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July 17, 2009
Bioflavonoid prevents metabolic syndrome and obesity in mice
In an article published online on July 10, 2009 in the journal Diabetes, researchers in Ontario, Canada report that naringenin, a flavonoid present in citrus fruit, prevents weight gain and components of metabolic syndrome, a precursor to diabetes, in a rodent model.
For their study, Murray W. Huff of the Robarts Research Institute at the University of Western Ontario and his associates used low density lipoprotein receptor null mice that exhibit disordered lipids, insulin resistance, glucose intolerance and obesity when fed a high fat "Western" diet. The animals were divided to receive regular chow, a high fat diet, or high fat (42 percent of calories) diets containing 1 or 3 percent naringenin for four weeks, after which plasma cholesterol, triglycerides, glucose and insulin levels were measured, and other factors, including glucose and insulin tolerance, were assessed.
At the end of the treatment period, mice that received naringenin had lower triglyceride and cholesterol levels than with those that received the high fat diet without naringenin. Insulin resistance was prevented in the 3 percent naringenin-fed mice and glucose metabolism was normalized, compared to mice that received Western diets. "Furthermore, the marked obesity that develops in these mice was completely prevented by naringenin," added Dr Huff, who is the Director of the Vascular Biology Research Group at Robarts. "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."
The research team discovered that naringenin genetically reprograms the liver to burn extra fat as opposed to storing it. "We are examining the pharmacological properties of naringenin," Dr Huff stated. "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."
"These studies show naringenin, through its insulin-like properties, corrects many of the metabolic disturbances linked to insulin resistance and represents a promising therapeutic approach for metabolic syndrome," he concluded.
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Recent advances in dietary science have highlighted the crucial role of insulin in weight gain. Produced in the pancreas, insulin is a critical hormone for the control of blood sugar (glucose). Its job is to transport glucose into cells, where the glucose is burned as fuel. While this process is necessary for life, abnormalities in the insulin-glucose system caused by aging, lack of exercise and poor diet can cause major health problems. In aging, cells become more resistant to the effects of insulin. As cells become increasingly insulin resistant, the body compensates by increasing the number of insulin receptors on cells and secreting more insulin in an attempt to drive more blood sugar into muscle and liver cells (Fulop 2003).
Insulin resistance is a dangerous condition. Research suggests that adipose tissue (fat) is a source of pro-inflammatory chemicals that have a role in the development of insulin resistance (Sharma AM et al 2005). Insulin resistance is associated with obesity (in particular, abdominal obesity) (Greenfield JR et al. 2004). It is also associated with aging muscle (Nair KS 2005), physical inactivity, and genetics.
This increase in insulin (called hyperinsulinemia) and decreased insulin sensitivity have a number of harmful effects, including contributing to diseases associated with being overweight (Zeman et al 2005; Garveyet al 1998). Over time, high insulin and insulin resistance may lead to type 2 diabetes in susceptible individuals, a major risk factor for heart disease. A study sponsored by the NIH showed that over a 10-year period, hyperinsulinemia was associated with increased all-cause and cardiovascular mortality, independent of other risk factors (NIH 1985).
Controlling insulin levels as we age is essential for overall health, longevity, and weight management. An increasing number of physicians recognize the role of insulin resistance in the current obesity epidemic. The good news is that nonprescription drugs and low-cost dietary supplements that have demonstrated beneficial effects upon insulin action are already available.
Chromium is an essential trace element required for normal carbohydrate metabolism. Chromium increases insulin binding, the number of insulin binding receptors, and insulin sensitivity (Anderson 1997; Vincent 2000).
The Prostate Cancer Research Institute (PCRI) mission is to improve the quality of men’s lives by supporting research and disseminating information that educates and empowers patients, families and the medical community. PCRI is pleased to announce the 11th major conference devoted to prostate cancer, planned and/or produced by members of The Prostate Cancer Research Institute. As in the past, this conference will provide insight for patients, caregivers and medical professionals.
Moderated by the highly regarded Dr. Mark Moyad and Dr. Mark Scholz, this year’s conference will again focus on quality of life Issues. Faculty will talk about important lifestyle and health issues including diet and dietary supplements, erectile dysfunction, hormone blockade side effects and other current issues relating to advanced disease. Exciting up-and-coming technology and research will also be presented.