So what are Antioxidants anyway?

You read about them all the time these days - studies show that the antioxidants in wine, chocolate, berries, pomegranates and of course tea are good for you.    So that is a given!

But what does it really mean and what do they really do?

Lets see if I can explain it ...

Free Radicals

Firstly before we can know what an antioxidant does we need to understand Free Radicals.

Free radicals are highly reactive unbalanced molecules capable of damaging cell membranes and tissues within your body. 

Your metabolism automatically generates these free radicals, which are capable of causing cellular damage.  The body normally is capable of managing free radicals through internal systems – for example using them as part of our immune system.  

Also our exposure to environmental and dietary free radicals greatly increases the free radical load on the body.    There are many of these external sources of free radicals:-

• Pollution, ultraviolet rays from the sun, smoking, rancid fats, radiation, pesticides, medications, alcohol, stress, junk food.

WHAT ARE ANTIOXIDANTS?

Antioxidants are the body’s defence for reducing the damaging effects of free radicals.  Most commonly known antioxidants are vitamins and minerals such as vitamins A, C & E and the mineral selenium. 

Plants also contain antioxidants and each different plant will have a different type of antioxidant.

Antioxidants may provide protection to cell membranes from the damaging action of free radicals.

Antioxidants neutralise cellular free radicals, or unstable molecules that seek out the electrons of other cellular molecules in order to gain chemical stability.

By donating excess electrons to the unstable free radicals, these antioxidants are able to prevent a chain effect of cell degeneration that can lead to the disturbed cell cycles that cause cancer or other diseases that stem from cellular mutations.

An example of free radical action is what happens when you cut and apple in half and leave it on the bench – within minutes it will start turning brown!

This is free radical damage!

To stop this happening squeeze a little lemon juice on the apple – it stops and slows the browning!

This is an example of an antioxidant – in the case of the lemon Vitamin C!!

Flavonoids

These are a group of plant pigments with remarkable protection against free radical damage.  These compounds are largely responsible for the colour of fruits and flowers.  They are often called bioflavonoids and the two terms are interchangeable.

• Flavonoids serve as protectors against environmental stress, and seem to function as ‘biological response modifiers’.
• They appear to modify the reaction to other compounds such as allergens, viruses and carcinogens.
• They are anti-inflammatory, anti-allergic, anti-viral and anti-carcinogenic.
• As a whole group they tend to support the cardiovascular and circulatory system.
• But they also act as anti-clotting agents, help prevent atherosclerosis, strengthen collagen, stabilise capillary walls and reduce capillary leakage.
• Flavonoids are active against a wide range of free radicals. 

Over 4000 different flavonoids have been found. 

Some different flavonoids appear to have a preference for specific tissues.  For example – the flavonoids in milk thistle have an affinity for the tissues of the liver.  The flavonoids in Ginkgo have an affinity for the central nervous system.  The flavonoids in black tea tend to help the cardiovascular system.

Different Types of Flavonoids

Quercetin, rutin and hesperidin

Are found in fruits and vegetables, particularly in citrus fruits.

• They have an ability to increase the levels of vitamin C in the cells.  They also improve capillary permeability and blood flow and are thus good for preventing bruising. 
• Quercetin is one of the most active of the flavonoids.  It has a significant anti-inflammatory effect because it directly inhibits several processes that lead to inflammation.  For example it inhibits both the production of and the release of histamine and other allergic/anti-inflammatory components in the body.  Because of this action it is useful for reducing the symptoms of asthma and Hayfever.

Epicatechin

Found in cocoa

• Improves blood flow and therefore is good for cardiac health. 
• The major ingredient in dark chocolate has been found to have nearly twice the antioxidant of red wine. 

Proanthocyanidins and anthocyanodins

Are found in purple coloured foods such as grapeseed extract, bilberry, blueberries, blackcurrants, red grapes and red wine. 

Polyphenols

Are found in grape skin – often referred to as OPCs (oligomeric proanthocyanidins). 

• Both red and white wine contain flavonoids, however since red wine is produced by fermentation in the presence of grape skins, red wine has higher amounts and contains other antioxidants such asresveratrol. 
• They have shown in studies to reduce blood fat, lower blood pressure, prevent artherosclerosis and prevent blood clots.

Polyphenols are also the type of antioxidant found in Tea!

ANTIOXIDANTS IN TEA

The antioxidants found in the tea plant are classified as polyphenols and the four primary polyphenols are called catechins:

• epigallocatechin gallate (EGCG),
• epigallocatechin,
• epicatechin gallate
• epicatechin.

Like other antioxidants, polyphenols prevent against the oxidation, and consequential degeneration and mutation of cells.

• The tea catechins are responsible for the pungency and bitterness of tea.  Teas with a higher level of catechins, such as green tea, can be more bitter.
• Another feature of tea catechins is the very potent anti-microbial action.

In fresh leaf catechins can be up to 30% of the dry weight and due to this high level has one of the highest total flavonoid contents of all plants. 

EGCG

The EGCG is the dominant catechin – representing more than 50%.

EGCG shows almost 20x the anti-oxidative potency of vitamin E, and almost 10x that of vitamin C.

• The EGCG polyphenols in green tea have been found to lower the stress hormone, cortisol, in the blood faster, after a stressful event. 

They are present in nearly all teas made from Camellia sinensis - Catechins are highest in concentration in white and green teas, which black tea has less due to its oxidative preparation. 

Green Tea contains between 30-40% of water extractable polyphenols, which black tea contains between 3-10%

The longer the oxidation process, the less catechins.