Intake of dairy milk is associated with a greater risk of breast cancer
in women, according to a new study conducted by researchers at Loma Linda
University Health.
Dairy, soy and risk of breast cancer: Those confounded milks, published
in the International Journal of Epidemiology, found that even
relatively moderate amounts of dairy milk consumption can increase women’s risk
of breast cancer — up to 80% depending on the amount consumed.
First author of
the paper, Gary E. Fraser, MBChB, PhD, said the observational study gives
“fairly strong evidence that either dairy milk or some other factor closely
related to drinking dairy milk is a cause of breast cancer in women.
“Consuming as
little as 1/4 to 1/3 cup of dairy milk per day was associated with an increased
risk of breast cancer of 30%,” Fraser said. “By drinking up to one cup per day,
the associated risk went up to 50%, and for those drinking two to three cups
per day, the risk increased further to 70% to 80%.”
Current U.S.
Dietary guidelines recommend three cups of milk per day. “Evidence from this
study suggests that people should view that recommendation with caution,” Fraser
said.
Dietary intakes
of nearly 53,000 North American women were evaluated for the study, all of whom
were initially free of cancer and were followed for nearly eight years. Dietary
intakes were estimated from food frequency questionnaires (FFQ), also repeated
24 hour recalls, and a baseline questionnaire had questions about demographics,
family history of breast cancer, physical activity, alcohol consumption,
hormonal and other medication use, breast cancer screening, and reproductive
and gynecological history.
By the end of
the study period, there were 1,057 new breast cancer cases during follow-up. No
clear associations were found between soy products and breast cancer,
independent of dairy. But, when compared to low or no milk consumption, higher
intakes of dairy calories and dairy milk were associated with greater risk of
breast cancer, independent of soy intake. Fraser noted that the results had
minimal variation when comparing intake of full fat versus reduced or nonfat
milks; there were no important associations noted with cheese and yogurt.
“However,” he
said, “dairy foods, especially milk, were associated with increased risk, and
the data predicted a marked reduction in risk associated with substituting
soymilk for dairy milk. This raises the possibility that dairy-alternate milks
may be an optimal choice.”
A hazardous
effect of dairy is consistent with the recent AHS-2 report suggesting that
vegans but not lacto-ovo-vegetarians experienced less breast cancer than
non-vegetarians.
Fraser said the
possible reasons for these associations between breast cancer and dairy milk
may be the sex hormone content of dairy milk, as the cows are of course
lactating, and often about 75% of the dairy herd is pregnant. Breast cancer in
women is a hormone-responsive cancer. Further, intake of dairy and other animal
proteins in some reports is also associated with higher blood levels of a
hormone, insulin-like growth factor-1 (IGF-1), which is thought to promote
certain cancers.
“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.”
Source: https://myfusimotors.com/2020/02/26/new-study-associates-intake-of-dairy-milk-with-greater-risk-of-breast-cancer/
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