Elsevier

Metabolism

Volume 37, Issue 2, February 1988, Pages 145-151
Metabolism

Polyunsaturated: Saturated ratio of diet fat influences energy substrate utilization in the human

https://doi.org/10.1016/S0026-0495(98)90009-9Get rights and content

Abstract

In order to examine the effect of dietary long chain fatty acid composition on energy substrate utilization, basal metabolism rate (BMR) and the thermogenic effect of food (TEF) were measured in eight subjects consuming diets varying only in diet fat polyunsaturated: saturated (P:S) ratio. Subjects consumed the low P:S (0.241 ± 0.02) and high P:S (1.65 ± 0.28) ratio diets for seven days using a crossover design. Fat and carbohydrate oxidation during BMT and TEF over 230 minutes after a breakfast meal were determined on days 1 and 7 of each diet period using open circuit respiratory gas exchange. On day 7, BMR respiratory quotient was reduced (P < .05) for the low P:S (0.826 ± 0.005) compared with high P:S (0.853 ± 0.014) ratio diet, resulting in an increased basal fat oxidation rate with low P:S (0.074 ± 0.006 g/min) compared with high P:S (0.059 ± 0.008 g/min) ratio diet feeding. The cumulative contribution of fat oxidation to TEF on day 7 was lower (P < .01) for the low P:S (1.35 ± 1.6 g) compared with high P:S (6.49 ± 0.8 g) ratio diets. This was paralleled by opposite differences (P < .05) in the contribution of carbohydrate oxidation to TEF (21.0 ± 3.0 g and 13.1 ± 3.4 g, respectively, for each diet treatment). On day 1 in subjects switching from either home and alternate test diets, and on day 7, caloric expenditure of TEF after low P:S was not statistically lower compared to the high P:S ratio diet. On day 1 subjects switching from the alternate diet showed a significant decrease (P < .05) in total fat oxidation of TEF after low P:S (13.5 ± 2.4 g) compared to high P:S (17.9 ± 1.6 g) ratio diets. These findings suggest that the long chain fatty acid composition of dietary fat modulates the oxidation of fat and carbohydrate acutely after meal feeding and after chronic feeding.

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  • Cited by (0)

    Supported by the National Institutes of Health (NIH AM 26678 and RR00055).

    1

    Dr Jones was supported by a fellowship from the Medical Research Council of Canada.

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