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Vitamin Supplements and cancer
Should People Take Vitamin Supplements?
With the exception of vitamin supplements that can cause harm, there is little reason to discourage people who wish to take vitamins from doing so. Taking vitamin supplements does not replace the need to eat a healthy diet, although taking vitamin supplements may be appropriate for people whose diet does not provide the recommended daily allowance of specific vitamins. Recommended daily allowance information is available from the Institute of Medicine's Dietary Reference Intake (DRI).
All patients should receive information about the benefits of a diet rich in fruit, vegetables, and legumes, as well as information about other foods and nutrients that should be emphasized or avoided.
What Are the Potential Harms of Vitamin Supplements?
Beta-carotene supplements were associated with an increased risk for lung cancer among smokers, especially heavy smokers, in 2 randomized clinical trials (RCTs); the effects of beta-carotene supplementation among nonsmokers are unknown.
Moderate doses of vitamin A may reduce bone mineral density. High doses of vitamin A may be toxic to the liver and put pregnant women at risk for delivering babies with birth defects.
People who choose to take vitamins should be encouraged to adhere to the dosages recommended in the DRI of the Institute of Medicine, since the potential harms of higher dosages outweigh the potential benefits.
What Does the USPSTF Recommend?
The U.S. Preventive Services Task Force (USPSTF) concludes that the evidence is insufficient to recommend for or against the use of supplements of:
Vitamins A, C, or E,
Multivitamins with folic acid,
Antioxidant combinations for the prevention of cancer or cardiovascular disease.
The USPSTF recommends against the use of beta-carotene supplements, either alone or in combination, for the prevention of cancer or cardiovascular disease.
This recommendation applies only to the use of vitamin supplements by healthy adults to prevent cancer and cardiovascular disease.
The Task Force did not review evidence for vitamin supplementation in patients with known or potential nutritional deficiencies—including pregnant and lactating women, children, the elderly, and people with chronic disease—or special populations of patients, such as those taking medicines that require vitamin supplementation.
