Effect of a fat spread enriched with medium-chain triacylglycerols and a special fatty acid-micronutrient combination on cardiometabolic risk factors in overweight patients with diabetes

Applications of Medium-Chain Triglycerides in Foods

In the 1950s, the production of processed fats and oils from coconut oil was popular in the United States. It became necessary to find uses for the medium-chain fatty acids (MCFAs) that were byproducts of the process, and a production method for medium-chain triglycerides (MCTs) was established. At the time of this development, its use as a non-fattening fat was being studied. In the early days MCFAs included fatty acids ranging from hexanoic acid (C6:0) to dodecanoic acid (C12:0), but today their compositions vary among manufacturers and there seems to be no clear definition. MCFAs are more polar than long-chain fatty acids (LCFAs) because of their shorter chain length, and their hydrolysis and absorption properties differ greatly. These differences in physical properties have led, since the 1960s, to the use of MCTs to improve various lipid absorption disorders and malnutrition. More than half a century has passed since MCTs were first used in the medical field. It has been reported that they not only have properties as an energy source, but also have various physiological effects, such as effects on fat and protein metabolism. The enhancement of fat oxidation through ingestion of MCTs has led to interest in the study of body fat reduction and improvement of endurance during exercise. Recently, MCTs have also been shown to promote protein anabolism and inhibit catabolism, and applied research has been conducted into the prevention of frailty in the elderly. In addition, a relatively large ingestion of MCTs can be partially converted into ketone bodies, which can be used as a component of "ketone diets" in the dietary treatment of patients with intractable epilepsy, or in the nutritional support of terminally ill cancer patients. The possibility of improving cognitive function in dementia patients and mild cognitive impairment is also being studied. Obesity due to over-nutrition and lack of exercise, and frailty due to under-nutrition and aging, are major health issues in today's society. MCTs have been studied in relation to these concerns. In this paper we will introduce the results of applied research into the use of MCTs by healthy subjects.

Effects of medium chain triglycerides supplementation on insulin sensitivity and beta cell function: A feasibility study

Objective

Medium chain triglycerides (MCT) have unique metabolic properties which may improve insulin sensitivity (Si) and beta cell function but data in humans are limited. We conducted a 6-week clinical trial of MCT oil supplementation.

Methods

22 subjects without diabetes (8 males, 14 females, mean ± standard error age 39±2.9 years, baseline BMI 27.0±1.4 kg/m²) were counseled to maintain their body weight and physical activity (PA) during the trial. Dietary intake, PA data, body composition, and resting energy expenditure (REE) were obtained through dietary recall, international PA questionnaire, dual x-ray absorptiometry, and indirect calorimetry, respectively. MCT prescriptions were given based on REE and PA to replace part of dietary fat with 30 grams of MCT per 2000 kcal daily. Insulin-modified frequently sampled intravenous glucose tolerance tests were performed before and after MCT to measure changes in Si, acute insulin response (AIR), disposition index (DI), and glucose effectiveness (Sg).

Results

MCT were well tolerated and weight remained stable (mean change 0.3 kg, p = 0.39). Fasting REE, respiratory quotient, and body composition were stable during the intervention. There were no significant changes in mean fasting glucose, insulin, insulin resistance, fasting total ketones, Si, AIR, DI, Sg, leptin, fructosamine, and proinsulin. The mean change in Si was 0.5 10⁻⁴ min^-1 per mU/L (95% CI: -1.4, 2.4), corresponding to a 12% increase from baseline, and the range was -4.7 to 12.9 10⁻⁴ min^-1 per mU/L. Mean total adiponectin decreased significantly from 22925 ng/mL at baseline to 17598 ng/mL at final visit (p = 0.02). The baseline clinical and laboratory parameters were not significantly associated with the change in Si.

Discussion

There were a wide range of changes in the minimal model parameters of glucose and insulin metabolism in subjects following 6 weeks of MCT as an isocaloric substitution for part of usual dietary fat intake. Since this was a single-arm non-randomized study without a control group, it cannot be certain whether these changes were due to MCT so further randomized controlled trials are warranted.

Dietary medium-chain triacylglycerols versus long-chain triacylglycerols for body composition in adults: systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To assess the effect of replacing dietary long-chain triacylglycerols (LCTs) with medium-chain triacylglycerols (MCTs) on body composition in adults.

METHODS

We conducted a meta-analysis of randomized controlled trials (RCTs), to determine whether individuals assigned to replace at least 5 g of dietary LCTs with MCTs for a minimum of 4 weeks show positive modifications on body composition. We systematically searched, through July 2013, the CENTRAL, EMBASE, LILACS, and MEDLINE databases for RCTs that investigated the effects of MCT intake on body composition in adults. Two authors independently extracted data and assessed risk of bias. Weighted mean differences (WMDs) were calculated for net changes in the outcomes. We assessed heterogeneity by the Cochran Q test and I(2) statistic and publication bias with the Egger's test. Prespecified sensitivity analyses were performed.

RESULTS

In total, 11 trials were included, from which 5 presented low risk of bias. In the overall analysis, including all studies, individuals who replaced dietary LCT with MCT showed significantly reduced body weight (WMD, -0.69 kg; 95% confidence interval [CI], -1.1 to -0.28; p = 0.001); body fat (-0.89 kg; 95% CI, -1.27 to -0.51; p < 0.001), and WC (-1.78 cm; 95% CI, -2.4 to -1.1; p < 0.001). The overall quality of the evidence was low to moderate. Trials with a crossover design were responsible for the heterogeneity.

CONCLUSION

Despite statistically significant results, the recommendation to replace dietary LCTs with MCTs must be cautiously taken, because the available evidence is not of the highest quality.