Drinking cow’s milk ‘unlikely to affect oestrogen levels’
It is unlikely that drinking cow’s milk affects oestrogen levels in the blood, researchers claim.
While oestrogen occurs naturally in cow’s milk, there has been some concern recently that consuming milk containing elevated amounts of the hormone could affect blood levels in humans, leading to an increased risk of some cancers. But following an investigation into the relationship between oestrogens in milk and blood oestrogen levels, researchers from the University of Ljubljana in Slovenia don’t see much need for concern.
Studying the different levels of milk oestrogen had on adult mice, they found that naturally occurring levels, and even levels as high as 100 times the average, had no effect on the animals. The study further determined that only when the mice were given 1,000 times more oestrogen than average did it have any impact on reproductive health.
"Our results suggest that oestrogens in milk, even when derived from cows in the third trimester of pregnancy, do not pose a risk to reproductive health," said Dr. Gregor Majdic in a statement. "Even oestrogens at concentrations 100 times higher than usually found in native milk did not cause any physiological effects in the present study."
Dr Majdic said the results indicated that naturally occurring hormones in milk are found in far too low concentrations to exert any biological effect on consumers.
Investigators caution, however, that these tests were done on mature mice and more research is needed to examine the effect oestrogen from milk has on the development of the reproductive system before and during puberty. While further exploration into the issue is needed, this is a promising finding in adult mice.
The study was published in the Journal of Dairy Science.