High fruit intake, lower alcohol consumption associated with lower breast cancer risk

Abstract

Researchers in 2 linked studies recently published in BMJ have revealed new data on the relation of alcohol and diet with breast cancer and heart disease.1, 2 The first study found that high fruit consumption during adolescence is associated with lower breast cancer risk, whereas the second reports that increased alcohol intake in later life is associated with an increase in breast cancer. Evidence about whether fruit and vegetable intake protects against breast cancer is conflicting. Most studies in this area have assessed intake during midlife and later, which may be after the period when breast tissue is most vulnerable to carcinogenic influences. As a result, researchers examined whether fruit and vegetable consumption would affect subsequent breast cancer risk. In the first study, participants included more than 90,000 premenopausal women aged 27 to 44 years from the Nurses' Health Study II who completed a questionnaire in 1991 on diet as well as more than 44,000 who completed a questionnaire in 1998 that focused on their diet during adolescence. The investigators concluded that high fruit consumption during adolescence (2.9 vs 0.5 servings per day) was associated with an approximately 25% lower risk of premenopausal breast cancer diagnosed in middle age. The association with adolescent fruit intake was stronger for both estrogen and progesterone receptor-negative cancers than estrogen and progesterone receptor-positive cancers. Specifically, apple, banana, and grape consumption during adolescence and orange and kale consumption during early adulthood were significantly associated with a reduced breast cancer risk; however, there was no link between the intake of fruit juice in either adolescence or early adulthood and risk. In an accompanying editorial, University of Oxford researchers note that although much more evidence is needed before conclusions can be drawn about the protective associations between adolescent fruit intake and breast cancer risk, fruit and vegetable intake should continue to be encouraged at all ages because of the known beneficial health effects.3 In the second study, Danish researchers analyzed the effect of a change in alcohol intake on the risk of breast cancer and heart disease. They followed the health of nearly 22,000 postmenopausal women in Denmark and found that women who increased their alcohol intake by 2 drinks per day over 5 years had an approximately 30% increased risk of breast cancer but an approximately 20% decreased risk of coronary heart disease in comparison with women who had stable alcohol intake. Decreased alcohol intake in women during the 5-year period, however, was not significantly associated with the risk of either breast cancer or coronary heart disease. The authors note that although their findings support the theory that alcohol is associated with breast cancer and coronary heart disease risk in opposite directions, the true effect of alcohol on ischemic heart disease is not certain. They add that although low to moderate alcohol consumption may provide some benefit to the heart, this is outweighed by an increased risk of breast cancer and other morbidities. Furthermore, heart disease risk can be substantially reduced by other lifestyle changes and drugs such as statins.