Sunflower Seeds Contain Coumestrol
There is no simple answer to this question. Plants containing estrogen mimics may be beneficial in some instances and hazardous in others, according to Patricia Whitten, an anthropologist working at the Laboratory of Reproductive Ecology and Environmental Toxicology at Emory University in Atlanta, Georgia. Scientists are just beginning to explore plant estrogens and how these hormone mimics in food affect us, so fundamental questions - such as how much we actually ingest in our foods - remain as yet unanswered. Because humans eat a varied diet, it is not clear whether we ingest sufficient quantities to worry about. The dose question is, moreover, inherently tricky when dealing with hormones. Depending on your age, sex, and hormonal status, the same dose can have wildly different effects. It will matter whether you are a man or a woman; a post menopausal woman or one still in her reproductive years; an adult, a child, or a baby developing in the womb.
Whitten has found that exposure to plant estrogens early in life can undermine the ability of rat pups to reproduce when they grow up. In her experiment, the rat mothers were given low doses of coumestrol, a plant estrogen found in sunflower seeds and alfalfa sprouts, which they passed on to their babies through their milk. Rats are considerably less developed than humans at birth, so in the days after birth they are undergoing stages of development that in humans occur in the womb.
"We think we've altered the sexual differentiation of the brain," Whitten says of the exposure. The females don't ovulate and are sterile because their brains do not respond to the hormone that triggers ovulation - an indication that they have been masculinized. The males, on the other hand, are feminized, showing less mounting behavior and fewer ejaculations. For a rat, the first ten days after birth are the critical period for the development of those areas of the brain linked to sexual behavior.
But the very same foods that disrupt development before birth or early in life might help to prevent disease in an adult. Evidence that foods high in plant estrogens, such as soybeans, might protect against breast cancer and prostate cancer has sparked a great deal of scientific interest and new research into plant estrogens. Numerous studies have linked estrogens, even those naturally occurring in the body, to cancer, suggesting that the greater a woman's lifetime exposure, the greater the risk. Researchers theorize that plant estrogens might be protective because they are weaker than the natural estrogens made in the body. If the occupy the estrogen receptors in the breast and displace natural estradiol, they might reduce a woman's lifetime exposure to estrogen.[1]
But the very same foods that disrupt development before birth or early in life might help to prevent disease in an adult. Evidence that foods high in plant estrogens, such as soybeans, might protect against breast cancer and prostate cancer has sparked a great deal of scientific interest and new research into plant estrogens. Numerous studies have linked estrogens, even those naturally occurring in the body, to cancer, suggesting that the greater a woman's lifetime exposure, the greater the risk. Researchers theorize that plant estrogens might be protective because they are weaker than the natural estrogens made in the body. If the occupy the estrogen receptors in the breast and displace natural estradiol, they might reduce a woman's lifetime exposure to estrogen.[1]
1. Theo Colborn, Diane Dumanoski, John Peterson Myers, Our Stolen Future, Penguin Books USA, NY, NY, March 1997, p. 79-80.
Further References: P. Whitten, "Chemical Revolution to Sexual Revolution: Historical Changes in Human Reproductive Development," in Chemically Induced Alterations, pp. 311-34.
P. Whitten and F. Naftolin, "Effects of a Phytoestrogen Diet on Estrogen-Dependent Reproductive Processes in Immature Female Rats," Steroids 57:56-61 (1992).
P. Whitten , E. Russell, and F. Naftolin, "Effects of a Normal, Human-Concentration, Phytoestrogen Diet on Rat Uterine Growth," Steroids 57:98-106 (1992).
P. Whitten, C. Lewis, and F. Naftolin, "A Phytoestrogen Diet Induces the Premature Anovulatory Syndrome in Lactationally Exposed Female Rats," Biology of Reproduction 49:1117-21 (1993).