Tea and It’s Benefits
Tea has been consumed for almost 50 centuries now and continues to be a very popular drink. In fact, black and green tea are the most widely consumed beverages in the world, next to water. Leaves of the camellia sinensis plant are brewed to make tea.
There are 4 major types of tea, as discussed below:
- White tea – These tea leaves are exposed to the least amount of processing of all the teas. The leaves used are young leaves or buds, they are therefore the ‘freshest’. This is a more expensive variety of tea.
- Green tea (unfermented) – The leaves are steamed or heated quickly. This process prevents the breakdown of the catechins (an antioxidant, discussed in more detail below).
- Oolong tea (semi fermented)– The processing of oolong tea is somewhere in between green tea and black tea. This a premium loose tea.
- Black tea (fermented) – This is the most processed form of tea. The leaves undergo treatment by heat and crushing. Fermentation gives black tea a stronger flavour.
Some evidence has suggested that white and green teas have more health benefits than oolong and black tea. This is relative to the degree of processing – tea that is processed less and more quickly has a shorter exposure to oxygen (oxidation) which can have damaging effects on the good properties of tea.
Studies of tea
There has been a lot of research conducted around the health benefits of drinking tea. The compounds in tea that are credited for its protective properties are called polyphenols.
|What are polyphenols?
Polyphenols are an antioxidant that can be obtained from the diet. Catechin is the main polyphenol in tea that is said to be responsible for the potential health benefits experienced.
Studies conducted in vitro and on animals have shown promising evidence to support the benefits tea has on preventing the development and progression of several chronic diseases – in particular cardiovascular disease and cancer. More research needs to be done to say for certain whether or not tea prevents certain chronic disease (and in what quantity), as studies in humans have drawn differing conclusions.
Why might tea not be protective?
Possible reasons that tea may not be effective in preventing or slowing progression of chronic disease is that catechins are not easily absorbed in the body. Additionally, there may be other factors inhibiting their absorption such as the flora in the gut and the addition of milk to tea.
Proposed health benefits of tea
Most of the studies that have shown a positive relationship between tea and anticancer properties have been more closely linked to green tea than black tea. The suggested benefits gained from regular tea consumption include:
- Helps towards a strong immune system
- Helps with gut function
- Reduction in the risk of cardiovascular disease
- Reduction in the risk of certain types of cancer
- Regulation of blood pressure
The mechanisms behind the protective effects of tea are listed below:
- Vasculoprotective effects – This means protection of the blood vessels. This helps to prevent against heart disease.
- Anti-oxidative effects – Prevents the oxidation of molecules, thereby reducing the production of free radicals that are damaging to cells.
- Anti-thrombogenic effects – This means protection against the formation of blood clots. The word thrombus means clot.
- Anti-inflammatory – Reduction of inflammation protects against heart disease. Green tea is also thought to curb the severity of liver disease due to its anti-inflammatory properties.
- Lipid lowering effects – Lipids include different types of fat. Green tea in particular is thought to lower “bad” cholesterol levels.
All of the 4 types of tea have a caffeine content. There are however decaffeinated versions.
The majority of studies conducted on tea have used caffeinated tea. The results can therefore not be transferred to decaffeinated tea varieties. It is possible that the decaffeination process removes the substances that are responsible for the health benefits received.
There may be more research needed on the extent to which tea promotes good health, however, the role tea plays in protecting against certain disease still looks promising! And if nothing else, it at least contributes towards daily water intake.
Contact us for results focused nutritional advice
This article was written by our nutritionist Belinda Elwin who is a Dietitians Association of Australia member and Accredited Practising Dietitian.
If you have questions about healthy eating choices or for a personalised meal plan, contact your local doctor who will arrange for you to see Belinda. For healthy eating advice, Contact us today!
Khan N, Mukhtar H. Tea Polyphenols For Health Promotion. J Life Sciences. July 2007 Volume 81(7).
Better Health Channel. Tea Leaves and Health. State Government of Victoria. Updated July 2013. Available from: Better Health Channel website.