General Description
L-carnitine is a vitamin-like nutrient, related in chemical structure
to the B vitamins. In the human body, L-carnitine is synthesized
from the amino acid lysine in the liver and kidneys. Dietary sources
of L-carnitine include meat and dairy products, with red meat being
the richest source. L-carnitine supplements are produced synthetically.
Health applications
Primary functions
In the body, L-carnitine plays a crucial role in the transport
and metabolism of fatty acids, helping the muscles utilize fat
as an energy source. Supplemental L-carnitine is popular for improving
energy levels in athletes and fatigue sufferers and for promoting
cardiovascular function in people with congestive heart failure.
Cardiovascular health
Most of the research on L-carnitine has focused on its potential
to improve cardiovascular function. Studies suggest L-carnitine
may help improve heart function in patients with congestive heart
failure,1-3 increase exercise tolerance in
patients with exercise-induced stable angina,4-6
and may even increase the life expectancy of heart attack sufferers.
7-9 Because these studies vary in design,
dosage, and the forms of carnitine used, more research is needed
to determine the usefulness of L-carnitine in the treatment of
cardiovascular disease.
Chronic fatigue syndrome
Because L-carnitine is known to play an essential role in energy
production, researchers are studying its potential in the treatment
of chronic fatigue syndrome (CFS). Low carnitine levels have been
observed in CFS patients, 10-12 and one study
showed improvement in CFS parameters with oral L-carnitine treatment.13
Larger studies are needed to verify these preliminary findings.
Dosage/toxicity
L-carnitine supplements are typically taken in doses ranging from
1 to 4 grams per day. It is generally well tolerated in this dosage
range, with no significant side effects reported in human clinical
studies. 14 There is no known toxicity with
L-carnitine, even at very high doses.15 |
