THE PHASES OF THE MENSTRUAL CYCLE
The monthly cycle is usually divided into three phases:
- menstruation
- follicular (or proliferative) phase
- luteal (or secretory) phase
Menstruation (days 1-6). A normal period lasts from one to eight days although the average is five. During menstruation levels of oestrogen and progesterone are at their lowest. This triggers the unfertilized egg and the lining of the womb to be shed, resulting in bleeding.
Follicular phase (days 7-14). PSH and small amounts of LH are produced by the pituitary gland. This triggers the ovaries to develop several small fluid-filled compartments (called primordial follicles) which contain eggs. The follicles produce increasing amounts of oestrogen as they mature.
Oestrogen levels peak just before ovulation and this triggers a surge of LH from the pituitary. The most mature egg at the time of the 'LH surge' is released from the ovary. Ovulation usually occurs within 36 hours of the LH surge.
Once a ripe egg has been released the other follicles degenerate. In the meantime the womb has also been active: its lining thickens and becomes spongy in preparation for pregnancy.
Luteal phase (days 15-28). The follicle that contained the egg is now called the corpus luteum. LH triggers the corpus luteum to produce progesterone which encourages the growth of the extra blood vessels in the womb needed for a pregnancy.
The corpus luteum remains for around 14 days after ovulation when it shrivels up and dies. Progesterone levels fall from around day 22 of the cycle.
Oestrogen levels also fall during this time and, as these hormones fall, the lining of the womb degenerates, so completing the cycle, PMS occurs during the luteal phase of the cycle, after ovulation.
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Womens health
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HOW FOODS CAN PREVENT BREAST CANCER: DECREASE ESTROGENS
Here's how to counter the ill effects of bad, recycled, chemical, and free estrogens.
Bad Estrogen
Even if you produce moderate to high amounts of estrogen, there is an emerging strategy to blunt its potency. You can actually channel your estrogen into good estrogen rather than bad estrogen by eating a diet high in cruciferous vegetables. Those include cauliflower, broccoli, and cabbage. Both exercise and low body fat also increase the production of good estrogen. Alcohol, polyunsaturated fats, and too much body fat all increase the production of bad estrogen.
Recycled Estrogen
When estrogen is transported from the bloodstream through the liver and into the bowel for disposal, it is assisted by large amounts of fiber in the bowel. That fiber binds to estrogen in the intestine so that the body cannot reabsorb it, ensuring that it is excreted with other waste products. However, when there is too little fiber in the diet, the estrogen remains free in the bowel and may be reabsorbed by the body into the bloodstream, raising the amount of estrogen in the bloodstream. A study at Tufts University showed that the more a woman's bowel movement weighed, the lower was her blood estrogen level. The assumption is that the increased weight of the bowel movement was due to the fiber.
Free Estrogen
The most effective way to decrease the amount of free estrogen in the blood is to build more of the carriers that bind estrogen in the blood and keep it from estrogen receptors. Lets look at the key strategies. The prime regulator of estrogen carriers is the hormone insulin, according to Banoo Parpia of the China-Cornell-Oxford Project. The lower you can drop your insulin, the more estrogen carriers your body manufactures. A low-fat diet also reduces the amount of free estrogen in healthy postmenopausal women. Soy also manufactures more carriers. A high-fiber diet helps to bind more free estrogen in your blood and keeps it at lower, safer levels. Many of these measures also decrease estrogen production, so you are cutting your cancer risk in at least two separate ways.
Chemical Estrogen
The most aggressive prevention includes avoiding animal and fish products with high fat contents that can pick up and concentrate large quantities of chemical estrogens and pesticides. The worst offenders and how to avoid them are found in the chapter "Step 8: Avoid Chemical Estrogens." Eating organic foods that have always been pesticide-free will help you to avoid contaminating breast fat. Washing all fruits and vegetables thoroughly will help remove pesticides. Since most women already have high stores of chemical estrogens in their breast fats there are two other strategies that have proved to be beneficial. First is breast-feeding, which flushes pesticides out of their storage site in breast fat. That does mean that your infant ingests milk with chemical estrogens, but pediatricians do not believe this is harmful. The most practical strategy of all is to consume large amounts of estrogen blockers such as soy, which block the effect of these chemicals at the estrogen receptors on breast cells.
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Womens health
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