Effects of exercise with or without blueberries in the diet on cardio-metabolic risk factors: An exploratory pilot study in healthy subjects

Abstract

Background. The improvement of insulin sensitivity by exercise has been shown to be inhibited by supplementation of vitamins acting as antioxidants.Objective. To examine effects of exercise with or without blueberries, containing natural antioxidants, on cardio-metabolic risk factors.Methods. Fifteen healthy men and 17 women, 27.6 ± 6.5 years old, were recruited, and 26 completed a randomized cross-over trial with 4 weeks of exercise by running/jogging 5 km five times/week and 4 weeks of minimal physical activity. Participants were also randomized to consume 150 g of blueberries, or not, on exercise days. Laboratory variables were measured before and after a 5 km running-race at maximal speed at the beginning and end of each period, i.e. there were four maximal running-races and eight samplings in total for each participant.Results. Insulin and triglyceride levels were reduced while HDL-cholesterol increased by exercise compared with minimal physical activity. Participants randomized to consume blueberries showed an increase in fasting glucose levels compared with controls, during the exercise period (blueberries: from 5.12 ± 0.49 mmol/l to 5.32 ± 0.29 mmol/l; controls: from 5.24 ± 0.27 mmol/l to 5.17 ± 0.23 mmol/l, P = 0.04 for difference in change). Triglyceride levels fell in the control group (from 1.1 ± 0.49 mmol/l to 0.93 ± 0.31 mmol/l, P = 0.02), while HDL-cholesterol increased in the blueberry group (from 1.51 ± 0.29 mmol/l to 1.64 ± 0.33 mmol/l, P = 0.006).Conclusions. Ingestion of blueberries induced differential effects on cardio-metabolic risk factors, including increased levels of both fasting glucose and HDL-cholesterol. However, since it is possible that indirect effects on food intake were induced, other than consumption of blueberries, further studies are needed to confirm the findings.

The Effect of Berry‐Based Food Interventions on Markers of Cardiovascular and Metabolic Health: A Systematic Review of Randomized Controlled Trials

“…Of the 23 RCTs, 17 studies achieved a total of six to eight “A” scores out of a max score of 8. Nine RCTs were either single blinded, did not use a third party to assign randomization, and/or had insufficient allocation concealment . In seven RCTs, a control that was not identical in terms of appearance, taste, and texture was used .…”

“…Nine RCTs were either single blinded, did not use a third party to assign randomization, and/or had insufficient allocation concealment . In seven RCTs, a control that was not identical in terms of appearance, taste, and texture was used . Five RCTs did not provide information on the characterization of the study products in terms of nutrient and polyphenol profiles …”

“…In seven RCTs, a control that was not identical in terms of appearance, taste, and texture was used . Five RCTs did not provide information on the characterization of the study products in terms of nutrient and polyphenol profiles …”

Effect of grape and other berries on cardiovascular health

“…They found no change in the other cytokines and chemokines tested. Three studies with blueberries resulted in no change in the cytokines or adhesion molecules tested or cRP . With cranberries, a dose escalation study (0–500 mL day −1 over 4 weeks) with low‐calorie 27% cranberry juice cocktail resulted in a reduction in the adhesion molecules sICAM‐1 ( P < 0.0001) and sVCAM‐1 ( P < 0.05) but no change in E‐selectin vs baseline .…”

“…Non‐medicated individuals with CVD risk factors consuming two portions of mixed berries daily experienced an increase in HDL‐C ( P = 0.006) but no change in TC or TG . One study with bilberry juice resulted in no change in TC or TG vs control, and three studies with blueberries (freeze‐dried blueberries, fresh blueberries and freeze‐dried wild blueberry powder) resulted in no change in TC, HDL‐C, LDL‐C or TG or in apo A‐1 or apo B vs control.…”