Table 2.
Clinical studies on the effects of dietary berry intervention (fresh or processed whole berries and juice) on insulin resistance in overweight/obese adults with cardio-metabolic risks
| Reference (year) | Participants | Study design | Intervention | Significant findings |
|---|---|---|---|---|
| Solverson et al. (2018)99 | Adult males with a BMI > 25 kg m−2, nondiabetic, nonsmokers, fasting BG < 126 mg dL−1; fasting TGs < 300 mg dL−1; free of gastrointestinal, metabolic, and CVD; sample size: n = 27 | Randomized, placebo-controlled crossover parallel-arm study | Whole blackberry 600 g day−1 (Tx1); or a calorie-matched artificially-flavored gelatin with high fat diet (Cx1) for seven days | ↓Respiratory quotient and insulin AUC in Tx1 ↑Insulin sensitivity in Tx1 |
| de Mello et al. (2017)100 | Adults with FBG 5.6–6.9 mmol L−1, and any two of the following: BMI 26–39 kg m−2; large WC; serum TGs > 1.7 mmol L−1; HDL < 1.0 mmol L−1 (men) or < 1.3 mmol L−1 (women); BP ≥ 130/≥85 mmHg; nondiabetic, free of terminal chronic disease; Sample size: n = 47 | Randomized, controlled, triple-arm study | Bilberry 400 g day−1 fresh-equivalent (Tx1); or strawberries 100 g day−1 + raspberries 100 g day−1 + cloudberries 100 g day−1(Tx2); or diet containing ≤80 g day−1 fresh berries (Cx1) for eight weeks | ↑Serum hippuric acid, insulin sensitivity and ↓FPG in Tx1 |
| Nilsson et al. (2017)101 | Adults, nonsmoking; BMI ≤ 28 kg m−2; FBG ≤ 6.1 mmol L−1; free of known metabolic disorders, GI disorder or known cognitive disorders; sample size: n = 40 | Randomized, controlled, crossover parallel-arm study | Berry beverage: 150 g blueberries + 50 g blackcurrant + 50 g elderberry + 50 g lingonberry + 50 g strawberry + 100 g tomatoes (Tx1); or water-based calorie-, pH-, and volume-matched control beverage (Cx1) for five weeks | ↓Total- and LDL-C from baseline and compared to control in Tx1 ↑BG and insulin in Cx1 compared to Tx1 |
| Paquette et al. (2017)102 | Adults with a BMI ≥ 25 kg m−2; nondiabetic; fasting insulin >60 pmol l−1; nonsmokers; free of chronic or acute disease; sample size: n = 41 | Double-blind, placebo-controlled, randomized, parallel-arm study | Beverage of strawberry + cranberry polyphenols 333 mg day−1 (Tx1) or flavor-matched beverage (Cx1) for six weeks | ↑Insulin sensitivity and ↓time of first-phase insulin-secretion response (30 min OGTT) in Tx1 |
| Schell et al. (2017)58 | Adults with BMI > 30 kg m−2, WC > 35 in (females) or >40 in (males), and radiographic evidence of knee OA | Randomized, double-blind, crossover parallel-arm study | Strawberry freeze-dried powder 50 g day−1 (∼500 g fresh-equivalent) (Tx1); or control powder (Cx1) for 12 weeks | ↓Knee pain, serum IL-6, IL-1β, and MMP-3 in Tx1; no effects on fasting glucose |
| Castro-Acosta et al. (2016)57 | Adults with a BMI of 18–35 kg m−2 and otherwise-healthy sample size: n = 23 | Randomized, double-blind, four-arm, crossover 2 h postprandial study | High-CHO meals with blackcurrant extract beverage in randomized order: 0, 150, 300, or 600 mg anthocyanins (600 mg extract ∼100 g fresh blackcurrants) | ↓Postprandial glucose, insulin, GIP, GLP-1 in the 600 mg group |
| Park et al. (2016)22 | Adults with large WC and any one of the following: FBG: 5.5–6.9 mmol L−1; fasting insulin >75th percentile of 13.13 μIU mL−1; HOMA-IR ≥ 1.0; sample size: n = 25 | Single-blinded, four-arm, placebo-controlled, 6 h postprandial study | Breakfast meal with one of four strawberry beverages in a randomized order: 0, 10, 20 or 40 g FDS (10 g FDS ∼ 110 g fresh strawberries) | ↓Post meal 6-hour insulin after 40 g FDS; pelargonidin-glucuronide inversely related to mean insulin after 20 and 40 g dose ↓Oxidized LDL after 20 g dose |
