pyruvate studier

[Benpressmannen]

McCarty MF, Gustin JC.
NutriGuard Research, Encinitas, CA 92024, USA.

In a recent pilot study, joint administration of pyruvate, hydroxycitrate (HCA), and carnitine to obese subjects was associated with a remarkable rate of body-fat loss and thermogenesis, strongly suggestive of uncoupled fatty-acid oxidation. Hepatocytes possess an uncoupling mechanism--reverse electron transport--that enables fasting ketogenesis to proceed independent of respiratory control. Electrons entering the respiratory chain at the coenzyme Q (CoQ) level via FAD-dependent acyl coA dehydrogenase, can be driven 'up' the chain by the electrochemical proton gradient to reduce NAD+; if these electrons are then shuttled to the cytoplasm, returning to the respiratory chain at the CoQ level, the net result is heat generation at the expense of the proton gradient, enabling the uncoupled flow of electrons to oxygen. Pyruvate's bariatric utility may stem from its ability to catalyze the rapid transport of high-energy electrons from mitochondria to the cytoplasm, thus stimulating electron shuttle mechanisms. By enabling rapid mitochondrial uptake of fatty acids and thus disinhibiting hepatocyte ketogenesis, HCA/carnitine should initiate reverse electron transport: concurrent amplification of electron shuttle mechanisms by pyruvate can be expected to accelerate this reverse electron transport, thereby decreasing the electrochemical proton gradient. As a result, hepatocytes may be able to convert fatty acids to CO2 and heat with little net generation of ATP. These considerations suggest that it may be feasible to render hepatocytes functionally equivalent to activated brown fat, such that stored fat can be selectively oxidized in the absence of caloric restriction. Other measures which enhance the efficiency of hepatocyte electron shuttle mechanisms may increase the efficacy of this strategy.

Publication Types:
Review
Review, Tutorial
PMID: 10416948 [PubMed - indexed for MEDLINE]

[Benpressmannen]

Effect of pyruvate and dihydroxyacetone on metabolism and aerobic endurance capacity.

Ivy JL.

Department of Kinesiology and Health Education, University of Texas at Austin, USA.
Pyruvate and dihydroxyacetone are three carbon compounds that when infused directly into the blood or taken orally produce strong metabolic effects. When chronically fed to animals as part of their diet, pyruvate plus dihydroxyacetone reduce the rate of weight gain and body fat content during growth. These alterations in growth pattern appear to be the result of an increased loss of calories as heat at the expense of storage of lipid. Pyruvate-dihydroxyacetone supplementation has also been found to improve the insulin sensitivity of insulin resistant rats and reduce plasma cholesterol levels induced by a high cholesterol diet as well as lower blood pressure and heart rate in obese individuals. When infused in rats during prolonged treadmill running, pyruvate reduced run time to exhaustion by approximately 67%. However, when provided as an oral supplement for several days, it has enhanced aerobic endurance capacity. The mechanism of action is unclear, but available data suggest that the increase in performance following pyruvate-dihydroxyacetone supplementation may be a result of an increased reliance on blood glucose, thus sparing muscle glycogen. In summary, chronic supplementation of pyruvate-dihydroxyacetone may be beneficial from a preventive medicine prospective as well as for certain athletic endeavors.
Publication Types:
Review
Review, Tutorial
PMID: 9624640 [PubMed - indexed for MEDLINE]

[Benpressmannen]

Inhibition of regain in body weight and fat with addition of 3-carbon compounds to the diet with hyperenergetic refeeding after weight reduction.

Stanko RT, Arch JE.
Department of Medicine, Montefiore University Hospital, University of Pittsburgh Medical Center, PA 15213-2582, USA.

OBJECTIVE: To investigate the efficacy of the 3-carbon compounds pyruvate and dihydroxyacetone (PD) in inhibiting reaccumulation of body weight and fat with refeeding after weight loss. DESIGN: Longitudinal, in Clinical Research Center. After weight loss induced by hypoenergetic diet (1.3 MJ/d) for 3 weeks, refeeding with hyperenergetic diet (1.5 x resting energy expenditure) for 3 weeks. Refeeding diet randomized to contain PD or placebo (PL, polyglucose) as approximately 20% of energy intake. SUBJECTS: 17 obese healthy women (n = 8 in PL group, n = 9 in PD group) (age: 22-60 y, weight: 72.5-139.7 kg). MEASUREMENTS: Resting energy expenditure (REE), body composition (by bioelectrical impedance), nitrogen balance, serum proteins, biochemical profile, thyroid hormones, and insulin, before and after refeeding and weight and fat gain. RESULTS: Refeeding with a hyperenergetic diet, weight gain was significantly less in patients receiving PD compared to placebo (1.8 + 0.2 kg vs 2.9 +/- 0.1 kg, P < 0.01). Body fat regain was also less with feeding of PD (0.8 +/- 0.2 kg vs 1.8 +/- 0.2 kg, P < 0.01). Body protein metabolism, as measured by nitrogen balance, serum protein concentrations and fat free mass, was similar in subjects consuming either PD or PL. CONCLUSIONS: We conclude that 3-carbon compounds decrease weight gain and reaccumulation of body fat, without decreasing body protein gain, in obese subjects with hyperenergetic refeeding subsequent to weight loss.

Publication Types:
Clinical Trial
Randomized Controlled Trial
PMID: 8910097 [PubMed - indexed for MEDLINE

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