| Rooibos as antioxidant
There is now a general belief amongst scientists that certain food
substances, so-called antioxidants, can play a role in preventing
cancer, cardio-vascular diseases and ageing. Examples of well
known antioxidants are vitamin C and vitamin E, two food substances
which form part of a normal healthy diet. Our food also contains
other components with strong antioxidant activity, known as flavonoids.
Since Rooibos is very rich in flavonoids, it is highly likely that the
health promoting properties are linked to the antioxidant effects of
flavonoids.
The role of oxygen free
radicals in Rooibos Tea
Our bodies use oxygen to convert food items such as fat and sugar
into energy, in this process, oxygen is converted to water, and each
water molecule normally takes up four electrons. However some
oxygen may escape before the conversion is complete, and this results in
about 2% of the oxygen having an electron deficit. These particles
are called free radicals or super oxide radicals. They may also be
formed in the human body through other processes, such as air pollution,
smoking and exposure to radiation. Free oxygen radicals are
extremely reactive and can cause damage to body proteins and fats, and
also to the hereditary material of cells, known as DNA. The oxygen
free radical (super oxide radical) can be converted to even more
damaging radicals by a chain reaction.
Fortunately our bodies have some protective mechanisms against the
harmful effects of free oxygen radicals and other even more powerful
radicals such as the so-called peroxides and hydroxyl radicals.
The protective mechanisms are enzymes and antioxidants.
Some enzymes in the human body are capable of neutralizing the oxygen
free radicals as soon as they are formed. The best known of such
enzymes is called SOD (super oxide dismutase). SOD and other
enzymes convert super oxide and damage to lipids and to DNA This
mechanism slows down in later life, so that the damage may accumulate
and become visible as the process of ageing, when tissues lose their
elasticity. Damage to the hereditary material (DNA) in a normal
cell may cause it to become a cancer cell. It is also
thought that free radicals may play a role in the development of
cardiovascular disease such as atherosclerosis (here the coronary
arteries become blocked by a gradual thickening of the wall).
Antioxidants in Rooibos prevents damage
The chain reaction of damage in the
human body caused by free radicals can be interrupted by
antioxidants. Vitamin E, which is found in vegetable oils, is the
most effective antioxidant. It stops the chain reaction by
becoming a radical itself, but since it is stable, no further damage is
done. Other well known antioxidants are vitamin C and carotenoids,
found in fruit and vegetables. Finally, there are the flavonoids,
which occur in abundance in Rooibos.
Flavonoids and free radicals in Rooibos Tea
Flavonoids are powerful antioxidants, and have more antioxidant
activity than vitamin C. Laboratory studies have shown that the
antioxidant activity of Rooibos is more or less similar to that of black
tea and green tea. The flavonoids of Rooibos are now well
known. The major one is aspalathin, found only in Rooibos and
nowhere else. Several other flavonoids have been identified,
including nothofagin, vitexdn, lsovitex, orietin, isoorientin, luteolin
and quercetin. in the process of fermentation, aspalathin may be
converted to other substances but these possibly have even better
antioxidant properties than aspalathin itself. Much research
remains to be done on Rooibos flavonoids, but it is reasonable to assume
that the health promoting properties are partly due to the antioxidant
effects of the flavonoids. |
