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16 Dietary Supplements Aimed at Enhancing Performance: Efficacy and Safety Considerations
Pages 331-340

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From page 331...
... National Academy Press JO Dietary Supplements Aimed at Enhancing Performance: Efficacy and Safety Considerations Timothy J Maher1 INTRODUCTION Consumers have used amino acids as dietary supplements for many years in the hope of producing a wide variety of effects, including enhanced physical performance, improved quality of sleep, analgesic relief, and accelerated muscle mass development.
From page 332...
... Because consumers primarily used supplemental amino acids presumably to enhance physiological functions or produce pharmacological responses, rather than to affect any nutritional function, a significant dilemma was faced by the expert panel. No credible evidence was available in the scientific literature indicating that a normal, healthy individual would benefit nutritionally in any way from supplementation of the diet with any single amino acid.
From page 333...
... (Glassman and Platman, 1969; Hull and Maher, 1990; Hull et al., 1994~. The expert panel concluded, based on the scientific evidence available, that the only safe form of amino acid ingestion was via protein in the diet and that there was no evidence to support a safe upper level of any individual amino acid intake in the form of a dietary supplement beyond that found in typical protein foods.
From page 334...
... The use of highly processed soybean protein isolates and concentrates as part of the diet can provide all, or a portion of, the daily protein requirements in an increasingly palatable form. Additionally, differences between countries in the incidence of many diseases including heart disease, hormone-dependent cancers, and osteoporosis have been epidemiologically associated with the degree of dietary soybean protein consumption (Knight and Eden, 1996~.
From page 335...
... Although administration of L-tryptophan, the precursor of serotonin, has been shown to increase serotonin in the brain of experimental animals and affect numerous serotonergic-mediated behaviors, this amino acid is no longer available for unrestricted use due to the above described association with the EMS epidemic. However, another approach to increasing central serotonergic function without the exogenous administration of the individual amino acid precursor involves the consumption of carbohydrate which, by virtue of its ability to increase insulin release, enhances the uptake from the circulation of large neutral amino acids (LNAA)
From page 336...
... did not significantly alter the serum tryptophan:LNAA ratio or the behavioral and cognitive performance parameters monitored. The ability of this dietary supplement to alter the mood and performance decrements associated with the premenstrual period in some women may offer an alternative strategy to addressing this syndrome with a relatively benign intervention.
From page 337...
... · Choline supplementation for endurance activities should be considered and requires careful investigation under a varieW of applicable military conditions. It is therefore recommended that approaches to fortify military rations with supplemental amino acids, protein, or additional compounds be Initiated.
From page 338...
... 1984. Diurnal variations in plasma concentrations of basic and neutral amino acids and in red cell concentrations of aspartate and glutamate: Effects of dietary protein.
From page 339...
... In light of the practicality of any studies actually being completed, and in light of most of the data you showed and I did review that Document 12 for the NIH symposium on protein supplements that was held, and I was not impressed that there was really much evidence of detrimental effects, and with the layers of proposed tests that would be run before any studies would be done, I am concerned that any further investigation would be precluded without a sufficient basis in many cases for implementing these additional screening tests. TIMOTHY MAHER: I think that we have the two extremes.
From page 340...
... So I don't understand why the FDA, cannot design standards for quality control, at least for amino acids, before we have these tremendous studies of efficacy.


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