The AAFP has said it concurs with a Feb. 24 recommendation(www.uspreventiveservicestaskforce.org) from the U.S. Preventive Services Task Force (USPSTF) against using beta-carotene or vitamin E supplements to prevent cardiovascular disease (CVD) or cancer.
The AAFP also agrees with the USPSTF that evidence currently is insufficient to assess the balance of benefits and harms of using multivitamins or single- or paired-nutrient supplements (with the exception of beta-carotene and vitamin E) for the prevention of these conditions.
These recommendations pertain only to healthy adults who have no special nutritional needs. The recommendations do not apply to children; women who are pregnant or who may become pregnant; or people who are chronically ill, hospitalized or have a known nutritional deficiency.
Overview of Recommendations
Dietary supplement usage is common in the United States, especially among women and older adults. Forty-nine percent of adults used at least one dietary supplement between 2007 and 2010, and 32 percent reported using a multivitamin/multi-mineral supplement, according to the USPSTF recommendation statement.
- The AAFP has said it concurs with a Feb. 24 recommendation from the U.S. Preventive Services Task Force (USPSTF) against using beta-carotene or vitamin E supplements to prevent cardiovascular disease (CVD) or cancer.
- The Academy agrees with the USPSTF that evidence currently is insufficient to assess the balance of benefits and harms of using multivitamins or single- or paired-nutrient supplements (with the exception of beta-carotene and vitamin E) for the prevention of these conditions.
- The findings were based on 26 studies that examined the benefits and harms of using vitamin and mineral supplements for primary prevention of CVD and cancer, as well as effects on all-cause mortality in healthy individuals without known nutritional deficiencies.
In addition, the substantial effect of CVD and cancer on morbidity and mortality in the United States has been well-described in the scientific literature, and many supplements are promoted to prevent these conditions.
The evidence review on which the task force based its findings included 26 studies(www.uspreventiveservicestaskforce.org) that examined the benefits and harms of using vitamin and mineral supplements for primary prevention of CVD, cancer, or all-cause mortality in healthy individuals without known nutritional deficiencies. Overall, the USPSTF found no consistent evidence that the supplements evaluated affected all-cause mortality or incidences of the two conditions in this population.
Few studies have evaluated the effectiveness of vitamin and mineral supplements in the primary prevention of CVD and cancer in nutrient-sufficient adults, and those that have been published used a wide variety of supplements, in different doses, with different study objectives and populations, and usually for short durations.
Two large trials found a small, borderline-significant benefit from multivitamin supplements on cancer in men only and no effect on CVD, the task force noted, but the applicability of these results is limited. High-quality studies involving vitamins A, C, or D; folic acid; selenium; and/or calcium were scant and showed no clear evidence of benefit or harm.
The review did confirm, however, the established harm of beta-carotene supplementation on lung cancer incidence and death for individuals at high risk for lung cancer while failing to discern any benefit on CVD and cancer incidence.
"[Beta-carotene] was tested with the hope and suggestion that it might reduce lung cancer in the high-risk group," said USPSTF Co-vice Chair Michael LeFevre, M.D., M.S.P.H., of Columbia, Mo. "But it actually increased the risk of lung cancer.
"It is very unlikely that it would increase the risk in a high-risk group and decrease the risk in the average population. So we recommend against the use of beta-carotene in the general population with respect to the prevention of heart disease and cancer," LeFevre told AAFP News.
"The vitamin E recommendation is based on an accumulation of studies that basically led us to be moderately certain that there is no benefit for prevention of heart disease or cancer," LeFevre added. "Those same studies did not suggest significant harm, but the task force has to see some benefit to recommend something, not just absence of harm."
Food is Foundation; Supplement When Necessary
The task force starts with the assumption that good food improves health and that good nutrition specifically has been associated with a reduction in both heart disease and cancer, LeFevre explained. Supplements are intended for use when there is a true nutrient deficiency.
Specific groups of patients with well-defined conditions may benefit from certain nutrients, according to the USPSTF recommendation. For example, women planning to become pregnant should receive a daily supplement containing folic acid to help prevent neural tube defects in their infants. The USPSTF also recommends vitamin D supplements for older patients at risk for falling.
"One of my favorite ways of phrasing this as a family physician in talking with my patients is, 'My mother probably got it right when she told me to eat my vegetables,'" LeFevre said.
"As family physicians, probably our most important role is to discuss the value of good nutrition and physical activity in the promotion of health. When my patients ask me about supplements, I usually start by talking about food first. Start with good food."