Vitamin C, E & Beta Carotene Supplements Provide No Added Protection From Cancer.

An exhaustive Women's Antioxidant Cardiovascular Study has just been completed by Harvard Medical School and subsequently published (January 2009 issue) in the Journal of the National Cancer Institute. It states that there is no basis for a recommendation that individuals increase dietary levels of antioxidants as a means of reducing cancer risk or the risk of dying from cancer.

Dr. Lin discusses the background and the need for undertaking this study - "Observational studies had suggested that a diet high in fruits and vegetables, both of which are rich with antioxidants, may prevent cancer development,"

Initially, 8171 women were randomly assigned in this double-blind, placebo-controlled trial of vitamin C (500 mg of ascorbic acid daily), natural-source vitamin E (600 IU of {alpha}-tocopherol every other day), and beta carotene (50 mg every other day).

Subsequently, out of these, 7627 women who were free of cancer before the random assignment took place were selected for the study, and took beta carotene, vitamin C, vitamin E, or a combination of supplements for an average of 9.4 years. However, at the end of the study there were no significant reductions in their risk of cancer.

Over the duration of this study, 624 women developed invasive cancers and 176 died from their respective disease. When compared to women who took placebo, the relative risk of developing cancer was nearly identical to the vitamin C group, the vitamin E group and the beta carotene group. There were no statistically significant effects of use of these three antioxidants on total cancer incidence. Similarly, no effects of these antioxidants were observed on cancer mortality.

One promising result from this study and one that will need further studying was the trend toward protection against colorectal cancer with vitamin E supplementation.

A negative outcome which needs further study was the elevated lung cancer risk in the beta carotene dosage, with modest excess overall cancer risk in smokers and heavier drinkers. Additionally, harmful effects from vitamin C achieved statistical significance and raise questions about the chemopreventive abilities of ascorbic acid.

Study conducted by: Dr. Jennifer Lin, Nancy R. Cook, Christine Albert, Elaine Zaharris, J. Michael Gaziano, Martin Van Denburgh, Julie E. Buring, JoAnn E. Manson.

Of The Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA

SOURCE: Journal of the National Cancer Institute, January 7, 2009.