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Recent Flavonoid Findings: From Healthy Aging to Potential Heart Protection

Flavonoids in Health and Disease Prevention

Observational studies suggest that flavonoid-rich diets may lower the risk for a variety of chronic diseases, particularly cardiovascular disease. Abundant in fruits and vegetables, tea, and wine, these polyphenolic nutrients may contribute to risk reduction by decreasing oxidative stress and inflammation – two pathways underlying many age-related health problems, including AMD.

This issue of EduFacts highlights recent research exploring the role of flavonoids in health and disease prevention. One study takes a holistic approach in evaluating the potential of flavonoids, while the others provide insight into how these nutrients might confer protection.

Flavonoids & Healthy Aging in Women

There are several subclasses of flavonoids, and food databases are now available to quantify the different types of flavonoids in the diet. Using these expanded databases, Harvard researchers investigated the relationship of flavonoid intake at midlife to overall health and wellbeing in women as they age (1).

Analyzing data from 13,800 participants in the Nurses Health Study who were initially free of chronic diseases and in their mid-fifties, the researchers identified 1,500 women who met their “healthy aging” criteria after a 15 year follow-up.

Healthy aging was defined in relation to usual aging at 70, and based on reaching 70 or older without a major chronic disease or having impaired physical or mental function.

Women with the highest intake of several flavonoid subclasses had greater odds of healthy aging. Specifically, flavones, flavonones, anthocyanins and flavonols bolstered the odds by 32%, 28%, 25% and 18%, respectively (all p-trend ≤ 0.02).

Consistently, consuming more of the major sources of these flavonoids – oranges, berries, onions, and apples – increased the likelihood of health and wellbeing in this population.

Berries, Blood Pressure & Arterial Stiffness

Florida State University investigators found that blueberries, a concentrated source of anthocyanins, produce clinically significant reductions in both diastolic and systolic blood pressure of 5.1% and 6.3% respectively, while improving the health of arteries in women with pre- and Stage 1 (mild) hypertension (2).

Of the 48 women randomly assigned to get 22 g of blueberry powder (equivalent to 1 cup of fresh berries) or placebo powder daily, those in the berry group had meaningful drops in blood pressure (p<0.05), increased levels of artery-relaxing nitric oxide (p<0.01), and a reduction in arterial stiffness at the end of 8 weeks (p<0.01). No changes in these parameters were seen in the placebo group.

The researchers conclude that consuming blueberries regularly can potentially delay the progression of high blood pressure and reduce CVD risk in post-menopausal women. Several additional small trials testing the effects of blueberries in pre-hypertension have reported similar results.

Flavonoids May Cut Smog-Related Heart Risks

Heart rate variability, the beat-to beat changes in heart rate, allows the cardiovascular system to respond to changes in the need for blood flow and oxygen. Low heart rate variability is a predictor of heart-related death, and air pollution can reduce the heart’s ability to vary its rhythm.

Researchers from Harvard’s School of Public Health report that higher flavonoid intake cushioned the effects of air pollution on heart function in 573 elderly men participating in the Normative Aging Study (3). Comparing clinical measures with air quality data collected over 11-years, the investigators saw heart rate variability decline when smog levels rose for 48 hours.

They also evaluated whether over methylation of Toll-like receptor 2 (TLR2), a protein fundamental to the immune response, impacts the smog-associated effect on the heart. It did. Greater methylation of TLR2, a reversible epigenetic process, worsened heart rate variability during smoggy periods. However, the association between heart rate variability and pollution levels was far weaker among men consuming the most flavonoids.

While these findings are preliminary, it’s quite possible that flavonoids trigger epigenetic changes that help counter the heart’s susceptibility to the hazardous effect of pollution. There’s a growing body of evidence, for instance, that certain polyphenols can reduce over methylation of DNA in critical genes associated with cancer.

References

1. Samieri C, et al. Dietary flavonoid intake at midlife and healthy aging in women. Am J Clin Nutr. 100:1489-97, Dec. 2014.
2. Johnson SA, et al. Daily blueberry consumption Improves blood pressure pnd arterial stiffness in post-menopausal women with pre- and Stage 1-hypertension: A randomized, double-blind, placebo-controlled clinical trial. J Acad Nutr Diet. Jan 2, 2015 [Epub ahead of print].
3. Zhong J, et al. Toll-like receptor 1 methylation and dietary flavonoid intake modify the association between fine particle exposure and cardiac autonomic dysfunction: The Normative Aging Study. Circulation 130:A15898, 2014.