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Nov 13, 2018

Study Questions the Benefits of Vitamin D and Omega-3 Supplements

Five-year study finds vitamin D and omega-3 supplements do not reduce risk for heart events and cancer in healthy adults.

Vitamin D and omega-3 supplements failed to reduce risk of cancer or heart events in a five-year trial of nearly 26,000 healthy U.S. adults. Findings were recently presented at the American Heart Association Scientific Sessions in Chicago and question the use of vitamin D and omega-3 supplements for the prevention of heart disease and cancer.

Known as the VITAL (Vitamin D and Omega-3) Trial, this study explored the long-term benefits of vitamin D and omega-3 fatty acids in adults over 50. It specifically looked at the impact of daily supplements on risk of developing cancer, heart disease and stroke in healthy adults.

The VITAL trial is one of the largest studies of its kind, the results of which experts hope will shed some light on the benefits of vitamin D and omega-3 supplements.

Vitamin D is an essential nutrient that supports the immune system and helps regulate the absorption of calcium. Vitamin D is naturally produced by our body when exposed to sunlight, but can also be found in certain seafood, vegetables and fortified foods like milk and cereal.

Omega-3 fatty acids, which are typically found in fish, nuts and seeds, are also an important nutrient and have been shown to promote heart health and protect against heart disease—the No. 1 killer of Americans.

The question, however, is whether taking daily vitamin D or omega-3 supplements has long-term health benefits. Studies show that individuals who naturally get these nutrients through their diet or lifestyle tend to have better health and lower risk of death. But it’s unknown whether taking a daily pill with vitamin D or omega-3 fatty acids has the same effect over time.

To learn more, researchers assigned 25,871 U.S. adults to a random combination of omega-3 supplements, vitamin D supplements or placebo pills with no active ingredients. Participants were then followed for a median of five years, tracking key outcomes including cancer, heart attack, stroke, heart-related death.

All participants were free of cancer and heart disease at the start of the study and the average age was 67. The study was conducted at Brigham and Women’s Hospital in Boston, MA and findings were published under two separate articles in the New England Journal of Medicine.

What researchers found was that neither daily supplement had a significant impact on risk for heart events or cancer compared to placebo. Overall, there were 805 heart events and 1,617 cancer diagnoses among study participants during the follow-up period. But after analysis, researchers found no significant differences in these outcomes among participants in any single group.

Participants taking vitamin D took a daily dose of 2,000 IU per day, which is the currently recommended level of vitamin D for healthy adults. Those in the omega-3 group took 1g of omega-3 fatty acids a day, which is currently recommended by the American Heart Association to promote heart health and is equivalent to 1–2 servings of fish a week.

Despite overall findings, authors did note some evidence of benefits associated with supplements. For example, there was evidence of trend between daily omega-3 supplements and reduced risk for heart events. Researchers also found that when looking at specific outcomes, participants taking omega-3 supplements had significantly lower risk of heart attack than those taking the placebo.

However, authors ultimately conclude that daily omega-3 and vitamin D supplements failed to reduce risk of cancer and major heart events in healthy adults after five years.

Of course, that’s not to say that omega-3 fatty acids and vitamin D aren’t important for our health. Both are important nutrients that we should try to get enough of through our diet and lifestyle. Supplements may also be recommended by doctors when we don’t get enough vitamin D or omega-3 fatty acids naturally.

However, when it comes to preventing cancer and heart disease, findings suggest that we should stick to the tried and true methods for health promotion. That means staying active, eating healthy and addressing any known risk factors that can lead to cancer, heart disease and other chronic diseases.

Questions for You to Consider

  • What is vitamin D?
  • Vitamin D is an essential dietary nutrient, which can be found in foods like fish, eggs and fortified milk. Our bodies can also product vitamin D in response to exposure to sunlight. Vitamin D plays a number of important roles in our body, like helping with the absorption of calcium, and studies have shown that vitamin D deficiencies may be linked to increased risk for heart disease.
  • What foods are highest in omega-3 fatty acids?

  • Flaxseed and flaxseed oil are foods containing the most omega-3 fatty acids, followed by certain fish, fish oils and nuts. Certain plants and spices are also high in omega-3 fatty acid, such as fresh basil, dried oregano and grape leaves. 

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