Story at a glance
- Researchers said that by drinking up to 1 cup per day, the associated risk increased by 50 percent.
- For those drinking 2 or 3 cups per day, the risk increased by 70-80 percent.
- The study shows an association between milk consumption and breast cancer, but not causation.
A new study released this month suggests women who drink dairy milk, even as little as one cup per day, may be at an elevated risk of developing breast cancer.
The study published in the International Journal of Epidemiology from researchers at Loma Linda University Health found that even relatively moderate amounts of dairy milk consumption is associated with an increase of breast cancer risk of up to 80 percent, depending on the amount consumed.
“Consuming as little as ¼ to ⅓ cup of dairy milk per day was associated with an increased risk of breast cancer of 30 percent,” Gary E. Fraser, author of the paper, said.
“By drinking up to one cup per day, the associated risk went up to 50 percent, and for those drinking two to three cups per day, the risk increased further to 70 percent to 80 percent.”
Researchers observed the dietary intake of 53,000 women for nearly eight years, all of whom were initially cancer free.
By the end of the study, there were 1,057 women diagnosed with breast cancer, or about 2 percent of the total women who participated in the study. No clear associations were found between soy products and breast cancer, independent of dairy.
Fraser said the associations between breast cancer and dairy milk could be the result of the sex hormone content of dairy milk, as cows are lactating and about 75 percent of the dairy herd is pregnant.
“Dairy milk does have some positive nutritional qualities,” Fraser said, “but these need to be balanced against other possible, less helpful effects. This work suggests the urgent need for further research.”
The American Cancer Society (ACS) estimates more than 42,000 women will die from breast cancer in 2020. It’s the second leading cause of cancer death in women, behind lung cancer.
The nutrition study has some limitations, as this one was observational, making it difficult to confirm cause and effect. There could be other factors associated with milk consumption that are impacting breast cancer risk.
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