MCT Articles 3

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Enhanced thermogenesis and diminished deposition of fat in response to overfeeding with diet containing medium chain triglyceride

            (Baba, Bracco et al. 1982) Download

The mechanism whereby overfeeding with diet containing medium chain triglyceride (MCT) results in diminished body weight and fat was studied. Fifteen male Sprague-Dawley rats were fitted under anesthesia with gastrostomy tubes and divided into two groups. One group was fed MCT diet, the other an isocaloric diet containing long chain triglyceride (LCT) in excess (150%) of spontaneous calorie intake. Both diets, fed for 6 wk, derived 50% of calories from fat. Basal and norepinephrine (25 micrograms/100 g) stimulated 02 consumption and CO2 production, as well as metabolic rate were measured. After the rats were killed, total dissectible fat and fat cell size and number were determined. MCT rats gained 15% less weight than LCT controls (p less than 0.001). Total dissectible fat was significantly lower (p less than 0.001) in MCT group, as was mean adipocyte size (p less than 0.001). Resting and maximal norepinephrine-stimulated 02 consumptions were 39.7 and 22.1% higher in MCT than in LCT group, respectively. Resting and norepinephrine-stimulated metabolic rates were 38.8 and 22.2% higher in MCT than LCT fed rats, respectively. Overfeeding MCT diet results in decreased body fat related to increased metabolic rate and thermogenesis.

Medium-chain triglycerides: an update

            (Bach and Babayan 1982) Download

A review of the literature on the medical and nutritional use of medium-chain triglycerides (MCTs) since 1970 is presented with additional discussions on the various modifications and applications of the MCTs in the synthesis of certain structured lipids. The metabolism of MCTs in the liver and extrahepatic tissues is discussed along with further documentation of the use of MCTs in malabsorption and hyperlipidemia cases. Recent applications of MCTs and modified MCTs in hyperalimentation, deficiency in the carnitine system, epilepsy, obesity, and other special areas of application are cited. The use of medium-chain monodiglycerides for dissolving cholesterol gallstones is presented. The contraindications for the use of MCTs in ketosis, acidosis, and cirrhosis are also discussed. Suggestions for use of MCTs in a variety of medical and nutritional applications are presented.


Overfeeding with medium-chain triglyceride diet results in diminished deposition of fat

            (Geliebter, Torbay et al. 1983) Download

The study was designed to determine whether overfeeding rats with a diet containing medium-chain triglyceride (MCT) as the major fat source (45% of calories) would impede the expected gain in weight and body fat as compared to rats overfed with isocaloric amounts of diet containing long-chain triglyceride (LCT). For 6 wk rats were fed either MCT diet or LCT diet twice daily via a gastrostomy tube. MCT-fed rats gained 20% less weight (P less than 0.001) and possessed fat depots weighing 23% less (p less than 0.001) than LCT)-fed rats. Mean adipocyte size was smaller (p less than 0.005) in MCT- than in LCT-fed rats. Weights of carcass protein and water were similar for both groups as were concentrations of serum insulin and levels of physical activity. The decreased deposition of fat in the MCT-fed rats may have resulted from obligatory oxidation of MCT-derived fatty acids in the liver after being transported there via the portal vein, leaving almost no MCT derivatives for incorporation into body fat. MCT may have potential for dietary prevention of human obesity.

Dietary fats and adipose tissue fatty acid composition

            (Hashim 1983) Download

Weight-loss diet that includes consumption of medium-chain triacylglycerol oil leads to a greater rate of weight and fat mass loss than does olive oil

