Blackberry feeding increases fat oxidation and improves insulin sensitivity in overweight and obese males

Authors: SOLVERSON, PATRICK - University Of Maryland; Rumpler, William; LEGER, JAYME - University Of Maryland; REDAN, BENJAMIN - Food And Drug Administration(FDA); FERRUZZI, MARIO - North Carolina State University; Baer, David; CASTONGUAY, THOMAS - University Of Maryland; Novotny, Janet

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/2018
Publication Date: 8/9/2018
Citation: Solverson, P.M., Rumpler, W.V., Leger, J.L., Redan, B.W., Ferruzzi, M.G., Baer, D.J., Castonguay, T.W., Novotny, J. 2018. Blackberry feeding increases fat oxidation and improves insulin sensitivity in overweight and obese males. Nutrients. 10. https://doi.org/10.3390/nu10081048.
DOI: https://doi.org/10.3390/nu10081048

Interpretive Summary: Two-thirds of Americans can be classified as overweight or obese, leading to increased risk for cardiovascular disease, diabetes, cancer, and other morbidities, and burdening our health care system at a level of $147 billion annually. Lifestyle modification remains an attractive strategy for combating obesity, as dietary approaches offer solutions to weight loss and improved health without negative side effects. Anthocyanins, a class of red, blue, and purple hues in plants, are one of the main classes of compounds gaining substantial attention in regard to obesity. Studies have found that rodents consuming a high fat diet gain less weight when also consuming these colorful pigments. We investigated this phenomenon in humans. We conducted a feeding study in which men consumed blackberries every day for a week, then we used breath analysis to determine how many calories they were burning, and also their ratio of carbohydrate to fat burning. We also evaluated their ability to metabolize sugar. We found that blackberries not only increased fat burning, they also improved sugar metabolism. These results demonstrate how blackberries may improve health. These results will be used by scientists and health practitioners.

Technical Abstract: Berries and other anthocyanin-rich treatments have prevented weight gain and adiposity in rodent models of diet-induced obesity. Their efficacy may be explained by modulation of energy substrate utilization. However, this effect has never been translated to humans. The objective of this study was to evaluate the effects of berry intake on energy substrate use and glucoregulation in volunteers consuming a high-fat diet. Twenty-seven overweight or obese men were enrolled in a randomized, placebo-controlled crossover study with two treatment periods. Subjects were fed an investigator controlled, high-fat (40% of energy from fat) diet which contained either 600 g/day blackberries (BB, 1500 mg/day flavonoids) or a calorie and carbohydrate matched amount of gelatin (GEL, flavonoid-free control) for seven days prior to a meal-based glucose tolerance test (MTT) in combination with a 24 h stay in a room-sized indirect calorimeter. The washout period that separated the treatment periods was also seven days. The BB treatment resulted in a significant reduction in average 24 h respiratory quotient (RQ) (0.810 vs. 0.817, BB vs. GEL, p = 0.040), indicating increased fat oxidation. RQ during the MTT was significantly lower with the BB treatment (0.84) compared to GEL control (0.85), p = 0.004. A 4 h time isolation during dinner showed similar treatment effects, where RQ was reduced and fat oxidation increased with BB (0.818 vs. 0.836, 28 vs. 25 g, respectively; BB vs. GEL treatments). The glucose AUC was not different between the BB and GEL treatments during the MTT (3488 vs. 4070 mg·min/dL, respectively, p = 0.12). However, the insulin AUC was significantly lower with the BB compared to the GEL control (6485 vs. 8245 µU·min/mL, p = 0.0002), and HOMA-IR improved with BB (p = 0.0318). Blackberry consumption may promote increased fat oxidation and improved insulin sensitivity in overweight or obese males fed a high fat diet.