Posts Tagged "Estrogen"

National Institutes of Health researchers have shown that women’s cholesterol levels correspond with monthly changes in estrogen levels. This natural variation, they suggest, might indicate a need to take into account the phases of a woman’s monthly cycle before evaluating her cholesterol measures. On average, the total cholesterol level of the women in the study varied 19 percent over the course of the menstrual cycle.

In a typical cycle, estrogen levels steadily increase as the egg cell matures, peaking just before ovulation. Previous studies have shown that taking formulations which contain estrogen — oral contraceptives or menopausal hormone therapy — can affect cholesterol levels. However, the results of studies examining the effects of naturally occurring hormone levels on cholesterol have not been conclusive. According to the NIH’s National Heart, Lung and Blood Institute, high blood cholesterol levels raise the risk for heart disease.

The researchers found that as the level of estrogen rises, high-density lipoprotein (HDL) cholesterol also rises, peaking at the time of ovulation. HDL cholesterol is believed to be protective against heart disease.

In contrast, total cholesterol and low-density lipoprotein (LDL) cholesterol levels — as well as another form of blood fat known as triglycerides — declined as estrogen levels rose. The decline was not immediate, beginning a couple of days after the estrogen peak at ovulation. Total cholesterol, LDL cholesterol and triglyceride levels reached their lowest just before menstruation began.

Source: NIH News

Exposure to bisphenol A (BPA) through consumption of canned beverages is associated with increases in systolic blood pressure, according to a randomized crossover trial in Hypertension. BPA is a chemical found in many plastic bottles, food containers, and the linings of cans.  Sixty older adults (mostly women) had three study visits, during which they consumed two servings of soy milk provided one of three ways: in two glass bottles (least amount of BPA exposure), two cans (most BPA), or one glass bottle and one can. The sequence of serving containers was randomized.  Urinary BPA concentrations were significantly higher 2 hours after participants drank from two cans versus two glass bottles. Furthermore, systolic BP was roughly 4.5 mm Hg higher after two cans versus two glass bottles. The authors write that the observed increase in systolic BP “may cause a clinically significant increase of risk of cardiovascular disorders, such as heart diseases and peripheral arterial diseases.”  Bisphenol A (BPA) is produced in high volumes worldwide. It is used in the manufacture of polycarbonate plastics and epoxy resin, which are used in the linings of food or beverage cans, water bottles, and dental fillings. BPA has been detected in 95% of the population of the United States.

BPA is considered to be an endocrine-disrupting chemical, and it shows affinity for estrogen receptors. It was initially considered to be a weak xenoestrogen, but subsequent studies showed that BPA can have effects even at low concentrations.  In addition, pathways other than binding to estrogen receptors have been proposed. These include the thyroid hormone pathway, binding to glucocorticoid receptors and androgen receptors, or interfering with the central nervous system and immune system. Epidemiological studies have suggested that BPA could have adverse effects on human health.  Specifically, BPA exposure has been shown to be associated with increased production of liver enzymes, recurrent miscarriages, premature delivery of fetuses, inflammation and oxidative stress, decreased quality of semen, and male sexual dysfunction.

Source: NEJM Journal Watch

In 1978 the Bee Gees ruled the airwaves, Grease topped the box office and the U.S. Food and Drug Administration first proposed a rule on antibacterial hand soaps—a rule that would have eliminated an unnecessary and unsafe ingredient called triclosan. Thirty-five years later many things have changed, but the FDA has not. Just recently it proposed rules on antibacterial soaps that would remove triclosan-containing soap from the shelves—for the third time. Yet because the FDA has failed to finalize any of these proposals, triclosan has proliferated in the marketplace. It is now the most common active ingredient found in antibacterial consumer hand soaps.

It’s also common in our bodies. Triclosan has been measured in amniotic fluid, breast milk, human blood and the urine of 75 percent of Americans sampled over the age of six. Although it does not discriminate by gender or racial/ethnic group, it appears to increase in concentration as income increases. Despite little evidence of their effectiveness to reduce illness, triclosan-containing antibacterial soaps have dominated the market. Soap aside, triclosan can also be found in consumer products as diverse as cutting boards, shoes, lipstick and toothpaste.

In other words, we are continually exposed to triclosan. The problem is that triclosan is not safe. In animal studies it has been shown to interfere with the regulation of thyroid hormones (affecting metabolism and brain development), testosterone synthesis (decreasing sperm counts) and estrogen action (causing early onset of puberty). Exposure to triclosan has been shown to weaken heart muscle, impairing contractions and reducing heart function, and to weaken skeletal muscle, reducing grip strength. In aquatic environments fish exposed to triclosan were unable to swim properly.

Higher urinary levels of triclosan are associated with hay fever, allergies to airborne triggers (like ragweed and cats) and food (peanut, shrimp, dairy) allergies. Triclosan has even been associated with elevated body mass index in adults. Although the mechanism driving this association is not clear, researchers suggest that it could be due to changes in the gut flora or hormones.

There are also concerns about the potential impact of triclosan use on development of antibiotic resistance. Laboratory studies on bacteria exposed to triclosan demonstrate evidence of cross-resistance to critically important antibiotics including erythromycin, ciprofloxacin, ampicillin and gentamicin. Further, there is evidence that resistance to triclosan itself exists in Salmonella enterica, Staphylococcus aureus, streptococcus, Escherichia coli and other species of bacteria. Strains of Mycobacterium tuberculosis tolerant to triclosan have also showed resistance to the drug isoniazid (INH), which is used to treat tuberculosis. Although the overuse of antibiotics in humans and livestock is a greater contributor to the public health crisis of antibiotic-resistant bacteria, the potential increased risk of antibiotic resistance from the use of antimicrobial chemicals is unnecessary.

To add insult to injury, there is no added benefit to using triclosan (or any antibacterial) soaps. Triclosan is intrinsically ineffective against some bacteria like Pseudomonas aeruginosa and fungal infections. The FDA requires that to be considered effective these soaps must do more than remove bacteria; they must “provide a clinical benefit by reducing infections.” But studies show that using soap containing triclosan does not reduce human illnesses or infections any more than using regular soap. There have even been occasional reports of fatal bacterial outbreaks in hospitals using triclosan, including bacterial contamination of triclosan soap containers in a surgical intensive care unit.

Which brings us back to the FDA. In the rule it proposed in 1978 (and again in 1994 and 2013) the FDA said it does not have sufficient information to determine whether triclosan is safe or effective. In the absence of such a determination triclosan cannot be sold in the U.S.—but the FDA’s failure to finalize these proposals allowed the products to remain on the market. Therefore, in 2010 the Natural Resources Defense Council sued the FDA to compel it to finalize its rules. As a result of the settlement, the FDA now has to finish its rules on antibacterial soaps by September 2016. If at that time the FDA still cannot say triclosan is safe and effective, then antibacterial hand soaps can no longer contain triclosan. Until then, antibacterial soaps remain on the market and consumers are left to protect themselves from this harmful chemical.

Source: Scientific American