We analyse global research on how consuming non-alcoholic drinks such as arsenic-contaminated water, tea, coffee and maté affects the risk of developing cancer.
There is strong evidence that:
Recommendations have not been made about coffee as there are still too many unanswered questions.
A global recommendation about consumption of mate has not been made as this is consumed only in specific parts of the world. Nevertheless, the Expert Panel of scientists who judged the evidence advises that mate should not be consumed scalding hot in the traditional style.
There is no global recommendation for arsenic in drinking water, as individuals do not have the power to control whether or not their local water supply is contaminated. However, contamination of water supplies with arsenic is a public health issue. Authorities should ensure that safe water supplies are available when such contamination occurs. Water contaminated with arsenic should not be consumed.
Access to clean drinking water is essential to health. However, drinking water can be contaminated by harmful substances, including arsenic. Agricultural, mining and industrial practices can contaminate water with arsenic. Arsenic can also occur naturally in water due to natural geological deposits or volcanic activity.
The International Agency for Research on Cancer (IARC) has judged drinking water contaminated with arsenic to be carcinogenic to humans. The primary regions where high concentrations of arsenic have been measured in drinking water include large areas of Bangladesh, China and West Bengal (India).
Maté is an infusion (brewed using boiling water), which is drunk almost exclusively in parts of South America. It’s a type of herbal tea prepared from the dried leaves of the plant Ilex paraguariensis. Maté is traditionally drunk scalding hot through a metal straw. Drinking very hot beverages such as mate is graded by IARC as probably carcinogenic to humans.
Coffee and tea are the two most commonly consumed hot drinks. Coffee is made from ground, roasted coffee beans – the dried seeds of coffee plant berries. Many different qualities, varieties and forms of coffee are available. These include arabica and robusta coffee beans, roasted or green coffee beans, as well as instant coffee and soluble powders made from finely ground coffee beans.
There are also various different methods of preparing coffee depending on culture and personal preference. Decaffeinated coffee is produced by various processes, using water, organic solvents or steam, or by interfering with the expression of the gene coding for caffeine.
Tea is specifically the infusion of the dried leaves of the plant Camellia sinensis. Green tea, which is often preferred in China, is made from leaves that have first been cooked, pressed and dried. To produce black tea, the fresh leaves are withered, rolled repeatedly, allowed to turn deep brown and then air-dried until they are dark in colour.
Evidence on whether consumption of milk affects the risk of cancer is considered in the section on Meat, fish and dairy.
Consumption of sugar-sweetened drinks is a cause of weight gain, overweight and obesity. However, there is no direct link to cancer risk. For more on this, see the section on Obesity and weight gain.
There is no strong evidence in humans to suggest that artificially sweetened drinks with minimal energy content, such as diet sodas, are a cause of cancer.
Access to clean drinking water is essential to health.
The water content of the body is around 70%: men tend to have a higher proportion of water in their bodies than women, because women naturally have more body fat, which has minimal amounts of water.
Drinking water can contribute to intakes of essential elements, such as calcium, iron and copper, depending on its origin and the piping materials used. It can also be used as a vehicle to provide fluoride.
Even mild dehydration (water loss of 1-2% of body weight) can produce symptoms such as a dry mouth and headaches. Stopping all fluid intake causes death in days, with the exact length of time depending on the health of the individual and environmental conditions such as temperature and humidity.
Approximately 80% of water intake comes from drinks; food provides the other 20%.
Environmental conditions, health, activity levels and other factors determine the amount of water needed, but there is no international recommendation for daily consumption. The Institute of Medicine in the USA recommends 2.7 litres per day total water for women and 3.7 litres for men.
Public Health England advises drinking 6-8 glasses of fluid a day – around 1.2 litres – to prevent dehydration. Water, lower-fat milk and sugar-free drinks including tea and coffee all count.
Adults produce an average of around 1.5 litres of urine each day. An additional litre of water is lost through breathing, from the skin by evaporation or sweating, and in the faeces.
In 2018, we produced the Diet and Cancer Report, the third in our series of major reports looking at the many ways in which our diets, and how active we are, affect our cancer risk. You can find out much more about non-alcoholic drinks and the risk of cancer by downloading a pdf of the relevant chapter in the 2018 report. Please note, however, that this webpage may have been updated since the report was published.