Today I was presenting our work, my work, in collaboration with IARC on the temperature of beverages, the tea and other things that we drink, in Moshi, in my area where I come from. So we were looking at how much temperature do people drink hot tea, like at what temperatures. The reason that we are looking at this is because it has been shown that there is a correlation between how hot you drink your tea or coffee or anything to the development of oesophageal cancer. The biological plausibility behind that theory is that when you drink a very hot liquid you increase the thermal injury down your oesophagus which slowly can actually cause an atypia which probably may lead to the development of oesophageal cancer. The causal relationship is yet to be established but at least now we know that there is a very linear correlation between the two, between exposure to this risk factor and the development of oesophageal cancer.
The first study was done in Iran and, as I said, it was a correlation of about 100% between a hot beverage of above 60o centigrade and the development of oesophageal cancer. What we did in Moshi was really not to look on the correlation, we just wanted to establish a baseline of the temperature at which people drink their tea. We found that actually people in Moshi drink tea at a temperature higher than any temperatures that have been currently established in literature. So the comparables are the US, UK and Brazil. The closest is in Brazil where they start drinking their tea at a temperature of about 70 while in Moshi they start drinking their tea, they are comfortable to start drinking tea, at a temperature of about 72-73o centigrade which is very high.
Is there likely to be a similar causal relationship in other countries?
No, as I said, it has not been established to be a causal relationship but there is a correlation. There is a linear correlation that the more likely that you drink your tea then it has been shown to be hand in hand with increased chances of getting oesophageal cancer. So we probably cannot tie that to other regions, the reason being the way we prepare tea back home and the way other settings they prepare their tea is different. So back home we mix both milk and water together and we boil it and then we may actually add tea and sugar in the cooking pot which gives no time for tea to cool down before we start drinking. So as opposed to the setting that we are talking about, the UK and Europe and probably the US where they add cold milk after they serve their tea in a cup which really reduces the temperature, but also there is a longer span of drinking the tea which allows it to cool down. So the timespan that we found in Moshi in drinking the tea is an average of five minutes to finish the cup whereas, as you know, in the UK it may actually take longer because people do that while they are doing some work. In Tanzania people do that in the morning before they do anything else to kind of get that energy to be able to go to the field or to go to your work. We don’t drink tea while we are working. It might be starting now but the setting that we looked at is actually taking your tea before you go out for some work.
Are you advising people to drink cooler tea as a result of this study?
We are really not there yet. But what we know now is, as opposed to Iran, we drink where there is a correlation already. This correlation has been established, we know that we are drinking… people in Moshi drink their tea at a higher temperature. The good thing is we’ve started a better quality case control study where tea drinking temperature will be part of our ongoing research. We are going to establish now the more scientific correlation, the more scientific association, in terms of how much oesophageal cancer would be related to exposure to hot liquid drinking in Moshi.
How many people were involved in the study and how was it carried out?
Previous to this study we had done a previous study where we mapped out ten years’ worth of data of the cases from oesophageal cancer. We found out that there was one area called in Moshi where more cases had come from. So we decided for this small study that I’m describing, we decided to take a sample of 200 people, subjects not cases, from that area. What we did was to select 100 households and in each household we interviewed two people, so we gave out a self-reported questionnaire and we measured the temperature of the tea. Other things that we investigated were alcohol and smoking which are already known to be risk factors for oesophageal cancer.