The degree of saturation of fatty acids in dietary fats does not affect the metabolic response to ingested carbohydrate.

BACKGROUND

We are interested in the metabolic response to ingested macronutrients, and the interaction between macronutrients in meals. Previously, we and others reported that the postprandial rise in serum glucose following ingestion of 50 g carbohydrate, consumed as potato, was markedly attenuated when butter was ingested with the carbohydrate, whereas the serum insulin response was little affected by the combination.

OBJECTIVE

To determine whether a similar response would be observed with three other dietary fats considerably different in fatty acid composition.

DESIGN

Nine healthy subjects received lard, twelve received olive oil and eleven received safflower oil as a test meal. The subjects ingested meals of 25 g fat (lard, olive oil or safflower oil), 50 g CHO (potato), 25 g fat with 50 g CHO or water only. Glucose, C peptide, insulin, triacylglycerols and nonesterified fatty acids were determined.

RESULTS

Ingestion of lard, olive oil or safflower oil with potato did not affect the quantitative glucose and insulin responses to potato alone. However, the responses were delayed, diminished and prolonged. All three fats when ingested alone modestly increased the insulin concentration when compared to ingestion of water alone. When either lard, olive oil or safflower oil was ingested with the potato, there was an accelerated rise in triacylglycerols. This was most dramatic with safflower oil.

CONCLUSIONS

Our data indicate that the glucose and insulin response to butter is unique when compared with the three other fat sources varying in their fatty acid composition.