Lifestyle Changes to Manage Menopause

The Amount of Phytoestrogen That Is Absorbed

Because the body must convert or alter phytoestrogens through digestion, the actual amount of active compound that is absorbed varies. The relative potency is 0.1%-2.0% that of estradiol, a form of estrogen. In premenopausal women with high endogenous estrogens, phytoestrogen compounds compete for receptor sites with estrogens. Therefore, the net effect of phytoestrogens in premenopause may be anti-estrogenic (estrogen antagonist) because the activity on the receptor is much less.

In postmenopausal women who are taking exogenous estrogen therapy, again the net effect of phytoestrogens may be anti-estrogenic. In postmenopausal women with low levels of endogenous estrogen, occupation of the receptors by phytoestrogen compounds may increase the total estrogenic effect (estrogen agonist). This group of women (namely, postmenopausal, low endogenous estrogen, not on hormone replacement therapy) would be more likely to have vasomotor symptoms (eg, hot flashes and night sweats), have urogenital atrophy (eg, vaginal discomfort), and be at risk for osteoporosis. This is the group that could potentially benefit from phytoestrogen compounds in their diet.

This table shows the relative potency of phytoestrogens compared to estradiol, as cited in the journal Obstetrics and Gynecology .

Soy

The typical Asian diet contains 20-150 mg of isoflavones or 20-50 grams of soy protein per day. A typical diet supplementation would be a daily substitute of 50 grams of soy protein for the equivalent amount of animal protein. This is the equivalent of about 1 cup of soy flour. This amount would contain less than 350 mg of isoflavones, and an unknown amount of converted compounds would be biologically available. With certainty, the biologic effect of this amount of soy would be considerable less than 0.025 mg of transdermal estradiol, 0.5 mg of micronized estradiol, or 0.3 mg of conjugated equine estrogens (CEE).

A double-blind randomized controlled trial of 58 postmenopausal women comparing 45 grams of soy flour per day to 45 grams of wheat flour per day showed a 45% reduction in hot flashes with soy flour and a 25% reduction in hot flashes with wheat flour. An additional three studies support this finding. More information about soy can be found at the University of Illinois' StratSoy website .

Phytoestrogens and Bone Mineral Density

There is insufficient data on the potential effect of dietary intake of phytoestrogens on bone mineral density in postmenopausal women.

Soy and Lipids

A meta-analysis of the effects of soy consumption on lipids concluded that low density lipoprotein (LDL) could be modestly reduced by substituting daily servings of soy for animal protein. Some of the studies analyzed were poorly designed, and the analysis is subject to publication bias. Importantly, substituting soy means that the animal protein was removed from the diet. When we eat animal protein, we also eat animal fat. So it's difficult to separate the effect of removing animal protein and fat from the diet from a possible additional beneficial effect of adding soy. Any woman with elevated LDL needs to lower her daily fat content, especially saturated fats, which are found in animal-source food. Any method that accomplishes this goal will be helpful, and substituting soy products appears to be a safe and effective method.

Phytoestrogens and Endometrium

There are no studies of the effect of phytoestrogens on endometrium.

Legumes

Studies on the safety of phytoestrogens are limited, but legumes appear to be safe as part of a balanced diet, and in cultures throughout the world, a dietary intake of phytoestrogen-containing foods has not been shown to be harmful. Rather, those cultures appear to be realizing health benefits from a diet that has lower fat and animal-source content then the standard American diet. Although it is unlikely that people could suffer an "overdose" effect from enriching their diet with phytoestrogen-containing foods, it would be possible to take excess amounts of neutraceutical concentrations of phytoestrogen derivatives, such as the isoflavones and ipriflavone. Isoflavones are not the only biologically active substances in soy beans; there are also protease inhibitors, omega-3 fatty acids, and phytosterols—all of which would be absent in a capsule containing concentrated isoflavones.

Soy and phytoestrogens cannot be considered a substitute for estrogen replacement therapy (ERT) and hormone replacement therapy (HRT). The effects of combining phytoestrogens with ERT/HRT are not completely understood.

Ipriflavone

Ipriflavone is a synthetic isoflavone derivative which is structurally very similar to daidzein and genistein. When ipriflavone is consumed by a human, it is metabolized; the major metabolite is daidzein.

Two placebo-controlled randomized trials involving postmenopausal women with osteopenia (most commonly caused by osteoporosis), treated with either calcium and placebo or calcium and ipriflavone (200 mg three times a day) for two years, reported that women who received calcium experienced a decrease in vertebral bone density. The women who received calcium and ipriflavone did not have a loss of bone density.

A placebo-controlled randomized trial involving postmenopausal women with osteoporosis, treated with either calcium and placebo or calcium and ipriflavone (200 mg three times a day) for two years, reported that women who received calcium experienced a decrease in vertebral bone density. Women who received calcium and ipriflavone had a gain in vertebral bone density. To date, there is only preliminary data regarding the use of ipriflavone and bone fractures.

The Ipriflavone Multicenter European Fracture Study of postmenopausal women with osteoporosis should be published soon. There have not been reports of significant side-effects from ipriflavone. The long-term safety has not been established. Further prospective studies are need to clarify the role of ipriflavone in management of postmenopausal women.

Phytoestrogens and Other Areas of Study

At present, there is insufficient data on the potential effect of dietary intake of phytoestrogens on bone mineral density in postmenopausal women. Also, there are no studies of the effect of phytoestrogens on endometrium; this is possibly an area of future research.

Progesterone Creams

USP progesterone is the commercially prepared substance that is sold in bulk to companies to make capsules, oils, tablets, gels. It may also be added to creams and sold over-the-counter. There is no evidence that use of these creams can be substituted for prescribed progestogens for the purpose of opposing estrogenic effects on the endometrium. There is little consistency or quality control; the detectable amount of progesterone in over-the-counter creams varies extremely from 0 to 500 mg/ml.

A randomized placebo-controlled trial of 20 mg of progesterone cream applied to the skin daily reported an improvement in vasomotor symptoms in 83% of treated women and 19% of placebo subjects. There is insufficient evidence to support the use of over-the-counter USP progesterone creams for the management of menopausal symptoms. These products should not be substituted for a prescribed progestogen as part of an estrogen and progestogen replacement therapy regimen.