An Orange a Day Keeps Stroke Away & Improves Inflammation & Perhaps Neuroinflammation
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By Crystal Phend, Senior Staff Writer, MedPage Today
Published: February 23, 2012
"oranges are a richer source of flavanones.......Over 14 years of follow-up, high flavanone intake was associated with a 19% lower risk of ischemic stroke.....high intake of citrus fruits/juice tended to be associated with a reduced risk of ischemic stroke (RR, 0.90; 95% CI, 0.77-1.05; Q5 versus Q1). Citrus fruits and juices contain other constituents that may reduce the risk of stroke, including vitamin C and potassium.......blueberries were the main source of anthocyanins, and oranges/orange juice were the main contributors to flavanone and flavone intake......flavone intake was inversely associated with risk of total and ischemic stroke.....The main dietary sources of flavanones were orange and grapefruit juices (63%), oranges (34%), and grapefruits.......vitamin C intake was not associated with a reduction in total or ischemic stroke risk......Growing in vitro mechanistic evidence suggests potential beneficial effects of specific flavonoids and their biologically active metabolites in reducing ischemic stroke development, including inhibitory effects on platelet function, thrombosis, inflammation, and protection against ischemia-reperfusion injury and arrhythmia.....Specifically, for several subclasses, including flavones and anthocyanins, evidence is emerging for beneficial effects by suppressing neuroinflammation and improving cerebral blood flow......Increased consumption of fruits and vegetables has been associated with a reduced risk of stroke. In a meta-analysis of existing cohort studies,4 those consuming 3 to 5 servings/day and >5 servings/day had an 11% and 26% reduction in risk of stroke, respectively, compared with those consuming 3 servings/day. However, these data could not determine which specific fruits/vegetables or their constituents exerted these protective effects. Our findings suggest that bioactive compounds present in citrus may potentially be associated with a reduced risk of stroke. Further prospective studies are needed to confirm these associations together with further molecular mechanistic data on flavanones to inform and optimize the design of randomized trials of flavanone and citrus-based foods to potentially reduce ischemic stroke risk."
A compound found in oranges, grapefruit, and other citrus fruit may modestly reduce stroke risk among women, an observational study determined.
Women with the highest levels of flavanone in their diet were 19% less likely to have an ischemic stroke during 14 years of follow-up than those with the least flavanone intake (P=0.04), Aedin Cassidy, PhD, of the University of East Anglia in Norwich, England, and colleagues found.
· In this large study in women, total flavonoid intake was not inversely associated with risk of stroke; however, increased intake of the flavanone subclass was associated with a reduction in the risk of ischemic stroke.
· Citrus fruits/juices are the main dietary source of flavanones, and in this study they tended to be associated with a reduced risk for ischemic stroke, but the association did not reach significance.
As the main source of these antioxidants, citrus fruit and juice showed a similar trend (relative risk 0.90, 95% CI 0.77 to 1.05), they reported in the April issue of Stroke: Journal of the American Heart Association.
Vitamin C has gotten most of the praise for the protective effect of citrus found in prior stroke studies, but in Cassidy's analysis of the Nurses' Health Study, the vitamin didn't correlate with total or ischemic stroke or attenuate the link to flavanones.
Most of the flavanones consumed by women in the study came from orange and grapefruit juice (63%). But eating the whole fruit would likely be a better way to boost intake, the researchers suggested.
"Given the higher flavanone content of citrus fruits and the sugar content of commercial fruit juices, public health recommendations should focus on increasing citrus fruit intake," they recommended in the paper.
Flavanones are one of six types of commonly consumed flavonoids, which various studies have linked individually to different benefits -- hypertension risk reduction with anthocyanins, lower stroke risk in some studies of flavonols -- but never looked at all simultaneously.
Cassidy's group broke down food frequency data from nearly 70,000 women participating in the Nurses' Health Study for total flavonoid intake and for each component.
With dietary reports every four years over a total 14 years of follow-up, the researchers found big variations in total flavonoid intake, ranging from an average 761 mg per day in the top quintile to 97 mg per day in the bottom quintile.
Tea was the biggest contributor to those levels, followed by apples and oranges or orange juice.
