| 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. 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).
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 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. |
