DRINKING VERY HOT TEA INCREASES RISK OF CANCER
Last week, I read an article by CNN that reported researchers found that drinking very hot tea almost doubles the risk of cancer. The research was published in the International Journal of Cancer. The devil’s in the details, and I will take this opportunity to add my two cents worth to the debate on healthy tea. I feel there’re two important points from the article.
First, the research is not new as a report in 2018 by Annals of Internal Medicine found there could be link between cancer and very hot tea drinking, but only in people who also smoke and drink alcohol. This latest research is the first to pinpoint a specific temperature.
People who drink tea at warmer than 60˚C (140˚F) and drink more than 700ml of tea per day (about 2 large cups), had a 90% higher risk of esophageal (windpipe/throat) cancer compared to those who drank less tea and at cooler temperatures. According to International Agency Research on Cancer (IARC), esophageal cancer is the eighth most common cancer globally and claims 400,000 victims annually.
Putting this new research into perspective, since 2016, IARC had announced drinking very hot beverages, not just tea, as a potential carcinogen. From the same CNN article, it quoted Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, saying heat was the issue rather than the type of beverage.
Second, the new research was conducted based on a sample size of 50,045 people in Iran, aged between 40 and 75. In UK, Europe and US, tea is rarely consumed above 65˚C (149˚F), but in places like Iran, Russian, Turkey and South America, it’s common to drink at that temperature or hotter.
Temperature & tea’s antioxidants levels
Lots of articles had been written about healthy tea benefits. Antioxidants are the compounds that help reduces the risk of cancer. In general, the less ‘processed’ or more ‘natural’ a tea, the higher antioxidants level. Temperature, steeping duration and taste factor into the equation of a tasty and healthy tea.
According to Journal of Food Science, white tea showed the most antioxidants when left to steep for a long time regardless of hot or cold water, barring taste. Green tea’s antioxidants peak when steeped in cold water for long time. Oolong tea is very sensitive to high temperatures, and if you want oolong to show the most antioxidant, it’s a good idea to infuse it cold. Black tea produce the most antioxidants when brewed for a short time in very hot water.
Cold brew tea
Cold brew tea is often associated with Summer, but actually it’s a drink for all seasons. In our office, tea is served daily. No surprises. We love a comforting hot brew to warm ourselves in chilly days as well as a cold brew to keep ourselves hydrated.
There’s no elaborate tea recipe per say to make cold brew tea, unlike making a tea mocktall. Making cold brew tea is really simple. Substitute hot water with room or cold water in a jar with either loose leaf tea or tea bags. Leave in refrigerated to steep. The tea should be ready to drink within 2 to 3 hours or if you prefer a richer brew; leave it to steep overnight.
I imagine there’re many choices of teas suitable for cold brew. Within our own Quinteassential range of nine unique teas, all are suitable for cold brewing except Signature Breakfast, which is a black tea blend.
Besides antioxidants, there’re a host of compounds that are beneficial to the body. There’re many research that showed cold and room temperature may be the best method to brew healthy tea. For example, hot infusion in a short steeping time showed rapid extractive power, but compound degradation. While cold infusion showed higher level of healthy molecules.
Results are permutations of tea types, temperature, and steeping time. The latest research about hot tea and cancer is an interesting read and good to know; perhaps over a cup of tea, hot or cold. But I wouldn’t loose sleep over it. Cheers!