I don’t blame you for being confused about the news coverage of several large investigations on vitamin D and fish oil and another on a prescription brand of fish oil. All three were published in the New England Journal of Medicine in November 2018. The aim of the first two joint studies was to determine if omega-3 fatty acids (found in fish oil) and vitamin D supplements can help reduce the risk of heart attacks and cancer.
For vitamin D, results of the 5.3-year study showed that while it didn’t prevent cancer, it was associated with a reduced risk of death from the disease. Lead researcher, JoAnn Manson of Boston’s Brigham and Women’s Hospital, said that because cancer can take many years to develop, a study lasting longer than a decade might be needed to determine if the disease occurs less often in people taking vitamin D. None of the 25,871 participants, age 50 or older, had had cancer, a heart attack or a stroke when the study began. Some took 2,000 IU of vitamin D3 daily during the study plus one gram of omega-3s or placebos. Dr. Manson noted that vitamin D and omega-3s aren’t known to interact with each other in ways that would affect health.
The study results also showed that taking omega-3s for 5.3 years didn’t lower the risk of heart-related deaths or cancer. But they did show some benefits, including a 28 percent lower risk of heart attack among those taking the supplements. This risk dropped to 40 percent among those who ate little fish and fell by 77 percent among African Americans. Another interesting secondary finding: among those taking omega-3s, African-Americans had a greater reduction in risk of heart problems than whites, no matter how much (or how little) fish the African-Americans consumed. Be aware that omega-3s are essential fatty acids which means the body cannot make them, so they must be obtained from the diet. I recommend eating oily cold-water fish two to three times per week.
Dr. Manson’s team has also investigated the effects of vitamin D and omega-3S on diabetes, depression, autoimmune diseases and cognitive impairment. The results are expected in 2019.
A third trial looked at the effects of a prescription form of omega-3s (icosapent ethyl) in patients who were taking statins to prevent a first or subsequent cardiovascular event. Most of the study participants had atherosclerosis (hardening of the arteries) or diabetes plus at least one other cardiovascular risk factor. Among those taking the prescription omega-3s, the risk of heart attack dropped by 31 percent, of stroke by 28 percent and of death due to cardiovascular causes by 20 percent. The 8,000 patients participating were randomized to take the omega-3s or a placebo twice a day and were followed for an average of five years. Study leader Deepak L. Bhatt, M.D., M.P.H., of Brigham and Women’s, said the findings may be “the biggest development in cardiovascular prevention since statins.”
Andrew Weil, M.D.
Deepak L. Bhatt et al, “Cardiovascular Risk Reduction with Icosapent Ethyl for Hypertriglyceridemia.” New England Journal of Medicine, November 10, 2018, DOI: 10.1056/NEJMoa1812792
JoAnn E. Manson et al, “Marine n−3 Fatty Acids and Prevention of Cardiovascular Disease and Cancer,” New England Journal of Medicine, November 10, 2018, DOI: 10.1056/NEJMoa1811403
JoAnn E. Manson et al, “Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease.” New England Journal of Medicine, November 10, 2018, DOI: 10.1056/NEJMoa1809944