Environmental Exposures in Utero

Can we compensate for environmental exposures that happen to us in utero? Research by Dana Dolinoy, assistant professor of environmental health sciences, suggests we can—if we eat right.

In a series of animal studies, Dolinoy has been looking at maternal exposure to Bisphenol A, or BPA, an industrial chemical that exists “in everything from CDs to sunglasses,” she says. Pregnant women are typically exposed to BPA when they ingest food or drink that’s been stored in cans or hard plastic bottles containing the chemical. Dolinoy has found that in laboratory mice, maternal exposure to BPA changes the epigenome—the layer of molecules that sits on top of the genome and, like a dimmer switch, regulates the degree to which individual genes are turned on or off.

Mouse mothers who receive a moderate level of BPA in their diet during pregnancy and lactation—similar to the level of exposure a human mother might get—tend to give birth to offspring who have yellow fur and become obese. That’s because their epigenomes are less methylated, and methylation affects gene expression and suppression.

But mouse mothers whose diet is supplemented with methyl donors such as folic acid, choline, betaine, and Vitamin B12—many of which are found in leafy green vegetables—tend to give birth to lean offspring with brown fur. The same is true for mouse mothers whose diet is supplemented with soy.

Her findings lead Dolinoy to believe that nutritional supplements can counteract the negative effects of BPA—and possibly of other environmental exposures.

She is applying for funding to conduct followup studies in humans, and is beginning collaborative work with SPH epidemiologist Amr Soliman to assess BPA exposure in pre-adolescent girls.

Down the line, Dolinoy would like to study the effects of nutritional supplementation on exposures to lead, tobacco smoke, and arsenic.

Is Obesity in Your Head?

New research suggests that genes that predispose people to obesity act in the brain, and perhaps some people are simply hardwired to overeat.

An international research team co-directed by SPH biostatistician Goncalo Abecasis has found six new genes that help explain body mass index and obesity, and all but one of the genes are tied to the brain rather than to metabolic functions, such as fat storage and sugar metabolism. In addition to the six new genes, the team has confirmed the role of two other genes previously associated with obesity.

It’s significant that five of the six new genes also impact brain function, because the findings suggest people could simply be programmed to overeat, says SPH postdoctoral researcher Cristen Willer, lead author on the study. The brain, she says, has two main functions related to weight: appetite control and the regulation of one’s total energy balance (whether you burn more calories or conserve more energy). “Clearly this suggests that some aspects of eating behavior may be something you’re born with.” —by Laura Bailey