Blackberry Feeding Increases Fat Oxidation and Improves Insulin Sensitivity in Overweight and Obese Males

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.

Anthocyanins as Antidiabetic Agents—In Vitro and In Silico Approaches of Preventive and Therapeutic Effects

“…Twenty-seven overweight or obese men were enrolled in a randomized, placebo-controlled crossover study. Subjects were fed a high-fat diet which contained either 600 g/day blackberries or a calorie and carbohydrate matched amount of gelatin for seven days [ 38 ]. Blackberry consumption may promote increased fat oxidation and improved insulin sensitivity in overweight or obese males fed a high fat diet.…”

Blackberry polyphenols: review of composition, quantity, and health impacts from in vitro and in vivo studies

“…Diabetes complications can be exacerbated by oxidative stress. Antioxidant consumption has been reported to help prevent such complications from worsening (Solverson et al, 2018). These authors tested seventeen overweight or obese men by feeding them either 600 g of blackberries, or carbohydrate-matched gelatin of the same caloric content.…”

“…These authors tested seventeen overweight or obese men by feeding them either 600 g of blackberries, or carbohydrate-matched gelatin of the same caloric content. The results showed that fat oxidation and insulin sensitivity increased for the men fed blackberries, with younger subjects demonstrating the best improvement (Solverson et al, 2018). A cross sectional study of 1,997 women investigated flavonoid consumption broken down by class against diabetesrelated markers such as fasting glucose, insulin, and C-reactive protein.…”

Protective Effects of Anthocyanins in Obesity‐Associated Inflammation and Changes in Gut Microbiome

“…Recently published study by Solverson et al. (2018) showed that overweight or obese men fed a HF diet, which included 600 g blackberries per day for 1 week, exhibited increased insulin sensitivity and fat oxidation …”