Polyphenols: Bioflavonoids

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:

The interactions between the members of a large sub-class of polyphenolic phytonutrients, the bioflavonoids, and human cells, tissues and organs have been studied in great depth. Many investigators have discovered and confirmed that when consumed in sufficient amounts, the bioflavonoids are positively associated with the health and function of many body systems.

The way some bioflavonoids work might be surprising. In many cases, they act to maintain the activation of normal body control mechanisms so that these systems do not go out of tune. Laboratory experiments have demonstrated that many bioflavonoids, such as quercetin in apples, fisetin in strawberries, epigallocatechin-3-gallate in green tea, galangin from flower pollen, hydroxycinnamic acid in broccoli and genistein in soy, maintain the internal life cycle regulation of the body’s cells. This helps the body comply with its needs for normal cell turnover, replacement and renewal as, over the years, the body experiences the physical and biochemical “wear and tear” of daily life. It is the best means the body has to “sweep out the old” and make room for the new.

As shown by the results of recent published studies, bioflavonoids foster normal life cycles in human cells.11,12,13 While abnormally long lifetimes may seem to mean healthier aging, in fact, normal life cycles help cells, tissues and organs stay healthy and fully functional longer – and in so doing, promote healthy aging. A normal life cycle for cells includes the process of living healthy and dying when their functionality and utility have come to an end. It is the process of normal life, repair, death and renewal of cells that leads to healthy organs and systems of the body. Thus, maintaining these normal processes is what leads to optimal health and an interruption of these functions can have disastrous consequences on the body.

Further benefits from increased dietary intake of bioflavonoids include the promotion of healthy cognitive function. In a recently completed and published study of rat brain functions fisetin (found in strawberries) was seen to increase the ability to recall old memories (by facilitating the process known as “long-term potentiation” with the hippocampus, the functional center of memory recall in rats and humans).14 This outcome probably resulted from the combination of properties of fisetin: antioxidant, cell function stabilizer and neural network enhancer.

Although not completely understood yet, the actions of another bioflavonoid, resveratrol (from grapes), within the brain contribute to the promotion of healthy brain longevity. As reported very recently in Bioorganic and Medicinal Chemistry resveratrol in the brain prevents the formation of molecular aggregates that interfere with information transmission between brain cells.15 By maintaining open channels of communication, resveratrol sustains healthy cognitive functioning.

Resveratrol also plays active roles in heart health. As shown in a report published recently in the Journal of Molecular and Cellular Cardiology resveratrol supports capillary function within the heart muscle, increasing the oxygenation of the muscle and its contractile efficiency.16

Recent studies highlight several distinct mechanisms whereby resveratrol can offer benefits to cardiovascular health. Studies show that resveratrol is an inefficient antioxidant in vitro, that is, in laboratory studies. However, when studied in vivo, i.e. in living systems, resveratrol shows an amazing ability to scavenge free radicals. Research suggests that the cardiovascular-protective effects stem from three major mechanisms of action: antioxidant, inflammatory-support and support of nitric oxide release. Nitric oxide release is necessary for enhancing circulation and supporting the health and integrity of blood vessels. These mechanisms lead to several distinct benefits that can be attributed to resveratrol supplementation. Some of these effects include protection of lipids from oxidative damage, supportive effects on normal heart rhythms, relaxation of blood vessels, which supports healthy circulation, and a reduction in free radical effects on cardiac tissue.17 Given these broad effects on cardiovascular health, resveratrol appears to hold promise as a polyphenol that provides long-term and comprehensive benefits for heart function.

Resveratrol is just one of the many heart-healthy polyphenols. The catechins in green tea are a subclass of polyphenols that includes epigallocatechin-3-gallate (EGCG) and that contribute to cardiovascular health by protecting the integrity of the interior lining of blood vessels. The results of a study published recently in Cardiovascular Research have shown that catechins function as antioxidants by inhibiting the secretion of certain enzymes by over-stimulated vascular smooth muscle cells which can be detrimental to the linings of blood vessels.18 EGCG and other catechins from tea also regulate the production of nitric oxide, stimulating blood vessel health and vasodilation, ultimately promoting circulatory function. By doing so, catechins enhance blood vessel function and structure.

