To reduce a woman’s risk of developing breast cancer, a new study shows that eating a healthy diet and reducing alcohol consumption may be a step in the right direction. The researchers reviewed a group of earlier studies that included over 400,000 participants, and say that the study is the first of its kind to include such a comprehensive review of previous work on breast cancer, nutrition, and alcohol.

While it may seem intuitive that there could be a connection between diet and cancer risk, earlier studies have led to mixed results (the link between alcohol and cancer has been much clearer). The team, led by Sarah Brennan of Queen’s University Belfast, combed the literature and reanalyzed data from 18 earlier studies – looking at such a large sample increases the odds of finding a connection, if one exists.

Women who scored highest on the prudent diet measure had an 11% lower risk of developing breast cancer than those who ate the least healthy diet. In addition, women who consumed the most alcohol had a 21% increased risk of developing breast cancer.

The researchers looked at women who ate “prudent” or healthy diets, consisting of more fruits, vegetables, whole grains, fish, and low-fat dairy products to those who ate a Western-style or unhealthy diet, which typically consists of fewer fruits and veggies and more meat, sweets, high-fat dairy products, and refined carbohydrates. Women who scored highest on the prudent diet measure had an 11% lower risk of developing breast cancer than those who ate the least healthy diet. In addition, women who consumed the most alcohol had a 21% increased risk of developing breast cancer. The authors write that they were surprised to find no overall association between the Western diet and breast cancer risk. But they did note that when only case-control studies were analyzed (those that directly compared participants who either suffered from or were free of breast cancer), a link between the Western diet and breast cancer was seen.

The authors conclude that their “results provide evidence of a small inverse association between a prudent/healthy dietary pattern and a positive association between a drinker dietary pattern and breast cancer risk.” While it’s believed that consuming alcohol is linked to higher estrogen levels in a woman’s body and therefore increased cancer risk, the exact reasons behind the connection between a healthy diet and reduced cancer risk are still unclear. While researchers continue to work on this question, it can’t hurt to cut down on one’s consumption of red meat and fats where possible, and start munching on more fruits, veggies, and whole grains – foods that have already been shown to offer a variety of other health benefits.

The study is published in the March 2010 issue of the American Journal of Clinical Nutrition.