Sunday, 27 April 2014 07:22

Benifits of L-Carnitine

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What is L-Carnitine?

L-carnitine is a trimethylated amino acid that plays essential roles in many areas of the body, including fatty acid translocation and muscle function. Carnitine is also acetylated into the ester Acetyl-L-carnitine (ALCAR) in the brain, liver, and kidney. ALCAR also plays a variety of roles in the body, including increasing acetylcholine production and stimulation of protein and membrane phospholipid synthesis. Orally administered L-carnitine and ALCAR have profound anti-aging and nutrient repartitioning properties, and the effects of supplementing with them have been extensively researched in many areas, including exercise performance, weight loss, treatment of Alzheimer's, Parkinson's, diabetic neuropathy, depression and many other neurological disorders, treatment of alcoholism, treatment of cardiovascular diseases, insulin resistance, and many others.

What benefits does L-Carnitine have?

Cardiovascular benefits - The carnitines have considerable potential in the treatment of cardiovascular disease. Rodent studies with L-carnitine have shown decreased triglyceride and cholesterol levels and protection against arrhythmia and ischemia, and a study with ALCAR found a reversal of the age-related decline in mitochondrial function in the heart. A study on the three-year survival rate of patients with dilated cardiomyopathy supplemented with L-carnitine (n=37) or placebo (n=33) found one death in the L-carnitine group and six in the placebo group, and concluded that L-carnitine had a considerable effect. Another study found over a 10% reduction in cardiac events following suspected myocardial infarction, and other human studies have found reduced arrhytmia, significant improvement in patients with congestive heart failure, and reduced cholesterol and triglycerides.

Improved cognitive function - ALCAR plays a strong role in the brain in many ways, and has beneficial effects in many conditions including Alzheimer's and Parkinson's. Studies in aged rodents show markedly improved memory and learning capacities, while studies in younger rodents show a variety of promising effects as well. Other rodent studies have shown that ALCAR significantly protects the brain against a variety of stresses, such as ischemia and repurfusion and mitochondrial uncoupling. It also protects against peripheral nerve trauma, "almost eliminating neuron loss", and in vitro neuronal apoptosis. ALCAR also increases levels of dopamine, amino acids, and acetylcholine in the brain, as well as facilitating cholinergic activity.

One of the primary mechanisms for the improved cognitive function and anti-aging properties seen with ALCAR is its ability to prevent oxidation and inflammation. Administering ALCAR reduces lipid peroxidation, prevents or reverses many age-related increases in markers of oxidative and inflammatory events in the cortex, reduces damage to nucleic acids (DNA/RNA) and proteins, and also increases the levels of other antioxidants in the brain. Administering ALCAR also prevents mitochondrial decay, restores depleted ATP levels, and restores the activity of many key enzymes that decline with age such as carnitine acetyltranferase, mitochondrial complexes III and IV, sodium potassium adenosine triphosphatase, and glutathione-S-transferase.

ALCAR supplementation is also accompanied by many positive structural changes in the brain in both the young and the old. It stimulates nerve growth factor (NGF) binding, and rodent studies indicate significantly more regenerative elements and reduced degenerative elements. A study that measured the regenerative capacity of myelinated fibers in young and old rats found that ALCAR significantly increased the density of regenerating myelinated fibers (RMF) and increased the density of axon diameters in both, as well as reducing degenerative elements, and another rat study with ALCAR found increased synaptic numeric densities and improvements in energy provision at nerve terminals in both young and old rats, as well as 10-20% increases in synapses smaller than .08 microns.

Improved hearing and visual function - Two animal studies indicate a significant reduction in noise-induced and age-induced hearing loss with ALCAR. One measured outer hair cell (OHC) density after three weeks of noise exposure, and found less than a 10% reduction with ALCAR as opposed to 60% with placebo, and noise induced threshold shifts were less than 10 dB in the ALCAR group as opposed to 30-35 dB with placebo. A six-week study with aged rats found ALCAR to improve auditory thresholds by upregulating mitochondrial function and reducing oxidative stress.

Improvements in visual function have been noted as well. A preliminary study on guinea pigs found an improvement in alignment to ocular responses and enhancement of optical nerve growth, and hypothesized that ALCAR can increase visual function. In vitro, ALCAR also prevents the buildup of advanced glycation end products (AGEs) in the eye, which are a known cause of macular degeneration.

Reduced stress and depression - In rats, ALCAR protects against the decreases in dopamine and testosterone that normally occur after exposure to both acute and chronic stress and decreases other markers of stress, and no tolerance develops to this effect. Preliminary human studies in the elderly and those undergoing treatment for certain conditions indicate a reduction in depression and fatigue and an improvement in quality of life.

What application does L-Carnitine have?

The carnitines are excellent supplements for athletes, as well as anyone who wants to look and feel thier best. Studies with both ALCAR and L-carnitine have shown that they have potent nutrient repartitioning effects, and there are some studies indicating that L-carnitine can increase exercise performance.

In one study, both young and old rats were supplemented with ALCAR and compared with age-matched controls. Nutrient partitioning and muscle mass and function were among the factors measured. Body weight did not differ significantly between the two groups, but there were strong differences in the fat to protein ratios. The young rats fed ALCAR had slightly higher body protein levels (not statistically significant) and significantly less body fat, while the old rats fed ALCAR had much high body protein levels and the same amount of body fat. ALCAR may be especially useful for older people, as one rat study found that long-term administration prevents the progressive increase in the size of fat cells that normally occurs with age.

Another study looked at the effects of carnitine (.68 g) and choline (.94 g) supplementation on fat metabolism in healthy women. In the treatment groups, body fat decreased .7-1.3% over 35 days (as opposed to no difference in the placebo group). They also found that when the supplemented groups exercised, the ability to utilize fat as energy substrate increased (5). Animal studies have also shown L-carnitine to reduce obesity and improve nitrogen utilization. However, there has been one human study in moderately obese premenopausal women in which no weight loss or repartitioning effect was found with L-carnitine.

When looking at the effects of the carnitines on exercise performance, we no longer have to rely so much on animal studies. Various studies have shown that L-carnitine improves exercise performance in people with heart problems or impaired exercise tolerance, as well as people recovering from hemodialysis. However, the influence on exercise performance on healthy individuals is less clear. L-carnitine definitely changes the response and effects of exercise, as evidenced by decreased muscle soreness and decreased pyruvate and lactate concentrations and higher ALCAR concentrations post-exercise, as well as studies showing it to increase utilization of fat as a fuel source during exercise. A study with L-carnitine L-tartrate also showed it to favorably effect many markers of recovery from squat exercises. The real world effect of this is not conclusively known, and two recent reviews stated that further studies are needed before the effect can be determined on healthy individuals. Regardless of the present lack of human studies showing a definite ergogenic effect, the nutrient partitioning properties and improved recovery alone make carnitine a worthwhile supplement, and there are also many added benefits.

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