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Although there is plenty of evidence synthetic hormone replacement therapy (HRT) can affect women in serious, harmful ways, little is known about why estrogen use can be so risky. A recent study by researchers at the Medical College of Georgia may have found the answer.
Changes in blood vessel chemistry may explain the dramatic flip-flop in estrogen's function that occurs in older women, taking it from a dilator of vessels to a potentially dangerous constrictor.
Scientists had been concerned about recent studies that showed HRT was tied to doubling a woman's risk of venous thrombosis, a type of blood clot that travels through the veins to the lungs, as well as heart attack and stroke.
Researchers focused on estrogen's effects on blood vessels and, specifically, its impact on the smooth muscle cells that allow blood vessels to contract, thereby regulating blood pressure and blood flow. They found estrogen targets nitric oxide synthase 1, one of three versions of the enzyme that makes the powerful vasodilator, nitric oxide. And, after trying to block estrogen's activity by inhibiting nitric oxide, estrogen had converted into a constrictor agent, increasing blood pressure.
Another key finding: Normal aging decreases levels of the cofactors L-arginine and tetrahydrobiopterin -- both critical to nitric oxide synthase's production of nitric oxide. So, instead of making nitric oxide, estrogen was producing the powerful age-promoting -- and apparently vasoconstricting -- oxygen-free radical, superoxide that causes lots of cellular damage.
Just another reminder that synthetic progestins like Provera are responsible for nearly all the side effects and should rarely be used by any woman. And, the most popular estrogen women use -- Premarin -- comes from horse estrogens.
There are far better estrogen options. For most women, all they need is estradiol, which is bioidentical to the primary human female hormone. What the FDA and most doctors and patients do not realize is that bioidentical hormone supplements can actually optimize your health. Ideally, these levels should be monitored by either blood, urine or serum so they reach a target level that correspond to the reference ranges for healthy young women.
Medical College of Georgia February 16, 2005