A dose-response evaluation of freeze-dried strawberries independent of fiber content on metabolic indices in abdominally obese individuals with insulin resistance in a randomized, single-blinded, diet-controlled crossover trial

Mol Nutr Food Res. 2016 May;60(5):1099-109. doi: 10.1002/mnfr.201500845. Epub 2016 Mar 29.


Scope: This study evaluated the dose-response relationship of strawberries, an anthocyanin-rich fruit, on postprandial glucose and insulin concentrations in individuals with insulin resistance (IR), including changes in plasma anthocyanins, markers of oxidative stress, and inflammation.

Methods and results: In a randomized controlled, four-arm, dose-response, crossover trial, 21 adults with IR consumed a high-carbohydrate, high-fat meal with one of four beverages containing 0 g freeze-dried whole strawberry powder (0g FDS, control), 10, 20, or 40 g FDS, controlled for fiber. Blood was collected at 0 min and at 30 min intervals postmeal until 2 h, then hourly until 6 h. Postmeal insulin concentrations (6 h) were significantly reduced after the 40-g FDS beverage compared to other beverages (p < 0.05). Postmeal 6 h glucose concentrations were not different, although mean insulin:glucose ratio was significantly different among beverages (p < 0.05). Pelargonidin-glucuronide was inversely associated with mean insulin concentrations after the 20 and 40 g FDS (p < 0.05). Oxidized low-density lipoprotein was reduced after 20 g FDS (p < 0.05) and IL-6 was not different among treatments. Strawberry intake reduced the insulin demand to manage postmeal glucose in obese individuals with IR, which was related to plasma anthocyanin/pelargonidin concentrations.

Conclusion: The data support a role of strawberries in improving insulin sensitivity in people with IR.

Trial registration: ClinicalTrials.gov NCT01199848.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anthocyanins / blood
  • Beverages / analysis
  • Biomarkers / blood
  • Blood Glucose / metabolism
  • Cross-Over Studies
  • Diet
  • Dietary Fiber / administration & dosage*
  • Dietary Fiber / analysis
  • Female
  • Fragaria / chemistry*
  • Freeze Drying
  • Humans
  • Insulin / blood
  • Insulin Resistance*
  • Interleukin-6 / blood
  • Lipoproteins, LDL / blood
  • Male
  • Meals
  • Middle Aged
  • Obesity, Abdominal / diet therapy*
  • Oxidative Stress
  • Postprandial Period
  • Single-Blind Method


  • Anthocyanins
  • Biomarkers
  • Blood Glucose
  • Dietary Fiber
  • IL6 protein, human
  • Insulin
  • Interleukin-6
  • Lipoproteins, LDL
  • oxidized low density lipoprotein
  • pelargonidin

Associated data

  • ClinicalTrials.gov/NCT01199848