Thursday, September 15, 2011

What are Bioflavonoids?


Once known as "Vitamin P" and semi-essential nutrients
4000 flavonoid compounds have been characterized and classified
Group of plant pigments that are largely responsible for colors of many fruits and flowers
Useful in treatment and prevention of many health conditions

Four categories:

PCO (Proanthocyanidins)

most potent PCOs are those bound to other PCOs
exist in many plants and red wine
commercially available sources are from grape seeds and bark from the maritime pine


serves as backbone for other flavonoids such as citrus flavonoids: rutin, quercitrin, hesperidin
these derivatives have sugar molecules attached to the backbone
most active of the flavonoids

Citrus bioflavonoids

include rutin, quercitrin, hesperidin, naringin
standardized mixture of rutinosides known as hydroxyethylrutosides (HER)
clinical results have been obtained in treatment of capillary permeability, easy bruising, hemorrhoids, and varicose veins

Green Tea Polyphenols

derived from tea plant camellia sinensis
produced by steaming the fresh cut leaf
polyphenol indicates presence of phenolic ring in the chemical structure
polyphenols = flavonoids
polyphenols in green tea: catechin, epicatechin, epicatechin gallate, epigallocatechin gallate, and proanthocyanidins
epigallocatechin gallate = most significant active compound

Dietary Sources

Citrus fruits
Green Tea
Red Wine

Average Daily Intake = 150-200 mg

Beneficial Effects

referred to as "nature's biological response modifiers" - modify body's reaction to compounds such as allergens, viruses, and carcinogens
powerful antioxidants by giving protection versus oxidative and free radical damage
prevents formation of oxidized cholesterol through antioxidant effects
greater antioxidant effects than Vitamins C, E, Selenium, and Zinc


increase intracellular Vitamin C levels
decrease capillary permeability and fragility
scavenge oxidants and free radicals
inhibit destruction of collagen

crosslinks collagen fibers to reinforce the natural crosslinking
prevents free radical damage

inhibits enzymatic cleavage of collagen by enzymes secreted by leukocytes in inflammation and microbes in infections
prevents release and synthesis and compounds that promote inflammation and allergies (histamines, prostaglandins, leukotrienes)
antioxidant effects are beneficial in:

aging process
chronic degenerative diseases (heart disease, arthritis, and cancer)
fat and cholesterol oxidation

antioxidants are produced by:

inhibiting xanthine oxidase noncompetitively(oxygen free radicals)
on the cellular level: PCOs are incorporated into the cell membranes along with the antioxidant effects offer great protection to cells against free radical damage.


anti-inflammatory activity due to inhibition of initial processes of inflammation

inhibits manufacture and release of histamine

potent antioxidant activity and Vitamin C sparing action
beneficial effects for diabetics

helps prevent diabetic cataracts, and retinopathy
enhances insulin secretion
protects pancreatic beta cells from free radical damage

antiviral activity

activity vs. herpes virus type 1, parainfluenzae3, polio virus type 1, and respiratory syncytial virus
in vivo, inhibits viral infection
may be of some benefit in the common cold

Citrus Bioflavonoids

antioxidant effects
increase intracellular Vitamin C, rutin, hesperidin, and HER
beneficial effects on capillary permeability and blood flow like PCOs
anti-allergy and anti-inflammatory effects like quercetin

Green Tea Polyphenols

potent antioxidant effects
increase activity of antioxidant enzymes in the small intestines, liver, lungs, and small bowel
inhibit formation of cancer causing compounds like nitrosamines in vitro

suppressing activation of carcinogens
trapping cancer causing agents
forms of cancer that green tea prevents best:

cancers of GI tract (stomach, small intestine, pancreas, colon)
cancer of the lungs
estrogen related cancers (inhibits estrogen interaction with its receptor)

consumption of green tea with meals inhibits formation of nitrosamines (nitrites combined with amino acids)

Principle Uses


Treatment of venous and capillary disorders

venous insufficiency
varicose veins
capillary fragility

Diabetic retinopathy and macular degeneration
Prevention of heart disease and strokes
Lowers blood cholesterol levels
Shrinks size of cholesterol deposits in the artery
Inhibits platelet aggregation and vascular constriction


