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In June 2016, the International Agency for Research on Cancer (IARC) announced that it had lowered the level of cancer risk for us from drinking coffee. It was very good news.
The question came from afar. Specifically from 1991, when the evaluation of the studies then available by the IARC experts led to classifying coffee consumption as “possibly carcinogenic to humans.”
But the science corrects itself, and 25 years later, after an exhaustive review of more than a thousand studies in humans and animals, the same agency concluded that there was not enough evidence – scientific knowledge or evidence based on scientific knowledge – on the carcinogenicity of coffee.
And, therefore, their consumption was classified in group 3. There is only one group below, group 4, for an exposure that “probably does not cause cancer.”
Above group 3 there are three groups: 2B (substances or activities “possibly carcinogenic to humans”, which includes lead), 2A (substances or activities “probably carcinogenic to humans”, where the red meat and infection by malaria) and 1 (substances or activities «carcinogenic to humans», where the tobacco and alcohol).
With a commendable interest –not without disappointments–, a large part of society, its media and social organizations are often dealing with the results of the evaluations of the IARC and other global regulatory organizations. Organizations whose relative planetary influence we also live during the covid-19 pandemic.
Before bringing to our lips an evaluation of the
IARC or another scientific institution should let it cool for a minute. If we have a report on the possible carcinogenicity of coffee, red meat or any other exposure, it is understood that it is convenient to calm down. In fact, thinking calmly is a practice that is less used than desirable, but very useful, and often within everyone’s reach.
Well, after the minute of rest we can sip the evaluation little by little, appreciating its nuances. This time, the first sip is pleasant, as the agency reassures us: the level of cancer risk associated with drinking coffee has decreased. Best of all, it calms with a scientific basis.
IARC experts are top-tier researchers. They work systematically, exhaustively, rigorously, independently and transparently. This time they have analyzed in depth, with human intelligence, more than a thousand studies, which is said soon. Approximately half of them have been carried out in laboratories, and the rest in human populations that live and consume coffees of all kinds and in all kinds of real circumstances.
Today “analyzing real data” is promoted as if it were a new trend. As I tell you in Nearby Epidemiology (Triacastela, 2022), doctors, epidemiologists and other professionals have spent years studying real people and populations living in real conditions. That is different from studying volunteers under experimental, unusual conditions, such as in the so-called phase I clinical trials of drugs and vaccines, for example.
That yes, as in a good oriental coffee, in the evaluation of the IARC there is a trace of uncertainty. Oh! Science is what you have. Same as life…
During the covid-19 pandemic we have also experienced uncertainties and learned from them. This does not imply that we should be aware of all the new studies every day: we can wait for the rigorous evaluations that from time to time assess what is known. The work of global organizations like the IARC is not trivial, it is complex and relevant.
Let’s keep sipping that coffee. We can also appreciate that it is good – that it tastes good – that scientific knowledge changes. Knowledge tastes good. Knowing tastes good.
In the last decades we have learned a lot of things. For example, how to do better research and studies with greater validity (with less bias). Often overcoming mistakes, such as those made by associating coffee with pancreatic cancer or urinary bladder cancer. Mistakes made years ago by excellent researchers. We have also learned to better integrate biological, clinical and epidemiological knowledge.
Meanwhile, many crops, roasts and, therefore, the coffees we buy, how we prepare them and consume them, have improved. We can enjoy many positive changes.
Although almost nothing is perfect. And our attitudes to social change are powerfully influenced by our current economy, culture, history and choices.
Awareness of the rich biological, clinical, and psychosocial effects of coffee, tea, and other beverages containing methylxanthines dates back to ancient times. Today, caffeine is the most consumed psychoactive agent. It has been dubbed “the world’s most popular drug.” Many plants contain it, but it is also synthesized and added to foods and beverages. Caution there. It has various clinical uses, for example as a treatment of apnea (shortness or suspension of breathing) in premature neonates, or together with analgesic substances in pain medications. Drinking coffee practically never affects the physical health of the vast majority of healthy people.
Then there is the endless number of substances contained in the hundreds of different coffees that we drink on earth. Its countless aromas, in atmospheres so different, so similar. The no less fascinating secular cultures of coffee in the world, and those common gestures that bring us together when drinking it: fingers, cups, aromas, lips, throats, flavors, terraces… world coffees. Coffees, and conversations, and affections.
So let’s savor the good news from IARC, sip by sip, without becoming obsessed, with perspective. Calm. Thinking also of the many disorders whose risk is not increased by coffee either. Although there are some that do, because from a certain dose it can enhance nervousness or anxiety; and, in some people, cause sleep disturbances.
We can know how much coffee is reasonable to drink without side effects. If you like, drink it in moderation. He is too old to know how many cups and at what times.
Enjoy the profession of living and that art or ritual – drinking coffee – in your own way.
Miquel Porta Serra. Professor, Hospital del Mar Institute for Medical Research – IMIM
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