Dietary Strawberries Improve Biomarkers of Antioxidant Status and Endothelial Function in Adults with Cardiometabolic Risks in a Randomized Controlled Crossover Trial

Abstract

Strawberries, a popularly consumed berry fruit, are rich in bioactive compounds with antioxidant effects. In this study, we examined the effects of two dietary achievable doses of strawberries on the antioxidant status and biomarkers of endothelial function in adults with features of metabolic syndrome and a confirmed low baseline of fruit and vegetable intake. In a 14-week randomized controlled crossover study, participants were assigned to one of three groups for four weeks separated by a one-week washout period: control powder, one serving (low dose: 13 g strawberry powder/day), or 2.5 servings (high dose: 32 g strawberry powder/day). Blood samples and health data were collected at baseline and at the end of each four-week phase of intervention. Thirty-three participants completed all three phases of the trial. Significant increases were observed in serum antioxidant capacity and superoxide dismutase activity as well as decreases in lipid peroxidation after both low and high dose strawberry phases when compared with the control phase. Significant decreases were also observed in soluble vascular cell adhesion molecule-1 and tumor necrosis factor-α with the high dose strawberry phase. These data confirm that consuming strawberries for four weeks significantly improves antioxidant status, endothelial function, and inflammation in adults with cardiometabolic risks.

Immunostimulatory and anti-inflammatory impact of Fragaria ananassa methanol extract in a rat model of cadmium chloride-induced pulmonary toxicity

“…TNF has been hypothesized to be a key mediator in the development of Cl2-caused toxicity ( 73 ). In addition, these results were compatible with those of many study findings that SE inhibited the translocation of NF-κB and GM-CSF , decreasing release of proinflammatory cytokines, such as IL-1β and TNF-α ( 74 ). Moreover, SE downregulated the expression of NF-κB and GM-CSF , leading to downregulation of proinflammatory cytokines, such as IL-1β and TNF-α , demonstrating the anti-inflammatory activity of strawberries ( 70 , 75 , 76 ).…”

Effect of Dietary Berry Supplementation on Antioxidant Biomarkers in Adults with Cardiometabolic Risks: A Systematic Review of Clinical Trials

“…All included studies were randomized controlled trials—30 used a parallel design and 24 used a crossover designed. Overall, 37 studies measured the effects of berries in adults with features of MetS [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ] ( Table 1 ) and 17 studies measured these same effects in adults with obesity or overweight [ 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , ...…”

“…The 37 studies measuring outcomes in adults with features of MetS included 14 different dietary berries. Overall, 21 studies assessed only oxidative stress biomarkers [ 28 , 30 , 31 , 32 , 34 , 36 , 37 , 38 , 40 , 42 , 43 , 45 , 48 , 50 , 51 , 53 , 54 , 56 , 58 , 59 , 60 , 61 ], 13 studies assessed both oxidative stress and antioxidant biomarkers [ 27 , 29 , 35 , 39 , 41 , 42 , 44 , 46 , 47 , 52 , 55 , 57 , 62 ], and 3 studies assessed only antioxidant biomarkers [ 33 , 49 , 63 ].…”

“…In addition to antioxidant capacity, three studies also measured enzymatic activity related to oxidative stress [ 27 , 39 , 46 ]. Low dose (25 g) and high dose (50 g) of freeze-dried strawberry powder consumed for 12 weeks statistically significantly increased plasma antioxidant capacity with an immense effect ( d = 4.33 and 7.60, respectively) [ 46 ].…”

“…Both doses of the intervention also immensely increased serum whole blood glutathione reductase ( d = 4.61 and 10.75, respectively), while only the low dose had a significant impact on serum catalase (76% increase) with a large effect ( d = 2.07) [ 46 ]. Freeze-dried strawberry powder at a low dose (13 g) and high dose (32 g) consumed for four weeks also statistically significantly increased serum antioxidant capacity [ 27 ]. Interestingly, these doses had lower antioxidant capacity increases from baseline (25% and 40%, respectively) and only had a moderate effect on the outcome ( d = 0.37 and 0.62, respectively) [ 27 ].…”