Report: The pros and cons of coffee
Coffee lowers the risk of developing type 2 diabetes, depression, Parkinson’s, Alzheimer’s – and the list goes on. There are, however, cases where coffee isn’t very good for us.
A recent review of all the relevant research about coffee and a number of public health diseases concludes that coffee is good for us.
But – there is always a but – there are also cases where coffee isn’t so good for us, and we also do not know exactly why coffee is good for us. Since the report is available in Danish only, we’ll let the main author elaborate:
“It was important to us to debunk some of the myths around coffee, and that’s what we have done,” says Professor Kjeld Hermansen of Aarhus University’s Department of Clinical Medicine.
”For instance, coffee does not cause cancer or problems with the heart. There are, however, cases where we should be careful with our coffee consumption.”
The pros of coffee
Our report includes a number of studies which indicate that regular coffee consumption can inhibit the development of some types of cancer.
The report states that a moderate intake of coffee can have a health-promoting effect. An intake of three to four cups a day is associated with:
- A 25-percent reduction in the risk of developing type 2 diabetes and Parkinson’s disease.
- A 10-percent reduction in the risk of apoplexy.
- A beneficial effect on Alzheimer’s disease and depression.
”In fact, our report includes a number of studies which indicate that regular coffee consumption can inhibit the development of some types of cancer,” says Hermansen.
However, although the report is based on a huge dataset, there are very few clear-cut conclusions to be drawn, he says: “The report mainly includes indications, so further research is needed in this field.”
Coffee is not great for everyone?
Those who should be careful with their coffee consumption include anxiety sufferers, pregnant women and those who consume insufficient amounts of calcium.
- For people who suffer from an anxiety disorder, caffeine can have an anxiety-inducing effect.
- Pregnant women should drink no more than three cups a day, as a higher consumption may be harmful to pregnancy.
- For people with a low calcium intake, caffeine may be harmful, as it increases the calcium excretion in the urine and may therefore increase the risk of fractures and osteoporosis.
It is important to keep in mind that when we are talking about ’coffee’, we’re talking about a drink that contains many different substances. We cannot actually say which of these substances, or which combinations of these substances, have a positive effect.
The keyword here is ’caffeine’, says the professor, since much of the research in this field has only focused on the effects of caffeine, and this has been equated with coffee.
We don’t know why coffee is healthy
The question is what we mean when we talk about ’coffee’. Are we referring to the caffeine, or is it the combination of the hundreds of bioactive substances found in coffee, the full effects of which will probably never be examined separately?
”It is important to keep in mind that when we are talking about ’coffee’, we’re talking about a drink that contains many different substances. We cannot actually say which of these substances, or which combinations of these substances, have a positive effect,” he says.
“The positive effect of coffee on e.g. type 2 diabetes is also observed in decaffeinated coffee, which suggests that it isn’t necessarily the caffeine that does the trick.”
In order to demonstrate a significant effect of the bioactive substances, it would require large intervention studies and control groups where each of the substances is studied individually, and this would be extremely difficult and expensive.
”The existing studies about coffee are mainly observational studies, i.e. large population studies in which it is difficult to establish any solid causal effects.”
Coffee is not just coffee
Any true coffee fan would agree that coffee isn’t just coffee. There are great differences between, say, espresso, filter coffee and instant coffee, and there may be great differences in the health-promoting effects depending on which kind of coffee we drink.
”What we know mainly stems from the good old filter coffee. We actually don’t know a lot about the more modern coffee types such as cappuccino and instant coffee,” says the professor, adding that there is no data that documents the effects of large amounts of coffee, whether it be ‘new’ or ‘classic’ coffee.
“There is no solid data for consumption of more than eight cups of coffee a day, and it is not right to assume that the more coffee you drink, the healthier it is. The most positive effect is achieved by drinking three to four cups a day. We don’t know about the effects of very large quantities of coffee.”
Hermansen and his team of researchers are planning to take another look at the report in a couple of years’ time and then compare its findings with the latest research.