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.
浆果和其他富含花青素的治疗方法可以防止饮食诱发肥胖的啮齿动物模型的体重增加和肥胖。它们的功效可以通过调节能量基板的利用来解释。然而，这种效应从未在人类身上出现过。本研究的目的是评估摄入浆果对高脂肪饮食的志愿者能量底物使用和葡萄糖调节的影响。27名超重或肥胖男性被纳入一项随机、安慰剂对照交叉研究，有两个治疗期。研究人员给受试者喂食了一种研究人员控制的高脂肪(40%的能量来自脂肪)饮食，其中包括600克/天的黑莓(BB, 1500毫克/天的黄酮类化合物)或卡路里和碳水化合物等量的明胶(GEL，(无类黄酮对照)，并在房间大小的间接热量计中停留24小时，然后进行基于膳食的葡萄糖耐量试验(MTT)。在治疗期间的洗脱期也是7天。BB治疗显著降低了平均24小时呼吸商(RQ) (0.810 vs. 0.817, BB vs. GEL, p = 0.040)，表明脂肪氧化增加。MTT期间，BB治疗组的RQ(0.84)显著低于GEL对照组(0.85)，p = 0.004。晚餐时间4小时的分离显示了类似的处理效果，RQ降低，脂肪氧化增加，BB(分别为0.818 vs. 0.836, 28 vs. 25 g;BB vs. GEL治疗)。MTT期间，BB和GEL处理的葡萄糖AUC无差异(分别为3488和4070 mg·min/dL, p = 0.12)。然而，与凝胶对照组相比，BB组胰岛素AUC显著降低(6485 μ U·min/mL vs. 8245 μ U·min/mL, p = 0.0002)， HOMA-IR改善(p = 0.0318)。对于超重或肥胖的高脂肪饮食的男性，食用黑莓可以促进脂肪氧化和改善胰岛素敏感性。
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