Susie Hewson is marketing director of Bodywise UK, which produce Perfect Woman Extract of Wild Mexican Yam Herbal Feminine Cream. Perfect Woman is a body cream for external use with 8.5 per cent yam extract. "The extract has a three-fold effect," explains Hewson. "It mimics the effect of progesterone, it has a homeopathic effect with the other herbs in the cream, and it encourages the body to make its own progesterone. PMT is caused when hormones are out of balance; the cream helps rebalance them."
Perfect Woman, available from independent health stores, costs pounds 19.99 for a pot that lasts two months. "You use between a quarter and a half teaspoon on your skin two or three times a day," explains Susie Hewson. "And you don't use it right through the month. For example if you have PMT you would use it in the second half of your cycle, from ovulation through until you start your period." And, erm, where exactly do these doses go? "On the soft tissues of the body - the inner thighs, insides of the arms and the tummy," says Susie Hewson. "The active ingredients are taken up by the fatty tissue under the skin."
Yams are also the mainstay of "natural hormone replacement therapy". "Natural" HRT, pioneered in the US, uses extract from yams and soya; this can be removed, treated so that it is identical to human progesterone, and used in capsule or cream form. In this country, the Medicines Control Agency, which is responsible for licensing drugs, will only allow such preparations to be prescribed by doctors. This is much to the chagrin of pro-yam campaigners, who believe that synthetic hormones should be avoided if possible, and that the "natural" (well, natural-ish) version produces fewer side-effects.
In this country, yams remain untested. A two-year trial at Chelsea and Westminster Hospital was recently given the go-ahead - and none too soon, says Susie Hewson. "Pharmaceutical companies push synthetic compounds because they can be patented; women deserve more choice."