Flavonoid

FLAVONOID

Description

What are flavonoids?

Flavonoids, an amazing array of over 6,000 different substances found in virtually all plants, are responsible for many of the plant colors that dazzle us with their brilliant shades of yellow, orange, and red.

Classified as plant pigments, flavonoids were discovered in 1938 when a Hungarian scientist named Albert Szent-Gyorgyi used the term "vitamin P" to describe them.

The chemistry of flavonoids is complicated, and within the non-technical term "flavonoids" can be found many different chemical groups of substances. These groups include flavonols, dihydroflavonols, flavones, isoflavones, flavanones, anthocyanins, and anthocyanidins. Within each of these groups fall hundreds, and sometimes thousands of different flavonoids.

For example, well-known flavonols include quercetin, rutin, and hesperidin, while well-known flavones include apigenin and luteolin. Flavonoids may also be named directly after the unique plant that contains them. Ginkgetin is a flavonoid from the ginkgo tree, and tangeretin is a flavonoid from the tangerine.

How it Functions

What is are the functions of flavonoids?

Protection of cell structures

Most flavonoids function in the human body as antioxidants. In this capacity, they help neutralize overly reactive oxygen-containing molecules and prevent these overly reactive molecules from damaging parts of cells. Particularly in oriental medicine, plant flavonoids have been used for centuries in conjunction with their antioxidant, protective properties. Scultellaria root, cornus fruit, licorice, and green tea are examples of flavonoid-containing foods widely used in oriental medicine. While flavonoids may exert their cell structure protection through a variety of mechanisms, one of their potent effects may be through their ability to increase levels of glutathione, a powerful antioxidant, as suggested by various research studies.

Vitamin C support

The relationship between flavonoids and vitamin C was actually discovered by mistake. Dr. Albert Szent-Gyorgyi, the Nobel Prize winning researcher who discovered flavonoids, was attempting to make a preparation of vitamin C for one of his patients with blood vessel problems. The preparation he gave the patient was not 100% pure--it contained other substances along with the vitamin C. It worked amazingly well.

Later, when Dr. Szent-Gyorgyi purchased a pure solution of vitamin C, he found it was not nearly so effective with his patient. He suspected flavonoids as the magic addition to vitamin C in his first impure preparation. Present-day research has clearly documented the synergistic (mutually beneficial) relationship between flavonoids and vitamin C. Each substance improves the antioxidant activity of the other, and many of the vitamin-related functions of vitamin C also appear to require the presence of flavonoids.

Inflammation control

Inflammation--the body's natural response to danger or damage--must always be carefully regulated to prevent overactivation of the immune system and unwanted immune response. Many types of cells involved with the immune system--including T cells, B cells, NK cells, mast cells, and neutrophils--have been shown to alter their behavior in the presence of flavonoids. Prevention of excessive inflammation appear to be a key role played by many different chemical categories of flavonoids.

Antibiotic activity

In some cases, flavonoids can act directly as antibiotics by disrupting the function of microorganisms like viruses or bacteria. The antiviral function of flavonoids has been demonstrated with the HIV virus, and also with HSV-1, a herpes simplex virus.

Deficiency Symptoms

What are deficiency symptoms for flavonoids?

Excessive bruisability, nose bleeds, swelling after injury, and hemorrhoids can be indicators of flavonoid deficiency. Generally weakened immune function, as evidenced by frequent colds or infections, can also be a sign of inadequate dietary intake of flavonoids.

Toxicity Symptoms

What are toxicity symptoms for flavonoids?

Even in very high amounts (for example, 140 grams per day), flavonoids do not appear to cause unwanted side effects. Even when raised to the level of 10% of total caloric intake, flavonoid supplementation has been shown non-toxic. Studies during pregnancy have also failed to show problems with high-level intake of flavonoids.

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect flavonoids?

Heat, degree of acidity (pH), and degree of processing can have a dramatic impact on the flavonoid content of food. For example, in fresh cut spinach, boiling extracts 50% of the total flavonoid content.

With onions (a less delicate food), boiling still removes about 30% of the flavonoids (and specifically, a group of flavonoids called the quercitin glycosides). Overcooking of vegetables has particularly problematic effects on this category of nutrients.

Factors that Affect Function

What factors might contribute to a deficiency of flavonoids?

Poor intake of fruits and vegetables--or routine intake of high-processed fruits and vegetables--are common contributing factors to flavonoid deficiency. It is difficult to overemphasize the impact of processing and a non-whole foods diet on flavonoid intake. If the pulpy, fibrous parts of fruits are eliminated from the juice, and the vibrant natural colors of canned vegetables are lost during repeated heating, risk of flavonoid deficiency is greatly increased.

Nutrient Interactions

How do other nutrients interact with flavonoids?

