Diet and Nutrition

Diet and Nutrition (and Exercise)

The diet is an important part of cancer treatment. Eating the right kinds of foods before, during, and after treatment can help the patient feel better and stay stronger. (go here for best nutritional web sites and advice on exercise). Go here and here and here for a recent review on diet and cancer, and go here for a study on the risks of alcohol. Go here for good advice on a healthy diet.

Epidemiological studies (comparing cancer rates in different parts of the world) suggest that diet plays a significant role in the development of cancer. Despite this, there is however little evidence that modifying diet will prevent cancer (a large study of low fat diets and high fiber did not lower the risk of breast, colon or other cancer, go here and here) and virtually no evidence that once cancer has developed it can be treated with dietary regimens.

There have been numerous studies where taking vitamin supplements increased cancer and can interfere with the effectiveness of treatment (go here and here). A recent study showed no significant benefit from B vitamins in preventing cancer in women (go here). Another large study showed that women taking multivitamins was of no benefit in lowering the risk of cancer (go here). A recent NCI trial showed that taking a lot of multivitamins increased the risk of dying of prostate cancer (go here). Another study showed that taking folic acid may increase the risk of advanced cancer (go here). Also read the whole section on nutrition and herbals in the alternative medicine section here and the section on cancer prevention).

Vitamin Supplementation to Prevent Cancer Counseling Release Date: June 2003

Summary of Recommendations

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; or antioxidant combinations for the prevention of cancer or cardiovascular disease.

Rationale: The USPSTF found poor evidence to determine whether supplementation with these vitamins reduces the risk for cardiovascular disease or cancer. The available evidence from randomized trials is either inadequate or conflicting, and the influence of confounding variables on observed outcomes in observational studies cannot be determined. As a result, the USPSTF could not determine the balance of benefits and harms of routine use of supplements of vitamins A, C or E; multivitamins with folic acid; or 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.

Rationale: The USPSTF found good evidence that beta-carotene supplementation provides no benefit in the prevention of cancer or cardiovascular disease in middle-aged and older adults. In 2 trials restricted to heavy smokers, beta-carotene supplementation was associated with higher incidence of lung cancer and higher all-cause mortality. The USPSTF concludes that beta-carotene supplements are unlikely to provide important benefits and might cause harm in some groups.