Illustration: Roger Harris/Science Source

Health News from Tufts

BRAIN & BODY

Why It’s Hard to Diet

We tried low-fat. We tried high-protein and low-carb. But the inescapable conclusion is that there’s only one way to lose weight: eat less. Why is that so much easier said than done?

That’s what Emmanuel N. Pothos, associate professor of pharmacology and experimental therapeutics and neuroscience in the School of Medicine’s Department of Integrative Physiology and Pathobiology, and his colleagues are trying to understand. Pothos’ research focuses on the reward system in the brain that makes us want food. As it turns out, this system depends heavily on the chemical dopamine, which is normally released when an animal eats a meal. Dopamine produces a pleasurable sensation that lets the animal know it has satisfied a primal need.

Starvation, however, alters this otherwise tidy feedback loop. When an animal is having a hard time finding enough food, the brain doesn’t want it to feel satisfied after just one meal, so it releases less dopamine. Pothos and other researchers have seen corroborating evidence in the lab: the brains of underweight animals release less dopamine than those of normal-weight animals.

Oddly, the brains of overweight animals release less dopamine as well. And human brain imaging by other researchers indicates that something similar is likely going on in people. “Even though they are mirror opposites, the undernourished and the obese share two things—an increased motivation to eat and a deficient brain dopamine system,” Pothos says.

A number of factors can knock the reward system off kilter: genetic predisposition, the environment a baby encounters in the womb, gaining or losing weight, and certain diseases, including addiction. Yet the situation, while difficult to correct, is not hopeless. Exercise may offer a solution—and not just because it can burn off calories. Pothos says there’s early evidence that regular exercise, in addition to all its other benefits, can help reset the dopamine reward system. (FROM TUFTS NOW)

Stress and the Gums

We all know what contributes to gum disease—poor brushing, forgetting to floss, avoiding checkups, smoking. But what about a tough day at the office? Surprisingly, such stress might be an important factor, according to a Journal of Biological Regulators & Homeostatic Agents article by Evangelos Papathanasiou, DG11, an assistant professor of periodontology at Tufts School of Dental Medicine, and Theoharis Theoharides and Iro Palaska, two pathobiologists at Tufts’ Sackler School of Graduate Biomedical Sciences.

Under stress, they note, people manufacture more of the hormone cortisol, which, in the gums, seems to stimulate certain immune-system cells to step up their production of proteins. The extra proteins could increase inflammation, and the inflammation could speed the progression of gum disease, the researchers say. Papathanasiou and Theoharides are developing experiments to test the hypothesis. One possibility is to investigate the antioxidant and anti-inflammatory effects of plant compounds called flavonoids on people experiencing different levels of stress. (FROM TUFTS DENTAL MEDICINE)

NUTRITION

Magnesium Cuts Diabetes Risk

Getting enough magnesium in the diet may reduce the risk of diabetes, especially for those who already show signs of heading that way.

A Tufts study led by Adela Hruby, N10, MPH10, N13, and published in Diabetes Care found that healthy people with the highest magnesium intake were thirty-seven percent less likely to develop high blood sugar or excess circulating insulin, common precursors of diabetes. Among people who already had such conditions, those who consumed the most magnesium were thirty-two percent less likely to develop diabetes than those consuming the least. The second association held true even when researchers accounted for other healthful factors, such as fiber, that often go along with magnesium-rich foods.

Only half of Americans get the recommended daily amount of magnesium in their diet, which is 400 to 420 milligrams for men and 310 to 320 milligrams for women. You can find it in whole grains, vegetables, fish, nuts and seeds, and dark chocolate. (FROM TUFTS NUTRITION)

CATS & DOGS

Eye Care for Pets

Pets don’t have to read an eye chart to keep a driver’s license or wear prescription glasses to see the tiny text on a smartphone. But they experience many of the same eye problems that people do, including cataracts, glaucoma, and injuries to the cornea—unbeknownst to their owners.

“Dogs and cats are very good at memorizing their environment,” says Christopher Pirie, one of Cummings School’s three board-certified veterinary ophthalmologists. “We see lots of patients that have pretty advanced visual dysfunction without their owners being aware of it simply because the layout of their home never changed.”

Watch out for tearing, squinting, red eyes, cloudy eyes, eye discharge, color changes in the eye, and a tendency to rub, paw, or scratch the eye. Another red flag is clumsiness and confusion in low-light conditions. And if an older pet is sleeping more and becoming less active, don’t be so quick to attribute it to aging. The animal may be trying to cope with eye pain.