Gutiérrez-Salmeán G, Ortiz-Vilchis P, Vacaseydel CM, et al. Acute effects of an oral supplement of (-)-epicatechin on postprandial fat and carbohydrate metabolism in normal and overweight subjects. Food Funct. March 2014;5(3):521-527.
After eating, serum glucose and fatty acid levels rise. These levels fall as glucose and fats are metabolized or stored within the tissues of the body. In recent studies, postprandial hyperglycemia and hyperlipidemia have been associated with an increased risk of cardiovascular disease in individuals who do not show these risk factors when fasting. Both metformin and gliptins have been shown to improve postprandial metabolism, but the adverse effects associated with these medications are likely to limit their use to patients with type 2 diabetes. Green tea (Camellia sinensis) extracts which are high in flavonoids have been considered as a potential mediator of postprandial metabolism; however, the authors state that the large number of constituents of green tea make it hard to analyze. Since there have been a number of studies demonstrating the benefits of cocoa (Theobroma cacao) for cardio and metabolic health, the authors tested the effect of (-)-epicatechin (EPI), one of the flavonoids found in cocoa, on postprandial metabolism in overweight and normal weight subjects in this open-label, crossover, pilot study.
Twenty subjects between the ages of 20 and 45 years old with a body mass index (BMI) between 18.5 and 30 kg/m2 were recruited. The authors do not state the location, although it was most likely Mexico, or the means by which the subjects were recruited. Subjects were excluded if they were pregnant, lactating, had chronic liver disease, cancer, or were using dietary agents that altered postprandial metabolism. Height, weight, BMI, and fat mass were measured for each individual. Subjects were then divided into a normal weight group (BMI between 18 and 24.99 kg/m2, n =12) and an overweight group (BMI > 25 kg/m2, n =8). Each subject was analyzed on 2 separate days. The first day provided the control. On the second day, which occurred after a 1-week washout, subjects were given 1 mg/kg of EPI (Sigma Chemicals®; USA) 30 minutes before the blood samples and respiratory quotient (RQ) were measured. On the days the subjects were analyzed, serum glucose and triglycerides and RQ were measured before ingestion of the nutritional supplement Ensure® Regular (Abbott Nutrition; Lake Forest, Illinois). Serum glucose and triglycerides and RQ were then measured 2 and 4 hours after ingestion. Prior to testing, subjects were asked to fast for 10 hours and to not consume alcohol or engage in strenuous exercise for 48 hours. Student's paired t-tests, non-parametric tests, and mixed-model analyses were used to analyze the data.
The subjects were approximately equally divided among men (n = 11) and women (n = 9) and, after anthropometric measures, 12 subjects were placed in the normal weight group and 8 in the overweight group. The overweight subjects had a significantly higher baseline RQ and lower baseline fat metabolism than the normal weight subjects (both P < 0.05). The postprandial change in RQ was also different between groups. The normal weight subjects had a sharp increase in RQ from 0 to 2 hours and then a sharp decline at 4 hours. The overweight subjects' RQ was stable over the first 2 hours but dropped from 2 to 4 hours. EPI lowered RQ at all time points in both groups except for the initial time point in the normal weight subjects. This decrease was significant (P < 0.05) 2 hours into the study for both groups and at 4 hours in the normal weight subjects (P < 0.05).
EPI also increased the percentage of calories metabolized from fat. This increase was significant at 2 hours in both groups (P < 0.05). When data for both weight groups were combined, glycemia was significantly reduced with EPI treatment (P < 0.05), but only at 4 hours for the normal weight individuals (P < 0.05) and at the start of the study for overweight subjects (P < 0.05). Triglyceridemia was significantly lower at time 0 for normal weight subjects (P < 0.05) and at 2 hours for overweight individuals (P < 0.01). There was a trend for both glycemia and triglyceridemia to be reduced with EPI in both groups. Subjects were also divided by percent body fat, and the data were reanalyzed. High body fat subjects increased fat metabolism (P = 0.0015) and had reduced glycemia and triglyceridemia (P = 0.0042 and 0.0033, respectively) with EPI treatment. Only triglyceridemia was reduced with EPI treatment in subjects with normal body fat (P = 0.0033).
EPI reduced postprandial RQ, glycemia, and hyperglycemia and increased fat metabolism in both normal and overweight individuals. This effect was greater in overweight individuals. Despite this trend, not all differences between treatments within weight groups were significant. The small sample size of this pilot study likely contributed to the lack of statistical significance in some of the comparisons, but the results suggest that further study of the effect of EPI on postprandial metabolism is warranted. Other studies in animals have found that EPI is a potential activator of AMP-activated protein kinase and results in an increase in oxidative metabolism. The authors emphasize the importance of using postprandial measurements when evaluating individual risk of cardiovascular disease and the potential benefits of low doses of EPI on improving postprandial metabolism. This study was supported by a grant from CONACYT Mexico and a gift from Cardero Therapeutics, Inc. (Los Altos Hills, California).–Cheryl McCutchan, PhD