November, 2000: Asia
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Drawing of a single Trifolium spp. flower, sectioned longitudinally. The aerial portion of the plant illustrates the chevrons on the leaves and Trifolium spp. inflorescence. (From Simpson and Ogorzaly, Economic Botany: Plants in Our World, 2d ed., © 1995, McGraw-Hill Publishing Company.)
Root nodules on roots of bur clover, Medicago spp. (From Stern, Introductory Plant Biology, 8th ed., © 2000, McGraw-Hill Companies.)
After the age of 35, estrogen production in a woman’s body begins to wane over the next 10 to 15 years, a phase of life known as perimenopause. Estrogen is a hormone that stimulates secondary sex characteristics in women as well as helping maintain bone strength, skin elasticity, and a healthy circulatory system. Certain chemical, emotional, and physical characteristics are associated with the decline in estrogen, and one way to make the transition more bearable is through hormone replacement therapy. Studies have shown that women undergoing hormone replacement therapy show increased skin elasticity, a decrease in bone fractures, less difficulty with vasomotor upsets (hot flashes), and improved psychological well-being. However, hormone replacement therapy is not without risks, including increased occurrence of breast and uterine cancer.
Overall, women in North America, western Europe, and Australia experience greater estrogen deficiency than women in Asia, Central America, and the Mediterranean region. Researchers have linked several of the effects of estrogen deficiency to diet. For example, women in Asia, who tend to eat a diet high in legumes, have blood levels of phytoestrogens (natural plant estrogens) 20 to 30 times greater than those of most American women. American and European women tend to include fewer legumes in their diets.
Hormone replacement therapy can include the use of progesterone and estrogen or synthesized estrogens such as stibestrol and ethynyl estradiol. But recently, researchers have turned to phytoestrogens derived from food plants as a safer alternative. Several phytoestrogens have been identified and classified into groups. These groups include flavones, flavanones, flavonols, chalcones, lignans, and isoflavones; the most potent are the isoflavones. Many of these phytoestrogens are found in several fruits, vegetables, and cereal grains, but isoflavones are found only in legumes. A traditional legume-based diet offers 30—60 mg/day of isoflavones, specifically genistein, biochanin, daidzein, and formononetin.
Red clover, a legume scientifically known as Trifolium pratense, is one source of natural phytoestrogens. For the past 15 years, Novogen, a pharmaceutical company based in Stamford, Connecticut, has worked toward producing a dietary supplement derived from specially cultivated red clover. This supplement, called Promensil, delivers a standardized 40 mg of the four isoflavones.
Trifolium is in the Fabaceae family. This family of legumes is economically important as both fodder and human food, including soybeans (Glycine max), alfalfa (Medicago sativa), beans (kidney, black, and chick), and peanuts (Arachis hypogaea). Most members of Fabaceae have root nodules with nitrogen-fixing bacteria (Rhizobium spp.). This mutualism enables legumes to grow on relatively poor soils and to enrich nitrogen-poor soils in the process (nitrogen is a limiting nutrient for terrestrial plants). Other members are cultivated ornamentals such as the twining Wisteria. Fabaceae characteristically have a single carpel flower and a fruit that is a one-chambered pod. Trifolium is a bee-pollinated herb, with the anther and style emerging when the keel (a longitudinal ridge formed by two united lower petals) is temporarily depressed by the insect’s weight. This bee-foraging results in clover honey, a commercially valuable product.
References, Websites, and Further Reading
Promensil literature, published by Novogen, Inc., Stamford, CT, 1999.
http://encarta.msn.com "Estrogen," Microsoft® Encarta® Online Encyclopedia 2000. © 1997—2000 Microsoft Corporation.
http://www.promensil.com Novogen pharmaceutical website for Promensil dietary supplement, including clinical trials and suggested reading
http://www.tmc.tulane.edu/ecme/eehome/ Tulane University Medical Center: Environmental estrogens and other hormones
Stern, Introductory Plant Biology, 8th Edition
Chapter 5: Roots and Soils
Mutualism, pp. 73—74
Root nodules and nitrogen fixation, p. 75
Chapter 8: Flowers, Fruits, and Seeds
Structure of flowers, pp. 129—32
Dry fruits: legumes, pp. 134, 136
Chapter 11: Growth
Nutrients, vitamins, and hormones, pp. 188—95
Chapter 24: Flowering Plants and Civilization
Pollination, p. 421
Pollination ecology, pp. 425—30
Chapter 25: Ecology
Nitrogen cycle, p. 468—70
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