So far soya good

Drinking two glasses of soya milk a day could relieve older women from the curse of hot flushes, claim researchers.

They found that a couple of daily servings of foods made from the soya plant led to a reduction in the frequency and severity of hot flushes by up to 26 per cent.

Their work is the most comprehensive review so far looking at the effects of soya in foods such as tofu, soya-fortified milk and dairy products on menopausal symptoms. Soya contains isoflavones, or oestrogen-like plant hormones, which are believed to have a beneficial effect on health. The latest evidence comes from a review of 19 studies involving more than 1,200 women.

Many women have turned to natural remedies to cope with symptoms such as hot flushes, night sweating and mood swings because they fear the side-effects of hormone replacement therapy, according to some experts.

Hot flushes occur suddenly, lasting about four minutes on average, and produce an uncomfortable feeling of intense heat. Sufferers may break out in sweat during the day, while hot flushes at night can disrupt sleep. The symptoms are caused by the dilation of blood vessels in the skin and are linked to hormone imbalances, but are still not fully understood.

Mixed findings

There have been mixed findings on the effectiveness of soya in alleviating flushes, with some studies suggesting benefits and others showing no effect.

However, the authors of the review, published in Menopause, the journal of the North American Menopause Association, blamed much of the discrepancy on small sample sizes and inconsistent methodology.

Co-author professor Melissa Melby, of Delaware University, said: "When you combine them all, we've found the overall effect is positive."

The interest in soya and menopause stems from Japan, where researchers found that the low frequency of hot flushes in women could be attributed to lifelong high soya consumption.

But Melby added: "If you're 50 and have never touched soya, it's not too late. We've found that it still helps."

The researchers said that when women consumed soya for 12 weeks or more, the drop in the frequency of hot flushes was about threefold greater than in shorter trials.

Melby said that ingesting at least 54mg of soya isoflavones daily for six weeks to a year reduces the frequency of hot flushes by 20.6 per cent and their severity by 26 per cent.

Each gram of soya protein in soya beans and traditional soya foods provides about 3.5mg of isoflavones. Two 454g glasses of soya milk, or 198g of tofu, provide approximately 50mg of isoflavones.

Supplements containing at least 19mg of genistein, one of the two main types of isoflavones, were more than twice as effective at reducing frequency than lower amounts.

Melby said that the genistein result was particularly relevant because the compound is the primary isoflavone in soya beans and soya foods.

She said, "Eating soya foods, or using supplements derived from whole soya beans, may work better for women."

However, a report last year found soya tablets, made from the soya plant, do not cut symptoms of menopause in older women.

Long-term treatment with soya products has also raised concerns that it can cause the womb lining to thicken.