Introduction

Pyruvate is a three-carbon compound that occurs naturally in the body and is generated by the breakdown of glucose (glycolysis) and the catabolism of amino acids. Pyruvate supplementation has been the subject of many clinical trials and animal studies, often in conjunction with dihydroxyacetone (a related three-carbon compound), and has been found to improve endurance, cause significant fat loss, and improve heart function. This article briefly discusses some of the possible benefits of pyruvate supplementation.

Fat loss

The most well-known benefit of pyruvate supplementation is fat loss. This effect was first established in a series of high-dose studies conducted by Dr. Stanko at the University of Pittsburgh School of Medicine. He first found that when pyruvate and dihydroxyacetone were added to the diets of rats and swine, there was a significant reduction in body fat without any reduction in body protein or muscle content [1-2], and this effect has been confirmed in multiple studies since then [3-5]. This was followed by two clinical trials in which high doses of pyruvate and dihydroxyacetone (totaling 33-100 grams and containing 19-44 grams of pyruvate) enhanced fat loss without effecting nitrogen balance in subjects on low or very low calorie diets. The weight loss seen from pyruvate over placebo in these trials was .9 kg and 1.6 kg over a period of three weeks [6-7]. Dr. Stanko then conducted a study which demonstrated that pyruvate inhibited fat gain, but not the gain in fat free mass, during a period of weight gain [8].

Given the impractical high dosing schedule in these studies, two other studies, which Dr. Stanko was not associated with, have since been conducted. Both studies were double blind and placebo controlled and used 6 grams of pyruvate (as calcium pyruvate) a day for 6 weeks. The first used 53 subjects, and the pyruvate group lost 4.8 lbs of body fat and gained 3.4 lbs of lean body mass compared to the placebo and control groups, in which these variables did not change [19]. In the second study, in which 26 subjects participated, the pyruvate group lost 5.5 pounds more body fat and had 2.7% lower body fat than the placebo group (in which no weight loss was seen). Lean body mass was the same in both groups, but the pyruvate group experienced decreased fatigue and increased vigor on the Profile of Mood State (POMS) checklist [9]. A pilot study conducted by McCarty et al. [10] is also suggestive, despite the fact that it was inadequately controlled and did not undergo peer review. 8 g of pyruvate, 1.5 g of hydroxycitrate, 250 mg of L-carnitine, and 600 mcg of chromium were given to 16 obese or grossly obese subjects, along with dietary counseling. Average weekly fat loss in this group was 2.3 kg, and barring academic dishonesty, such weight loss is inexplicable by dietary counseling alone, suggesting that some of the supplements may have been involved.

The mechanism of action for fat loss due to pyruvate is not fully known, but some hypotheses have been suggested. Animal studies indicate a variety of effects, including increased resting metabolic rate, elevated thyroxine, increased fatty acid oxidation, and decreased lipogenesis [3, 5, 9]. Pyruvate administration also decreases food intake in rats [4], although this would not effect the outcome of the clinical trials discussed above in which caloric intake was equivalent in both groups. A direct uncoupling effect from pyruvate is also a possibility, and is the proposed mechanism for the fat loss seen in the McCarty study, in which subjects reported elevated body temperature [10].

Endurance capacity

Another potential benefit of pyruvate supplementation is increased endurance capacity. Once again, this was first reported by studies done by Dr. Stanko. In two separate studies, he found that pyruvate and dihyrdoxyacetone taken over seven days (compared to carbohydrates) increased submaximal arm and leg endurance capacity and glucose utilization in muscle [11, 12]. Increased aerobic endurance capacity from oral pyruvate supplementation has also been seen in rats [13], and there is a wealth of animal data indicating that pyruvate in supraphysiological concentrations lessens the reductions in phosphocreatine and ATP in the heart during high workstates [14] and this could very well be the case with skeletal muscle as well.

Since the time of Dr. Stanko's studies, two other studies have been done that have showed no statistically significant benefit from pyruvate supplementation. However, both of these studies had some methodological flaws. The first, evaluating cycling capacity, used low doses (7 grams of creatine and pyruvate combined). Although it was not statistically significant (probably due to small sample size of 14), there was a trend toward increased work output in the creatine pyruvate group [15]. The second study [16] utilized a sample size of only 7 individuals. Also, contrary to earlier data, they found no elevation in blood pyruvate or other variables from pyruvate supplementation, with the exception of an increase in lipolysis. Since the data is presently contradictory, a benefit in endurance performance is not conclusively indicated, but there is a clear possibility of a beneficial effect.

Other benefits

One of the most important benefits of pyruvate is that it can improve heart function, especially in the case of injury. Pyruvate both increases energy reserves in the heart (as discussed above), increases the activity of antioxidant enzymes, and has a direct antioxidant action. These benefits have been seen in both animal studies and with pyruvate infusions in humans, but it is as of yet unknown if oral supplementation provides a significant benefit in humans [17]. In animal models, pyruvate administration also protects against ischemic injury to various organs such as the small intestine, liver, and kidneys [18].

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