Talkin' About Tea

We all love a good brew whether its Yorkshire tea, pg tips or green that’s your cup of tea, as Brits we drink on average 165 million cups a day! I’ve been thinking recently what are the benefits of tea? Most people will have heard of green tea and how its magical properties are claimed to help you lose weight and live forever but I’m going to look at how and why this has come about and is it the best brew we could be drinking?

Green, white, black, oolong; all these teas comes from the plant Camellia sinensis or ‘Chinese tea,’ they are just prepared differently or harvested at different stages in the plants life creating these different varieties. 20% of the harvest of Camellia sinensis is for green tea, which is prepared from the fresh, young leaves which are gently steamed, pan-fried and then dried ready to infused and drunk as tea. 78% of the world’s resources are harvested for black tea, which comes from the leaves also but is fermented before drying.  Oolong is part fermented black tea and white tea is made from the buds and young leaves of the tea plant which are steamed and dried, whilst undergoing minimal oxidation, it could be argued that white and green tea are the least processed it could be that these are better for your health and could contain a higher level of antioxidant polyphenols and flavonoids.

Green vs black: as they are prepared differently there are differing properties and benefits of each one. All tea varieties contain flavonoids which are compounds that are reported to give antioxidant effects which can contribute to decreasing risk of heart disease and cancer and reduce inflammation. It is thought that green tea contains higher levels of catechins and polyphenols flavonoids, which are speculated to be affected by growing conditions, leaf age and storage during transport of tea. There is some sceptism on the lack of evidence of whether there is significant difference of polyphenol levels between green and black tea. Both contain caffeine which affects thinking and alertness and may improve brain function by stimulating the release of neurotransmitters in the brain, this could be very useful in improving and/or preventing severity of Parkinson’s disease. Green tea contains phytoestrogens and also the amino acid, L-theanine.

Green tea when drunk is likely to be effective for high cholesterol as studies have shown people who consume more green tea have lower levels of LDLs (low-density lipoprotein i.e. the ‘bad kind’) and higher levels of HDLs (high-density lipoproteins) and can reduce total cholesterol in people with high cholesterol blood levels. There is some evidence that drinking green tea regularly may reduce risk of coronary heart disease (particularly in men moreso), and could lower high blood pressure, although there is some conflicting evidence on this but there are further suggestions it may also help those with low blood pressure particularly in the elderly. Green tea could potentially be very beneficial for women who are post-menopausal as some studies show regular, long-term consumption of green tea could increase bone mineral density therefore reducing risk of osteoporosis and possibly increasing bone density for those who already may have osteopeonia or osteoporosis. Green tea bags can be used once brewed and removed from the cup, and allowed to cool can be used as a compress to soothe and also can be laid on the eyes to decrease puffiness under the eyes, and to relieve tired eyes or headache, and also to stop gums from bleeding after a tooth is pulled.

One of the most common effects of drinking green tea that comes up is that it increases metabolism and therefore could help overweight people lose weight faster and more effectively. However, there is conflicting evidence regarding whether green tea beverages can reduce BMI and overall weight, it seems the higher amount of catechins and caffeine present may have an effect but when trials isolated caffeine alone, found it does not have an effect but green tea with the natural caffeine content present may have a slight effect on reducing waist circumference and BMI. Most research shows that if the only factor changed in the diet is drinking green tea, it is likely not going to reduce overall body weight or BMI.

Black tea seems to have similar effects and properties to green tea; with studies showing the possible benefits could be helping with low blood pressure after eating, lowering risk of heart attacks, osteoporosis and lower risk of Parkinson’s disease. The fermentation of tea leaves produces a constituent, theaflavins which cause the pigment of black tea and are not present in green tea and may have antioxiandt and possible mutagenic effects. Black tea also contains gallic acid which is thought to have a calming effect. Black tea generally contains more caffeine than non-fermented green tea, both in the region of 2-4%. The tannin content in black tea may also have antioxidant effects, although should be taken with care of iron levels are low, as tannins can inhibit absorption of iron in the gut and so could worsen anaemia particularly if drunk with meals so should be drunk 2 hours away from food. There is some speculation that drinking black tea with milk added inhibits some of these beneficial constituents as it may bind the antioxidants preventing them from being absorbed in the gut. There is not enough evidence to prove this though, so cannot be confirmed.

Dosage maximum 3 x daily ideally away from meals. Some research has shown that the longer the brewing time the phenolic content increases potentially increasing antioxidant property, in which they were tested between 0.5 minutes and up to 10 minutes. 

There are some possible negative effects to drinking tea mostly if drunk in very large amounts, it contains naturally occurring caffeine due to the xanthine constituents, too much caffeine can cause headaches, anxiety and sleep disruption and isn’t recommended in high amounts for pregnant or breastfeeding mothers (no more than 3 small cups per day). Although there is less caffeine content in green (2-4%) and white tea varieties than black, there is still caffeine content in all types of tea. The present constituents; theophylline and aminophylline which in large amounts can cause heart palpitations, insomnia and convulsions. Too much black tea would be consuming five or more cups in a day and is when possible unsafe side effects could occur such as headaches, nervousness, vomiting, diarrhoea, tremor, dizziness or confusion.