PDF
(Download)
|
- Cranberry (Vaccinium macrocarpon)
- Arterial Stiffness
- Augmentation Index
|
Date:
07-31-2013 | HC# 031333-477
|
Re: Cranberry Juice Consumption May Reduce Arterial Stiffness in Overweight Men
Ruel
G, Lapointe A, Pomerleau S, et al. Evidence that cranberry juice may improve
augmentation index in overweight men. Nutr
Res. 2013;33(1):41-49.
Endothelial
dysfunction, the impairment of the normal functions of the inner lining of the
blood vessels, is associated with cardiovascular disease (CVD) risk factors
that can lead to arterial stiffness. The augmentation index (AIx) is an index
of arterial stiffness measured by peripheral pulse wave analysis. Healthy
nutritional habits, including increasing the consumption of fruits and
vegetables and reducing dietary fat intake, are important in helping to prevent
and treat CVD through improved lipoprotein-lipid and inflammatory profiles and
endothelial function. The cardioprotective potential of fruits and vegetables
is due to their high content of polyphenolic compounds such as flavonoids,
which play a beneficial role in protecting against inflammation and oxidative
stress. Cranberries (Vaccinium macrocarpon)
are rich in polyphenols such as phenolic acids, flavonols, anthocyanins, and proanthocyanidins.
The authors conducted a short-term, placebo-controlled, double-blind, crossover
study at Université Laval in Quebec, Canada to examine the effect of consuming a
low-calorie cranberry juice cocktail (CJC) on the AIx and cardiometabolic
profile of overweight men.
The
authors recruited 35 sedentary, otherwise healthy, overweight men (mean age = 45
± 10 years) with a body mass index (BMI) of ≥ 25 kg/m2 and a waist
circumference of ≥ 90 cm (35.4 inches). The men were nonsmokers and were not
taking medications that affected lipid or insulin metabolism or blood pressure.
After
a 4-week run-in period during which the subjects drank 500 mL of water daily to
get used to that amount of liquid in their usual diet, they were randomly
assigned to drink 500 mL daily of either a low-calorie CJC (27% juice) or
placebo juice (PJ) for 4 weeks (2 boxes of 125 mL of juice in the morning and 2
in the evening). Then, after a 4-week washout period, the subjects began the
other treatment for another 4 weeks.
The
CJC and PJ (Ocean Spray Cranberries, Inc.; Lakeville-Middleboro, Massachusetts)
had a similar taste, color, texture, and vitamin C content, but no cranberries
were in the PJ. Each daily serving of the CJC contained 500 mg of total
polyphenols, 20.8 mg of anthocyanins, and 21.84 g of carbohydrates.
At
baseline and after week 4, body weight, height, waist and hip circumferences,
and blood pressure were measured; BMI and waist-to-hip ratio values were
calculated; and fasting blood samples were drawn. The subjects also completed a
food frequency questionnaire at those 2 visits.
At
baseline and at 4 weeks, the resting AIx was measured by applanation tonometry,
during which peripheral artery waveforms were recorded on the subjects' radial
artery. Waveforms were recorded again at 5, 10, 15, and 20 minutes after the
subjects inhaled 400 μg of salbutamol, which elicits the synthesis of nitric
oxide (NO) and a vascular response used as a proxy measure of
endothelium-dependent vasodilation. The same technique was used to measure arterial
stiffness during endothelium-independent radial artery vasodilation at 3, 5,
10, 15, 20, and 30 minutes following sublingual administration of 400 μg of glyceryl
trinitrate (GTN), an NO donor used to treat angina and heart failure. The
cardiometabolic profile, which assesses risks associated with type 2 diabetes
mellitus and CVD, was determined for each subject before and after each phase
of the study.
The
subjects were separated into groups made up of those with metabolic syndrome
(MetS+) (n = 13) and those without metabolic syndrome (MetS-) (n = 22), using
the criteria for metabolic syndrome as defined by the National Cholesterol
Education Program.
At
baseline, although at the high end for total fat intake and the low end for
carbohydrate intake, the daily energy and nutrient intakes of the subjects fell
within the nutritional recommendations for Canadian adults. The MetS+ subjects
had a higher BMI, higher circulating triglycerides (TG), and lower high-density
lipoprotein cholesterol (HDL-C) levels compared with the MetS- subjects.
The
authors report that the salbutamol reduced the AIx by 10.8% ± 6.4% compared
with resting values (P < 0.0001). GTN further decreased the values by 2.1% ±
6.0% compared with salbutamol (P < 0.05). However, these changes in the AIx
responses to salbutamol and GTN did not significantly differ between subjects
who consumed the CJC or PJ.
Although
no significant difference was noted in the AIx changes between the subjects who
consumed the CJC or PJ, a statistically significant within-group decrease was
noted in the AIx (P < 0.05 compared with baseline) in subjects who consumed
the CJC.
No
significant differences were noted in other cardiometabolic variables between
those subjects drinking the CJC or PJ.
Comparing
the AIx values in the MetS+ and MetS- subjects, the authors report no
significant differences in the responses to salbutamol and GTN after
supplementation; however, they noted a significant within-group decrease in the
resting AIx values in MetS- subjects who drank CJC (P < 0.05 compared with
baseline). In those same subjects, significant increases in the AIx responses
to salbutamol and GTN were observed (P < 0.05 compared with baseline).
Although these results may seem contradictory, say the authors, earlier studies
have shown that, "Vascular tone is positively correlated with
flow-mediated dilation in healthy individuals, and thus, a more relaxed (and
possibly wider) artery at rest has a lower endothelium-dependent vasodilation
response."
The
authors previously reported that CJC supplementation was associated with
reductions in circulating oxidized low-density lipoprotein (OxLDL) and adhesion
molecule concentrations (inflammation and oxidative stress markers) in men.1,2
This was not supported, however, in the present study, where no significant changes
in those markers were reported after the CJC supplementation. Although the
differences in the design of the studies may explain the discrepancies, say the
authors, the lack of effect of the CJC on plasma OxLDL and adhesion molecule
levels in the current study agrees with previous reports showing that CJC
consumption for 2 weeks had no effect on oxidative stress markers3
and that supplementing men and women with a 54% CJC for 4 weeks did not reduce cell
adhesion molecule concentrations.4
These
authors found that although CJC consumption did reduce the resting AIx in
overweight men, the decrease was not significantly different from those
drinking the PJ. The significant within-group decrease in the AIx following the
CJC consumption, however, warrants further investigation.
—Shari
Henson
References
1Ruel G, Pomerleau S,
Couture P, Lamarche B, Couillard C. Changes in plasma antioxidant capacity and
oxidized low-density lipoprotein levels in men after short-term cranberry juice
consumption. Metabolism. 2005;54(7):856-861.
2Ruel G, Pomerleau S,
Couture P, Lemieux S, Lamarche B, Couillard C. Low-calorie cranberry juice
supplementation reduces plasma oxidized LDL and cell adhesion molecule concentrations
in men. Br J Nutr. 2008;99(2):352-359.
3Duthie SJ, Jenkinson
AM, Crozier A, et al. The effects of cranberry juice consumption on antioxidant
status and biomarkers relating to heart disease and cancer in healthy human
volunteers. Eur J Nutr. 2006;45(2):113-122.
4Dohadwala MM,
Holbrook M, Hamburg NM, et al. Effects of cranberry juice consumption on
vascular function in patients with coronary artery disease. Am J Clin Nutr. 2011;93(5):934-940.
|