However, total flavonoid intake didn't predict ischemic stroke risk in the multivariate-adjusted model (P=0.36 for trend).
These results suggested "that flavanones may be another important cardioprotective constituent of citrus fruits," Cassidy's group wrote. "However, in a population-based study like ours, it is impossible to disentangle the relative influence of all the constituents of citrus fruits."
An impact from flavanones is plausible, they noted, pointing to experimental evidence that two flavanones, naringenin and hesperetin, act on neuroprotective pathways with effects on nitric oxide release. Naringenin was the strongest anti-inflammatory of all the flavonoids tested in one study.
A trend appeared for the flavones at the highest intake level of more than 3 mg per day compared with the lowest at less than 1 mg per day, but the difference wasn't statistically significant (adjusted relative risk 0.88, 95% CI 0.72 to 1.08).
The same was true for anthocyanins (blueberries were the main source) and flavan-3-ols (predominantly consumed from tea).
None of the compounds impacted hemorrhagic stroke risk.
Individual flavonoids are likely to differ in benefits because of different mechanisms through their specific structural characteristics, the researchers noted.
They cautioned that residual or unmeasured confounding was possible despite the detailed adjustment used in the study.
Another limitation is that the actual flavonoid content in foods consumed may have differed from levels recorded because of wide variability based on where the food was grown and during what season and how it was cultivated and processed.
Randomized trials are needed to test flavanone and citrus foods for reduction of ischemic stroke risk, the group concluded.
Black Tea Cuts Blood Pressure
By Todd Neale, Senior Staff Writer, MedPage Today
Published: January 23, 2012
Regular consumption of black tea -- which is rich in flavonoids -- significantly reduced blood pressure, a randomized, placebo-controlled trial showed.
Drinking three cups each day for six months lowered both diastolic and systolic blood pressure by 2 to 3 mm Hg (P≤0.05), according to Jonathan Hodgson, PhD, of the University of Western Australia in Perth, and colleagues.
Even those small changes could have a large impact on health at the population level, they reported in a research letter in Archives of Internal Medicine.
Those differences would be associated with a 10% reduction in the prevalence of hypertension and a 7% to 10% decrease in the risk of cardiovascular disease, they said.
Hodgson and colleagues conducted a randomized trial that included 95 men and women ages 35 to 75 (mean age 56 for men and 57 for women) who were regular tea drinkers. The participants had a mean body mass index of 25 kg/m2 and a mean daytime ambulatory systolic blood pressure of 121 mm Hg at baseline.
During a four-week run-in period, all of the participants consumed a low-flavonoid diet along with three cups of regular leaf tea per day.
During the six-month intervention period, the participants were randomized to three cups per day of either 1,493-mg powdered black tea solids that contained 429 mg of polyphenols and 96 mg of caffeine or a placebo drink matched in flavor and caffeine content.
From baseline to six months, there were no changes in energy and nutrient intake, urinary sodium and potassium excretion, or body weight in either group.
There were, however, differences in 24-hour ambulatory blood pressure, driven mostly by daytime readings.
For systolic, readings were 2.7 mm Hg lower at three months and 2.0 mm Hg lower at six months in the participants who were drinking tea.
For diastolic, the differences were 2.3 and 2.1 mm Hg, respectively.
Hodgson and colleagues noted that previous short-term randomized trials exploring the effects of black tea on blood pressure may have failed to demonstrate significant effects because they were underpowered to find small but clinically significant differences.
It is also possible, they noted, that longer-term consumption is needed to make an impact.
As for why black tea would lower blood pressure, the researchers pointed to effects on endothelial function.
Endothelial dysfunction may be an early marker for changes in blood pressure, and there is evidence that tea consumption improves endothelial function. Also, a previous study by Hodgson and colleagues showed that tea flavonoids affect nitric oxide status and reduce levels of endothelin.
"This could contribute to reduced vascular tone and lower blood pressure," the authors wrote.
Another possible mechanism involves the effects of tea flavonoids on body weight and visceral fatness.
"A recent meta-analysis suggests that green tea and its flavonoids -- many of which are structurally similar to black tea flavonoids -- together with caffeine can reduce body weight and abdominal fatness," wrote the researchers, who noted that, although there was no change in body weight in the current study, information on abdominal fatness was not available.