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 PERFORMANCE?
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.