Tea consumption has also been found to be protective of heart function over the long-term. Studies suggest that higher tea consumption leads to better protection of cardiac function with age. Tea contains numerous beneficial polyphenols, including the catechin EGCG. Furthermore, tea rich in EGCG has been shown to support circulation and promote antioxidant activity.19

Cranberries are similarly considered one of the more heart-healthy fruits because of their high polyphenol content. Surprisingly, cranberries have a higher amount of total polyphenols per serving than blueberries, apples, red grapes or strawberries.20 Cranberries are particularly high in flavonoids, and also contain a small amount of resveratrol. Research conducted on cranberries shows that they support the body’s antioxidant defenses and protect cholesterol molecules from free radical damage. Laboratory research using cranberry powder found that it stimulated the major cellular antioxidant systems including superoxide dismutase, catalase and peroxidase. Studies in humans have found that the polyphenolics in cranberries increase antioxidant nutrient levels in the blood, increasing the protection of the cardiovascular system.

Several polyphenols show cardiovascular and supportive effects by working as antioxidants, supporting the body’s normal inflammatory response, protecting lipids and cholesterol molecules from oxidative damage, and by directly influencing the function of the heart muscle. The consumption of a wide variety of polyphenolic compounds, including the ones mentioned above, can yield far-reaching benefits for cardiovascular wellness.

Next Best Kept Secrets to Healthy Aging topic:
Polyphenols as Antioxidants

11. Yang JH, Hsia TC, Kuo HM, Chao PD, Chou CC, Wei YH, Chung JG. Inhibition of lung cancer cell growth by quercetin glucuronides via G2/M arrest and induction of apoptosis. Drug Metab Dispos 2006;34:296-304.
12. Lu X, Jung J, Cho HJ, Lim DY, Lee HS, Chun HS, Kwon DY, Park JH. Fisetin inhibits the activities of cyclin-dependent kinases leading to cell cycle arrest in HT-29 human colon cancer cells. J Nutr 2005;135:2884-2890.
13. Murray TJ, Yang X, Sherr DH. Growth of a human mammary tumor cell line is blocked by galangin, a naturally occurring bioflavonoid, and is accompanied by down-regulation of cyclins D3, E, and A. Breast Cancer Res 2006;8:R1 (doi: 10.1186/bcr1391).
14. Maher P, Akaishi T, Abe K. Flavonoid fisetin promotes ERKdependent long-term potentiation and enhances memory. Proc Natl Acad Sci U S A 2006;103:16568-16573.
15. Riviere C, Richard T, Quentin L, Krisa S, Merillon JM, Monti JP. Inhibitory activity of stilbenes on Alzheimer’s ß-amyloid fibrils in vitro. Bioorg Med Chem 2007;15:1160-1167.
16. Penumathsa SV, Thirunavukkarasu M, Koneru S, Juhasz B, Zhan L, Pant R, Menon VP, Otani H, Maulik N. Statin and resveratrol in combination induces cardioprotection against myocardial infarction in hypercholesterolemic rat. J Mol Cell Cardiol 2006 (doi:10.1016/j. yjmcc.2006.10.018).
17. Penumathsa SV, Maulik N. Resveratrol: a promising agent in promoting cardioprotection against coronary heart disease. Can J Physiol Pharmacol. 2009;87(4):275-86.
18. El Bedoui J, Oak MH, Anglard P, Schini-Kerth VB. Catechins prevent vascular smooth muscle cell invasion by inhibiting MT1-MMP activity and MMP-2 expression. Cardiovasc Res 2005;67:317-325.
19. Wolfram S. Effects of green tea and EGCG on cardiovascular and metabolic health. J Am Coll Nutr. 2007;26(4):373S-388S.
20. McKay DL, Blumberg JB. Cranberries (Vaccinium macrocarpon) and cardiovascular disease risk factors. Nutr Rev. 2007;65(11):490-502.

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