In vitro, helps virtually all inflammatory and allergic conditions

hay fever
rheumatoid arthritis

Beneficial in diabetes and cancer

Citrus Bioflavonoids

Venous insufficiency
Improve microvascular blood flow and clinical symptoms (pain, tired legs, night cramps, and restless legs)
Improve venous function
Relieve hemorrhoidal signs and symptoms in pregnant women

Green Tea Polyphenols

Used principally to prevent cancer

Available Forms


Grape seed extract (92%-95%) and pine bark extract (80%-85%)
Used interchangeably, but grape seed extract is preferred
Grape seed extract is considered more potent and more effective than pine bark extract because only grape seed extract has gallic esters of proanthocyanidins which are the most active free radical scavenging PCOs


Available in powder and capsule forms
For anti-inflammatory effects, combination of Bromelain (pineapple enzyme) may provide additional benefit by enhancing absorption of quercetin
Amount of Bromelain should equal quercetin

Citrus Bioflavonoids

Mixed preparations are most widely used
Least active and quantified source of flavonoids

Green Tea Polyphenols

Commercial preparations that have been decaffeinated and concentrated for polyphenols (60%-80%)
1 cup = 300-400 mg of polyphenols
Downside = this dose also contains 50-100 mg of caffeine

Dosage Ranges


Preventive and antioxidant=50 mg/day of grape seed extract or pine bark extract
Therapeutic purposes dose=150-300 mg/day of either extract


200-400 mg taken 20 minutes before meals three times a day

Citrus Bioflavonoids

2000-6000 mg/day

Green Tea Polyphenols

For green tea extract standardized for 80% polyphenols and 55 % epigallocatechin gallate, the dose=300-400 mg/day

*Look for level of epigallocatechin gallate and total content of polyphenol

Safety Issues


safe, no toxicities, no side effects


Well-tolerated in humans
no side effects when taken in large quantities for long periods of time
safe for use in pregnancy
allergic reaction may occur-uncommon, but should result in discontinuation of product

Citrus Bioflavonoids

extremely safe
no side effects
safe in pregnancy

Green Tea Polyphenols

no side effects or toxicities
if product contains caffeine, overconsumption may result in a stimulant effect


Do not interact with any drugs
citrus bioflavonoids containing naringin may interact with drugs

naringin is found in grapefruit juice
can increase oral bioavailability of drugs like nifedipine, felodipine, verapamil, and terfenadine
inhibits breakdown of various drugs including: caffeine, coumarins, and estrogens

Vitamin C-Bioflavonoids may enhance the effects of vitamin C


Evans CA and Miller NJ. "Antioxidant activities of flavonoids as bioactive components of food." Biochemical Society Transactions. 24(3):790-795, 1996.
Hertog Michael, et al. "Flavonoid Intake and Long-term Risk of Coronary Heart Disease and Cancer in the Seven Countries Study." Archives of Internal Medicine. 155:381-386, 1995.
Kandaswami Chithan, et al. "Ascorbic acid-enhanced antiproliferative effect of flavonoids on squamous cell carcinoma in vitro." Anti-Cancer Drugs. 4:91-95, 1993.
Lale A, Herbert JM, et al. "Ability of Different Flavonoids to Inhibit the Procoagulant Activity of Adherent Human Monocytes." Journal of Natural Products. 59:273-276, 1996.
Murray MT. "Flavonoids." Encyclopedia of Nutritional Supplements. p. 320-331.
So Felicia, et al. "Inhibition of proliferation of estrogen receptor positive MCF-7 human breast cancer cells by flavonoids in the presence and absence of excess estrogen." Cancer Letters. 112:127-133, 1997.
Wiseman H. "Role of dietary phyto-oestrogens in the protection against cancer and heart disease." Biochemical Society Transactions. 24(3):785-789, 1996.
Xiao-duo Ji, et al. "Interactions of Flavonoids and Other Phytochemicals with Adenosine Receptors." Journal of Medicinal Chemistry. 39:781-787, 1996.

Thanks to the University of North Carolina School of Pharmacy for the use of this article.

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