Dietary medium- and long-chain triacylglycerols accelerate diet-induced thermogenesis in humans.

This study investigated the effects of a liquid meal containing medium- and long-chain triacylglycerols (MLCT) on diet-induced thermogenesis (DIT) and was conducted in double-blind cross-over manner. Twenty subjects participated in this examination. The subjects consumed the liquid meal, which was made with 14 g of canola oil (LCT, long-chain triacylglycerols) or MLCT containing about 12% medium-chain fatty acids (MCFA). Oxygen consumption and carbon dioxide production were measured by indirect calorimetry. Resting energy expenditure (REE) was determined based on there parameters, applying the equation of Weir. Increase in DIT after ingesting the liquid meal with MLCT during 6h was significantly greater than with LCT (P<0.05). The results suggest that the substitution of MLCT for cooking oil is useful to control body weigh and fat in subjects.

Effects of phytosterol ester-enriched vegetable oil on plasma lipoproteins in healthy men.

It has been reported that phytosterol esters reduce cholesterol absorption and lower serum cholesterol concentration. There have been very few studies published on the effect of dose of phytosterol esters less than 1.0 g/day on plasma cholesterol levels in healthy subjects using commonly consumed foods. In this study, we evaluated the effect of 0.45 g/day (as free sterol) phytosterol ester-enriched dissolved in vegetable oil on plasma lipoproteins in sixty healthy males with slightly elevated total cholesterol concentration. This study was conducted in a randomized, double-blind, placebo-controlled, and arm parallel study. A total of 14 g/day of phytosterol ester-enriched vegetable oil containing 0.45 g phytosterol (as the major free sterol) was compared with a control vegetable oil containing 0.04 g phytosterol (as the major free sterol). All subjects did not change their usual dietary habit and consumed foods that included about 360 mg/day cholesterol for 12 weeks. In subjects with higher total cholesterol concentrations (>200mg/dL), the phytosterol enriched-vegetable oil significantly reduced total cholesterol (10.3%, P<0.05), very low density (VLDL) lipoprotein cholesterol (22.5%, P<0.05), and remnant-like lipoprotein (RLP) cholesterol (24.7%, P<0.01) compared with the control vegetable oil. A reduction in low density lipoprotein (LDL) cholesterol concentration was also observed. In particular, the improvement in serum lipoprotein was more pronounced in subjects with higher total cholesterol concentrations. Triglycerides and high density lipoprotein (HDL) cholesterol did not change significantly. Plasma concentration of fat-soluble vitamins (tocopherol and retinol) and beta-carotene were not statistically significantly affected by phytosterol ester-enriched vegetable oil. These findings indicate that a daily consumption of phytosterol ester as low as 0.45 g/day (as free sterol) is effective in lowering blood total cholesterol concentration and RLP cholesterol concentration. Lower total cholesterol, VLDL cholesterol and RLP cholesterol due to consumption of the phytosterol ester-enriched vegetable oil may be helpful in reducing the risk of CHD in the population.

Effect of dietary medium- and long-chain triacylglycerols (MLCT) on accumulation of body fat in healthy humans.

We investigated whether a structured medium- and long-chain triacylglycerols (MLCT) diet could decrease accumulation of body fat in healthy humans. The study was conducted under a double-blind randomized design. Ninety-three subjects participated in this study. However, 10 subjects could not consume the specified meal, and one subject wished to opt out. Consequently, the study included 82 subjects. The experimental subjects consumed the test bread, which was made with 14 g of MLCT containing 1.7 g MCFA, daily at breakfast during the study period of 12 weeks, and the control subjects consumed bread made with long-chain triacylglycerols (LCT). All subjects consumed the same standard packaged meals. Body composition parameters were body weight, total body fat and abdominal fat, and blood analyses included serum cholesterol, triacylglycerols and phospholipids. Significant decreases of body weight, the amount of body fat, subcutaneous and visceral fat were noted in the MLCT group as compared with those of the LCT group for 12 weeks (P<0.05). Furthermore, a significant decrease in serum total cholesterol was noted in the MLCT group as compared with that of the LCT group at 8 weeks (P<0.05). However, other serum parameters were not different between the MLCT and LCT groups. The results suggest that the daily intake of MLCT diet could result in a reduction in body weight and in accumulation of body fat, and, moreover, it could reduce serum total cholesterol.

Effect of medium-chain triglycerides on the postprandial triglyceride concentration in healthy men.

