Carnitine Supplement Review

by Dr. Bill Misner, Ph.D

 L-Carnitine: Prices and Ordering Information

CARNITINE(y-trimethylamine-beta-hydroxybutarate, C7H15NO3) is an dipeptide amino acid made from two aminos, methionine and lysine in the presence of vitamins B-1, B-6 and the mineral, Iron. Vegetarians and endurance athletes may deplete both forms of Carnitine(the naturally occurring L-Carnitine, and/or Acetyl-L-Carnitine).

How do adequate tissue stores of Carnitine aid performace?

Carnitine has a major role in the following specific physiological functions:

1. It transfers fatty acids across mitochondria cell membranes for conversion to muscle contractile energy.
2. It increases the rate the liver metabolizes fats.
3. It dramatically prevents DNA degeneration and promotes repair of DNA strand mutation from free radical stress.
4. It reduces the build up of acids and metabolic wastes.
5. It increases oxygen availability and respiratory efficiency.

Endurance athletes rapidly deplete Carnitine

The best food sources of Carnitine are organ meat, fish, muscle meats, and milk products. The optimal daily diet supplies only 300 mg. per day, but the endurance athlete requires between 3000-4000 mg. per day! Even when an athlete obtains max-dietary sources, intense training can deplete Carnitine stores more rapidly than the body can replenish it.

Subjects who cycled at only 55% VO2 Max lost 20% of their muscle store of Carnitine.(JOURNAL OF APPLIED PHYSIOLOGY, 1983;55:489.) Maximal exercise causes a much greater drop causing extreme depletion similar to that of patients who suffer from Carnitine deficiency disease.(BIOCHEMISTRY BIOPHYSICS ACTA, 1990;1034:17-21.

During the first hour of exercise Carnitine mobilizes fatty acids in muscle mitochondria supplying 35-39% of the caloric needs, but after 90 minutes or so later at the same rate of exercise fatty acid conversion becomes the predominant fuel supplying 65-70% of the caloric requirements. During prolonged exercise, blood lipids increase dramatically. There is always more than adequate fatty acids available for conversion IF there is adequate levels Carnitine to "ferry" long chain fatty acids through mitochondrial membranes. Symptoms of Carnitine deficiency are extreme muscle weakness with high blood lipids.(JOURNAL OF LABORATORY CLINICAL MEDICINE, 1984;104:166-175, and MEDICAL SCIENCE SPORTS EXERCISE, 1984;16:263-268) Body fat peripheral accumulation is enhanced when these excessive serum lipid counts are not carried to the mitochondrial matrix for conversion to energy.

How much Carnitine and what kind

Oral L-Carnitine has been shown correct deficits from endurance training to between 40-90 minutes. (RESPIRATORY QUARTERLY, 1990;61:80-84.) Some of the early studies with L-Carnitine dose amounts have shown that a dose of 4000 milligrams per day improved VO2 Max performance dramatically. (CARNITINE THE VITAMIN BT PHENOMENOM, Dell Publ.1984, EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY,1985;54:131-135, CLINICAL ASPECTS OF HUMAN CARNITINE DEFICIENCY, Pergamon Press, NY,1986.)

As previously mentioned, the best planned diets of food-sourced L-Carnitine(LC) supply only 300 mg. of LC, but the need exceeds 3000 mg. for prolonged or intense exercise activities beyond 90 minutes. L-Carnitine(LC), Acetyl-L-Carnitine(ALCAR) are excellent choices for oral repletion.

From over 20 reliable studies out of over 70 "other works" reviewed, it is my present persuasion that use of both LC & ALCAR in a 50-50 mixture may have a slight advantage over using only one form of Carnitine. Effective dose rates appear to be between 2-4000 mg. per day for a 2-week loading period may be the most inexpensive means to raising blood serum levels and muscle stores of this valuable endurance substrate. Even when extreme endurance athletes regularly take 4000 grams per day, no toxic side effects have been observed.