Animals fed a high fat diet and supplemented with the flavonoid did not gain weight, while other signs of the metabolic syndrome were also prevented, according to findings published in the journal Diabetes.
“The marked obesity that develops in [mice fed a high fat diet] was completely prevented by naringenin,” said lead researcher Murray Huff from the University of Western Ontario.
“What was unique about the study was that the effects were independent of caloric intake, meaning the mice ate exactly the same amount of food and the same amount of fat. There was no suppression of appetite or decreased food intake, which are often the basis of strategies to reduce weight gain and its metabolic consequences,” he added.
If the study’s findings can be repeated in other studies, including human trials, it could see naringenin added to the list of compounds with potential to prevent the metabolic syndrome.
Metabolic syndrome (MetS) is a condition characterised by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type-2 diabetes and cardiovascular disease (CVD).
The Ontario-based researchers divided mice into four groups: one group was fed on normal chow (control group), while the other three groups were fed a high-fat, or Western, diet (42 per cent calories from fat) for four weeks. Two of the high-fat groups were also supplemented with either 1 or 3 per cent naringenin.
The animals fed only the high-fat diet became insulin and glucose intolerant, and obese. However, supplementation with the flavonoid reversed the increases in triglyceride and cholesterol levels, prevented the development of insulin resistance and completely normalized glucose metabolism, said the researchers.
Commenting on the mechanism, Huff and his co-workers note that naringenin was associated with an activation of PPAR-gamma coactivator 1 alpha, (PGC1-alpha)/PPARalpha-mediated transcription program in the liver, leading to a burning of excess fat, rather than storing it.
“Thus, naringenin, through its correction of many of the metabolic disturbances linked to insulin resistance, represents a promising therapeutic approach for metabolic syndrome,” wrote the researchers, led by Huff from the University of Western Ontario.
uff confirmed that research was ongoing in this are. “The next step is to find out if naringenin prevents heart disease in animal models and to explore the feasibility of clinical trials to determine its safety and efficacy in humans,” he said.
Grapefruit heart benefits
Previously, Israeli researchers reported that eating a red grapefruit a day could reduce cholesterol by 15 per cent and triglycerides by 17 per cent and protect against heart disease (Journal of Agricultural and Food Chemistry, 2006, Vol. 54, pp 1887-1892).
The Israeli research, which included by in vitro and human studies, was said to be the first to look at different grapefruit types and their influence on humans who suffer from high blood cholesterol (hyperlipidemia) and hardening of the arteries (atherosclerosis), both of which play major roles in heart disease.
Published online ahead of print, doi:10.2337/db09-0634
“Naringenin prevents dyslipidemia, apoB overproduction and hyperinsulinemia in LDL-receptor null mice with diet-induced insulin resistance”
Authors: E.E. Mulvihill, E.M. Allister, B.G. Sutherland, D.E. Telford, C.G. Sawyez, J.Y. Edwards, J.M. Markle, R.A. Hegele, M.W. Huff