(Press-News.org) Asian women who consumed an average of 200 milligrams or more of caffeine a day—the equivalent of roughly two cups of coffee—had elevated estrogen levels when compared to women who consumed less, according to a study of reproductive age women by researchers at the National Institutes of Health and other institutions.
However, white women who consumed 200 milligrams or more of caffeine a day had slightly lower estrogen levels than women who consumed less. Black women who consumed 200 milligrams or more of caffeine a day were found to have elevated estrogen levels, but this result was not statistically significant.
Total caffeine intake was calculated from any of the following sources: coffee, black tea, green tea, and caffeinated soda.
Findings differed slightly when the source of caffeine was considered singly. Consuming 200 milligrams or more of caffeine from coffee mirrored the findings for overall caffeine consumption, with Asians having elevated estrogen levels, whites having lower estrogen levels, and the results for blacks not statistically significant. However, consumption of more than one cup each day of caffeinated soda or green tea was associated with a higher estrogen level in Asians, whites, and blacks.
The changes in estrogen levels among the women who took part in the study did not appear to affect ovulation. Studies conducted in animals had suggested that caffeine might interfere with ovulation.
The study was published online in the American Journal of Clinical Nutrition.
"The results indicate that caffeine consumption among women of child-bearing age influences estrogen levels," said Enrique Schisterman, Ph.D., of the Division of Epidemiology, Statistics and Prevention Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the NIH institute where some of the research was conducted. "Short term, these variations in estrogen levels among different groups do not appear to have any pronounced effects. We know that variations in estrogen level are associated with such disorders as endometriosis, osteoporosis, and endometrial, breast, and ovarian cancers. Because long term caffeine consumption has the potential to influence estrogen levels over a long period of time, it makes sense to take caffeine consumption into account when designing studies to understand these disorders."
The study authors noted that 89 percent of U.S. women from 18-34 years of age consume the caffeine equivalent of 1.5 to two cups of coffee a day.
The study's first author was Karen C. Schliep, Ph. D., M.S.P.H., from the University of Utah, Salt Lake City, who conducted the study during a research appointment at NICHD. Dr. Schliep undertook the research with Dr. Schisterman and colleagues at the University of Utah, the NICHD and the State University of New York at Buffalo.
More than 250 women from 18 to 44 years old participated in the study between 2005 and 2007. On average, they consumed 90 milligrams of caffeine a day, approximately equivalent to one cup of caffeinated coffee.
Most of the participants in the study reported to the study clinic one to three times a week for two menstrual cycles. Their visits were scheduled to correspond with specific stages of the menstrual cycle. At the visits, the women reported what they had eaten in the last 24 hours and answered questions about their exercise, sleep, smoking and other aspects of their lifestyle and reproductive hormone levels were measured in blood. The study authors noted that collection of these details during multiple time points across two menstrual cycles produced more precise information about the link between caffeine and hormones than was possible in earlier studies. The researchers also noted that the study participants were more racially diverse than those who took part in previous studies.
INFORMATION:
About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD): The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's website at http://www.nichd.nih.gov/.
About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
END
NEW YORK – January 26, 2012 – When a firm experiences a negative shock – e.g. a drop in revenues, loss of the CEO – it will face difficulties when raising new debt for many reasons. The most obvious reason for this difficulty is that the fundamentals of the firm are weaker and lenders recognize that there is less chance the firm can generate the necessary cash flows to repay the loan. Another primary reason is that a lender may worry that the bad news will scare off other creditors and will drive the firm into bankruptcy. This leads to the possibility of inefficient "creditor ...
Bethesda, MD – In his State of the Union address, President Barack Obama presented the nation with a new economic blueprint which includes maintaining our commitment to funding research and development that can improve our quality of life. Noting that "innovation also demands basic research," the President urged Congress not to gut investments in the nation's research budgets. He also pointed out that students come from all over the world to train at American research institutions. "Don't let other countries win the race for the future. Support the same kind of research ...
Montreal, January 26, 2011 – 'Stand by me' is a common refrain when it comes to friendship but new research from Concordia University proves that the concept goes beyond pop music: keeping friends close has real physiological and psychological benefits.
The presence of a best friend directly affects children going through negative experiences, as reported in the recent Concordia-based study, which was published in the journal Developmental Psychology and conducted with the collaboration of researchers at the Cincinnati Children's Hospital Medical Center and the University ...
DURHAM, N.H. – People with disabilities trying to find employment in the U.S. hospitality industry face employers who are often reluctant to hire them because of preconceived notions that they cannot do the job and that they are more costly to employ that people without disabilities, according to new research from the University of New Hampshire.
UNH researchers Andrew Houtenville, associate professor of economics and research director of the UNH Institute on Disability, and Valentini Kalargyrou, assistant professor of hospitality management, analyzed data from 320 ...
In a study that holds major implications for breast cancer research as well as basic cell biology, scientists with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a rotational motion that plays a critical role in the ability of breast cells to form the spherical structures in the mammary gland known as acini. This rotation, which the researchers call "CAMo," for coherent angular motion, is necessary for the cells to form spheres. Without CAMo, the cells do not form spheres, which can lead to random motion, loss ...
MIT researchers have discovered that certain photosynthetic ocean bacteria need to beware of viruses bearing gifts: These viruses are really con artists carrying genetic material taken from their previous bacterial hosts that tricks the new host into using its own machinery to activate the genes, a process never before documented in any virus-bacteria relationship.
The con occurs when a grifter virus injects its DNA into a bacterium living in a phosphorus-starved region of the ocean. Such bacteria, stressed by the lack of phosphorus (which they use as a nutrient), have ...
Lab scientists and international collaborators have created the shortest, purest X-ray laser pulses ever achieved, fulfilling a 45-year-old prediction and ultimately opening the door to new medicines, devices and materials.
The researchers, reporting today (Jan. 26) in Nature, aimed radiation from Linac Coherent Light Source (LCLS), located at the Stanford Linear Accelerator Center (SLAC), at a cell containing neon gas, setting off an avalanche of X-ray emissions to create a new "atomic X-ray laser."
"X-rays give us a penetrating view into the world of atoms and ...
GALVESTON, Jan. 26, 2012 – Discoveries made in some underwater caves by Texas &M University at Galveston researchers in the Bahamas could provide clues about how ocean life formed on Earth millions of years ago, and perhaps give hints of what types of marine life could be found on distant planets and moons.
Tom Iliffe, professor of marine biology at the Texas A&M-Galveston campus, and graduate student Brett Gonzalez of Trabuco Canyon, Calif., examined three "blue holes" in the Bahamas and found that layers of bacterial microbes exists in all three, but each cave had specialized ...
PASADENA, Calif.—A key feature of human and animal brains is that they are adaptive; they are able to change their structure and function based on input from the environment and on the potential associations, or consequences, of that input. For example, if a person puts his hand in a fire and gets burned, he learns to avoid flames; the simple sight of a flame has acquired a predictive value, which in this case, is repulsive. To learn more about such neural adaptability, researchers at the California Institute of Technology (Caltech) have explored the brains of insects and ...
Could depression in adulthood be tied to a parent's level of education? A new study led by Amélie Quesnel-Vallée, a medical sociologist from McGill University, suggests this is the case.
Drawing from 29 years of data from the National Longitudinal Survey of Youth 1979 (NLSY79), Quesnel-Vallée and co-author Miles Taylor, an assistant professor in the Department of Sociology at Florida State University, looked at pathways between a parent's education level and their children's education level, household income and depressive symptoms.
The team found that higher levels ...
