Abstract
L‐carnitine is an essential nutrient that plays critical roles in energy metabolism. Although L‐carnitine has not been listed as an essential nutrient in Japanese Dietary Reference Intake, a variety of severe clinical symptoms appears when L‐carnitine is deficient in the body, resulting in deterioration of quality of life. While L‐carnitine is partially bio‐synthetized in the body, it could easily be deficient, when oral intake is insufficient, because the majority of L‐carnitine in the body is derived from food intake. Therefore, patients, particularly elderly, with no or poor oral intake who are malnourished and/or sarcopenia definitely need intensive nutritional management and are required to use nutritional formulas of total parenteral and enteral nutrition that contain sufficient amount of L‐carnitine in order to prevent L‐carnitine deficiency as well as to reduce pain and oxidative stress of skeletal muscle. L‐carnitine is also expected to be useful for power athletes who are not L‐carnitine deficient to boost athletic performance because of the efficient energy supply by stimulating fat oxidation. These results suggest that supplementation of L‐carnitine is useful for patients with L‐carnitine deficiency, as well as for normal healthy subjects and power athletes by increasing L‐carnitine pool in the body．
