Poręba R, Skoczyńska A, Gać P, et al. Drinking of chokeberry juice from the ecological farm Dzięciołowo and distensibility of brachial artery in men with mild hypercholesterolemia. Ann Agric Environ Med. 2009;16:305-308.
The activities of nutritionally active substances, such as polyphenols, have been shown to play a protective role in the cardiovascular system. For example, the anthocyanins in polyphenolic compounds have an anti-sclerotic effect because of their anti-inflammatory, antioxidant, hypolipemic, and hypoglycemic properties. Furthermore, anthocyanin consumption has been shown to decrease blood pressure in middle-aged men and in patients with hypertension or metabolic syndrome. Chokeberry (Aronia melanocarpa) fruit, which is widely used in juice and wine production, is rich in polyphenols and anthocyanins and has recently been shown to have an anti-atherosclerotic effect. The first stage in the development of atherosclerosis involves endothelial dysfunction, which is evaluated on the basis of brachial artery dilation (BAD). The objective of the present study was to assess the influence of chokeberry juice consumption on endothelial function and on nitric oxide (NO) levels in mildly hypercholesterolemic men.
mildly hypercholesterolemic men (i.e., total serum cholesterol: > 200 mg/dL)
with no history of pharmacologic treatment to lower cholesterol levels were
enrolled in the present study. The subjects had a mean age of 53.9 years and a
mean body mass index of 27.4 kg/m2. The subjects consumed 250 mL of
chokeberry juice daily. Endothelial function (based on measurements of brachial
artery diameter via flow-mediated dilation [FMD]), serum lipids (triglyceride
and total, high-density-lipoprotein, and low-density-lipoprotein [LDL] cholesterol
levels), and NO levels were measured at the beginning of the study (I), after 6
weeks of regular consumption of the juice (II), after 6 weeks of abstaining
from juice consumption (III), and then again after another 6 weeks of regular consumption
of juice (IV). The juice was obtained from the Dzięciołowo farm in
Significant decreases in serum total cholesterol, LDL cholesterol, and triglycerides were observed, according to the authors. No significant differences in high-density-lipoprotein cholesterol were observed between the 4 measurement time periods. Significant increases in serum NO were observed. FMD increased significantly during the study.
At the beginning of the study, 13 of the 35 subjects (37.1%) had a FMD ≥ 7%, regarded as standard; after 6 weeks of juice consumption, 29 of the 35 subjects (82.9%) had a FMD ≥ 7%; and after 6 weeks of abstaining from juice consumption followed by an additional 6 weeks of consumption, all 35 subjects had a FMD ≥ 7%. Mean FMD values increased progressively over each period from 6.54% at baseline to 9.56%, 10.83%, and 11.04%, respectively. In addition, the consumption of chokeberry juice for 6 weeks and then for an additional 6 weeks after a 6-week pause in consumption resulted in a significant decrease in serum lipid concentrations in mildly hypercholesterolemic men. The authors concluded that "regular drinking of chokeberry juice has a beneficial effect on endothelial function and lipid metabolism in men with mild hypercholesterolemia."
—Brenda Milot, ELS
Peer Reviewer Comments:
While the authors' conclusions are technically true, the conduct and analysis of this trial are problematic, making interpretation of these results difficult. The major problem has to do with the complete lack of controlling for multiple testing. First, a specific primary endpoint should have been named but was not. FMD Max % is standard for such studies, but the authors list 2 others (BAD and NO). Furthermore, they list 4 cholesterol endpoints and do not distinguish them as secondary. Finally, there are 4 time points yielding 6 possible tests for each parameter.
These authors should have reported the ANOVAs for each parameter AND reduced the p-value for significance based on the number of parameters they wanted to test. Then, they should have predetermined which time point pairs they wanted to test if the ANOVA was significant, AND reduced the p-value for significance for the number of tests they performed. As reported, the only p-values that might be interesting are ones P<0.001 (i.e., FMD% between baseline and after baseline); BAD and FMD are highly correlated.
While 35 participants in an FMD study is typically enough to detect meaningful changes, unexplained is what appears to be no change in NO, which is typically considered the mediator of FMD. One might expect NO to increase after consumption, decrease when stopped, and then increase; the elevation between time points 1 and 4 may simply be spurious.
are interesting findings from this pilot study, which indicate that in healthy
males with mildly elevated cholesterol, FMD may improve after consumption of chokeberry
juice. The effects on cholesterol appear to be positive for modest reductions
in LDL and triglycerides, but these results are preliminary.