Jennifer Lovejoy, Arivale Chief Science Officer, PhD
Three new studies1,2,3 on the use of vitamin D and omega-3 supplements have caused a stir in the national media – and not in a good way. Take this NPR headline for example: “Vitamin D and Fish Oil Supplements Mostly Disappoint in Long-Awaited Research Results.”
So, does that mean it’s time to toss out your supplements?
Past studies have shown that people with low blood levels of vitamin D are at higher risk of cancer4 and cardiovascular disease5, while those with low levels of omega-3s are at higher risk of cardiovascular disease.
However, levels of vitamin D and omega-3s are highly intertwined with other healthy lifestyle factors – such as physical activity, diet, and weight – which makes it difficult to know whether it’s the nutrients themselves or other factors that are actually influencing disease risk.
The three new studies published this month in the New England Journal of Medicine are the latest to address the question of whether vitamin D or fish oil supplements actually have cancer or cardiovascular benefits.
Two of these new studies were based on the Vitamin D and Omega-3 Trial (VITAL). This large, well-conducted randomized controlled trial examined vitamin D (2000 IU per day) and a fish-based omega-3 (460mg of EPA and 380mg of DHA) for the prevention of cancer and cardiovascular disease among men 50 and older and women 55 and older in the United States.
The study was designed to examine the effect of supplementation on invasive cancer of any type and major cardiovascular events, which includes heart attack, stroke, and death from cardiovascular causes. Participants were followed for a median of five years.
These two VITAL studies found supplementation of either vitamin D or omega-3s did not result in a lower incidence of invasive cancer or cardiovascular events than a placebo. These findings didn’t vary no matter participants’ baseline levels of vitamin D or omega-3s.
The third new study was based on the Reduction of Cardiovascular Events with Icosapent Ethyl–Intervention Trial (REDUCE-IT). Participants had elevated triglyceride levels and were receiving statin therapy. They were randomly assigned to receive 2g of icosapent ethyl or purified EPA (the ethyl ester of EPA from fish oil) twice daily or a placebo for the prevention of cardiovascular events.
After following participants for a median of five years, researchers found that cardiovascular events occurred in 17.2 percent of the patients in the purified EPA group, as compared with 22.0 percent of the patients in the placebo group. This amounts to a 25 percent reduction in cardiovascular events among the patients who received purified EPA compared to those who received a placebo.
What can we take away from these recent studies on vitamin D and omega-3 supplements? Should we abstain from these supplements, or continue to use them?
For vitamin D, while no conclusive invasive cancer or cardiovascular benefits were found for the general population of older adults in VITAL, it’s possible certain subgroups of individuals may benefit from taking vitamin D supplements, though additional studies will be needed to confirm this. Furthermore, there are other potential benefits for vitamin D (for example, to all-cause mortality6 and respiratory health7) which have yet to be ruled out. Most importantly, however, is that there is strong scientific evidence showing specific vitamin D levels are needed to maintain bone health8,9,10. So, taking a supplement if your vitamin D blood levels are low is still consistent with evidence for optimizing overall wellness.
For omega-3s, while no conclusive invasive cancer or cardiovascular benefits were identified for the general population of older adults in VITAL, researchers did observe a reduction in heart attacks in those taking the supplement versus the placebo. However, this benefit could be due to chance and needs confirmation from future studies. In the REDUCE-IT study, purified EPA supplementation provided clear cardiovascular benefit among participants with elevated triglycerides and who were receiving statin therapy. And, other studies have shown benefits of omega-3 supplements in people with high triglycerides, inflammation, high blood pressure, and other risk factors for cardiovascular disease, so it’s important for people with these risk factors, and with low blood levels of omega-3s, to consider a supplement.
In summary, these studies don’t discredit the use of vitamin D or omega-3 supplements, but rather shed some light on where their benefits may or may not lie. Deciding whether to take a vitamin D or an omega-3 supplement depends on a myriad of factors such as current blood levels, personal health history, and genetics.
[Arivale Hot Topics address health stories currently in the news. The Arivale Clinical Team’s commentary on these news articles is not a review of the scientific evidence, nor an endorsement of a specific study, and is not meant as official medical opinion.]