A daily dose equivalent to about one serving of fresh strawberries per day was also associated with an almost 3% reduction in total cholesterol, report researchers from University of Arizona, Lafayette College, Texas Tech University and Pennsylvania State University.
The new data, published in the Journal of the American Nutrition Association, adds to the potential heart health benefits of strawberries and their extracts. In 2010, 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).
The new study also notes that, despite the improvements to LDL and total cholesterol, no other cardiovascular disease (CVD) risk factors, such as blood pressure and triglyceride levels were affected by the strawberry consumption.
In addition, the researchers noted that the lower dose (13 grams per day) produced better results than a higher dose of 40 grams per day of the freeze-dried strawberry powder.
Led by the University of Arizona’s Chesney Richter, the researchers recruited 20 middle-aged overweight or obese adults (mean age = 50) to participate in their clinical trial. The subjects, who also had moderately elevated LDL-cholesterol levels, were randomly assigned to one of three groups: No supplementations (the control group), or low (13 g per day) or high dose (40 g per day) for four weeks. Each intervention was separated by a two week “washout” period before crossing over to a different group.
The results showed that the LDL cholesterol levels in the low dose group decreased by 4.9% compared to the high dose group, but this difference was not significant compared to control.
A significant effect compared to both the control and high-dose groups was observed for total cholesterol (TC), with the low dose associated with 2.8% and 2.4% reductions, respectively.
Interestingly, the researchers also found that inflammatory status may impact the effects of the freeze-dried strawberries. When they removed people with ongoing inflammation, as determined by elevated levels of CRP (C-reactive protein), they found that the strawberry supplementation had greater impacts on LDL, and also improvements in non-HDL cholesterol levels were also observed. Significant decreases in small VLDL particles and LDL size were also detected following low-dose strawberry supplementation.
“Our secondary analyses indicate that acute and/or ongoing CRP elevation may cause changes in other physiological measures and dampen the effect of strawberry supplementation,” wrote the researchers. “Additional research is needed to clarify these potential dose-response implications, evaluate the role of baseline health status, and investigate effects on other emerging CVD risk factors such as the gut microbiome.”
The research was funded in part by the California Strawberry Commission.
Source: Journal of the American Nutrition Association
Published online ahead of print, doi: 10.1080/07315724.2021.2014369
“Randomized Double-Blind Controlled Trial of Freeze-Dried Strawberry Powder Supplementation in Adults with Overweight or Obesity and Elevated Cholesterol”
Authors: C.K. Richter et al.