Huntington's Disease supplements
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Creatine is naturally synthesized in the human body from amino acids primarily in the kidney and liver and transported in the blood for use by muscles. Approximately 95% of the body's total creatine content is located in skeletal muscle. Creatine was discovered in the 1800s as an organic constituent of meat. In the 1970s, Soviet scientists reported that oral creatine supplements may improve athletic performance during brief, intense activities such as sprints. Creatine gained popularity in the 1990s as a "natural" way to enhance athletic performance and build lean body mass. It was reported that skeletal muscle total creatine content increases with oral creatine supplementation, although response is variable. Factors that may account for this variation are carbohydrate intake, physical activity, training status, and muscle fiber type. The finding that carbohydrates enhance muscle creatine uptake increased the market for creatine multi-ingredient sports drinks. Use of creatine is particularly popular among adolescent athletes, who are reported to take doses that are not consistent with scientific evidence, and to frequently exceed recommended loading and maintenance doses. Published reports suggest that approximately 25% of professional baseball players and up to 50% of professional football players consume creatine supplements. According to a survey of high school athletes, creatine use is common among football players, wrestlers, hockey players, gymnasts, and lacrosse players. In 1998, the creatine market in the United States was estimated at $200 million. In 2000, the National Collegiate Athletic Association (NCAA) banned colleges from distributing creatine to their players. Creatinine excreted in urine is derived from creatine stored in muscle.
The main function of L-carnitine is to transfer long-chain fatty acids in the form of their acyl-carnitine esters across the inner mitochondrial membrane before beta-oxidation. In humans, it is synthesized in the liver, kidney, and brain and actively transported to other areas of the body. For example, 98% of the total body L-carnitine is confined to the skeletal and cardiac muscle at concentrations approximately 70 times higher than in the blood serum. Supplementation may be necessary in rare cases of primary carnitine deficiency, which may be caused by a defect in carnitine biosynthesis, a defect in carnitine active transport into tissue, or a defect in renal (kidney) conservation of carnitine. Known conditions of secondary deficiency of carnitine (insufficiency), in which L-carnitine is effective, include chronic stable angina and intermittent claudication characterized by distinct tissue hypoxia (low oxygen levels). Another condition that may benefit from carnitine supplementation is decreased sperm motility. Although use in preterm infants suggests carnitine supplementation may aid in maintaining or increasing plasma carnitine levels and possibly weight gain, carnitine is not routinely added to preterm total parenteral nutrition (TPN). However, soy-based infant formulas are fortified with carnitine to levels found in breast milk. In 1986, the U.S. Food and Drug Administration (FDA) approved L-carnitine for use in primary carnitine deficiency. D-carnitine or DL-carnitine may cause secondary L-carnitine deficiency and should not be used.
Coenzyme Q10 (CoQ10) is produced by the human body and is necessary for the basic functioning of cells. CoQ10 levels are reported to decrease with age and to be low in patients with some chronic diseases such as heart conditions, muscular dystrophies, Parkinson's disease, cancer, diabetes, and HIV/AIDS. Some prescription drugs may also lower CoQ10 levels. Levels of CoQ10 in the body can be increased by taking CoQ10 supplements, although it is not clear that replacing "low CoQ10" is beneficial. CoQ10 has been used, recommended, or studied for numerous conditions, but remains controversial as a treatment in many areas.