Resveratrol and Diabetes
Resveratrol and Blood Sugar
Red Wine Compound May Curb Diabetes
Resveratrol, an antioxidant found in red wine, may counter type 2 diabetes and insulin resistance, a new study shows. Insulin is a hormone that controls blood sugar. When the body becomes less sensitive to insulin, that's called insulin resistance, a condition that can lead to type 2 diabetes. Resveratrol curbs insulin resistance in mice, Chinese scientists report. They included Cheng Sun and Qiwei Zhai of the Chinese Academy of Sciences in Shanghai. If the findings apply to people, it might be possible to create new resveratrol drugs that could be a "valuable new strategy for treating insulin resistance and type 2 diabetes," write the researchers. But don't count on a glass of wine to do the same thing. It would take quite a bit of wine to reach the same level of resveratrol.
"According to our findings, people might need to drink about three liters of red wine each day to get sufficient resveratrol -- about 15 milligrams -- for its biological effects," Zhai says in a news release.
The researchers aren't recommending that anyone rely on wine to help their insulin sensitivity.
Resveratrol is found in grapes (especially in red wine), raspberries, peanuts, and other plants that use resveratrol to defend against threats such as disease.
Sun's team found that insulin-resistant mice become more sensitive to insulin when given resveratrol. The scientists' experiments with cells in test tubes show that resveratrol spurs a gene called SIRT1 to become more active, boosting insulin sensitivity.
Resveratrol, the molecule found in grapes (and the red wine produced from them) and certain other plants, is actively being tested in research laboratories around the world in hopes to find both prevention and relief for illnesses such as cancer and heart disease. Clinical trials of resveratrol are also currently under way to combat other diseases, including diabetes.
In late 1999, research was published of a study that showed that type 2 diabetic participants that drank two five-ounce glasses of red wine with their meal experienced lowered incidences of the production of compounds that can produce vascular damage, an interesting result to say the least for those studying diabetes. More recently, studies on mice have shown that even low levels of resveratrol doses can improve their sensitivity to hormone insulin. The findings could lead to the development of new therapies for both prevention and treatment of type 2 diabetes. Continuing research will hopefully tell if resveratrol might have further benefits for not only type 2 diabetes and diabetic vascular disease, but other insulin disorders as well.
Resveratrol is known to activate a gene called SIRT1, and SIRT1 is linked not only to insulin secretion, but also to better insulin sensitivity in mice. Other research has found a connection between SIRT1 and glucose metabolism. Researchers have reported that insulin resistant disorders like diabetes block normal activation of SIRT1, a factor resulting in the active study of SIRT1 activating compounds, of which resveratrol in certainly a front runner.
Ongoing investigation is required before resveratrol supplementation can be responsibly approved for diabetes disorders, but early findings have given enough initial positive results to warrant further research for scientists and medical researchers alike.
— Even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a new report. As insulin resistance is often characterized as the most critical factor contributing to the development of type 2 diabetes, the findings "provide a potential new therapeutic approach for preventing or treating" both conditions, the researchers said.
The research group also confirmed that increased levels of an enzyme called SIRT1, which earlier studies had linked to longevity, DNA repair, and insulin secretion, improve insulin sensitivity in mice. Resveratrol is known to activate the SIRT1 enzyme.
The results suggest that "red wine might have some benefits for insulin sensitivity, but it needs to be confirmed by further investigation," said Qiwei Zhai of the Chinese Academy of Sciences. Given the potential complications of drinking alcohol, "an even better option may be to find other natural foods enriched with resveratrol or foods supplemented with resveratrol," he added, noting that the chemical is also an active ingredient in other plants, including one called Polygonum cuspidatum used in traditional Chinese and Japanese medicine.
Diabetes mellitus, the most common endocrine disorder, currently affects more than 170 million people worldwide and is expected to affect more than 353 million by the year 2030, Zhai said. Type 2 diabetes, which accounts for more than 90 percent of diabetes cases, is characterized by the resistance of body tissues to stimulation by the peptide hormone insulin. Insulin normally lowers blood glucose levels by facilitating the sugar's uptake, mainly into skeletal muscle and fat tissue, and by inhibiting glucose production in the liver. Currently, alleviating insulin resistance is still one of the key avenues to treating type 2 diabetes.
