Blueberry anthocyanin intake attenuates the postprandial cardiometabolic effect of an energy-dense food challenge: results from a double blind, randomized controlled trial in metabolic syndrome participants

Peter J. Curtis, Lindsey Berends, Vera van der Velpen, Amy Jennings, Laura Haag, Preeti Chandra, Colin D. Kay, Eric B. Rimm, Aedín Cassidy*

*Corresponding author for this work

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Abstract

Background & Aims: Whilst the cardioprotective effects of blueberry intake have been shown in prospective studies and short-term randomized controlled trials (RCTs), it is unknown whether anthocyanin-rich blueberries can attenuate the postprandial, cardiometabolic dysfunction which follows energy-dense food intakes; especially in at-risk populations. We therefore examined whether adding blueberries to a high-fat/high-sugar meal affected the postprandial cardiometabolic response over 24h.

Methods: A parallel, double-blind RCT (n=45; age 63.4±7.4 years; 64% male; BMI 31.4±3.1 kg/m2) was conducted in participants with metabolic syndrome. After baseline assessments, an energy-dense drink (969 Kcals, 64.5g fat, 84.5g carbohydrate, 17.9g protein) was consumed with either 26g (freeze-dried) blueberries (equivalent to 1 cup/150g fresh blueberries) or 26g isocaloric matched placebo. Repeat blood samples (30, 60, 90, 120, 180, 360 min and 24h), a 24h urine collection and vascular measures (at 3, 6, and 24h) were performed. Insulin and glucose, lipoprotein levels, endothelial function (flow mediated dilatation (FMD)), aortic and systemic arterial stiffness (pulse wave velocity (PWV), Augmentation Index (AIx) respectively), blood pressure (BP), and anthocyanin metabolism (serum and 24h urine) were assessed.

Results: Blueberries favorably affected postprandial (0 to 24 h) concentrations of glucose (p<0.001), insulin (p<0.01), total cholesterol (p=0.04), HDL-C, large HDL particles (L-HDL-P) (both p<0.01), extra-large HDL particles (XL-HDL-P; p=0.04) and Apo-A1 (p=0.01), but not LDL-C, TG, or Apo-B. After a transient higher peak glucose concentration at 1h after blueberry intake ([8.2 mmol/L, 95%CI: 7.7, 8.8] vs placebo [6.9 mmol/L, 95%CI: 6.4, 7.4]; p=0.001), blueberries significantly attenuated 3h glucose ([4.3 mmol/L, 95%CI: 3.8, 4.8] vs placebo [5.1 mmol/L, 95%CI: 4.6, 5.6]; p=0.03) and insulin concentrations (blueberry: [23.4 pmol/L, 95%CI: 15.4, 31.3] vs placebo [52.9 pmol/L, 95%CI: 41.0, 64.8]; p=0.0001). Blueberries also improved HDL-C ([1.12 mmol/L, 95%CI: 1.06, 1.19] vs placebo [1.08 mmol/L, 95%CI: 1.02, 1.14]; p=0.04) at 90 min and XL-HDLP levels ([0.38 x10-6, 95%CI: 0.35, 0.42] vs placebo [0.35 x10-6, 95%CI: 0.32, 0.39]; p=0.02) at 3h. Likewise, significant improvements were observed 6h after blueberries for HDL-C ([1.17 mmol/L, 95%CI: 1.11, 1.24] vs placebo [1.10 mmol/L, 95%CI: 1.03, 1.16]; p<0.001), Apo-A1 ([1.37 mmol/L, 95%CI: 1.32, 1.41] vs placebo [1.31 mmol/L, 95%CI: 1.27, 1.35]; p=0.003), L-HDLP ([0.70 x10-6, 95%CI: 0.60, 0.81] vs placebo [0.59 x10-6, 95%CI: 0.50, 0.68]; p=0.003) and XL-HDLP ([0.44 x10-6, 95%CI: 0.40, 0.48] vs placebo [0.40 x10-6, 95%CI: 0.36, 0.44]; p<0.001). Similarly, total cholesterol levels were significantly lower 24h after blueberries ([4.9 mmol/L, 95%CI: 4.6, 5.1] vs placebo [5.0 mmol/L, 95%CI: 4.8, 5.3]; p=0.04). Conversely, no effects were observed for FMD, PWV, AIx and BP. As anticipated, total anthocyanin-derived phenolic acid metabolite concentrations significantly increased in the 24h after blueberry intake; especially hippuric acid (6-7-fold serum increase, 10-fold urinary increase). In exploratory analysis, a range of serum/urine metabolites were associated with favorable changes in total cholesterol, HDL-C, XL-HDLP and Apo-A1) (R=0.43 to 0.50).

Conclusions: For the first time, in an at-risk population, we show that single-exposure to the equivalent of 1 cup blueberries (provided as freeze-dried powder) attenuates the deleterious postprandial effects of consuming an energy-dense high-fat/high-sugar meal over 24h; reducing insulinaemia and glucose levels, lowering cholesterol, and improving HDL-C, fractions of HDL-P and Apo-A1. Consequently, intake of anthocyanin-rich blueberries may reduce the acute cardiometabolic burden of energy-dense meals.
Original languageEnglish
Pages (from-to)165-176
JournalClinical Nutrition
Volume41
Issue number1
Early online date27 Nov 2021
DOIs
Publication statusPublished - Jan 2022

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