor of medicine at the University of California San Diego whose research has found an association between eating chocolate and lower body weight.
The National Institutes of Health is also expected to provide some of the funding, but that has not yet been secured, according to Howard Sesso, co-leader of the study at Brigham. “These types of trials can’t be done unless they have a collaboration with industry,” Sesso said, “since the cost of the pills and packaging can become quite prohibitive.”
He said that industry representatives will have no input on the study design and no involvement in the writing of the manuscript.
Golomb said it was “disappointing” that participants in the study would be given cocoa extract pills instead of actual chocolate. “I’m also generally an advocate of eating whole foods.”
Cocoa supplements were chosen over chocolate, Manson said, to prevent weight gain from excess calories.
Older people, in particular, may have a hard time absorbing adequate nutrients from their diet, so a daily multivitamin may prove useful to meet certain deficiencies. Still, she added, “a multivitamin should never be used as a substitute for a healthful and balanced diet” because whole grains, fruits, and vegetables contain nutrients beyond vitamins and minerals and probably play a far bigger role in cancer prevention.
Participants will be randomly chosen to be mailed either blister packs of cocoa extract and multivitamin pills or of placebos for one or both for at least four years. They will agree not to take multivitamins on their own and will grant the researchers access to their medical records; 1,500 participants will have blood samples taken and analyzed.