A comprehensive analysis of 119 studies has found that it takes only 1 glass of wine or any other kind of alcoholic drink a day to increase risk of breast cancer. It was also found that vigorous exercise like fast bicycling or running reduces the risk of pre-menopausal as well as post-menopausal breast cancer. There was also strong evidence confirming a previous finding that post-menopausal breast cancer risk is reduced with moderate exercise.
Worldwide research on how breast cancer risk is affected by exercise, weight and diet was evaluated, which included data from 12 million women and approximately 260,000 breast cancer cases.
There was strong evidence found that risk of pre-menopausal breast cancer is increased by 5% and risk of post-menopausal breast cancer is increased by 9% with drinking the equivalent of a beer or a small glass of wine a day.
The most active vigorously exercising pre-menopausal women had a 17% reduced risk and women who were post-menopausal had a 10% reduced risk of breast cancer in comparison to the least active women. Moderate activity, like gardening and walking, was associated with a 13% reduced risk for the most active women compared to the least active.
The report also showed:
- Overweight or obesity increases the most common, post-menopausal type breast cancer risk.
- A reduced breast cancer risk for mothers who breastfeed.
- Post-menopausal breast cancer risk increases with greater weight gain.
There was also some limited evidence for non-starchy vegetables reducing risk for the less common types of estrogen-receptor negative breast cancer. Limited evidence also shows an association with dairy and diets high in calcium as well as carotenoid containing foods and a reduction in risk of some types of breast cancer. Foods such as apricots, carrots, kale and spinach are good sources of carotenoids, a group of phytonutrients with health benefits.
Although there are risk factors that cannot be controlled such as a family history of breast cancer, being older and early menstrual period, the results of this report confirm that women can modify lifestyle risk factors to reduce breast cancer risk.
The evidence from this report is clear that limiting alcohol, being physically active, and keeping a healthy weight are all steps women can take for reducing their risk of breast cancer.