A cup a day? Two? Or would you prefer no coffee at all? There are different opinions on the subject of coffee consumption: Studies often contradict each other in their recommendations as to whether and how many cups of coffee a day are healthy. Current research at least suggests that coffee does not increase the risk of cardiovascular disease.
Coffee can be good for your health, but the reverse is not necessarily true for caffeine, which is found in caffeinated energy drinks and shots.
Coffee works differently from person to person – for this reason alone, a specific recommendation for consumption is problematic for the general public.
According to current knowledge, coffee consumption does not cause cardiovascular problems.
Many of us don’t even start the day without a cup of coffee in the morning. Coffee is an emotional topic, for most people enjoying it is part of everyday life. But is that a good thing or a bad thing?
Is coffee healthy or not? After all, the natural product contains around 1000 different ingredients, some of which are still being researched by science. And the effect of coffee on our health is the subject of numerous studies, which come to different conclusions.
Current Studies: Is Coffee Healthy?
A recent review article published in the New England Journal of Medicine in 2020 suggests that moderate coffee consumption may even have health benefits. With a consumption of three to five cups of coffee a day, the physicians around Prof. Dr. Rob M. van Dam a reduced risk of chronic diseases such as cardiovascular disease, type 2 diabetes, some cancers and Parkinson’s disease.
Another 2019 study is from Queen Mary University of London and was funded in part by the British Heart Foundation. She studied the effect of coffee on the heart. The positive conclusion is that even 25 cups a day is no worse for the arteries than drinking less than one cup a day – so not harmful to heart health.
Even with more than three cups of coffee a day, no stiffening of the arteries
The 2019 UK study involved 8,412 subjects. The researchers divided them into three groups according to their coffee habits: less than one cup a day, between two and three cups a day, and more than three cups a day. The scientists then scanned the participants’ hearts using MRI and infrared pulse wave analysis. The researchers also included factors such as age, weight and smoking.
The result: The people in the third group also had no higher probability of artery stiffening (due to calcium deposits) than the subjects in group one. The heavy drinkers drank an average of five cups of coffee a day – only in a few cases actually 25 cups of coffee. “We would like to study these people more closely in the future to help make a recommendation for a safe border,” said Kenneth Fung, one of the study’s authors, in the university’s statement.
Not all coffee is equally good: In our coffee test, many ground coffees performed poorly. On the one hand, we found pollutants suspected of being carcinogenic and, on the other hand, we criticize the manufacturers’ lack of efforts to protect human rights and environmental protection in the production countries.
Safe coffee limit: 25 cups or just 6 cups a day?
However, the study result has already been interpreted by many media as a “safe limit” – although the researchers do not give an explicit recommendation to actually drink 25 cups of coffee per day. Fung admits in a statement that the investigation shows no causal relationship. But she proves “that coffee is not as bad for the arteries as previous studies suggest.”
One of these earlier studies, from the University of South Australia, came up with a very different “ceiling”: six cups of coffee per day. After that, the risk of heart disease increases by up to 22 percent – due to high blood pressure. Data from the British biobank of around 350,000 people aged 37 to 73 were included in the large analysis, published in the journal “The American Journal of Clinical Nutrition”.
Coffee studies that contradict each other
“There are several conflicting studies saying different things about coffee and it can be difficult to sort out what we should and shouldn’t believe,” says Metin Avkiran, deputy medical director of the British Heart Foundation. However, the British study rules out one of the potential adverse effects of coffee on our arteries.
The risk of coffee is difficult to assess
The International Agency for Research on Cancer (IARC), which is based at the World Health Organization (WHO), carried out a new hazard classification for coffee in 2016: Since then, the IARC has classified coffee as “”not classifiable in terms of its carcinogenicity for humans”. Previously, coffee was still “possibly carcinogenic (=carcinogenic) in humans”.
In this context, the Federal Institute for Risk Assessment (BfR) points out that the risk assessment for a complex mixture such as coffee is only of limited value. BfR President Professor Dr. dr Andreas Hensel explains: “Every food can regularly, but usually only in traces, contain substances that have carcinogenic potential. However, health-promoting substances are often also effective.”
According to the BfR, coffee contains substances that promote health as well as ingredients that, in isolation, can have a carcinogenic effect on humans. According to the current study situation, however, there is no evidence of a carcinogenic potential through coffee.
Irrespective of this, however, the BfR points out the health risk posed by caffeine. Caffeine can therefore lead to nervousness, insomnia, cardiac arrhythmia, increased blood pressure and gastrointestinal disorders.
For healthy adults, however, a temporary intake of up to 200 mg of caffeine – about two cups of filter coffee – is considered harmless to health. Adults can drink about twice that amount throughout the day – that’s four cups of coffee. For pregnant and breastfeeding women, it should not be more than two cups of coffee a day. However, this information is not recommended drinking amounts, but only amounts that are considered harmless to health in a healthy general population.
Coffee works differently from person to person
A weakness of previous studies on coffee and its effects on health: Previous studies often did not consider an unhealthy lifestyle as a risk factor. For example, it is important to consider whether coffee drinkers are also smokers – which is often the case. Otherwise, one may mistakenly attribute a harmful effect to coffee that should actually be attributed to cigarettes.
What should not be forgotten in all this: Coffee (and the caffeine it contains) affects people differently – and for this reason alone it is problematic to make a specific recommendation for consumption for the general public.
Is drinking coffee good for your bones?
Another long-standing scientific debate surrounding coffee is the risk of osteoporosis. In 2013, Swedish researchers examined the connection in a large long-term study with 61,433 women born between 1914 and 1948. They came to the conclusion that excessive coffee consumption leads to a slight decrease in bone density. However, there is no significantly increased risk of osteoporosis.
In November 2019, scientists from the University of Hong Kong published a study that came to an even more positive conclusion: regular coffee drinkers even had a higher bone mineral density. However, the study with 564 adult subjects was comparatively small – and the investigation was mainly based on the self-report of the participants.
dr Chad Deal of the Cleveland Clinic, who was not involved in the study, nevertheless commented confidently on the result in a press release: “For anyone who drinks a lot of coffee and is concerned about the health effects, this is good news. It seems to be working out that coffee in general is probably good for bone health.”
Coffee is not the same as caffeine
The research group around Dr. In her study, Rob Van Dam from the University of Singapore points out that a distinction must be made between coffee and caffeine. The health benefits that coffee consumption may bring do not necessarily apply to caffeinated beverages such as energy drinks or shots. These could be quite dangerous – especially together with alcohol. Cardiovascular, psychological and neurological disorders are among the side effects and complications of caffeinated beverages.
Conclusion: Coffee can be part of a healthy diet
Our conclusion: Öko-Test has already pointed out in the past that coffee has another problem that is not taken into account in the studies: it contains the substance acrylamide, which is a by-product of coffee roasting. In animal experiments, acrylamide causes cancer and damages the genome, which in all probability also applies to humans. Individual coffee products repeatedly attract attention with increased values - even if the exposure has decreased in recent years. In our current coffee test, the laboratory we commissioned also found increased levels of acrylamide from our point of view.
If the pollutant has been reduced as much as possible by the producers, luxury coffee can definitely be part of a healthy diet. But we find it difficult to set a specific limit on how many cups of coffee it should be per day.
The current study situation can be interpreted in such a way that the consumption of almost five cups a day does not entail any major risks – however, the recommendation per se cannot be applied to everyone. Compared to the Apotheken Umschau, nutritionist Dr. Anna Flögel: “At least moderate consumption is more likely to be associated with a generally reduced risk of illness”. In this context, moderate coffee consumption means two to four cups of coffee a day.