Antioxidants are components which help to protect cells from harmful “free radicals”, known as oxidants. Free radicals occur naturally in the body as a by-product of the respiration process and can bring about cell damage. Antioxidants help to prevent this cell damage, which can contribute to ageing and a number of chronic diseases, including cancer and heart disease and strokes.
It was thought until comparatively recently that green tea was the most effective antioxidant-containing tea and that green-tea catechins (the unoxidized polyphenols present in tea leaf) alone were the antioxidants giving tea its health-giving attributes. It is now well known that the theaflavins and thearubugins produced by the condensation of oxidized catechins, during the fermentation stage of black tea manufacture, are equally effective antioxidants (Leung et al 2001). The catechins present in tea flush and as such in green tea are: Expressed as a % of dry weight Epicatechin 1 – 3% Epicatechin gallate 3 – 6% Epigallocatechin 3 – 6% Epigallocatechin gallate 9 -13% Catechin 1 – 2% Gallocatechin 3 – 4% During manufacture of Black Tea these catechins get oxidized & polymerized (condensed), for example : Epicatechin + Epigallocatechin gallate + Oxygen —> Theaflavin The paired catechins as they appear in Black Tea are now known to be equally effective antioxidants. The body produces free radicals (FRs) under certain conditions. Carcinogens and radiation from the environment facilitates the formation of FRs. These FRs within the body cause oxidative changes to DNA (the genetic material present in all cells). Changes to DNA carry the risk of cancers. The FRs are inhibited and destroyed by the antioxidants in tea, both green and black tea. Green and black tea comes from Camellia Sinensis. Green tea is unfermented, steamed immediately after plucking, and retains a lighter colour and flavour. Black tea is allowed to ferment and is then dried, resulting in a darker leaf colour and a more flavour and aroma.
Research conducted at the University of Newcastle shows that drinking tea could help improve memory and also slow the development of Alzheimer’s disease. The functioning of the brain cholinergic system, which is involved in attention and memory declines during normal aging and is further affected in Alzheimer’s disease. Current drugs for the symptomatic treatment of dementia are aimed at enhancing the associated cholinergic deficit by inhibiting acetylcholinesterase, an enzyme that cleaves the neurotransmitter acetylcholine. Butyrylcholinesterase increases in the brains of people with Alzheimer’s disease and may play a role in the progression of the disease by its ability inter alia to hydrolyse the neurotransmitter Acetylcholine. Inhibition of both these enzymes is one of the objectives in treating cognitive dysfunction associated with diseases such as Alzheimer’s disease. During the study it was found both green and black tea inhibited the activity of the enzyme acetylcholinesterase, and also hinder the activity of the enzyme butyrylcholinesterase. It was further observed that Green tea obstructed the activity of beta-secretase, which plays a role in production of protein deposits in the brain that are associated with Alzheimer’s disease. So this study reports that tea infusions in vitro have dual anti-cholinesterase and anti-β-secretase activities relevant to the treatment of dementia. Previous studies have shown that both green tea and black tea possess pharmacologically protective, properties such as antioxidative, anticarcinogenic, neuroprotective and hyppocholesterolaemic effects. This study indicates that Tea, Camellia sinensis has the potential to enhance cholinergic function and therefore may have a role in ameliorating and cholinergic deficit in Alzheimer’s disease and other age related memory impairments. The effects of tea infusions on the cerebral cholinergic system and β-secretase in vivo will depend on the levels of the enzymes in the brain, the type and chemistry of the tea, infusion concentration (strength), dose (number of cups per day) and duration of consumption. It is also possible that regular consumption of tea by patients with dementia prescribed cholinesterase inhibitors may alter the effects of such drugs. Clinical and scientific investigation of the chemistry and activities of cholinomimetic and anti- β-secretase compounds in C. sinensis, and cognitive effects of tea consumption is warranted in order to establish the relevance of these novel findings to the maintenance of cognitive function in old age and in diseases such as Alzheimer’s Disease.
Tea contains fluoride and therefore drinking tea makes a significant contribution to daily fluoride intake and the reduction of tooth decay. It has been found that not only fluoride but the polyphenols in tea also act to reduce tooth decay. Recent studies have further revealed that tea inhibits the growth of other harmful microorganisms in the oral cavity.
Many in vitro studies have demonstrated the anti-oxidant properties of both black and green tea, as well as the antioxidant activity of the polyphenols in tea. Further studies have shown that these anti-oxidant components of tea are absorbed into the blood circulation from the digestive tract and act as anti-oxidants in body systems. These findings indicate that tea drinking helps to reduce the risk of heart disease, stroke and cancer, common degenerative diseases.
An Amino Acid found in plants which was first referred to by Dr. R. L. Wickremasinghe in 1978 in context of its influence on the quality of tea. Subsequent research conducted in Japan and elsewhere suggests that L-theanine facilitates relaxation and may benefit the regulation of blood pressure in humans, as well as mental clarity, concentration and the immune system. L-theanine is different to caffeine in producing a calming effect. It is the predominant amino acid component in tea and whilst the amount of L-theanine in tea depends on several factors – climate, soil and sunlight – clinical studies suggest that consuming 6-8 cups of tea a day would offer 200-400mg of L-theanine whilst it is said to be effective in doses ranging from 50mg to 200mg. Fresh Tea in particular is likely to be rich in L-theanine and researchers recommend it, amongst other things, for coping with stress and also for increasing ‘life energy’.