This study compared the serum lipid concentrations after a single dose of medium-chain triglycerides (MCT) or long-chain triglycerides (LCT) between individuals grouped according to the body mass index (BMI). Twenty-five males participated as volunteers, the test diet containing 10 g of MCT or LCT. Blood samples were collected up to 6 h after the intake of a test diets. The LCT diet resulted in significantly greater increases in areas under the curves (AUCs) for serum and chylomicron triglyceride in the BMI > or = 23 kg/m2 group than those in the BMI < 23 kg/m2 group. The magnitude of response after intake of the MCT diet by the BMI > or = 23 kg/m2 group was significantly lower than that after the LCT diet. These results suggest that, in subjects with BMI > or = 23 kg/m2, the intake of MCT is preferable to that of LCT for maintaining postprandial triglyceride at a low concentration.

Effects of margarine containing medium-chain triacylglycerols on body fat reduction in humans.

We found previously that the ingestion of margarine containing medium-chain triacylglycerols (MCT) resulted in a significant increase in postprandial thermogenesis when compared with long-chain triacylglycerols (LCT). Diets that included margarine containing MCT and LCT were compared for 12 weeks in 73 subjects to investigate the effects on body weight, body fat, areas of subcutaneous and visceral fat, serum total cholesterols, triglycerides, lipoproteins, plasma glucose, serum insulin, total ketone bodies, and the activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltranspeptidase. We conducted a double-blind, controlled study and used blended rapeseed oil and soybean oil (LCT) as a comparison. Two groups ingested 2100-2400 kcal/day of energy, 65-73 g/day of total fat, and 14 g/day of test margarine (5 g/day of MCT or LCT). The subjects on the MCT diet demonstrated significant decreases in body fat weight (- 3.8 +/- 2.4 kg vs - 2.4 +/- 1.7 kg; MCT vs LCT, mean +/- SD), subcutaneous fat (- 38.2 +/- 29.9 cm(2) vs - 22.6 +/- 19.3 cm(2)), and visceral fat (- 12.2 +/- 11.2 cm(2) vs - 1.6 +/- 12.8 cm(2)) after 12 weeks. There were no clinical differences in measured blood parameters. We suggest that the postprandial increase in thermogenesis and control of postprandial triglyceride levels may explain these results.

Effects of dietary medium-chain triacylglycerols on serum lipoproteins and biochemical parameters in healthy men.

The objective of this study was to investigate effects of dietary medium-chain triacylglycerols (MCTs) on serum lipid levels, liver function, and hepatic fat accumulations in healthy men. Eleven subjects consumed 2200-2600 kcal daily, of which 70-80 g was fat; the fat included 40 g of MCTs or else 40 g of long-chain triacylglycerols (blended vegetable oil). The diet was followed for 4 weeks in this controlled double-blind study. At the end of the experiment, significant differences were not found in the concentrations of serum total cholesterol, very low density lipoprotein cholesterol, low density lipoprotein cholesterol, and high density lipoprotein cholesterol between the groups. Serum triglycerol levels were not significantly different in the groups. Adverse effects from ingestion of MCTs on liver functions, the liver-to-spleen ratio on computed tomography (an index of fatty liver), or results of blood tests were not seen. The results suggest that the long-term effects of dietary MCTs on serum cholesterol were similar to those of unsaturated fatty acids found abundantly in vegetable oil, and that consumption of MCTs in the amount of 40 g/day for a month does not cause liver fat accumulation or liver dysfunction.

Comparison of diet-induced thermogenesis of foods containing medium- versus long-chain triacylglycerols.

The purpose of this study was to investigate the effect of 5-10 g of medium-chain triacylglycerols (MCT) on diet-induced thermogenesis in healthy humans. The study compared diet-induced thermogenesis after ingestion of test foods containing MCT and long-chain triacylglycerols (LCT), using a double-blind, crossover design. Eight male and eight female subjects participated in study 1 and study 2, respectively. In both studies, the LCT was a blend of rapeseed oil and soybean oil. In study 1, the liquid meals contained 10 g MCT (10M), a mixture of 5 g MCT and 5 g LCT (5M5L), and 10 g LCT (10L). In study 2, the subjects were given a meal (sandwich and clear soup) with the mayonnaise or margarine containing 5 g of MCT or LCT. Postprandial energy expenditure was measured by indirect calorimetry before and during the 6 h after ingestion of the test meals. Diet-induced thermogenesis was significantly greater after 5M5L and 10M Ingestion as compared to 10L ingestion. Ingestion of the mayonnaise or margarine containing 5 g MCT caused significantly larger diet-induced thermogenesis as compared to that of LCT. These results suggest that, in healthy humans, the intake of 5-10 g of MCT causes larger diet-induced thermogenesis than that of LCT, irrespective of the form of meal containing the MCT.