By Erin Dummert RD, CD

For years, questions about the link between dairy foods and ovarian cancer have gone unanswered. Unfortunately researchers still haven’t clearly identified the association, leaving the public with little direction. What does current research say about this confusing subject?

Does dairy decrease risk?
A 2002 study published in the American Journal of Epidemiology found that a woman's risk of ovarian cancer was decreased the more dairy products she consumed. However, this study showed that low-fat milk decreased the risk of ovarian cancer, but whole milk did not. Butter also decreased the risk of ovarian cancer, but yogurt, cheese and ice cream did not. (1)

Or, does dairy increase risk?
More recent research performed in Sweden found that women who ate 4 or more servings of dairy foods a day— including milk, yogurt, ice cream and butter—had twice the risk of developing ovarian cancer. This study showed that women who drank two or more glasses of milk a day had twice the cancer risk as those who drank one glass or less a day.(2)

A report from an ongoing study involving 80,000 nurses in the United States published in 2000 found a 44% increase in ovarian cancer risk among frequent milk drinkers (over infrequent milk drinkers). In both studies, milk was identified as the dairy product having the most impact on ovarian cancer risk. (3)

What’s in dairy?
Until recently, researchers thought that eating low-fat or nonfat dairy products helped protect against ovarian cancer. However, in the Swedish study mentioned above, ovarian cancer risk increased no matter what type of milk the women drank. To explain their results, the Swedish researchers suggest that lactose (milk sugar) may be responsible. There are also other studies that have shown a link between galactose, a smaller sugar molecule derived from lactose, and ovarian cancer.

Conclusion
These studies, and many before, suggest a link between dairy and ovarian cancer risk, however the picture remains unclear. The benefits of dairy products are clear. Calcium and magnesium for bone and colon health are just two. However, the public must weigh all of the risks and benefits. If you are concerned about your risk for ovarian cancer and choose to limit or eliminate dairy products, it is strongly recommended that you first discuss this choice with a registered dietitian to ensure you can replace the important nutrients found in dairy products.