Present-day research has clearly documented the synergistic (mutually beneficial) relationship between flavonoids and vitamin C. Each substance improves the antioxidant activity of the other, and many of the vitamin-related functions of vitamin C also appear to require the presence of flavonoids.

  

Health Conditions

What health conditions require special emphasis on flavonoids?

Flavonoids may play a role in the prevention and/or treatment of the following health conditions:

• Allergy
• Asthma
• Atopic dermatitis
• Candida infection
• Cataracts
• Diabetes
• Gout
• Hemorrhoids
• Macular degeneration
• Migraine
• Periodontal disease
• Stomach ulcer
• Varicose veins

Food Sources

What foods provide flavonoids?

Virtually all fruits, vegetables, herbs and spices contain flavonoids. They are also found in other types of food, including dry beans (where they give red beans,black beans, and speckled beans their color) and grains (where the color provided by flavonoids is usually in the yellow family). Products made from the foods above (for example, wines made from grapes) also typically contain a wide variety of flavonoids.

While the flavonoid family is too complex to report all of its food connections, some highlights are especially important. In the fruit family, it is berries that come out highest in the chemical category of flavonoids called anthocyanins. Black raspberries, for example, may contain up to 100 milligrams of anthocyanins per ounce.

Green tea has flavonoid components called catechins that may reach 1,000 milligrams (or 1 gram) per cup. In general the more colorful components of the food--like the skins of fruits--contain the highest concentration of flavonoids. An exception to this rule, however, is the white pulpy inside of oranges. Unlike the watery orange-colored sections of this fruit, which contain virtually all of its vitamin C, the orange's flavonoids are found in the white pulpy portion inside the skin and surrounding the sections

What Does A Tea Leaf Contain? - Fresh-cut tealeaves consist of 75-80% water. A variety of green tea flavors are formed through the combination of three main taste components:

 Catechin– Bitterness & Astringency

 Caffeine– Bitterness
Theanine & Amino Acids– Flavor & Sweetness

In this section you'll learn what's in a tea leaf, and about the effect of these specific ingredients in green tea: Catechin, Caffeine, the Amino Acids Theanine & Butyric Acid, Vitamins A, B1, B2, B3, C, E, F, K, P, & U, Chlorophyll, Minerals, Pectin, Saccharides, Saponin and a handy comparison of ingredients in green teas.

Catechin - Catechin is a tannin peculiar to green tea because the black tea fermentation process reduces catechins in black tea. Catechin is a powerful, water soluable polyphenol and antioxidant that is easily oxidized.

Several thousand types are available in the plant world. As many as two thousand are known to have a flavon structure and are called flavonoids. Catechin is one of them.

Research aimed at finding the active compounds in green tea revealed that its protective effects are due chiefly to catechins. Tea contains four main catechin substances: EC, ECg, EGC and EGCg, all of which are inclusively called catechin. Epigallocatechin gallate (EGCG) is the most powerful of these catechins. EGCG as an antioxidant is about 25-100 times more potent than vitamins C and E. One cup of green tea provides 10-40 mg of polyphenols and has antioxidant effects greater than a serving of broccoli, spinach, carrots, or strawberries. The high antioxidant activity of green tea makes it beneficial for protecting the body from oxidative damage due to free radicals. Research shows that green tea may help the arterial wall by reducing lipids. Green tea can protect against experimentally induced DNA damage, and slow or halt the initiation and progression of undesirable cell colonies. Studies show evidence that green tea provides immunoprotective qualities, particularly in the case of patients undergoing radiation or chemotherapy. White blood cell count appear to be maintained more effectively in patients consuming green tea compared to non-supplemented patients.

Green tea is manufactured from fresh, unfermented tea leaves; the oxidation of catechins is minimal, and hence they are able to serve as antioxidants. Researchers believe that catechin is effective because it easily sticks to proteins, blocking bacteria from adhering to cell walls and disrupting their ability to destroy them. Viruses have ‘hooks’ on their surfaces and can attach to cell walls. The catechin in green tea prevents viruses from adhering and causing harm. Catechin reacts with toxins created by harmful bacteria (many of which belong to the protein family) and harmful metals such as lead, mercury, chrome, and cadmium.

Tannin in green tea is mostly catechin and is a key component in its taste providing the astringency. The amount of catechin tends to increase as the season progresses. Spring tea (first crop) contains 12-13% catechin (13-17% as tannin) while summer tea (third crop) contains 13-14% (17-21% as tannin). If leaf order is compared, younger leaves include more catechin than mature ones. First leaves contain 14%, second 13%, third 12%, and fourth 12%. This explains why second and third crop summer teas are more astringent while Bancha is less so. Gyokuro green tea, whose leaves are covered during growth, contains less catechin and astringency (10% as tannin) because it gets less sunshine then Sencha