by Michael Woodhead  

Postmenopausal women who consume more meat and dairy products have higher levels of circulating sex steroid hormones that are linked to breast cancer risk, a Melbourne study shows.  

In a study of dietary patterns in 766 postmenopausal women, researchers from the Cancer Council Victoria and Melbourne University  found that levels of circulating oestradiol and sex hormone-binding globulin (SHBG) were associated with consumption of red meat and dairy products.  

The findings, published in the European Journal of Clinical Nutrition (online 11 Nov), showed  that levels of total and free oestradiol were about 15% higher in women with the highest consumption of dairy products. At the same time, levels of SHBG were negatively associated with red meat consumption.  

The study authors note that high levels of steroid hormones and low concentrations of SHBG have been consistently associated with increased risk of postmenopausal breast cancer.  

They say their findings lend support to the hypothesis that milk and dairy products are major sources of oestrogens in the human diet.  

Animal products may contain endogenous oestrogens or metabolites that contribute directly to levels of human circulating steroids, they say. Meat and dairy products might also contribute to steroid production if they are a source of cholesterol, they add.  

However, the study found no association between consumption of cholesterol nor of  processed meat, chicken, eggs, fish or protein and circulating steroid hormones.  

“Given the well established role of steroid hormones in breast cancer etiology for postmenopausal women, these findings may have important health implications,” they conclude.