The cause of ovarian cancer is unknown. Current evidence from the American Institute for Cancer Research does not support any association between milk and milk product consumption and an increased risk of ovarian cancer. Some hypotheses indicate that the lactose component of dairy may increase the risk of ovarian cancer through its action on ovarian cells. However, other studies highlight the anti-tumour compounds in dairy foods, especially calcium and vitamin D. Previous research was mainly focused among women of European ancestry.
European versus African Americans
Yet most of this previous research is among women of European ancestry. With African Americans at higher risk of low vitamin D levels and many have trouble digesting lactose, it’s possible these factors do affect African American women, the authors hypothesised. This study analysed data, among participants in a population-based case-control study of ovarian cancer, in African-American women in 11 states. African-American women ages 20 to 79 with newly diagnosed ovarian cancer were compared to healthy, self-identified African-American women. The 490 women diagnosed with ovarian cancer and 656 control participants answered questions on the phone about how much dairy they consumed, how much time they spent in the sun and other lifestyle factors.
Lactose and whole milk are worst
The authors observed that women with the highest intake of whole milk and lactose had an increased risk of ovarian cancer, compared with those who consumed the least. However, calcium intake through food and/or supplement was associated with a decreased associated risk (-49%)of ovarian cancer. No association was found for skim milk, low-fat milk, cheese and yogurt. Some evidence also suggested that women who spent 23 or more hours a week outside during the summer months, had a lower associated risk of ovarian cancer compared to women who spent six or fewer hours outside per week
These findings suggest therefore that a high-calcium, low-lactose diet, and moderate sun exposure in summer months may reduce the risk of ovarian cancer in African–American women.