| Novotny et al. (2015)60 | Adults with a BMI between 20 and 38 kg m−2; nondiabetic; nonsmokers, fasting TGs < 3.39 mmol L−1; sample size: n = 56 | Double-blind, placebo-controlled, parallel-arm study | LCCJ or a flavor/calorie-matched placebo beverage (480 mL day−1 for eight weeks) | ↓Serum TG, CRP, glucose, insulin resistance, diastolic BP after LCCJ supplementation |
| Basu et al. (2014)21 | Adult nonsmokers; large WC > 35 inches (females), >40 inches (males) and any two of the following lipid criteria: total-C >200 mg dL−1; LDL-C >100 mg dL−1; TGs > 150 mg dL−1; HDL-C < 50 mg dL−1 for women, < 40 mg dL−1 for men; not taking lipid lowering medications; sample size: n = 60 | Randomized, dose-response controlled study | Low-dose 25 g day−1 strawberry powder (Tx1) or low-dose calorie- and fiber-matched control 25 g day−1 (Cx1); high-dose 50 g day−1 strawberry powder (Tx2) or high-dose calorie- and fiber-matched control (Cx2) for 12 weeks | ↓Total- and LDL-C in Tx2 compared with Cx1, Cx2, and Tx1; ↓MDA compared with Cx1 and Cx2 in Tx1 and Tx2; no effects on BG and insulin resistance |
| Lehtonen et al. (2011)62 | Adult females not pregnant; premenopause; BMI: 26–34 kg m−2; total-C 4.5–8 mmol l−1, LDL-C >2.5 mmol l−1, TGs < 4 mmol l−1, BG < 6 mmol l−1, insulin < 25 mU l−1, BP < 160/99 mmHg; non-diabetic and free of chronic diseases; sample size: n = 80 | Randomized, crossover, four-arm study | Bilberry 100 g day−1 (Tx1); or sea buckthorn dried 100 g day−1 fresh-equivalent (Tx2); or sea buckthorn extract 5 g day−1 (Tx3); or sea buckthorn oil 5 g day−1 (Tx4) for 33–35 days | ↓WC from baseline in Tx1 and Tx2; ↓BW in Tx1 from baseline; ↓VCAM in Tx1 and Tx4 ↓ICAM in Tx3 |
| Jin et al. (2010)63 | Adult women not pregnant; premenopause, without chronic disease; BMI including normal weight, overweight and obese; sample size: n = 117 | Randomized, double-blind, placebo-controlled parallel-arm study | Fruit + vegetable powder, 6 capsules per day (Tx1); or fruit + vegetable + berry powder, 6 capsules per day (Tx2); or appearance-matched placebo, 6 capsules per day (Cx1) for 60 days | ↓MCP-1, MIP-1β, and RANTES; ↑SOD and micronutrients in Tx1 + Tx2; BG and insulin not reported |
| Stull et al. (2010)19 | Adults with BMI of 32–45 kg m−2 and non-diabetic insulin resistance sample size: n = 32 | Randomized, double-blind, placebo-controlled parallel-arm study | Freeze-dried whole blueberries 45 g day−1 (∼2 cups fresh-equivalent) (Tx1); or calorie-matched control beverage (Cx1) for 6 weeks | ↑Insulin sensitivity (determined by exogenous glucose infusion divided by fat-free mass) in Tx1 |
AUC: Area under the curve, BG: blood glucose, BMI: body mass index, BP: blood pressure, C: cholesterol, CRP: C-reactive protein, Cx: control group, FBG: fasting blood glucose, FDS: freeze-dried strawberries, FPG: fasting plasma glucose, GIP: gastric inhibitory polypeptide, GLP: glucagon-like peptide, HOMA-IR: Homeostatic Model Assessment of Insulin Resistance, IL: interleukin, LCCJ: low carbohydrate cranberry juice, LDL: low-density lipoprotein, MCP: monocyte chemotactic protein, MDA: malondialdehyde, MIP: macrophage inflammatory protein, MMP: matrix metalloproteinase, OGTT: oral glucose tolerance test, RANTES: Regulated upon Activation, Normal T cell Expressed and Secreted, SOD: superoxide dismutase, TG: triglycerides, Tx: treatment group, WC: waist circumference.