sábado, noviembre 26, 2005

vida media de los nutrientes

La vida media de ciertos nutrientes, especialmente los hidrosolubles (ADEK son las vitaminas liposulubles), es corta. Por vida media se entiende el tiempo que tarda una dada cantidad de una sustancia en reducirse su concrentración en el cuerpo a la mitad por procesos biológicos.

La vida media de la vitamina B1 es de 2.5 horas. Por lo tanto conviene distribuir las dosis en varias tomas en el día o usar fórmulas de liberación controlada.

"The half-lives of certain important nutrients, especially water-soluble ones, such as the B-vitamins, are relatively short. (Half-life is the time required for any given amount or concentration of a nutrient to decrease by half, through biological processes.)

For example, the half-life of oral thiamine (vitamin B1) is only about 2.5 hours.1 So if it’s advantageous to maintain high levels of this vitamin (in your liver, for example) and not to let down your safety shield, it’s advisable to take three, or preferably four, servings daily. Otherwise your body is left with less than optimal protection against free radicals and is thus more susceptible to disease. With regard to vitamin C, which also has a short half-life, Linus Pauling advocated taking it throughout the day in divided doses, which overcomes this problem.2

Tallaksen CM, Sande A, Bohmer T, Bell H, Karlsen J. Kinetics of thiamin and thiamin phosphate esters in human blood, plasma and urine after 50 mg intravenously or orally. Eur J Clin Pharmacol 1993;44(1):73-8.
Hickey S, Roberts H. Ascorbate: The Science of Vitamin C. Lulu Press, Inc., Napa, California, 2004."