6 Amino Acids Unleash the Energy

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Protein and amino acid supplements receive a lot of attention on health-food store shelves, and there's a good reason.

Protein, as the second-most-plentiful substance in the body (after water), is needed for the growth and repair of every cell in the body. Muscles, not surprisingly, are primarily made up of protein.

Skin, hair, nails, antibodies, many hormones, and enzymes are also mostly comprised of, you guessed it, protein.
Protein profile

How much? A continual daily consumption of protein is necessary, since the body cannot store protein for later use. Nutrition experts recommend that protein should account for 10-12 percent of the calories in a balanced diet. However, requirements for protein are affected by age, weight, state of health, and other factors. Without regular access to protein, the body will break down the protein in muscle tissue and use those amino acids to meet the needs of more vital organs.

Dietary sources. The richest dietary sources of the essential amino acids (again, protein's building blocks) are animal foods, such as meats, fish, poultry, dairy products, and eggs. Vegetable sources of protein (such as beans, peas, and grains) generally fall short in one or more essential amino acids.

Although animal sources of protein offer more complete amino-acid profiles, the downside to these foods is that they often additionally provide large amounts of fat (especially unhealthful saturated fat), cholesterol, and extra calories. Since plant foods do not each lack the same amino acids, eating a variety of plant sources of protein can provide the body with the whole range of amino acids it requires.

How much is too much? Having established the importance of protein in the diet, however, it must be pointed out that the average American diet provides more protein than is needed by the body. And when the body has more protein than it requires, excess nitrogen is excreted as urea in urine, and the rest of the protein molecule can either be used for energy or stored as fat. For most people, this excess nitrogen excretion can be handled by the kidneys, but the kidneys of some people (particularly those with kidney-related health problems) can be overburdened by the extra nitrogen. Another problem with excessive protein intake is that protein, in large quantities, can increase excretion of calcium, according to an article in the Journal of the American Dietary Association.
Profiles of 6 key amino acids

The protein consumed in the diet cannot be used directly by the body. Instead, the body breaks down dietary protein into its constituent amino acids and then uses these amino acids to synthesize the proteins needed by the body.

Twenty different amino acids are needed to build the various protein used in the body. Of these, half can be made by the body itself, while the other half (called essential amino acids) must come from the diet. The classification of an amino acid as essential or non-essential does not reflect its importance, since all 20 amino acids are necessary for health. Instead, this classification system simply reflects whether or not the body is capable of manufacturing a particular amino acid.
1. Creatine.

Creatine, which is a combination of the three amino acids arginine, glycine, and methionine, assists in the production of energy and the building of muscle. For this reason, creatine is a popular supplement with body builders and other athletes. Almost all of the creatine in the body is stored in the muscles.

Creatine serves the body as a quickly available source of energy for muscle contraction. It increases the synthesis of muscle protein and assists in the formation of certain growth promoters. Creatine also promotes protein synthesis, as discussed in a recent article in the International Journal of Sports Nutrition.

The best results with creatine are seen when it is used in combination with regular exercise. The amount of creatine taken during the loading and maintenance phases should be fine-tuned, based upon an athlete's weight and intensity of workouts. As a general guideline, 20 g per day of creatine can be taken during the loading phase and 5-10 g per day during the maintenance phase.
2. Lysine.

Lysine plays several roles in the body, including the regulation of nitrogen balance and the absorption of calcium, according to an article in the journal Nutrition. Lysine is also important in the formation of collagen. Research suggests that lysine may inhibit the replication of the herpes simplex virus that causes cold sores, as well as helping to regulate blood pressure and reducing cholesterol levels, as discussed in the Journal of the American College of Nutrition.
3. N-acetyl Cysteine (NAC).

N-acetyl cysteine (NAC), an altered form of the amino acid cysteine, helps the body synthesize glutathione (an antioxidant). It has been shown that low levels of glutathione can leave the body vulnerable to further immune compromise in HIV-infected individuals. Researchers L.A. Herzenberg, et al., at Stanford University Medical School randomly provided either NAC supplements (3,200-8,000 mg per day) or a placebo to 204 HIV-infected men and women for two months. The study participants were invited to continue taking NAC, if they desired, for another six months of the study.

According to the researchers, NAC supplements improved glutathione levels in the HIV patients, "...suggesting that N-acetylcysteine administration can improve their survival [and] establishes [glutathione] deficiency as a key determinant of survival in HIV disease."
4. Arginine.

The amino acid arginine is considered semi-essential, since adults do manufacture sufficient quantities. During periods of growth, a dietary source of arginine is required. Therefore, arginine is necessary for growth, but not for maintenance, of the body.

