Is there a link between air pollution and obesity?

Medical research has long supported the fact that exposure to ultrafine particulate matter increases the risk of various respiratory, cardiovascular, and pulmonary illnesses. Incidences of asthma, heart attacks, and chronic bronchitis are all higher in areas where the concentration of ultrafine particulate matter is higher. The correlation between particulate matter and these health issues is particularly pronounced in children, as well as low-income communities, which are often located closer to the sources of particulate matter (highways, factories, power plants) than their higher income neighbors.

Over the past decade, new studies have emerged that link air pollution to two of this country’s most pressing (and expensive) health epidemics: obesity and type II diabetes. Both are not only on the rise in terms of diagnoses, but also in terms of the costs associated with treatment. Even after controlling for factors such as genetics, income levels, weight, diet and exercise, Harvard researchers found a “consistent and significant” relationship between Type II diabetes prevalence and exposure to ultrafine particulate matter in a recent study published in Diabetes Care.

Results of an animal study published by Ohio State University researcher Qinghua Sun in late 2010 revealed that early exposure to ultrafine particulates led to the accumulation of abdominal fat and insulin resistance in mice even if they ate a normal diet. Exposure levels for animals in the study were similar to those found in U.S. cities.  The study compared mice fed a high-fat diet with those fed a normal, healthy diet, and exposed some members of both groups daily to ultrafine particulate matter, controlling for all other factors. In the end, all of the mice exposed to air pollution, including those fed a normal diet, had increased abdominal and subcutaneous (under the skin) fat.

These findings suggest that fine particulate pollution exposure alone, in the presence of a normal diet, may lead to an increase in fat cell size and number, and also have a proinflammatory effect.

Source: http://www.forbes.com/sites/amywestervelt/2011/10/10/two-new-reasons-to-worry-about-air-pollution-obesity-and-diabetes/

Naringenin, a compound from grapefruit, helping to reduce insulin resistance

A complex of naringenin and cyclodextrin may help to substantially reduce the absorption of fat and sugar in the body, according to study published in PLoS One.

The research team, from Harvard and the Hebrew University of Jerusalem, found their complex increases the absorption of naringenin by 11 times. They reported that a single dose given to rats before a meal reduced the generation of very low density lipoprotein (VLDL) by 42 per cent, whilst insulin sensitivity was boosted by 64 per cent. The authors claim that their research is the first demonstration that a dietary supplement can change the way our body can react beneficially to a meal.

In recent years, polyphenols, and flavonoids in particular, have emerged as a class of natural products shown to have anti-oxidant, anti-atherogenic, and normolipidemic effects. One of the most abundant flavonoids is the citrus flavonoid-glycoside naringin, which is broken down into naringenin.

Previous research has previously shown that naringenin, responsible for the bitter taste in grapefruits, could potentially be used in the treatment of diabetes, arteriosclerosis and hyper-metabolism. However,  the absorption of naringenin in its natural form is usually very low, reducing its bioavailability. The solubility and transport through the intestinal epithelium of naringenin can be enhanced by forming a complex with a chyclodextrin.

When the complex was administered to rats just prior to a meal it caused a decrease in VLDL levels by 42% and increased the rate of glucose clearance by 64% compared to naringenin alone.

Source: PLoS ONE
Published online ahead of print, doi:10.1371/journal.pone.0018033
“Enhancement of Naringenin Bioavailability by Complexation with Hydroxypropoyl-β-Cyclodextrin”
Authors: M. Shulman, M. Cohen, A. Soto-Gutierrez, H. Yagi, H. Wang, et al