Utilization by the Rat of 1,3-Butanediol as a Synthetic Source of Dietary Energy

Abstract

To test the ability of the rat to utilize 1,3-butanediol (BD) as a source of dietary energy, rats were fed high fat diets in which carbohydrate was replaced by BD. These tests indicated that following an adaptation period of at least one week, BD had a caloric value of approximately 6 kcal/g. In a 30-week long-term study, rats were fed 30% fat diets containing 20 and 30% added BD. Other diets included in the study for comparative purposes contained 10 to 60% fat and variations in protein level. The principal effect was an impairment in utilization of the diet when BD was fed at the 30% level. No impairment in utilization was observed when rats were fed diets containing 20% BD. At the end of this 30-week study, urine was collected and blood and liver were taken for various assays. The assays included urine and serum ketone bodies, liver glycogen and phosphohexose isomerase, and serum glucose. Increasing levels of fat resulted in an increase in both serum and urinary ketone bodies. In contrast, increasing dietary BD levels produced essentially no change in both parameters. When the results of the other assays were examined, a similar pattern was obtained. Fat produced a decrease in liver phosphohexose isomerase and in serum glucose, whereas liver glycogen tended to increase. Feeding BD, however, resulted in an increase in liver phosphohexose isomerase, no significant change in serum glucose, and an increase in liver glycogen. The results of these studies do not support the hypothesis that BD is oxidized through β-hydroxybutyric acid.