Truth about ultra-hot drinks and our health
Herald reporter Jane Phare has drunk scalding-hot tea and ‘extra-hot’ coffee all her adult life. But could all that steaming liquid damage the throat and gut, and even lead to cancer?
I’ve got those annoying little “smokers’ lines” above my top lip. Odd, because I’ve never smoked — apart from coughing my way through a single Pall Mall Menthol as a teenager.
I’ve worked out they’re actually “blow lines”, from decades of first, cooling really hot cups of tea and second, pursing my lips to sip cautiously on a liquid I know will be too hot.
Hot tea was part of my upbringing, and then came the extra-hot coffee when I discovered cafe life.
Bliss . . . until I read studies that showed a link between drinking very hot liquids and oesophageal cancer. Having wrestled with breast cancer, twice, over the past 10 years, that possibility was alarming.
But it seems that all that blowing and lip pursing could have saved me, and never mind the smokers’ lines.
Experts in New Zealand are aware of the studies but say, calm down. The cancer link is more likely to be in countries like Iran, China, Turkey and in South America where people tend to drink large quantities of scaldinghot black, green or herbal tea over long periods of time. Even then, they’ve thrown doubt on the accuracy of the hot-drink studies, saying they don’t take into account other factors like smoking, cooking over an open fire, alcohol consumption and genetics.
In New Zealand, smoking, high alcohol consumption and obesity are far more likely to lead to oesophageal cancer than a hot cuppa.
The odd gulp of something too hot, burning the tongue, mouth and throat on its way down, is not going to cause cancer, they say.
The most common type in New Zealand is adenocarcinoma, but that’s associated with gastric reflux, and linked to obesity, which, incidentally, is linked to 13 different types of cancer.
Squamous cell carcinoma, the type of cancer overseas studies have linked to extra-hot drinks, is less common in New Zealand: around 400 cases a year compared to 3500 cases of bowel cancer. And those cases are unlikely to be caused by extra-hot coffees, gastroenterologists say.
Auckland gastroenterologist Alasdair Patrick, director of The MacMurray Centre, doesn’t think there’s a significant risk in New Zealand that those who drink hot tea or coffee will develop oesophageal cancer. “I don’t think we have our drinks as hot as they have them in countries like Iran.”
Emma Shields, the Cancer Society of NZ’s national adviser on cancer prevention, agrees. She says the studies were done in countries where traditionally drinks are drunk at extremely hot temperatures, like yerba mate, a herbal tea from South America. “It is traditionally served scalding hot (and drunk) through a metal straw.
“These are the sorts of hot drinks where this data has come from.”
Patrick lived in India as a child and remembers women on the trains drinking “seriously hot” tea.
“I couldn’t even put it in my mouth and these amazing women would just sit there and drink it.”
But normally, our reflexes protect us from swallowing something too hot.
“Generally if you drink something that’s too hot it will burn your mouth and tongue and you’ll spit it out.”
Patrick also wonders if tea drinkers in countries where squamous cell carcinoma is high boil their water for considerably longer to get rid of waterborne infections.
“Whereas we’re pretty happy to half boil our water and make a cup of tea as opposed to boiling it for five minutes.”
Scientists are not exactly sure why there is a link between hot drinks and oesophageal cancer. One theory is that the hot liquid gradually damages the oesophageal cells, which increases inflammation and sets off a cancer pathway.
Another theory is that hot drinks could damage the lining of the oesophagus allowing other cancercausing substances, like smoking, to find their way into the cells.
The advice to those who like their drinks extra hot is to wait a minute before taking the first sip, add a dash of milk or, by all means, create a few blow lines on the upper lip.
Generally if you drink something that’s too hot it will burn your mouth and tongue and you’ll spit it out.
Auckland Alasdair Patrick, gastroenterologist