WASHINGTON - Women who eat low-fat dairy foods may have a higher risk of
infertility than those who treat themselves to full-fat ice cream or cheese,
surprised US researchers said on Tuesday.
They found that women who ate
two or more servings of low-fat dairy foods a day had an 85 percent higher risk
of a certain type of infertility than women who ate less than one serving of
low-fat dairy food a week.
Women who ate one serving of high-fat dairy food a day were 27 percent less
likely to be infertile than women who avoided full-fat dairy foods.
It was not the finding that nutritionist Dr. Jorge Chavarro of the Harvard
School of Public Health in Boston had expected.
"We wanted to know whether dairy foods in general affected fertility,"
Chavarro said in a telephone interview. "There was pretty strong evidence in
animal studies suggesting that a specific sugar in dairy, lactose, could be
But little work had been done in humans, so Chavarro and colleagues looked at
data from the Nurses Health Study, an ongoing survey of tens of thousands of
women who fill out regular questionnaires about their diet, activity and health.
They chose the records of 18,555 women aged 24 to 42 who had tried to become
pregnant or had became pregnant between 1991 and 1999.
Chavarro said most were of European origin - possibly an important factor
because people of northern European descent are less likely to be lactose
The women who ate the most low-fat dairy foods were the most likely to report
they suffered from anovulatory infertility, when the body fails to produce
enough egg cells.
Writing in the journal Human Reproduction, Chavarro said he found no
difference between women who ate the most dairy and those who ate little or
none. He found the differences only when he broke down the types of dairy
"It was a bit of a surprise to us that high-fat dairy foods were positively
related to fertility," he said. "There is really not a very clear explanation.
It is possible that dairy fat or something along with dairy fat such as the
hormones in pregnant cows may be affecting ovulation in women."
He said more study was needed before conclusions could be drawn.
Chavarro's team had earlier found that women who ate more iron from
supplements and from plant foods were less likely to be infertile, and found no
link between fertility and various types of fats.
But he does not recommend that women trying to conceive use this as an excuse
to eat "buckets and buckets of ice cream."
"The benefit is at as low as one serving a day," he said.