Arginine participates in the wound-healing process, as discovered in research involving the elderly. This amino acid also supports a healthy immune system and promotes the secretion of several hormones, including glucagon, insulin, and growth hormone. Arginine is also a precursor to nitric oxide, which aids blood vessel dilation, accounting for this amino acid's role in male sexual function.
5. Carnitine.

Carnitine (also known as L-carnitine) is needed for the production of energy in the mitochondria (energy-generating centers) of cells. Some researchers suspect that individuals with chronic fatigue syndrome (CFS) may have mitochondria that do not function properly. Accordingly, deficiencies of carnitine have been reported in some people with CFS, as found through research conducted by H. Kuratsune, et al. Even more suggestive is a study that found that supplemental intake of 1 g (100 mg) of carnitine, taken three times per day, results in some alleviation of the symptoms of CFS, according to an article in Neuropsychobiology.

Although healthy people rarely experience a deficiency of the amino acid L-carnitine, individuals with HIV appear prone to such deficiency, and could benefit from supplementation. Carnitine deficiency is of concern because it is associated with lower energy levels and immune dysfunction, according to research done by M. Mintz.

Studies based on intravenous use of L-carnitine suggest that this amino acid might delay the progression to AIDS by inhibiting the destruction of white blood cells, confirmed by two recently published studies.
6. Histidine.

Histidine is another semi-essential amino acid (again, adults generally produce adequate amounts), but production may not be adequate during periods of growth. Histidine is also a precursor of histamine, a compound released by immune system cells during an allergic reaction. Research reports that histidine levels may be low in some individuals with arthritic conditions, as discussed in the Journal of Chronic Diseases.

If you're one of the many shoppers looking for these nutrients in your local health-food store, you're sure to find a wide variety of forms --powdered drink mixes, nutrition bars, and in single and combination supplement formulations.

PHOTO (COLOR): Victoria Dolby Toews
REFERENCES

Cifone, M.G., Alesse, E., Di Marzio, L., et al. "Effect of L-carnitine treatment in vivo on apoptosis and ceramide generation in peripheral blood lymphocytes from AIDS patients," Proc Assoc Am Physicians 109:146153, 1997.

Civitelli, R., Villareal, D.T., Agneusdei, D., et al. "Dietary L-lysine and calcium metabolism in humans," Nutrition 8:400-404, 1992.

Flodin, N.W. "The metabolic roles, pharmacology, and toxicology of lysine," J Am Col Nutr 16(1):7-21, 1997.

Gerber, D.A., et al. "Specificity of a low free histidine concentration for rheumatoid arthritis," Chron Dis 30:115, 1977.

Greenhaff, P.L. "Creatine and its application as an ergogenic aid," Int J Sport Nutr 5:94-101, 1995.

Heaney, R. "Protein intake and the calcium economy," J Am Diet Assoc 93(11):12591260, 1993.

Herzenberg, L.A., De Rosa, S.C., Dubs, J.G., et al. "Glutathione deficiency is associated with impaired survival in HIV disease," Proc Natl Acad Sci 94:1967-1972, 1997.

Hurson, M., Regan, M.C., Kirk, S.J., et al. "Metabolic effects of arginine in a healthy elderly population," J Parent Ent Nutr 19:227-230, 1995.

Kuratsune, H., Yamaguti, K., Takahashi, M., et al. "Acylcarnitine deficiency in chronic fatigue syndrome," Clin Infect Dis 18:S62-67, 1994.

Moretti, S., Alesse, E., Di Marzio, L., et al. "Effect of L-carnitine on human immunodeficiency virus-1 infection-associated apoptosis: a pilot study," Blood 15:3817-3824, 1998.

Plioplys, A.V., Plioplys, S. "Amantadine and Lcarnitine treatment of chronic fatigue syndrome," Neuropsycholbiol 35:16-23, 1997.

Mintz, M. "Carnitine in human immunodeficiency virus type 1 infection/acquired immune deficiency syndrome," J Child Neurol 10:S40-44, 1995.

http://www.vrg.org/nutrition/adapaper.htm "1997 ADA Position Paper on Vegetarianism" The Vegetarian Resource Group."

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By Victoria Dolby Toews

Victoria Dolby Toews, M.P.H., is a health and nutrition writer who lives in Oregon. She takes a comprehensive look at the history and health benefits of green tea in The Green Tea Book (Avery, 1998). The latest book by Victoria is The Common Cold Cure (Avery Publishing, 1999). She and coauthor Dr. Ray Sahelian share proven remedies for preventing and treating colds and the flu. To order books, ask your retailer to call: 1-800-548-5757.

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