Douglas Laboratories’ L-Carnitine supplements
supply pure, natural L-carnitine in capsule form.
L-carnitine is necessary for fatty acid metabolism and
energy production in cardiac and skeletal muscle. It is
involved in fatty acid oxidation as part of the
carnitine shuttle. L-carnitine shuttles fatty acids from
the cytosol (the cell fluid) into the mitochondria (the
cell’s powerhouses) for oxidation and energy
L-carnitine is necessary in muscle
whenever fat is utilized as an energy source. Heart
muscle always uses fat for its continuous energy
demands. Skeletal muscle begins using fat only after
its glycogen reserves are exhausted. This happens
after about one hour of continuous, strenuous
exercise, e.g., long-distance running, bicycling,
swimming, or mountain climbing.
Widely distributed in foods from animal, but not
plant sources, L-carnitine is also synthesized by the
liver and kidney from two essential amino acids
lysine and methionine. Human skeletal and cardiac
muscles contain relatively high L-carnitine
concentrations which they receive from plasma, since
themselves. About 95 % of the body’s L-carnitine
stores are located in skeletal and heart muscle.
L-carnitine is considered a conditionally essential
nutrient. In healthy people, plasma L-carnitine levels
are adequately maintained by the body’s own
synthesis and dietary sources. However, low Lcarnitine
plasma levels can be caused by hereditary
(primary) L-carnitine deficiency syndrome, or by
secondary L-carnitine deficiency. Patients with heart
failure excrete large amounts of L-carnitine in their
Oral L-carnitine is readily absorbed across the
intestinal mucosa and into the bloodstream. It is then
taken up from the portal vein into the liver and
subsequently released into the systemic circulation.
Most cells have a specific carnitine transporter.
Dietary L-carnitine comes mainly from animal foods.
Average non-vegetarian diets provide about 100 to
300 mg of L-carnitine per day. Vegetarian diets often
provide only trace amounts, since vegetables, fruits,
and cereals are negligible sources of L-carnitine.
L-carnitine may be a useful nutritional adjunct for
individuals who wish to support heart muscle
function or skeletal muscle performance.