Tea and grape compounds show mitochondrial benefits for overweight & obese people

08-Jun-2016 - Last updated on 09-Jun-2016 at 12:39 GMT

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Related tags Insulin sensitivity Obesity Adipose tissue

Supplements containing epigallocatechin-3-gallate and resveratrol may boost mitochondrial capacity and stimulate fat oxidation, says a new randomized, double-blind, placebo-controlled, parallel intervention trial.

Twelve weeks of supplementation with 282 mg per day of EGCG and 80 mg per day of resveratrol was associated with metabolic benefits, including improved skeletal muscle oxidative capacity and attenuated the increase in triacylglycerol concentrations, according to findings published in the American Journal of Clinical Nutrition.

“Importantly, the improved mitochondrial capacity and fat oxidation may improve physical condition and play a role in the prevention of weight gain and the worsening of insulin resistance in the long term,” wrote researchers from Maastricht University Medical Center, DSM Nutritional Products, and Wageningen University.

Polyphenols

The potential beneficial effects of polyphenols like EGCG and resveratrol include improving insulin sensitivity, reducing markers of oxidative stress, reducing inflammation, preventing body weight gain and insulin resistance (in rodent studies), reducing the absorption of fat in the intestine, and stimulating mitochondrial biogenesis by activating sirtuin 1 (Sirt1).

Resveratrol is most associated with activating Sirt1, a gene which is also activated during calorie restriction in various species, and linked to longevity.

The new study considered if there would be additive or synergistic effects from combining these two polyphenols. An earlier study from the same researchers found that short term EGCG plus resveratrol supplementation boosted energy expenditure in men, compared with placebo (Int. J. Obes. 2014; Vol. 38, pp. 698–706).

“Here, we investigated the effects of longer-term combined EGCG + resveratrol supplementation on metabolic profile, skeletal muscle oxidative capacity, fat oxidation, lipolysis, and peripheral, hepatic, and adipose tissue insulin sensitivity in overweight and obese nondiabetic subjects,” they explained.

tea plantations — EGCG is one of the four primary polyphenols found in fresh tea leaves, along with epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).Green tea contains between 30% and 40% of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3% and 10%.Image: iStockPhoto

Study details

The researchers recruited 38 overweight and obese people with an average age of 38 and randomly assigned them to receive either EGCG + resveratrol supplements or placebo for 12 weeks. Pure Encapsulations, Inc. provided the supplements.

Results showed that the polyphenol combination was associated with significant increases in oxidative capacity in muscle fibers, compared with placebo. Mitochondrial respiration was also found to be significantly increased following EGCG plus resveratrol supplementation.

However, unlike the previous study, no significant effects were recorded for energy expenditure, said the researchers. Nor was any effect on insulin sensitivity recorded.

“Although no significant effects on total fat mass were apparent, we found that EGCG + resveratrol tended to decrease visceral adipose tissue mass by [approximately] 11% compared with placebo,” wrote the researchers. “Because visceral adipose tissue is known to be detrimental to metabolic health, its reduction may be of physiologic importance in the long term.”

The study was supported financially by the ALPRO Foundation.

Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.115.122937
“Combined epigallocatechin-3-gallate and resveratrol supplementation for 12 wk increases mitochondrial capacity and fat oxidation, but not insulin sensitivity, in obese humans: a randomized controlled trial”
Authors: J. Most, et al.