Majority people in the world know and consume tea or coffee at least one time in a day. Some people drink more than one cup per day every day. But little do they know that tea can also be harmful if consumed in large amount.
Harmful Effects of Tea
So, how can tea be harmful? Let’s talk about this. But first let me tell you, here I am referring to those made up of milk, tea leaves, etc and not green tea. Tea is composed of polyphenols, alkaloids (caffeine, theophylline, and theobromine), amino acids, carbohydrates, proteins, chlorophyll, volatile organic compounds (chemicals that readily produce vapours and contribute to its odour), fluoride, aluminium, minerals, and trace elements.
Now, as you drink an excessive amount of tea, fluoride in it will cause skeletal fluorosis, which is a bone and joint disease. It is even difficult for doctors to diagnose this as its symptoms are very similar to other bone diseases. This can develop even if a person consumes doses of fluoride even as low as 10 mg/day. (NRC 1993; Whitford 1996; IOM 1997; ATSDR 2003). Even though the susceptibility of this disease is very subjective but still study suggests a positive relationship. To put this into perspective, a tea bag contains 0.4-0.5 mg of fluoride. So, you can calculate how much fluoride do you consume. Btw research also shows that skeletal fluorosis can also develop if a person consumes doses even as low as 5 mg/day.
Interestingly research also shows that drinking hot tea was strongly associated with a higher risk of oesophageal cancer. There is little evidence of health risks for adults consuming moderate amounts of caffeine (about 300 to 400 mg per day). Black teas have higher caffeine content followed by oolong tea. Green and white teas contain slightly less caffeine. Caffeine also has harmful effects such as insomnia, restlessness, headache, nausea, vomiting, etc if consumed excessively.
According to NCI (National Cancer Institute), amidst all the myths, there is no evidence or relationship between use of tea to prevent cancer. This myth is due to the fact that they contains polyphenols. These polyphenols are antioxidants, but there isn’t any hard fact about its role in treating cancer.
Yes, tea can be harmful, but generally, all these effects are applicable to someone who drinks it in large amounts for eg, about 3-4 litres daily (which surprisingly some people did e.g., the case of a 47-year-old woman). Research also showed that chance of prostate cancer in men is increased by 50% in those who drank 7+ cups than those who drank 0-3 cups. So if you drink 0-3 or even 4 cups you would be fine. For some extra health conscious people, you could switch to green tea.