Black cohosh and red clover are ineffective at reducing menopausal hot flashes. Nor do those popular herbal therapies have any effect on memory.

Those are the findings from two small but randomized and double-blinded studies published last week in the journal Menopause.

Hormone therapy (HT) (an estrogen plus progesterone combination) did reduce the incidence of hot flashes. No surprise there.

HT was also found to have a slight negative effect on memory. No real surprise there, either. For although early studies suggested that HT might improve memory, later, better-designed studies have found some negative (albeit modest) effects of HT, particularly the combination form, on verbal memory.

But I thought the most interesting finding from this study was the placebo's effect on hot flashes. During the 12 months of the study, the women who took a placebo reported a 63 percent reduction in the number of hot flashes they experienced weekly. That reduction was greater than for black cohosh (34 percent) and for red clover (57 percent).

HT resulted in the greatest reduction in hot flashes (94 percent), but, of course, it is no longer recommended for that purpose because of its strong association with an increased risk of stroke, heart disease and breast cancer.

The placebo finding was “higher than expected,” according to the authors of one of these studies. A few years ago, other researchers found that taking a placebo reduced hot flashes by about 50 percent.

What this suggests, of course, is that highly touted (and aggressively marketed) “natural” supplements for hot flashes are likely to be a waste of money.

What this also suggests is that time — and, I might add, a sense of humor — may be a menopausal woman's best friend.

NB: This research was partially funded by a National Institutes of Health grant. The lead author in the memory study has received grant support from the Soy Health Research Board and Wyeth Pharmaceuticals, maker of the HT drugs Premarin and Prempro. Menopause journal is published by the North American Menopause Society, a nonprofit organization funded largely by a long list of pharmaceutical companies, including the leading manufacturers of HT drugs.