The National Institutes of Health funded a study employing 25,871 healthy American men and women aged 50 or over, including 5106 African Americans. The study participants were divided into four groups and randomly assigned to taking supplements or placebo, and they were observed for an average of 5.3 years.
One group received 2,000 IU (international units) of vitamin D3 and 1 gram of omega-3 each day. The second group received vitamin D and instead of pills omega-3 instead of pills. The third group received omega-3 and a placebo with vitamin D. The last group received two placebo.
Pharmavite LLC from Northridge, California, donated vitamin D and a suitable placebo, and Pronova BioPharma from Norway and BASF donated Omacor, a fish oil sold under the Lovaza brand in the United States.
The results, published in The New England Journal of Medicine, are presented on Saturday at the American Heart Association conference in Chicago.
In many respects, the results are not surprising. The public has been attacked by a steady stream of information about the health benefits of vitamin D in recent years because research has linked low vitamin levels to conditions as diverse as diabetes, high blood pressure, cancer, heart disease and depression. Many primary care physicians routinely test vitamin D levels in patients and declare their deficiency, and the sale of supplements has risen sharply in recent years.
All the time, however, critics have questioned whether vitamin D is only an indicator of overall health and whether the threshold for deficiency has been set too high. The so-called solar vitamin is synthesized in the body when the skin is exposed to sunlight and is exhausted by smoking, obesity, poor nutrition and other factors. Some foods such as fatty fish, eggs and fortified milk also contain vitamin D.
Institute of Medicine in 2011. He concluded that most Americans get enough vitamin D, and the shortages have been overstated. The group also noted that reports of potential benefits associated with higher blood levels were inconsistent.