Canadian scientists have found that nobiletin, a substance found in high concentrations in tangerines, thwarted obesity and the onset of diabetes in lab mice. The researchers at the University of Western Ontario fed the mice a high-sugar, high-fat diet that mimicked the diet of many people in Western societies. One group of animals became obese, developing fatty livers and elevated levels of cholesterol and insulin-typical precursors to type 2 diabetes and cardiovascular disease. But a second group of mice, given the flavonoid nobiletin, did not develop the symptoms of the first group. The nobiletin prevented fatty buildup in the liver by blocking the genes that control the production of fat.
Flavonoids are compounds found in plants, often as pigments, that are highly anti-oxidative and anti-inflammatory. Nobiletin, which is found in citrus fruits, occurs in its highest concentration in tangerines. The Canadian scientists also found that nobiletin protected the lab mice from atherosclerosis, arterial plaque build-up that can lead to heart attack or stroke.
The research leader, Murray Huff, a vascular biologist at the university, had previously found a flavonoid in grapefruits, naringenin, that offered lab mice protection against obesity. Huff said, however, that nobiletin offers 10 times the level of protection against obesity that naringenin does.
Results of the Canadian study, published in the medical journal Diabetes, open the door for studies on nobiletin's effects on human test subjects.