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Originally Published NO June 2010
Flavonoids are polyphenolic antioxidants widely distributed throughout the plant kingdom. Some of their important functions are imparting vibrant colors to flowers and fruits, and also protecting them from microbial and insect attack. Can the innate properties of flavonoid-rich natural products provide protective effects in humans as well, helping to optimize mainstream preventive health management?
Natural Products Influencing Medicine
What if your physician prescribed daily use of oyster mushroom extract (Pleurotus ostreatus) for your hypercholesterolemia? Or Pacific Yew evergreen tree extract (Taxus brevifolia) as a chemotherapeutic regimen for cancer? Or cone snail extract (Conus magnus) to relieve agonizing chronic pain? Unbeknownst to many, they already do.
Today, primary-care physicians prescribe Mevacor (Lovastatin), a cholesterol-lowering agent originally derived from fungus. Oncologists create chemotherapeutic regimes for ovarian and breast cancer with Taxol (Paclitaxel), obtained from Yew tree bark. Pain-management teams (either anesthesiologists and/or physical medicine and rehabilitation physicians) utilize Prialt (Ziconotide), a non-opioid, non-NSAID ameliorating agent for severe and chronic pain, originally sourced from cone snails. These common drugs are derived from natural products and have only been introduced in major medical markets in the last 25 years.
There is no doubting how the pharmaceutical and natural-products industries influence one another. However, 50 years ago, the relationship between these two industries had grown out of sync. At the time, the new era of antibiotics drew the pharmaceutical industry's attention away from plant-derived natural products. It was not until the 1980s when biotechnology companies evolved and pharmaceutical ambitions intertwined with a reestablished interest in a natural-product approach.
Today, a trend has ignited in the natural-products industry toward introducing purified, natural compounds.
Science Uncovers Flavonoids' Health Benefits
Flavonoids have been studied for half a century. In the past two decades, however, an abundance of studies has emerged, strongly suggesting flavonoids' antioxidant power. Of these studies, two in particular have sparked the pursuit to investigate flavonoids' health potential in humans.
In 1993, Edwin Frankel, PhD, and his research team found that polyphenols extracted from red wine (later discovered to be flavonoids and resveratrol) are significantly more successful at inhibiting oxidation of low-density lipoprotein cholesterol compared to the effects of alpha-tocopherol, or vitamin E. This effect was subsequently suggested to explain the "French paradox"-why those in France tend to have a low incidence of coronary heart disease despite diets rich in saturated fats.
In that same year, another study contributed to the revitalized excitement behind flavonoids. The Lancet published an epidemiological study conducted in the Netherlands, called the Zutphen study, suggesting an inverse correlation between incidence of coronary heart disease and stroke and the dietary intake of flavonoids.
Since then, various clinical trials have shown the multiplicity of actions offered by all six flavonoid subtypes-flavan-3-ols (e.g., proanthocyanidin), flavanones (e.g., fisetin), flavonols, flavones (e.g., apigenin, diosmin, luteolin, nobiletin, tangeretin, anthocyanins, isoflavones), and other polyphenols (e.g., ellagic acid, punicalagins, resveratrol).
In studies, flavonoids have demonstrated a multiplicity of actions, acting against telomerase, cyclooxygenase, and lipoxygenase; decreasing xanthine oxidase, matrix metalloproteinase, angiotension-converting enzyme, proteasome, and sulphotransferase activities; interacting with sirtuins; and modulating signal-transduction pathways. These mechanisms equate to amelioration of health conditions such as, but not limited to, anxiety, dyslipidemia, cerebral and cardiovascular hemodynamics, neuroinflammation, and age-related degeneration.
Getting Your Flavonoids
The natural source of these flavonoids and other polyphenols include full-spectrum grape extract, red wine, flowers, teas, trees/shrubs, apples, berries, citrus fruits, onions, pomegranate, and green leafy spices.
The typical person consumes only 210 mg of flavonoids daily, based on the National Health and Nutrition Examination Survey's (NHANES) crosslink of the U.S Department of Agriculture flavonoid database, as well as food consumption data and dietary supplements data of approximately 9000 adults.
Studies by the Salk Institute demonstrated that in order to obtain neuroprotective effects from fisetin alone, the human equivalence dose (HED) should be approximately 50 to 125 mg/day. This means that one would have to consume, daily, 10 to 30 apples, or 200 to 400 onions, or 300 to 500 strawberries. That being said, there is great potential for supplements of a single dietary flavonoid, or as part of a flavonoid-rich preparation in a functional food/beverage, in the promotion of optimal nutrition and healthy aging.
A Bright Future
In most cases, it is impossible to consume the recommended amount of fruits and vegetables required to obtain the level of flavonoids required to receive ultimate health benefits. However, by adding purified sources of these flavonoids to a healthy diet, you can obtain the health benefits of these compounds.
From a natural-products industry perspective, purified compounds are gaining interest as the industry looks at developing more science-based evidence around different ingredients. One of the benefits of these purified compounds is that they make it easier to develop clinical trial protocols and duplicate the results of a particular ingredient.
From a practical perspective, investing in the potential of natural products and their active, pure compounds to optimize quality of life is a worthy cause-one that is finally gaining deserved recognition.
Anh Thu Tran is nutrition consultant and R&D coordinator at Cyvex Nutrition (Irvine, CA). She holds a MD from St. George's University; a MS in nutrition from Loma Linda University; and a BSc in biology and women's studies from University of California, Irvine. She will work under the University of California, Davis, Family Residency Network in June.