Daisuke Shiiba

The short-term effect of diacylglycerol oil consumption on total and dietary fat utilization in overweight women.

Diacylglycerol (DAG) is a natural component of edible oils with metabolic characteristics distinct from those of triacylglycerol (TAG). Consumption of DAG oil (containing >80% DAG) induces greater fat oxidation than consumption of TAG oil. We compared the effects of 4 days of DAG oil consumption with those of TAG oil consumption on total and dietary fat oxidation over 24 h in overweight women using a whole‐room respiratory chamber. Overweight (BMI (kg/m2) ≥25) females participated in this double‐blind, crossover‐controlled trial. The subjects consumed test diets containing either TAG or DAG oil as 15% of their total caloric intake (mean test oil intake was 33.0 ± 3.1 g/day) during each 4‐day treatment. Fat oxidation and energy expenditure were measured in a respiratory chamber on the 4th day of each treatment. Compared with TAG oil, DAG oil consumption significantly increased total fat oxidation and dietary fat oxidation in overweight subjects. Total energy expenditure (TEE) and carbohydrate (CHO) oxidation did not significantly differ between DAG oil and TAG oil consumption in overweight subjects. Compared with TAG oil, DAG oil consumption enhanced total fat oxidation and dietary fat oxidation in overweight subjects. The enhanced fat metabolism in overweight subjects that consumed DAG oil partly explains the greater loss of body weight and body fat related to DAG oil consumption in weight‐loss studies.

Serum Retinol, α-Tocopherol, and β-Carotene Levels Are Not Altered by Excess Ingestion of Diacylglycerol-Containing Plant Sterol Esters

Background: Diacylglycerol (DAG) suppresses the postprandial increase in serum triglycerides, and has antiobesity effects. On the other hand, plant sterol esters (PSE) lower serum cholesterol levels in hypercholesterolemia. Thus, DAG-containing PSE (PSE/DAG) would be expected to maintain an appropriate serum cholesterol level and decrease the risk of arteriosclerotic disorders. Several recent studies, however, report negative effects of PSE on serum fat-soluble (pro)vitamin levels. The objective of this study was to investigate the effect of PSE/DAG on serum retinol, β-carotene, and α-tocopherol levels using a threefold excess of the effective dose obtained in our previous study. Methods: A randomized placebo-controlled double-blind parallel study was performed in healthy and mildly hypercholesterolemic subjects, in which the subjects ingested 1.2 g PSE/30 g DAG for 2 weeks in the form of mayonnaise-type products. Triacylglycerol (TAG) mayonnaise was used as a control. Result: There were no subjective adverse effects or changes in serum retinol, α-tocopherol, and β-carotene levels, abdominal symptoms, hematologic values, or blood biochemical values. Conclusion: Ingestion of a threefold excess of PSE/DAG for 2 weeks had no adverse effects compared to ingestion of conventional TAG mayonnaise.

Measurement of resistant starch content in cooked rice and analysis of gelatinization and retrogradation characteristics

Digestion-resistant starch (RS) has many physiologic functions. The RS content is measured by enzymatically degrading flour samples according to the method of the Association of Official Analytical Chemists. Experiments have been performed with wheat, corn, and other grains, but there are no data for cooked rice grains in the form ingested by humans. Thus, we investigated a method to measure RS that is suitable for cooked rice grains using rice cultivars that are reported to differentially increase postprandial blood glucose in humans. Using a method for cooking individual rice grains and optimized enzyme reaction conditions, we established an RS measurement method. We also found that the amylopectin crystal condition affects the RS content measured using our method. Graphical abstract The order of RS content measured by our method that optimized the sample form and enzyme reaction time is consistent with that of digestibility in humans.