The effectiveness of two popular dietary supplements, vitamin D and fish oil, will be put to the test in a large, five-year U.S. government-sponsored study, the Associated Press reported.
The study is designed to determine whether either supplement reduces the risk of developing heart disease, cancer or stroke, as proponents claim.
One quarter of the participants will be black, the AP said, noting that dark-skinned people can't produce much vitamin D from sunlight. Some experts believe this is why blacks suffer higher rates of stroke, heart disease and cancer than whites.
Fish oil, or omega-3 fatty acid, is widely touted for improving heart health, but previous studies haven't established its safety or benefits.
Noting that other supplements, such as vitamins E and C, have fared poorly in recent tests, a study leader advised restraint. "We should be cautious before jumping on the bandwagon to take mega-doses of these supplements," said Dr. JoAnn Manson, who will co-lead the study with Dr. Julie Buring of Brigham and Women's Hospital in Boston, according to the AP.
Set to start later this year, the new study will include 20,000 older adults who will be assigned to take vitamin D, fish oil, both supplements or placebo pills, the AP said.