New York: A mix of certain traditional Chinese herbs thought to have weak estrogen-like activity might help ease menopausal hot flashes, a small clinical trial suggests.

But the herbal mix, dubbed Jiawei Qing`e Fang, is not widely available. And while the new study suggested some benefits, it had enough limitations that the true effects of the herbs are still unclear, according to an expert not involved in the work.

For the study, reported in the journal Menopause, researchers in China randomly assigned 72 women to either take Jiawei Qing`e Fang everyday for eight weeks, or use a placebo mix of starches that were made to look, taste and smell like the herbs.

All of the women were relatively young — between the ages of 45 and 55 — and either had irregular menstrual periods, or had recently stopped menstruating. At the outset, all said they were having at least 14 bouts of hot flashes per week.

After eight weeks, women on the herbal mix showed a 70 percent drop in their hot flash “score” — which reflects how often and how severe their hot flashes were. The placebo group also showed a big, though not as dramatic, improvement: a 56 percent decline in hot flash scores.

The benefit in the placebo group may reflect psychological effects (that is, women who thought they were receiving the real thing felt better), according to senior researcher Dr. Xiumei Gao, of Tianjin University of Traditional Chinese Medicine in China.

But the current findings suggest that Jiawei Qing`e Fang has benefits beyond the placebo, Gao told Reuters Health in an email.

There`s also some lab research suggesting that the trio of herbs used in the mixture has estrogen-like activity — which, in theory, could help cool hot flashes.

The mix used in this study was based on a traditional Chinese preparation known as Qing E Fang, whose first recorded use for menopause symptoms goes back more than 1,000 years, according to Gao.

The researchers used two herbs from that formulation — cortex eucommia and fructus psoraleae — plus a third, called Salvia miltiorrhiza that is used in Chinese medicine to treat “gynecologic diseases.”

The study is interesting, said Dr. Gregory A. Plotnikoff, director of the Institute for Health and Healing at Abbott Northwestern Hospital in Minneapolis.

But there are also a number of important limitations to the research, according to Plotnikoff, who researches herbal medicine, including its use for menopause symptoms.

For one, he told Reuters Health in an email, the placebo response in this study “is huge in comparison to most clinical trials and every menopausal hot flash trial I have ever reviewed.”

And that raises questions, Plotnikoff said — including whether women in the study could have been reporting hot flash improvements in order to “prove something,” or even to please the researchers.

He also said that the study was simply too small to know whether the statistically bigger improvement in the herb group was a real advantage over the placebo group. The difference was “barely” statistically significant, Plotnikoff said, and “could easily disappear” if a larger group had been studied.

Gao said that a further, larger trial is now underway to try to confirm the current findings.

But even if the herb mix proves to be better than a placebo, Plotnikoff questioned the appeal it would have. The herbs are thought to have estrogen-like activity, and many women want hot flash relief without hormonal effects.

Right now, hormone replacement therapy (HRT) is considered the most effective therapy for severe hot flashes.

But its use sharply dropped after a large 2002 U.S. clinical trial found that women on hormones had higher rates of heart attack, stroke, breast cancer and blood clots than placebo users.

Experts now advise that if women use HRT for menopausal symptoms, they should take the lowest possible dose for the shortest time possible.

There are several herbal or “natural” products marketed for easing menopause symptoms, including black cohosh, soy, red clover and dong quai. But there is little evidence from clinical trials on whether they work, according to the North American Menopause Society.

Black cohosh is probably the best studied, but trials have come to mixed conclusions about whether it is helpful.

If hot flashes are not severe, experts say, simple steps like avoiding hot and spicy foods, turning down the thermostat, or relaxation techniques, such as yoga or meditation, may help.

For most women, hot flashes gradually get better with time.

Another issue with the current study, according to Plotnikoff, is that the women were fairly young and in the middle of transitioning to menopause — a time when hot flashes are naturally highly variable.

Because of that, Plotnikoff said, data from such women would not be accepted by the US Food and Drug Administration as evidence of an effective hot flash remedy.