You may not think too much about estrogen other than to be aware that it is a female sex hormone. However, the Cleveland Clinic says that estrogen affects almost every organ or tissue in the body, including the obvious ones like the uterus, breasts and ovaries, but also the heart, blood vessels and blood clotting. Estrogen even affects cholesterol levels.
Estrogen
In menstruating women, estrogen levels rise steadily during the menstrual cycle, peaking just before ovulation, and then gradually falling. This pattern repeats with each menstrual cycle. After menopause, of course, estrogen declines steadily. Estrogen has been found to increase HDL cholesterol, the "good" cholesterol. HDL cholesterol helps to protect against heart disease; HDL stands for high-density lipoprotein. Estrogen decreases LDL or low density lipoprotein cholesterol, which can cause arteriosclerosis if it is too high.
Estrogen and Cholesterol
The National Institutes of Health reports that researchers have found women's cholesterol levels correspond with monthly changes in estrogen levels. The cholesterol of the women studied by the NIH varied as much as 19 percent over the course of the menstrual cycle. As estrogen levels rose, HDL cholesterol also rose, peaking about the time of ovulation. In contrast, the total cholesterol and LDL cholesterol dropped as estrogen rose. Total cholesterol and LDL were lowest just before menstruation began, which is also when the estrogen levels in the body are lowest.
Estrogen Medications
Oral contraceptives contain estrogen and progesterone, another female sex hormone. Progesterone decreases HDL cholesterol. The balance of hormones in a particular birth control pill will be the deciding factor as to the net effect on cholesterol. The Cleveland Clinic says that doctors used to think menopause caused an increase in heart disease due to changes in cholesterol levels. This led to the use of hormone replacement therapy for menopause.However, further studies showed women on hormone replacement therapy actually had an increased risk of heart attack in the first year of treatment.
Research
Researchers at the University of Texas Southwestern Medical Center reported that in rodents, a cholesterol byproduct called 27-hydroxycholesterol prevents estrogen from binding to receptors in the heart. In premenopausal women, 27-hydroxycholesterol is relatively low compared to estrogen, but that changes during menopause. The results of the study may explain why women are better protected from heart disease than men prior to menopause, and why hormone therapy doesn't protect some women from heart disease after menopause.
Considerations
If you have high cholesterol or questions about the relationship of estrogen to cholesterol, consult a health care professional.
References
- American Heart Association; Good Vs. Bad Cholesterol; June 2011
- Cleveland Clinic; Rethinking Old Ideas: Estrogen & Heart Disease; Leslie Cho, MD; 2011
- Dr. Donnica.com; Cholesterol: The Good, The Bad, And The Triglycerides; Donnica Moore, MD;2006
- National Institutes of Health; Women's Cholesterol Levels Vary With Phase Of Menstrual Cycle; August 2010
- University of Texas Southwestern Medical Center; Cholesterol-Regulating Protein Maintains Fat-Storage, Fat-Burning Balance; Amanda Seigfried; April 12, 2005
- American Heart Association; Women and Cholesterol; June 2011
