Liquid oil lowers glucose, carbohydrate oxidation in Chinese men
Liquid oil yields reductions in carbohydrate oxidation (COX) and postprandial glycaemic responses, as well as increases in fat oxidation (FOX) as compared with oleogel fat in Chinese males, a new study reveals.
In contrast, the saturation of the dietary fat had no effect on energy expenditure (EE), appetite, glycaemic response and substrate oxidation.
“We found that liquid oil promoted the oxidation of dietary fats over carbohydrates as energy sources but did not affect EE. The degree of saturation of dietary fats did not induce significantly different effects in any outcome measurements,” said researchers from the National University Health System in Singapore.
Over the course of a 195-minute whole-room calorimetry (WRC) session, 16 Chinese males showed significant changes in capillary glucose, EE and COX and FOX rates (p<0.001). [J Nutr 2017;147:1138-1144]
Significant between-treatment interactions (p=0.04) were found only in blood glucose excursions. The coconut oil (CO)- and sunflower oil (SO)-containing diets had significantly lower glycaemic increases at 30 minutes compared with control (orange juice and rice porridge alone), coconut oleogel (CG) and sunflower oleogel (SG) diets (p=0.03 for treatment).
At almost 140 minutes, all diet treatments had significantly greater glycaemic increases compared with control (p<0.05).
There was no significant difference in total EE (kcal/180 min) among the control (284±21), CO (288±23), CG (286±27), SO (285±20) and SG (287±18) diets. Total COX (41.4±5.2, 40.4±4.6, 41.0±9.6, 42.8±7.5 and 42.6±6.5 g/180 min, respectively) and FOX (13.2±3.4, 14.4±2.4, 13.4±5.0, 12.9±3.2 and 13.5±3.4 g/180 min, respectively) also did not differ among the groups.
The incremental area under the curve (iAUC) of glucose (mmol/L) also remained statistically constant among the control (177±69), CO (171±73), CG (195±76), SO (173±61) and SG (198±87) diets.
There were no significant interactions among the diets with respect to hunger (p=0.92), preoccupation of thoughts with foods (p=0.99), fullness (p=0.95), prospective eating (p=0.98) and desire-to-eat (p=0.99).
Diets were then grouped into three according to the physical form of the dietary fat: control, oils (SO and CO) and oleogel (SG and CG). There were significant differences in glucose excursions (p<0.001) and COX rate (p=0.03) over time among the three groups.
Specifically, at 30 minutes, the oil diet resulted in lower blood glucose than the oleogel and control diets, while at 140 minutes, glucose was lower in the oleogel diet compared to control and oil diets (p<0.05 for both).
The oil diets also showed significantly slower COX and higher FOX at 45 minutes compared with the oleogel and control groups (p<0.05 for both).
“[T]he encapsulation of oil within the polymer network of oleogel limits the effects of the dietary fats on glycaemic control,” explained researchers. “Therefore, the lower postprandial glycaemia after liquid-oil ingestion could be explained by the slower gastric emptying rates.”
In contrast, authors wrote, “Postprandial EE after the ingestion of test meals was not significantly different between the control and other treatments with varying oil physical forms (liquid oil compared with oleogel) and saturation (CO compared with SO).”
Participants were healthy Chinese males with body mass index ranging from 18 to 30 kg/m2 and without chronic diseases. None were on glucose control-altering medications. Each 195-minute test session included resting EE measurement, test meal consumption (15 minutes) and postprandial measurements (180 minutes) inside WRC.
Five test breakfast meals were prepared: one without additional dietary fat and the remaining four with either CO, SO, CG or SG.
“In conclusion, the application of novel food ingredients and food processing techniques to enhance the nutrition benefits of food is emerging as a growth area,” claimed investigators.