Nutritional consequences of the Maillard reaction. Amino acid availability from fructose leucine and fructose tryptophan in the rat

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The biological availability of the Amadori compounds fructose L leucine and fructose L tryptophan was examined in weanling rats. Relative to 14C L leucine, the apparent absorbability of fructose 14C L leucine was about 60%, but the incorporation of its radioactivity in the liver was less than 1.5%. Oral administration of fructose 14C L tryptophan showed that only a small percentage of the radioactivity was absorbed and incorporated. The absorption occurred mostly in the large intestine and was largely prevented after pretreating the rat with antibiotics. Intravenous injection of fructose 14C L tryptophan resulted in an accumulation of the counts in the plasma while a negligible incorporation of counts took place in the liver. Although the essential amino acids were highly unavailable when supplied to the rat in the form of the Amadori compound, the fructose tryptophan was preferable to the total absence of tryptophan from the diet as seen in the readiness of the liver polysomes to remain assembled as well as in the ability of the animal to recover. The effect of the intestinal flora was discussed in relation to the absorption and utilization of the Maillard reaction products.

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Journal of Nutrition