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Many plants contain chemicals that closely resemble the female hormone oestrogen and mimic its action in the body by competing at the hormone receptor sites at a cellular level.
The most well known sources of plant oestrogens (phytoestrogens) are soy products, hops, grapes, liquorice, alfalfa, Black Cohosh and pomegranates.
The benefits of soy
It has long been recognised that Asian women who consume large amounts of soy in their diets have relatively low levels of reproductive and hormone-related diseases. Indeed, there is no equivalent to ‘hot flushes’ in the Japanese language because the menopause is not a significant event for women with diets high in phytoestrogens.
Over 200 studies around the world (Cassidy et al, American Journal of Clinical Nutrition 1994; Clarkson et al, Trends Endocrinol Metab 1995, etc.) have now documented the benefits of a particular group of phytoestrogens that are present in soy products.
This group of Aglycone chemicals (without sugar) is known as the isoflavones and in soy there are three significant isoflavone compounds: daidzein, genistein, glycitein.
Biologically, any sugar attached to isoflavones must be removed in the intestinal tract before the isoflavone can be absorbed. For this reason many isoflavone supplements are pre-digested or fermented with lactic acid bacteria before combination with their carrier compounds to ensure optimal bio-availability.
Isoflavones may be beneficial to menopausal women: research has shown that a daily uptake of 50mg can reduce hot flushes by up to 40%, and there is evidence that isoflavones can prevent a loss of bone density. (see reports on the use of ‘natural’ progesterone to maintain and increase bone density).
The indications are that women with diets containing 25-75mg of isoflavones maintain physical, mental and emotional well being throughout their lives. In addition, isoflavones have been shown to be useful in minimising PMS symptoms which can result from hormone imbalances or the impact of poor diet and xeno-oestrogens especially in younger women.
Phytoestrogens, and in particular genistein, are powerful antioxidants and can improve the balance of cholesterol in the blood. Anderson et al (New England Journal of Medicine, 1995) reported a 12.9% reduction of LDL cholesterol and 10.5% reduction in harmful triglycerides with a daily dose of 47mg soy protein. There is also evidence that isoflavones help maintain or increase levels of HDL cholesterol, thus further reducing the risk of cardio-vascular disease.
How hormones work
For each hormone there will be receptor sites in various parts of the body. For oestrogen they have been identified throughout the body but especially in the reproductive system, the breasts and bones. The impact of phytoestrogens on breast tissue is amply demonstrated by the effect that excess beer (hops) can have on heavy drinking men!
Hormones act as ‘keys’ to unlock a secondary biochemical action at each receptor site. For example, when no hormone is present in the blood stream then the receptor site performs no function. However, when the appropriate hormone for the specific receptor, or a very similar chemical (e.g. a plant chemical or a synthetic drug designed to mimic the hormone) attaches to the receptor then the receptor initiates a biochemical reaction in its associated cells. For example cells may begin to proliferate in a specific way or another chemical may be released. Hormones can also have a psycho-chemical effect and create a feeling of fear or well-being.
Beware dangerous imitations
There are also many man-made chemicals in the environment that mimic oestrogen. These are known as xeno-oestrogens and they are found in many pollutants, packaging (Polystyrene and drink cans), plastics, pesticides, vinyl, even shampoos.
The combination of xeno-oestrogens with poor (junk) diets high in alcohol, sugar and caffeine, and the fact that so many synthetic female hormones from birth control pills are excreted into our watercourses, is seen as the primary cause for falling sperm counts in many animals (including man!), earlier puberty in girls and the increase in ‘hormonal’ conditions in women e.g. PMS and menopause.
In societies that are relatively free of the ‘benefits’ of Western society the incidence of PMS and menopausal problems are much rarer and medical intervention in the menopause (HRT) is much less common.
Saponins
Saponins are high-molecular weight glycosides combining a sugar element and a steroid aglycone or triterpene molecule. Diosgenin, the extract of wild mexican yam, is a steroid gylcoside.
The name comes from the Latin sapo (soap) because of the detergent action that many saponins exhibit. saponin containing plants have been recognised for many years and their names reflect this property e.g. soapwort, soapbark, soap root etc.
Whilst there has been a tremendous amount of clinical research into the oestrogenic effects of soy there has been little research into the biochemical action of saponins despite the fact the chemical basis of both saponins and isoflavones is essentially the same.
Soy contains a number of oestrogenic components including daidzein, genistein, glycitein and several isoflavones. There is a great deal of research confirming that these chemicals can have oestrogenic and anti-oestrogenic effects.
However saponins have now been ‘discovered’ by medical science and there are many research programmes underway around the world. Some of the better known saponins are yucca and wild mexican yam.
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