A widely-used food preservative to inhibit the growth of mold could be contributing to increasing rates of obesity and diabetes, a new study published by Israeli and American researchers has revealed.Today, diabetes affects more than 400 million adults worldwide, and the figure is expected to soar to more than 640 million by 2040. Growing attention is being paid to external factors such as diet and the environment to explain the increase.The joint study – conducted by researchers at Israel’s Sheba Medical Center at Tel HaShomer, Harvard’s T.H. Chan School of Public Health, and Brigham and Women’s Hospital in Boston – examined the effect of propionate, a food preservative used to extend the life of baked goods by inhibiting the growth of mold.When the researchers administered propionate to mice, they discovered that it set off a chain reaction resulting in a hormonal surge, producing more glucose and ultimately hyperglycemia, a defining characteristic of diabetes.When researchers gave the mice an equal amount of propionate to that used in a serving of food, the mice gained weight and developed a resistance to insulin.Researchers then conducted a double-blind placebo-controlled study on 14 people in good health. Those who ingested propionate showed higher levels of certain hormones, including glucagon, which works to raise the concentration of glucose in the bloodstream.The findings, published in the Science Translational Medical Journal, indicate that propionate plays a role in the metabolic process and could potentially contribute to the rise of obesity and diabetes. “The dramatic increase in the incidence of obesity and diabetes over the past 50 years cannot be attributed to genetic changes, and involves contributing environmental and dietary factors,” said Dr. Amir Tirosh, director of the Institute of Endocrinology at Sheba Medical Center, and one of the authors of the study.“One such factor that warrants attention is the extensive use of chemicals in the processing, preservation and packaging of foods. We are exposed to hundreds of these chemicals on a daily basis, and most have never been tested for their long-term metabolic effects.”While propionate has been approved by the US Food and Drug Administration, the researchers added, their findings suggest that alternative methods for food preservation should be evaluated.