Hot drink and soup lovers (like myself) panicked last week when scientists gathered at the International Agency for Research on Cancer (IACR) and concluded that drinking coffee and other “very hot drinks” may cause cancer. This was published in the medical journal, the Lancet.
Cancer From Hot Beverages Long Thought to be Possible
This is not the first time the harmful effects of hot drinks was examined. The carcinogenicity of coffee drinking was last assessed by IARC in 1991. At that time coffee was classified as “possibly carcinogenic to humans”.
For this re-evaluation, a much larger database of more than 1000 observational and experimental studies were studied.
When scientists examined the studies, they in fact found that coffee was protective against endometrial (womb) and liver cancer, and also showed antioxidant effects on the liver
When they examined the effects of drinking Mate (a South American beverage), however, they found that there was an association with drinking “very hot” mate and esophageal (gullet) cancer. Alarmingly, similar trends were found for drinking other hot and very beverages, such as tea.
The risk of contracting esophageal cancer were found to be about 2.4 times more than the general public who does not indulge in very hot drinks.
The Scientific Theory Behind Hot Drinks and Cancer
Hot beverages and food can cause damage to the lining of the esophagus when consumed. The damage induces an inflammatory response, and over time, the can lead to chronic inflammation, injuring the cells in the esophageal lining. Eventually, DNA damage occurs, leading to abnormal cell growth, and cancer.
How Hot is “Very Hot”?
The Working Group noted that the epidemiological evidence for very hot beverages and human cancer has strengthened over time. Additionally, new studies in experimental animals show that hot water above 65°C can act as a tumour promoter. The scientists at IARC concluded that drinking very hot beverages at above 65°C was classified as “probably carcinogenic to humans” (Group 2A).
What Should I Do? Stop Drinking My Favourite Soup?
There is no need to stop drinking your favourite mum’s-specialty watercress soup. But to be on the safe side, it will be good not to drink it too hot.
We often consume soups which come straight out of a boiling pot – and this is definitely too hot. As a rule of thumb, if it scalds, or requires you to blow at it to cool it down before you can drink if comfortably, the soup is definitely above 65°C.
Similarly, for hot teas (which are often infused in boiling water), do take time to let the drink cool down before you consume it. Don’t stop drinking your coffee and tea though – the antioxidant effects definitely outweigh any risk of esophageal cancer, especially when you do not go above the magic number of 65°C.