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Dietary protein and the prevention of glycemic dysregulation: effects of glutathione and cysteine intake

Clémence Blouet 
Abstract : ABSTRACT: Although it has been repeatedly demonstrated that amino acids alter several mechanisms involved in glycemic control, the impact of dietary protein quantity and quality on glucose homeostasis is still a matter of debate. Oxidative stress is acknowledged as an initiating factor in the pathogenesis of insulin resistance, but the effects of cysteine intake, the rate-limiting substrate for glutathione synthesis, on glycemic control has been overlooked. Following a review of the literature concerning the interactions between protein intake and glycemic control, with a special focus on sulfur amino acids intake, we present the results of our experimental studies conducted in rats. We investigated the effects of high-protein diets on body composition and glycemic control and evaluated the respective contribution of spontaneous decreased energy intake and increased protein intake in these effects. Thereafter, we focused on the effects of an increase in cysteine intake, using a cysteine-rich protein (whey protein enriched with α-lactalbumine) or a cysteine donor (N-acetylcysteine), on glutathione status and glycemic control in rats fed a high-sucrose diet, a model of diet-induced oxidative stress and insulin resistance. Glucose homeostasis was investigated both in the basal state and after several stimulations (meal, oral glucose load or i.v. insulin bolus) and in parallel, several markers of glutathione status, body redox status, nitric oxide production and bioavailability were assessed. Increasing protein intake reduced adipose tissue deposition and improved glycemic control in healthy rats. In rats fed a high-sucrose diet, a specific increase in cysteine intake improved glutathione status and prevented oxidative stress, alterations in glycemic control and decreased nitric oxide bioavailability. These results suggest that diet-induced mild oxidative stress leads to an increase in sulfur amino acid requirements and that the noncompletion of these extra requirements could favor the onset of metabolic dysregulations.
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Submitted on : Thursday, March 22, 2007 - 8:00:00 AM
Last modification on : Thursday, March 22, 2007 - 8:00:00 AM
Long-term archiving on: : Saturday, November 26, 2016 - 4:31:10 PM


  • HAL Id : pastel-00002270, version 1



Clémence Blouet. Dietary protein and the prevention of glycemic dysregulation: effects of glutathione and cysteine intake. Life Sciences [q-bio]. INAPG (AgroParisTech), 2006. English. ⟨NNT : 2006INAP0020⟩. ⟨pastel-00002270⟩



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