For most vitamin and mineral supplements, there is not enough evidence to recommend for or against taking them to prevent cancer and cardiovascular disease (CVD), according to new draft recommendations from the US Preventive Services Task Force.
While the evidence is still unclear for most vitamin and mineral supplements, there is evidence that two products do not reduce the risk of these diseases. The Task Force found no benefit of taking vitamin E, and actually found harms associated with taking beta carotene.
"The Task Force recommends against the use of vitamin E or beta carotene for the prevention of heart disease and cancer," said Task Force member John Wong, MD, vice chair for clinical affairs, chief of the division of clinical decision making, and a primary care clinician in the Department of Medicine at Tufts Medical Center, Boston, Massachusetts.
"The evidence shows there is no benefit to taking vitamin E and that beta carotene can be harmful because it increases the risk of lung cancer in people already at risk, such as those who smoke, and also increases the risk of dying from heart disease or stroke," he said in a statement.
The current draft recommendation remains unchanged from the previous guidelines issued in 2014.
The Task Force recommendations apply to community-dwelling nonpregnant adults. They do not apply to individuals with a known or suspected nutritional deficiency or special nutritional needs. The Task Force has a separate recommendation for women who are planning or able to become pregnant, and recommends the use of folic acid supplements.
Two Leading Causes of Death
CVD and cancer are the two leading causes of death in the United States, and combined, account for approximately half of all deaths, according to the Task Force. Inflammation and oxidative stress play a role in both diseases, and dietary supplements may have anti-inflammatory and antioxidative effects. This has served as the rationale for studying the use of dietary supplements as a means of preventing both CVD and cancer.
"Because heart disease and cancer are the two leading causes of death in the US, we want to look at whether taking vitamins and minerals help prevent these important diseases," explained Task Force member Chyke Doubeni, MBBS, MPH, family physician and inaugural director of the Mayo Clinic Center for Health Equity and Community Engagement Research, Rochester, Minnesota, in a statement. "However, there is not enough evidence to know if taking vitamin, mineral, and multivitamin supplements prevent these conditions, so the Task Force is calling for more research."
To update its 2014 recommendation statement, the Task Force conducted a review of the evidence on the efficacy of supplementation with single nutrients, functionally related nutrient pairs, or multivitamins for reducing the risk of CVD, cancer, and mortality in the general adult population. They also looked at the potential harms of using supplements.
Their main findings are as follows:
There is adequate evidence that beta carotene supplements and that vitamin E supplements provide no benefit in preventing CVD or cancer.
Adequate evidence has shown that beta carotene causes small harms in increasing the risk for lung cancer in persons who are at increased risk.
There is adequate evidence that vitamin E and multivitamins cause at most small harms.
Evidence is lacking as to the benefits of multivitamin supplements in preventing CVD or cancer.
There is inadequate evidence on the benefits of supplementing with either single or paired nutrients (other than beta carotene and vitamin E) in preventing CVD or cancer.
Evidence is limited as to the harms of supplementation with single or paired nutrients (other than beta carotene or vitamin E).
The Task Force noted that more research is needed to understand the effects of vitamin, mineral, and multivitamin supplementation on CVD and cancer outcomes, as well as understanding whether or not vitamin D supplementation has an effect on cancer mortality.
There is also a need for further research to tease out whether there is heterogeneity across specific populations, or by baseline nutrient level, especially among individuals with no known deficiencies.
As for recommendations from other organizations, the Task For points to the US Department of Health and Human Services' 2020-2025 dietary guidelines, which suggest that nutritional needs should be met primarily from foods and beverages — specifically, nutrient-dense foods and beverages. The American Heart Association also recommends that healthy individuals obtain an adequate amount of nutrients by eating a variety of foods in moderation, rather than by taking supplements.
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Cite this: Vitamins to Prevent Cancer and CVD: No, Says USPSTF - Medscape - May 04, 2021.