viernes, septiembre 01, 2006

l-carnitina o acetil-l-carnitina?

A pesar de que muchos afirman que la acetil l-carnitina (ALCAR) es superior a la l-carnitina (especialmente para las mitocondrias y el cerebro), este artículo  explica cómo una se transforma en la otra. Habrá que tener en cuenta también a los que usan ALCAR como . La carnitina es mucho más barata que la ALCAR por lo que no estaría mal empezar por la primera.

2. What form is best?

Pharmacologically speaking, there is little difference between supplementing with L-carnitine and supplementing with ALCAR. This is because ALCAR is deacetylated during or immediately after intestinal cell uptake, and then a certain amount of free carnitine is later reacetylated (1, 2). Similarly, it has been shown that supplementation with both L-carnitine and ALCAR increase tissue levels of both substances, and that the intestine creates significant amounts of ALCAR from carnitine (2, 3).

7. How should carnitine be taken?

The typical dosage for carnitine is 1-4 g/day (65). A study on the pharmacokinetics of oral L-carnitine in human subjects found no differences in plasma carnitine after 2 g vs. 6 g, indicating that 2 g is already more than the saturable dose (66). The half-life of the 2 gram dose was 6.5 hours, and this would imply that the ideal dosing schedule would be 1-2 grams 2-3 times daily, although many studies indicate beneficial effects with only .5-1.5 grams daily.

1. Iossa S, Mollica MP, Lionetti L, Crescenzo R, Botta M, Barletta A, Liverini G. Acetyl-L-carnitine supplementation differently influences nutrient partitioning, serum leptin concentration and skeletal muscle mitochondrial respiration in young and old rats. J Nutr 2002 Apr;132(4):636-42

2. Gross CJ, Henderson LM, Savaiano DA. Uptake of L-carnitine, D-carnitine and acetyl-L-carnitine by isolated guinea-pig enterocytes. Biochim Biophys Acta 1986 May 29;886(3):425-33 [abstract]

3. Gudjonsson H, Li BU, Shug AL, Olsen WA. In vivo studies of intestinal carnitine absorption in rats. Gastroenterology 1985 Jun;88(6):1880-7

L-Carnitine Description By David Tolson