For CVD prevention, evidence on vitamins inconclusive at best

Those looking for good news about the benefits of vitamins, multivitamins and minerals for CVD prevention have been disappointed recently.

A recommendation statement issued by the US Preventive Services Task Force (USPSTF) in February declared that current evidence on almost all supplements is insufficient to assess the balance of benefits and harms for the prevention of CVD and cancer. This is the first update since a 2003 recommendation.

Linda V. Van Horn, PhD, RD, from Northwestern 
University Feinberg School of Medicine, discussed 
the recent attention on vitamin supplementation.

Linda V. Van Horn, PhD, RD, from
Northwestern 
University Feinberg School
of Medicine, discussed 
the recent attention on
vitamin supplementation.

Image: Jim Ziv; reprinted with permission from
Northwestern University Feinberg School of
Medicine

There is, however, sufficient evidence to determine that beta carotene and vitamin E do not reduce the risk for CVD or cancer, and there is adequate evidence that beta carotene increases the risk for lung cancer in high-risk individuals, Virginia A. Moyer, MD, MPH, chair of the task force, and colleagues wrote in the statement published in Annals of Internal Medicine.

Other studies, reviews and meta-analyses on vitamins for CVD prevention released in the past year have been mostly negative, leading some to question whether any future research is warranted.

However, dietary supplement use remains common. Many supplements are advertised to prevent CVD and cancer. According to the USPSTF report, 49% of US adults used at least one dietary supplement from 2007 to 2010, and more than $28 billion was spent on dietary supplements in 2010.

Cardiologists should not necessarily assume the book is closed on the topic and should remain vigilant about keeping up with the latest research as their patients ask about the benefits of supplementation.

Effects, outcomes of supplementation

The negative effects of insufficient nutrition, such as adverse CVD outcomes for vitamin D-deficient individuals, are well recognized. However, the new USPSTF recommendation statement acknowledges that supplementation may not be the answer.

“Our recommendation is not that people stop taking supplements; rather, it is that people recognize that taking supplements is not going to benefit them in terms of preventing heart disease or cancer,” Moyer, who is vice president of maintenance, certification and quality for the American Board of Pediatrics, Chapel Hill, N.C., told Cardiology Today. The most important message from the report is that “while good nutrition is essential to overall health, the best way to get that is through a balanced diet rich in fruits and vegetables and whole grains. All of those things have been associated with reduced risk for CVD and cancer, whereas taking vitamin supplements has not been demonstrated to get that result.”

Similarly, the American Heart Association’s position is that nutritional deficiencies should be addressed via diet, not supplementation, Linda V. Van Horn, PhD, RD, an AHA spokeswoman and professor of preventive medicine at Northwestern University Feinberg School of Medicine, said in an interview.

“Because some studies have shown adverse events and outcomes from taking certain vitamin/mineral supplements, general encouragement to take supplements is unwarranted and potentially harmful,” she said. “For so many other reasons, including prevention of other chronic diseases, weight management and role modeling a healthy lifestyle for the family, dietary sources of nutrients, including dietary fiber, fatty acids and so on, are recommended over single- or dual-supplement use.”

Keith C. Ferdinand

Keith C. Ferdinand

This does not necessarily mean that there will be never be evidence for supplementation, said Keith C. Ferdinand, MD, FACC, FAHA, professor of clinical medicine at Tulane University, New Orleans, and chair of the National Forum for Heart Disease and Stroke Prevention.

“The lack of evidence in any review of present data does not mean a lack of a true association,” he told Cardiology Today. “Clinical studies have always had difficulty trying to define the relationship between vitamins, either as single or multivitamins, and their effects on CVD. There is biological plausibility, for instance, that still remains for the effects of vitamin D in CVD, especially in African Americans.”