Effect of a low-protein diet on acetaldehyde metabolism in rats.

The effect of dietary changes on liver alcohol and aldehyde dehydrogenase activities as related to effects on ethanol and acetaldehyde metabolism was investigated. Feeding rats for 8 weeks on diets rich in carbohydrate or fat, but with normal protein content, induced minor changes relative to giving a balanced diet. A low-protein, high-carbohydrate diet (5 per cent and 80 per cent of calory content, respectively) caused a significant reduction of both alcohol and aldehyde dehydrogenase activities in the liver. The activity of the high-Km aldehyde dehydrogenase in the microsomal and soluble fractions appeared to be more reduced than that of the low-Km enzyme in the mitochondrial fraction. The tail blood acetaldehyde was significantly higher in rats on the protein deficient diet in spite of their reduced ethanol elimination rates. The results suggest that protein deficiency deranges acetaldehyde metabolism and may thus increase the possible contribution of acetaldehyde to the effects caused by ethanol metabolism.