One month of eating 500 grams per day of the Alba cultivar of strawberries resulted in significant reductions to total cholesterol of almost 9%, LDL cholesterol of about 14%, and triglycerides of almost 21%, according to findings published in the Journal of Nutritional Biochemistry.
Improvements were also recorded in antioxidant status of the 23 healthy volunteers, while levels were reduced of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker for oxidative stress, wrote the researchers.
“Through the present study we added new favorable evidence of the effects of strawberries after 30-days consumption on the overall improvement of the plasma antioxidant status, highlighting a potential beneficial role on biomarkers of antioxidant status, lipid profile and platelet function,” they wrote. “Moreover, the potential effect of strawberry intake in improving the RBC antioxidant status and protection against oxidation was confirmed.
“The findings presented here are interesting, because they may partly explain the protective role of a diet rich in fruit and vegetables in preventing CVD and other chronic diseases mediated by oxidative stress.”
Strawberry science
The study adds to the potential heart health benefits of strawberries and their extracts. In 2009, researchers from Oklahoma State University reported that eight weeks of supplementation with a freeze-dried strawberry powder was associated with a reduction of LDL-cholesterol levels of 11% in obese people (Nutrition Research, Vol. 30, pp. 462-469).
A study in overweight women a year earlier reported that freeze-dried strawberry powder may reduce total and LDL cholesterol levels by 5 and 6%, respectively (Nutrition Journal, 8:43).
Study details
Led by José Alvarez-Suarez from Universita Politecnica delle Marche in Ancona, Italy, the researchers recruited 23 healthy volunteers with an average age of 27 to participate in their study. All participants had an initial 10 day period with no strawberries and a diet that was low in polyphenols. This was followed by 30 days of strawberry supplementation (500 grams per day) to their habitual diet, and then a further 15 days of washout where they avoided strawberries again.
Results showed that strawberry consumption produced beneficial effects on blood lipid levels, while also significantly decreasing markers of oxidative stress, including malondialdehyde (31% reduction), urinary 8-OHdG (30% reduction), and isoprostanes levels (28% reduction).
Daily strawberry consumption was also associated with significant decreases in the number of activated platelets, compared to control values.
The benefits were attributed to the high vitamin C and anthocyanin content of strawberries, along with the fiber content. Indeed, the strawberry dose was found to contribute about 0.17 g/day and 307.59 mg/day of vitamin C and anthocyanins, said the researchers. Strawberries are reported to contain 2 grams of fiber per 100 g.
“The findings supported the hypothesis that a strawberry-enriched diet may significantly improve the markers of oxidative stress, by decreasing lipid peroxidation oxidation and protecting cells against DNA,” they said.
Source: Journal of Nutritional Biochemistry
March 2014, Volume 25, Number 3, Pages 289-294. doi: 10.1016/j.jnutbio.2013.11.002
“One-month strawberry-rich anthocyanin supplementation ameliorates cardiovascular risk, oxidative stress markers and platelet activation in humans”
Authors: Alvarez-Suarez JM, Giampieri F, Tulipani S, Casoli T, et al.