Research Finds Disappointing Results for Vitamin D, Fish Oil

Many Americans take daily over-the-counter vitamin D and omega-3 fatty acid supplements, such as fish oil, in the hopes of reducing their risk of vascular events and cancer. Until recently, there has not been any definitive evidence proving or disproving the benefits of these supplements. However, a recent five-year research study funded by the National Institutes of Health provides new, conclusive evidence.

“Neither fish oil nor vitamin D prevent cancer or reduce the incidence of the major end points of heart disease,” said Dr. Arie Szatkowski, board-certified cardiologist with the Stern Cardiovascular Foundation and director of cardiovascular services at Baptist Memorial Hospital-DeSoto.

VITAL Research Study―Purpose and Outcomes

Nearly 26,000 healthy participants who are 50 years old and older took part in the VITAL research study at Brigham and Women’s Hospital in Boston. Participants had no history of cancer or heart disease, and 20% of participants were African American. The study was published in the New England Journal of Medicine and presented at the American Heart Association’s conference in 2018.

“The purpose of the trial was to see, once and for all, if there are benefits of taking natural supplements to ward off the development of cancers or ward off the development of certain heart conditions,” said Szatkowski.

Researchers separated participants into four groups. One group took 2,000 international units of vitamin D and 1 gram of fish oil, which contains omega-3 fatty acid. A second group consumed omega-3 and a placebo while a third group took vitamin D and a placebo. The last group consumed only placebos.

“Participants took these supplements daily, and they were followed by researchers for five years,” said Szatkowski. “This was the largest and longest trial of its kind for these two natural supplements. Researchers found no side effects from the supplements.”

Vitamin D Results

The VITAL research study found that taking the vitamin D supplement did not help reduce cardiovascular death, stroke or heart attack among participants.

“The study also concluded vitamin D has no benefits in preventing cancer,” said Szatkowski. “The door for vitamin D was more or less closed.”

However, Szatkowski cautions patients who are taking a vitamin D supplement from discontinuing use right away.

“Vitamin D has many other properties,” said Szatkowski. “It’s helpful for the immune system. Individuals with severely low vitamin D levels may have some fatigue and, in those individuals, supplements may help improve their symptoms and perhaps improve their immune system. If you’re someone who is thinking about adding or removing a vitamin D supplement from your diet, your first step is to talk with your doctor.”

Omega-3 Fatty Acid Results

Like the vitamin D supplement, the omega-3 supplement did not reduce cancer risk in study participants. It also had no effect on cardiovascular death or stroke. However, researchers found it reduced some heart attacks in a subset of patients with a history of vascular disease, as well as in African Americans and participants who had very little fish intake.

“We all need a certain amount of omega-3 in our diet,” said Szatkowski. “For those of us who eat at least two servings of fish a week, there may be no benefit at all of taking additional omega-3 fatty acids. If you eat no fish whatsoever, omega-3 fatty acids may reduce your risk of heart attack by 19%. But these outcomes need further investigation.”

According to the study, the omega-3 fatty acid supplement lowered the risk of heart attack by 28% when heart attack was considered separately from other cardiovascular events. The benefit appeared strongest in African Americans.

Maintain a Healthy Diet

The VITAL research results prove that taking vitamin D and fish oil supplements to reduce or prevent the risk of cancer and certain heart events is not effective. According to Szatkowski and others, additional studies are needed to focus on outcomes for African Americans and populations who do not consume fish.

For individuals who want to make a natural modification that can lower their risk of heart events and cancer, Szatkowski recommends a healthy diet.