Strawberry extracts show heart benefits in obese people
Freeze-dried strawberry powder equivalent to four servings of frozen strawberries was associated with a 4% decrease in total cholesterol levels, according to findings published in the British Journal of Nutrition.
In addition, the profile of LDL and HDL cholesterol improved towards a healthier profile, but no changes were observed in levels of inflammation, report researchers led by the USDA’s Susan Zunino.
Despite positive results, and benefits being observed within three weeks of supplementation, the authors caution that the pilot study was performed with only 20 participants.
“The present study provides data to support larger and more demographically diverse clinical trials with strawberries and other fruits to define the roles they may play in reducing morbidity and mortality associated with obesity,” they wrote.
The study was funded by the United States Department of Agriculture (USDA) and the California Strawberry Commission.
Strawberry science
The study adds to previous findings with strawberry powder supplementation. Last year, researchers from Oklahoma State University reported that eight weeks of supplementation 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
The USDA and UC Davis researchers performed a pilot study with 20 obese but otherwise healthy subjects aged from 20 to 50. The intervention involved a daily consumption of the equivalent of four servings of frozen strawberries as a freeze-dried powder (one serving is 80 grams) in a milkshake, yogurt, cream cheese, or beverage, or the same products with no added powder.
Results showed that, after three weeks, levels of cholesterol decreased in the strawberry but not the control products.
In addition, concentrations of small HDL-cholesterol particles decreased, while the particle size of LDL cholesterol increased.
“Evaluation of HDL particle sizes in patients with coronary artery disease revealed a significantly higher concentration of small HDL particles in the coronary artery disease group than in control subjects,” explained the researchers.
They added that smaller LDL particle size has also been reported to increase the risk of developing CVD, the metabolic syndrome and type-2 diabetes, and an increase, as seen in this study, represents a potential health improvement.
Fiber
Commenting on the potential bioactive components of strawberries, the researchers note that fiber may be behind the cholesterol-lowering benefits, since strawberries contain about two grams of fiber per 100 grams
“In the present study, each subject received about 8 g of extra fiber per day during the 3 weeks on the strawberry-enriched diet,” they note.
“These data suggest that prolonged consumption of strawberries may continue to improve the cholesterol-lowering effect of this fruit over time.”
Source: British Journal of Nutrition
Published online ahead of print, doi: 10.1017/S0007114511006027
“Effects of dietary strawberry powder on blood lipids and inflammatory markers in obese human subjects”
Authors: S.J. Zunino, M.A. Parelman, T.L. Freytag, C.B. Stephensen, D.S. Kelley, B.E. Mackey, L.R. Woodhouse, E.L. Bonnel
