Wednesday, October 3, 2007

Red wine is good....antioxidants are bad?????

I've posted before about the debate over the health benefits of red wine. Praised for its antioxidant properties it seems to be a good thing to drink for health. However, as I mentioned in that post, there remains some debate over the role of antioxidants.

Here are a couple of further studies for your consideration, one (potentially) on each side of the debate.

First of all....Red wine is good for you....

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 report in the October issue of Cell Metabolism

Low doses of a red wine ingredient fight diabetes in mice

SIRT1 Improves Insulin Sensitivity under Insulin-Resistant Conditions by Repressing PTP1B
Cheng Sun, Fang Zhang, Xinjian Ge, Tingting Yan, Xingmiao Chen, Xianglin Shi, and Qiwei Zhai

Insulin resistance is often characterized as the most critical factor contributing to the development of type 2 diabetes. SIRT1 has been reported to be involved in the processes of glucose metabolism and insulin secretion. However, whether SIRT1 is directly involved in insulin sensitivity is still largely unknown. Here we show that SIRT1 is downregulated in insulin-resistant cells and tissues and that knockdown or inhibition of SIRT1 induces insulin resistance. Furthermore, increased expression of SIRT1 improved insulin sensitivity, especially under insulin-resistant conditions. Similarly, resveratrol, a SIRT1 activator, enhanced insulin sensitivity in vitro in a SIRT1-dependent manner and attenuated high-fat-diet-induced insulin resistance in vivo at a dose of 2.5 mg/kg/day. Further studies demonstrated that the effect of SIRT1 on insulin resistance is mediated by repressing PTP1B transcription at the chromatin level. Taken together, the finding that SIRT1 improves insulin sensitivity has implications toward resolving insulin resistance and type 2 diabetes.

....and the other side of the story......

Avoiding sweets may spell a longer life, study in worms suggests

"A new study in the October issue of Cell Metabolism, a publication of Cell Press, reveals that worms live to an older age when they are unable to process the simple sugar glucose. Glucose is a primary source of energy for the body and can be found in all major dietary carbohydrates as a component of starches and other forms of sugar, including sucrose (table sugar) and lactose.

What’s more, Ristow’s group further demonstrated in their report that antioxidants and vitamins given to the worms erased the life-extending benefits of sugar deprivation, raising questions about the widespread use of antioxidant supplements, according to the researchers."

Free radicals are usually considered harmful, Ristow said, and scientists have generally thought that exposure to them would shorten life span. The new findings suggest that, at least in some cases, the opposite may be true.

Indeed, even when the researchers returned the worms to their normal environment, allowing them to again use glucose for energy, the worms’ increased defenses and longevity persisted, Ristow said. In contrast, treatment with antioxidant vitamins prevented the oxidative stress and the defenses against it, eliminating the life-boosting effects. Ristow called the result “scary” because it means that, rather than being protective, antioxidant pills may actually leave the body more vulnerable by thwarting those natural defenses.

Gulp ..... talk about heresy! Then again....this is not the only study to point in this direction recently! Remember this: Antioxidants may do you more harm than good and this: Studies force new view on biology of flavonoids

So what do we make of this?

Firstly we understand that sugar is bad....but I think the jury is still out on the benefits of antioxidants. Sorry if that sounds daft, but these last couple of studies are making me think.

Secondly, something in red wine is beneficial - resveratrol - in that it activates a genetic program involving insulin signaling and the gene SIRT1. However, this can also be done through calorie restriction or intermittent fasting?

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