            (St-Onge and Bosarge 2008) Download

BACKGROUND: Clinical studies have shown that consumption of medium-chain triacylglycerols (MCTs) leads to greater energy expenditure than does consumption of long-chain triacylglycerols. Such studies suggest that MCT consumption may be useful for weight management. OBJECTIVE: We aimed to determine whether consumption of MCT oil improves body weight and fat loss compared with olive oil when consumed as part of a weight-loss program. DESIGN: Forty-nine overweight men and women, aged 19-50 y, consumed either 18-24 g/d of MCT oil or olive oil as part of a weight-loss program for 16 wk. Subjects received weekly group weight-loss counseling. Body weight and waist circumference were measured weekly. Adipose tissue distribution was assessed at baseline and at the endpoint by use of dual-energy X-ray absorptiometry and computed tomography. RESULTS: Thirty-one subjects completed the study (body mass index: 29.8 +/- 0.4, in kg/m(2)). MCT oil consumption resulted in lower endpoint body weight than did olive oil (-1.67 +/- 0.67 kg, unadjusted P = 0.013). There was a trend toward greater loss of fat mass (P = 0.071) and trunk fat mass (P = 0.10) with MCT consumption than with olive oil. Endpoint trunk fat mass, total fat mass, and intraabdominal adipose tissue were all lower with MCT consumption than with olive oil consumption (all unadjusted P values < 0.05). CONCLUSIONS: Consumption of MCT oil as part of a weight-loss plan improves weight loss compared with olive oil and can thus be successfully included in a weight-loss diet. Small changes in the quality of fat intake can therefore be useful to enhance weight loss.

Thermogenesis from intravenous medium-chain triglycerides

            (Mascioli, Randall et al. 1991) Download

Eighteen hospitalized patients dependent on total parenteral nutrition (TPN) were randomly enrolled into a prospective study comparing intravenous long-chain triglycerides (LCT) with a physical mixture of 75% medium-chain triglycerides (MCT) and 25% LCT. The TPN was given continuously as amino acids and glucose over 5 days with the respective lipid emulsion given intermittently during each day for 10 hr. Indirect calorimetry was measured on each patient before the lipid emulsion was administered in the morning and again 10 hr later near the end of the lipid infusion, on days 1, 3, and 5. Resting energy expenditure, VO2, VCO2, and calculated fat oxidation were shown to increase during MCT infusion but not during LCT administration, (resting energy expenditure 899 +/- 37 to 1085 +/- 40, compared with 978 +/- 23 to 976 +/- 39, kcal/m2 body surface area [BSA]/day, respectively, p less than 0.0002; VO2: 129.9 +/- 5.2 to 157.2 +/- 5.9, compared with 140.9 +/- 3.6 to 141.2 +/- 5.9 ml O2/min/m2 BSA, respectively, p less than 0.0005; and VCO2: 110.7 +/- 4.4 to 127.5 +/- 4.3, compared with 118.3 +/- 2.8 to 118.0 +/- 5.3, ml CO2/min/m2 BSA, respectively, p less than 0.0076; calculated fat oxidation 10.7 +/- 1.5 to 19.3 +/- 2.4, compared with 20.0 +/- 2.7 to 20.0 +/- 3.6, kcal/m2 BSA/hr, respectively, p less than 0.014). Respiratory quotient tended to fall with lipid infusion but did not change statistically. Body temperatures were unaltered by either fat infusion. It is concluded that TPN consisting of MCT causes an increased thermogenesis, most likely through increased fat oxidation, reflective of MCT's property as an obligate fuel. The increased thermogenesis occurs without an increase in body temperature.

Enhancement of muscle mitochondrial oxidative capacity and alterations in insulin action are lipid species dependent: potent tissue-specific effects of medium-chain fatty acids

            (Turner, Hariharan et al. 2009) Download

OBJECTIVE: Medium-chain fatty acids (MCFAs) have been reported to be less obesogenic than long-chain fatty acids (LCFAs); however, relatively little is known regarding their effect on insulin action. Here, we examined the tissue-specific effects of MCFAs on lipid metabolism and insulin action. RESEARCH DESIGN AND METHODS: C57BL6/J mice and Wistar rats were fed either a low-fat control diet or high-fat diets rich in MCFAs or LCFAs for 4-5 weeks, and markers of mitochondrial oxidative capacity, lipid levels, and insulin action were measured. RESULTS: Mice fed the MCFA diet displayed reduced adiposity and better glucose tolerance than LCFA-fed animals. In skeletal muscle, triglyceride levels were increased by the LCFA diet (77%, P < 0.01) but remained at low-fat diet control levels in the MCFA-fed animals. The LCFA diet increased (20-50%, P < 0.05) markers of mitochondrial metabolism in muscle compared with low-fat diet-fed controls; however; the increase in oxidative capacity was substantially greater in MCFA-fed animals (50-140% versus low-fat-fed controls, P < 0.01). The MCFA diet induced a greater accumulation of liver triglycerides than the LCFA diet, likely due to an upregulation of several lipogenic enzymes. In rats, isocaloric feeding of MCFA or LCFA high-fat diets induced hepatic insulin resistance to a similar degree; however, insulin action was preserved at the level of low-fat diet-fed controls in muscle and adipose from MCFA-fed animals. CONCLUSIONS: MCFAs reduce adiposity and preserve insulin action in muscle and adipose, despite inducing steatosis and insulin resistance in the liver. Dietary supplementation with MCFAs may therefore be beneficial for preventing obesity and peripheral insulin resistance.

