Does Drinking Black Tea Have Any Negative Health Aspects?

Black tea is the main form of tea that is consumed in the western world. In the United Kingdom three quarters of the adult population drink tea daily, drinking on average about a pint a day.

Although many people know that black tea contains many components that are beneficial to ones health, such as flavonoids, essential oils and vitamins, black tea is also thought to have many negative aspects due to its caffeine content, and its effect on water retention.

Black Tea and Caffeine

A cup of tea on average contains around 40 mg of caffeine per cup (17mg/ml). This is much less than found in brewed coffee (~120mg per cup), and about 4 times that as is found in decaffeinated coffee (~10mg per cup).

Is caffeine good for you or bad for you? In short yes to both.

There are mixed health benefits related to the consumption of caffeine. It's positive impacts include increased alertness, cognitive performance and physical endurance when caffeine is consumed at a quantity of 60 to 400 mg per day (on average about one and a half to 10 cups of tea a day).

The negative aspects of caffeine consumption include dehydration, anxiety, insomnia and hypertension.

Black Tea and Mood

With regards to mood the consumption of black tea tended to be positive with increased alertness, ability to process information and happier moods (possibly due to the black tea component theanine). On the other hand the consumption of black tea also resulted in the negative aspects known from caffeine consumption such as a reduction in length and quality of sleep.

Black Tea and Fluid Balance

Caffeine is known to have a diuretic effect, it is therefore thought that the consumption of tea may lead to affects in fluid balance. When thinking about these diuretic effects of tea it is important to remember that tea is mainly water, and so you are dehydrating yourself through the effect of caffeine you are also rehydrating yourself with water. Research into tea consumption and its diuretic effects showed that about 300mg of caffeine, equivalent to seven cups of tea had to be drunk until a diuretic effect was seen.

So in conclusion the ill effects of black tea may be virtually eliminated if tea is not dunk in excess (seven cups a day), and many benefits can be obtained from a moderate consumption of black tea per day, say three or four cups; these include a reduction in the risk of heart disease, a possible reduction in the risk of colorectal cancer, and an increase in cognitive function.

References

Gardner et al (2007). Black tea – helpful or harmful? A review of the evidence. Journal of Clinical Nutrition. 61: to 18
Green and Suls (1996). The effects of caffeine on ambulatory blood pressure, heart rate, and mood in coffee drinkers. Behav Med: 111 to 128.
Food Standards Agency (2004). Survey of caffeine levels in hot beverages. FSA Surveillance Unit.
Maughan and Griffin (2001). Tea Drinking And Fluid Balance: A Review. Bond Tea Company: UK.