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Vol. LXVII, No. 19
September 11, 2015
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Digest

Low-Level Arsenic Exposure Before Birth Associated with Early Puberty, Obesity in Female Mice

Mice exposed to low-level arsenic in utero become obese adults. The control mouse (l) was not exposed to arsenic during embryonic development and is a normal weight. In comparison, mice exposed to arsenic at 10 parts per billion (c) and 42 parts per million (r) are visibly heavier. The study also determined that these exposed mice entered puberty earlier than controls.

Mice exposed to low-level arsenic in utero become obese adults. The control mouse (l) was not exposed to arsenic during embryonic development and is a normal weight. In comparison, mice exposed to arsenic at 10 parts per billion (c) and 42 parts per million (r) are visibly heavier. The study also determined that these exposed mice entered puberty earlier than controls.

Photo: NIEHS

Female mice exposed in utero, or in the womb, to low levels of arsenic through drinking water displayed signs of early puberty and became obese as adults, according to scientists from NIH. The finding is significant because the exposure level of 10 parts per billion used in the study is the current Environmental Protection Agency standard, or maximum allowable amount, for arsenic in drinking water. The study, which appeared online Aug. 21 in the journal Environmental Health Perspectives, serves as a good starting point for examining whether low-dose arsenic exposure could have similar health outcomes in humans.

“We unexpectedly found that exposure to arsenic before birth had a profound effect on onset of puberty and incidence of obesity later in life,” said NIEHS reproductive biologist and co-author Dr. Humphrey Yao. “Although these mice were exposed to arsenic only during fetal life, the impacts lingered through adulthood.”

The impacts Yao is referring to are obesity and early onset puberty, particularly in female mice. The researchers did not examine in this study whether males also experienced early onset puberty, but they did confirm that male mice exposed to arsenic in utero also displayed weight gain as they aged. Both low and high doses of arsenic resulted in weight gain.

NIH Study Shows No Benefit of Omega-3 or Other Nutritional Supplements for Cognitive Decline

While some research suggests that a diet high in omega-3 fatty acids can protect brain health, a large clinical trial by researchers at NIH found that omega-3 supplements did not slow cognitive decline in older persons. With 4,000 patients followed over a 5-year period, the study is one of the largest and longest of its kind. It was published Aug. 25 in the Journal of the American Medical Association.

“Contrary to popular belief, we didn’t see any benefit of omega-3 supplements for stopping cognitive decline,” said Dr. Emily Chew, NEI deputy clinical director.

Chew leads the Age-Related Eye Disease Study (AREDS), which was designed to investigate a combination of nutritional supplements for slowing age-related macular degeneration (AMD), a major cause of vision loss among older Americans. That study established that daily high doses of certain antioxidants and minerals—called the AREDS formulation—can help slow the progression to advanced AMD.

A later study, called AREDS2, tested the addition of omega-3 fatty acids to the AREDS formula. But the omega-3’s made no difference.

Where studies have surveyed people on their dietary habits and health, they’ve found that regular consumption of fish is associated with lower rates of AMD, cardiovascular disease and possibly dementia. “We’ve seen data that eating foods with omega-3 may have a benefit for eye, brain, and heart health,” Chew explained.

But in AREDS2, cognition scores of subgroups taking different supplements decreased to a similar extent over time, indicating that no combination of nutritional supplements made a difference.

Teens Using E-Cigarettes May Be More Likely to Start Smoking Tobacco

Students who have used electronic cigarettes by the time they start 9th grade are more likely than others to start smoking traditional cigarettes and other combustible tobacco products within the next year, according to a new study funded by NIH. E-cigarettes deliver nicotine to the lungs by heating a liquid solution that contains nicotine and other chemicals to produce an aerosol that the user inhales, a process often called “vaping.”

The study, published Aug. 25 in the Journal of the American Medical Association, compared tobacco use initiation among 222 students who had used e-cigarettes, but not combustible tobacco products, and 2,308 who had neither used e-cigarettes or combustible tobacco products when initially surveyed at the start of 9th grade. During the first 6 months after being surveyed, 30.7 percent of those who had used e-cigarettes started using combustible tobacco products such as cigarettes, cigars and hookahs, compared to only 8.1 percent of those who had never used e-cigarettes. Over the following 6 months leading into the start of 10th grade, 25.2 percent of e-cigarette users had used combustible tobacco products, compared to just 9.3 percent of nonusers.

“While teen tobacco use has fallen in recent years, this study confirms that we should continue to vigilantly watch teen smoking patterns,” said NIDA director Dr. Nora Volkow. “Parents and teens should recognize that although e-cigarettes might not have the same carcinogenic effects of regular cigarettes, they do carry a risk of addiction.”


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