THURSDAY, Nov. 22 (HealthDay News) -- Consuming soy products
doesn't prevent hot flashes and night sweats in most women, a large
Imagine sitting down for a job interview and suddenly feeling
very warm and starting to noticeably perspire. Or consider how it
feels to frequently lose sleep from drenching night sweats. Of all
the symptoms of menopause, women say hot flashes and night sweats
often are the most annoying.
The symptoms are caused by fluctuating or decreasing levels of
the female hormone estrogen.
Many women are not willing or able to take supplemental estrogen
to control hot flashes and night sweats, known as "vasomotor"
symptoms, related to widening and narrowing of blood vessels. Some
women opt to add dietary soy products like tofu and soy milk to
their diet. Also called phytoestrogens, they have a chemical
structure similar to estrogen and are thought to mimic the effect
of the female hormone in the body.
The study was published online recently and will appear in the
March 2013 print issue of the journal
"We were interested in finding ways to help women control their
own health, and we were hopeful that soy products would prove to be
a good alternative to hormone therapy," said lead study author
Ellen Gold, professor and chairwoman of the department of public
health sciences at the University of California, Davis.
Unfortunately, she said, soy "doesn't seem, on average, to prevent
these unpleasant symptoms before the onset of menopause."
The study analyzed data from a nationwide study that followed
more than 3,000 women who were beginning to experience changes
associated with menopause or had not yet begun to have symptoms of
menopause. Their ages ranged from 42 to 52 years old at the start
of the study.
Participants answered detailed surveys about their dietary
habits and fiber intake before they were involved in the study,
then at five- and nine-year follow-up points. Fiber was of interest
to the researchers because it is thought to increase the impact of
estrogen. The women also were asked annually about their menopausal
symptoms, including hot flashes and night sweats.
The study found no significant correlation between the intake of
dietary phytoestrogens or fiber and the beginning of menopausal
symptoms in women who had not yet experienced menopause when they
started the study.
Gold said that a randomized, placebo-controlled trial with a
diverse range of women would be necessary to prove any ability of
dietary phytoestrogens or fiber to prevent hot flashes and night
sweats, but she believes the results of this study suggest that it
is unlikely a significant effect would be seen.
Although other studies have looked at dietary soy and menopausal
symptoms, this study included more women and followed them for a
longer period of time than others did, the researchers said. The
study also included people representing a broader range of racial
and ethnic groups, including black, Hispanic, Chinese and Japanese
Although Asian women tend to report fewer vasomotor symptoms
than other women, the typical Eastern diet, thought to be high in
phytoestrogens, does not seem to be associated with fewer hot
flashes and night sweats.
Gold said she believes there may be subsets of women, due to
genetic and metabolic factors, who may benefit more from
phytoestrogens than others. And she doesn't discourage women from
taking soy products. "If women try it and it works for them, fine,"
The study has some limitations.
Dr. Wilma Larsen, chief of the division of gynecology at Scott
& White Healthcare in Temple, Texas, is concerned that the
study used data the women had written down or remembered.
"Any time you're relying on patients to self-report you're not
certain what they're actually doing," Larsen said.
Although Larsen said the study contributes new information
specifically about whether soy products are helpful in preventing
hot flashes and night sweats before they occur, she doesn't think
it will change what women do or what physicians recommend.
"I think this isn't going to prevent me from talking about a
healthy diet with patients or the value of phytoestrogens," Larsen
said. "And I'm certainly not going to be reassuring women that
they'll go through menopause without having to take any
The study was supported in part by the U.S. National Institutes
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