Do hot beverages really present risk?
IARC’s ruling for very hot beverages regarding throat cancer has no relevance to the great British cuppa, confirms scientific panel.
Contrary to media reporting today, tea does not cause oesophageal cancer or other cancers. Throat cancer, the 8th most common cancer is caused by a multitude of factors, including smoking, lifestyle, alcohol, obesity and genetics to name but a few factors.
Commenting on the reporting today, Dr Tim Bond from the Tea Advisory Panel notes:
“The confusion of today’s reporting has arisen from an announcement made today by The World Health Organisation’s International Agency for Research on Cancer (IARC).
It is important to note that IARC is only considering the temperature of beverages in this particular announcement launched today, and focuses solely on risks, not benefits. Tea itself continues to be given a clean bill of health since it was given a Group 3 rating by an IARC committee several years ago, defined as no evidence to enable any classification for cancer.
A recent literature review by the TAP revealed that regular tea consumption had either a beneficial effect by reducing the risk of cancer (272 publications including 177 mechanistic studies) or no impact on cancer risk (127 publications). In addition, laboratory and human intervention trials, including randomised-controlled studies, suggest that black and particularly green teas lower cancer risk.
Of particular note among these publications is a recent meta-analysis of 18 studies which found that drinking black tea was associated with reduced risk of mortality, cardiovascular disease and cancer. With regards to cancer deaths overall risk was reduced by 21% in the highest compared with the lowest category of tea drinking. For CVD mortality, overall risk was reduced by 12% in the highest category of black tea drinking (not statistically significant). The highest consumers of green tea had a significant 33% reduction in cardiovascular disease mortality compared with the lowest consumers. Both black and green teas significantly reduced all-cause mortality. High black tea consumption compared with low consumption reduced the risk of death by 10%, while high green tea green consumption reduced risk by 20%.
The Tea Advisory Panel is following the IARC proceedings closely noting that a 2A classification (probably carcinogenic to humans) set to be given to very hot beverages, including soup and coffee, was based on observational studies, the majority looking at populations living in the Middle and Far East, South America and in particular one cohort study from Japan which followed a group of subjects between 1965 and 1981.
Thankfully, this IARC ruling on temperature has no relevance to tea drinking in the UK where tea is typically consumed with milk. Preliminary research, undertaken found that a cup of tea (170ml water) cooled from 63 degrees C, before the milk, was added to 58.6 degrees C in three minutes. The milk (30 ml from the fridge) was added after the tea had brewed for 3 minutes. A study by UK burns doctors, supports this research data further. Using standardised beverages, the research which was published in the journal of Burns found that a cup of tea with 10 ml of milk cooled to less than 65 degrees C within 5 minutes. Also, the preferred temperature for hot drinks, according to consumers, was around 60 degrees C.
This is supported by the Royal Society of Chemistry which recommends drinking tea at 60-65 degrees C. This is described as a moderate temperature and does not present any health risk. IARC was concerned about the issue as people in other countries drink beverages at far hotter temperatures with temperatures as high as 70 degrees C observed in Iran and Tanzania.
TAP is hopeful that emerging evidence suggesting that tea drinking could reduce the risk of cancer may one day be recognised by health authorities in Europe as it is in the USA where the US National Cancer Institute reported that polyphenols in green tea and theaflavins and thearubigins in black teas possess several attributes which could help to prevent cancer. These include ‘substantial free radical scavenging activity’ which may protect cells from DNA damage caused by reactive oxygen species, inhibition of tumor cell proliferation and promotion of apoptosis (normal cell death), inhibition of angiogenesis and tumor cell invasiveness, and protection against damage caused by ultraviolet B radiation.
Tea and herbal infusions provide many other health benefits, according to clinical trials, such as heart health, reducing high blood pressure, supporting normal hydration, improving dental health and helping to maintain bone health. This is very good news for the 80% of British adults who regularly drink tea.
In conclusion, this latest announcement from IARC today for very hot beverages has no relevance to the great British cuppa enjoyed by millions of people daily. Tea has been confirmed by many organisations, such as Public Health England, as a healthy drink, which supports normal hydration. Emerging evidence suggests that tea contributes to heart health and may help to reduce the risk of cancer, although this needs to be backed up with further human studies. In the meantime, tea drinkers in the UK can continue to enjoy tea in the traditional way with a drop of milk which ensures that the temperature of tea sits within safe limits.