Earlier studies had reported a connection between SIRT1 and the processes of glucose metabolism and insulin secretion. However, whether SIRT1 was directly involved in insulin sensitivity remained largely unknown, the researchers said.
Now, the researchers report that SIRT1 levels are reduced in insulin-resistant cells and tissues and that treatments that block the enzyme's function lead to insulin resistance. Furthermore, increased SIRT1 activity improved insulin sensitivity. Similarly, resveratrol--at a dose of just 2.5 mg/kg/day--enhanced insulin sensitivity in cells. That low dose of resveratrol also reduced insulin resistance in animals fed a high-fat diet, the researchers showed.
"We found SIRT1 improves insulin sensitivity, especially under insulin-resistant conditions," Zhai said. "Furthermore, we found that resveratrol, at a very low dose compared with many previous studies, improves insulin sensitivity via SIRT1."
The findings suggest that those who drink red wine for the health-promoting benefits of resveratrol might "think about drinking less," Zhai said. Previously, he noted, the effects of resveratrol seen in mice had implied that humans might need to drink about 120 liters of red wine each day to get enough resveratrol to enjoy the same benefit. "According to our findings, people might need to drink about three liters of red wine each day to get sufficient resveratrol--about 15 mg--for its biological effects."
The researchers include Cheng Sun, Fang Zhang, Xinjian Ge, Tingting Yan, Xingmiao Chen, Xianglin Shi, and Qiwei Zhai of Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences in Shanghai.
This work was supported by grants from the National Natural Science Foundation of China (30400083 and 30570558), the Chinese Academy of Sciences (KSCX2-2-25, KSCX2-YW-N-034, and KSCX1-YW-02), the National Basic Research Program of China (973 Program, 2006CB503900 and 2007CB914501), the Science and Technology Commission of Shanghai Municipality (04 DZ14007), and the Program of Shanghai Subject Chief Scientist.
Reference: Sun et al.: "SIRT1 Improves Insulin Sensitivity under Insulin-Resistant Conditions by Repressing PTP1B." Publishing in Cell Metabolism 6, 307--319, October 2007. DOI 10.1016/j.cmet.2007.08.014
Resveratrol side effects.
Resveratrol, a compound found in red wine, could lower blood sugars but the side-effects might prevent its benefits. Research presented May 16, 2008 at the pediatric endocrinology unit at the Case Western Reserve in Ohio stated that “ all the studies we have to date have focused primarily on the GLUT 4 glucose transporters on the muscle tissue and adipose tissue”. This study looked at the GLUT 1 transporter cells. Resveratrol is a naturally occurring chemical found in grapes that has been shown to have cardioprotective, anti-inflammatory, hypoglycemic and antiviral properties. It is considered to be “anti-aging” by the media and is one of the hottest supplements in town.
Research continues on the properties and mechanisms of resveratrol for many parameters. Using clone 9 cells, known for their unique and exclusive expression of GLUT1 isoforms’ and extracts of resveratrol glucose transport was studied.
The results showed that in cells expressing the GLUT1 isoform, resveratrol blocks glucose transport by binding and inhibiting the GLUT 1 transporter. This could be a big issue with the preventive use of resveratrol as it is the brain, retina, placenta and red blood cells that express a large amount of this up- regulator. The study concluded that reservatrol helps lower blood sugar by stimulating the GLUT 4 transporters found in the tissues, particularly skeletal tissue.
Resveratrol is a very important supplement on the market, but needs more research and possible development before there is enough evidence to make recommendations, particularly where diabetes is concerned. Health professionals should be aware of potential drug /nutrient interactions as use of resveratrol with insulin or oral hypoglycemics may cause an unexpected drop in blood sugars as we have no standardized dosages for blood sugar control established.
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