October 07, 2009

Researchers study inflammation’s link to obesity

by K.C. Jaehnig

CARBONDALE, Ill. -- Inflammation, the body’s way of fighting off injury and illness, may in its low-grade guise actually contribute to disease. A number of recent studies suggest that minor but chronic inflammation plays a role in a host of ailments -- from Alzheimer’s to kidney disease to stroke.

Researchers at Southern Illinois University Carbondale are taking a closer look at low-grade inflammation in the body’s fat tissues, trying to uncover the complex interplay between it, obesity, the development of diabetes and fiber consumption.

“You see high levels of inflammation in the fat tissues of obese people,” said nutrition scientist Jeremy Davis, part of a multi-university research team, headquartered at SIUC, that studies diet and chronic disease.

“Inflammation likely contributes to insulin resistance, which leads to (adult-onset) diabetes. We believe that if you can block that inflammation in the fat tissue, you can prevent the development of diabetes.

“The question for us is whether there are things you can do through diet modification that would stop, or at least slow, the inflammation. The modifications would not reverse or prevent obesity but by dealing with the inflammation would improve health.“

The team’s early work with mice on high-fat diets showed an increase in inflammation throughout their bodies, including their fat tissue. The researchers also found that stopping that inflammation decreased their subjects’ insulin resistance.

Davis and the team have since focused on the effects of red wheat bran and certain soy compounds on inflammation. In work with rats genetically prone to obesity, they found that adding wheat bran to the rats’ diet improved their blood sugar levels, making them more responsive to insulin. The diet also lowered their cholesterol levels and reduced their liver weights, meaning they were less likely to develop “fatty liver” disease, which can lead to that organ’s failure.

The rats did, however, gain weight on the diet, but even that fact had an upside.

“Despite the greater fat mass, they still had a better distribution of fat,” Davis said.

“If the fat stays in the tissues and out of the liver and muscle, that can improve the health of an obese individual.”

As often happens in science, answers lead to new questions. In this case, the team hopes to discover what exactly causes the effects.

“The bran has fiber, but it also has other compounds, just like soy (the disease- and obesity-fighting properties of which the team is also studying),” Davis said. “It could be one, the other, or some combination.”

The team also is trying to determine why the fat of the rats in the study distributed itself as it did, an effect they’ve also found in obese rats on a soy-based diet.

“It may be there are compounds that affect how fat cells expand,” Davis said.

“If you expand the number of cells where fat can be stored, it may be that more sensitive organs will be protected.”

Other soy studies going on now are testing the anti-inflammatory effect of these compounds on muscle cells.

Food-based treatments for obesity-related inflammation and the diseases that accompany it -- the work’s ultimate goal -- could lower or even eliminate the use for drugs, which, in addition to costing money often cause unpleasant side effects. Wheat bran -- safe, readily available, relatively cheap and fairly palatable -- make it an ideal candidate for such use.

“I’d like to see researchers and companies work together to develop products that are healthier and make sure they get to consumers at a young age -- maybe even in the school lunch programs -- so they become widely acceptable,” said Davis, who also is a registered dietitian.

“If we have foods that consumers not only can afford but can enjoy, then over the long term we’ll see a decrease in the risk of developing diseases associated with obesity. Some of us have good genetics (for lifetime health), but most of us just aren’t that lucky.”