L-Carnitine Benefits, Side Effects and Dosage

What it is and what it claims to do:

Carnitine is an amino acid that plays a key role in our bodies’ ability to use fats for energy, which means we can burn them rather than store them. Carnitine has also been shown to increase exercise capacity and delay the onset of muscle fatigue and soreness.

Natural sources of Carnitine:

The highest concentrations of carnitine are found in red meat and dairy products. Other natural sources of carnitine include nuts and seeds (e.g. pumpkin, sunflower, sesame), legumes or pulses (beans, peas, lentils, peanuts), vegetables (artichokes, asparagus, beet greens, broccoli, brussels sprouts, collard greens, garlic, mustard greens, okra, parsley), fruits (apricots, bananas), cereals (buckwheat, corn, millet, oatmeal, rice bran, rye, whole wheat, wheat bran, wheat germ) and other ‘health’ foods (bee pollen, brewer’s yeast, carob, and kale).

Studies with L-Carnitine:

In a randomized, double-blind crossover study by Decombaz et. al. (1993), nine subjects were given 3 grams/day of L-carnitine for 7 days. Then at the end of the seven days, they completed a 20 minute bicycle exercise at 43% VO2 max. Respiratory quotient (RQ), heart rate (HR), rating of perceived exertion (RPE), and various blood parameters indicated no influence of carnitine supplementation on substrate utilization.

But then:

A Romanian study claims there are 6 DB studies with over 100 athletes and l-carnitine showing benefits acutely and chronically. Physiologie 1989 Apr-Jun;26(2):111-29.

More detail on that study:

Chronic and acute effects of L-Carnitina (vials of 1 g L-Carnitina endovenous; per orally administered vials of 1 g L-Carnitina; tablets of 1 g L-Carnitina) were recorded in 110 top athletes (rowing, kayak-canoe, swimming, weightlifting medium and long-distance runners), 47 girls and 63 boys, by six double blind placebo trials and cross over. Significant changes were registered after L-Carnitina treatment (both for a single dose or after 3 weeks of treatment) compared to placebo, for FFA, triglycenides, lactic acid after exercise, evoked muscular potential, plasma carnitine (free and acetyl-carnitine), urine carnitine (free carnitine) and others. The authors explain these changes by the increase of free carnitine, which permits a larger quantity of FFA to enter the mitochondria and to be more extensively used as energy source in endurance and strength efforts. Based on these results the authors recommend L-Carnitina as an ergogenic aid in elite athletes, especially in endurance and strength sports.

Supplements containing L-Carnitine are banned for sale and shipment into Canada.

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