Metabolic consequences of dietary medium-chain triglycerides in the rat

            (Wiley and Leveille 1973) Download

Relation of ketosis to metabolic changes induced by acute medium-chain triglyceride feeding in rats

            (Yeh and Zee 1976) Download

Medium-chain triglycerides (MCT) induce ketosis in several mammalian species including man. To clarify the regulation of this metabolic alteration, we fed rats either MCT or long-chain triglyceride (corn oil) and then attempted to correlate ketosis with changes in (i) concentrations of selected metabolites in plasma and (ii) the synthetic and oxidative capacities of the liver. By 1 hour after MCT feeding, plasma levels of total ketone bodies had increased 18-fold, with a maximum value reached 1 hour later. By contrast, total plasma ketones in rats fed corn oil were increased only about 2-fold at 2 hours after feeding and did not exceed this value at later intervals. Hepatic concentrations of ketone bodies also increased after MCT or corn oil feeding. Although plasma concentrations of glucose decreased and insulin increased in rats fed MCT, they were not affected by corn oil feeding. MCT-induced ketosis was depressed by glucose administration. Neither MCT nor corn oil feeding impaired utilization of glucose by the liver. Hepatic lipogenesis was suppressed 50% and 90% by MCT and corn oil feeding, respectively. A marked increase of long-chain fatty acids in plasma was observed in rats fed corn oil but not in rats fed MCT. The pronounced increase of ketones in MCT-fed rats was closely related to an elevation of octanoate. In liver slices of MCT-fed rats, ketogenesis from octanoate was 10-fold higher than from palmitate, and octanoate was oxidized 4 times more rapidly than palmitate. The ketosis of MCT-fed rats was depressed by administration of 4-pentenoic acid, a potent inhibitor of fatty acid oxidation. These results support the concept that ketosis induced by MCT stems from rapid oxidation of medium-chain fatty acids. Hyperinsulinemia, hypoglycemia and depressed lipogenesis resulting from MCT feeding appear to potentiate but not initiate ketosis.


References

Baba, N., E. F. Bracco, et al. (1982). "Enhanced thermogenesis and diminished deposition of fat in response to overfeeding with diet containing medium chain triglyceride." Am J Clin Nutr 35(4): 678-82.

Bach, A. C. and V. K. Babayan (1982). "Medium-chain triglycerides: an update." Am J Clin Nutr 36(5): 950-62.

Geliebter, A., N. Torbay, et al. (1983). "Overfeeding with medium-chain triglyceride diet results in diminished deposition of fat." Am J Clin Nutr 37(1): 1-4.

Hashim, S. A. (1983). "Dietary fats and adipose tissue fatty acid composition." Prev Med 12(6): 854-67.

Mascioli, E. A., S. Randall, et al. (1991). "Thermogenesis from intravenous medium-chain triglycerides." JPEN J Parenter Enteral Nutr 15(1): 27-31.

St-Onge, M. P. and A. Bosarge (2008). "Weight-loss diet that includes consumption of medium-chain triacylglycerol oil leads to a greater rate of weight and fat mass loss than does olive oil." Am J Clin Nutr 87(3): 621-6.

Turner, N., K. Hariharan, et al. (2009). "Enhancement of muscle mitochondrial oxidative capacity and alterations in insulin action are lipid species dependent: potent tissue-specific effects of medium-chain fatty acids." Diabetes 58(11): 2547-54.

Wiley, J. H. and G. A. Leveille (1973). "Metabolic consequences of dietary medium-chain triglycerides in the rat." J Nutr 103(6): 829-35.

Yeh, Y. Y. and P. Zee (1976). "Relation of ketosis to metabolic changes induced by acute medium-chain triglyceride feeding in rats." J Nutr 106(1): 58-67.