Amino acids are the basic building blocks of protein and can be obtained in an almost endless variety of supplemental forms including capsules, tablets, bars, and powdered mixtures. Products are available that provide a food like mixture of all twenty nutritionally important amino acids, while other products focus on the specific characteristics of isolated amino acids.
Amino acids are typically categorized based on their nutritional role as essential or nonessential. The body cannot produce essential amino acids, so they must be obtained from a dietary source. Nonessential amino acids can either be manufactured directly by the body or can be obtained by conversion from another amino acid. It is important to keep in mind that “nonessential” does not mean that these amino acids are unimportant. It simply means that, under ideal circumstances, there are routes other than the diet by which they can be obtained. Several of the nonessential amino acids are considered to be “conditionally essential” meaning that under certain conditions, such as injury, disease, increased stress, or intense physical activity, the body’s machinery is unable to generate adequate levels, and supplemental dietary sources are required.
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|Essential amino acids||Nonessential amino acids|
|Histidine (conditionally essential)||Proline|
Note: There are many other amino acids, but some can be produced in the body by combining or processing other amino acids from the diet (example: lysine and methionine are combined to produce carnitine).
The recommended dietary allowance for protein is 0.8 g per kilogram of lean body mass per day for a healthy adult. There is widespread controversy concerning the question of whether athletes should consume more protein than the average individual. There is good scientific support for the concept that a greater availability of amino acids promotes protein synthesis and reduces muscle loss that occurs during training. It is fairly well accepted now that athletes probably need closer to 1.0 to 1.8 g of protein per kilogram of body weight per day, particularly during strenuous training.
In most cases, amino acids and total protein intake are considered to be synonymous. In some cases, however, a specific amino acid may have unique characteristics that may lend beneficial effects in treating certain metabolic states. Some are as follows:
• Alanine – enlarged prostate
• Arginine – heart function, growth hormone stimulation
• Branched chain amino acids (valine, leucine, isoleucine) – sports performance
• Carnitine – heart support, sports performance, chronic fatigue, diabetes
• Creatine – sports performance
• Cysteine and N acetylcysteine (NAC) – lung function (bronchitis), antioxidant support
• Glutamie acid – enlarged prostate
• Glutamine – immune support, gastrointestinal maintenance Glycine enlarged prostate
• Ornithine and ornithine alpha ketoglutarate (OKG) – sports performance, wound healing
Phenylalanine – depression
• Taurine – diabetes, epilepsy, high blood pressure
• Tyrosine – alcohol withdrawal, Alzheimer’s disease, depression, increased alertness