If you’re an avid coffee consumer you must have been delighted to see in the news lately that coffee can have beneficial health effects. Coffee had previously confusingly been in the bad books blamed for everything from stunting growth to causing heart disease and insomnia.
It had also been shown that high consumption of unfiltered coffee (boiled coffee popular in Scandinavian countries or espresso invented in Italy and spread all over the world) fails to catch a compound called cafestol in the oily part of coffee that can increase the bad cholesterol or LDL.
Not so good.
So what changed?
The good news was based on a scientific review aimed to dispel some of that confusion, examining the evidence presented in 218 previous studies. It’s an example of the ever more popular meta-analysis of existing research that by combining previous findings strengthen the proof of the conclusions.
In synthesising the reported findings the researchers found that coffee consumption was more often associated with benefit than harm for a range of health outcomes across exposures. Three to four cups a day seemed to be optimal.
Drinking coffee was consistently associated with a lower risk of death from all causes and a lower risk of several cancers, as well as type 2 diabetes, gallstones and gout.
Liver conditions, such as cirrhosis, saw the greatest benefit associated with coffee consumption. There also seemed to be beneficial associations between coffee consumption and Parkinson’s disease, depression and Alzheimer’s disease.
Overall, there was no consistent evidence of harmful associations between coffee consumption and health outcomes, except for those related to pregnancy and for risk of fracture in women.
Spoiling the good news story
We shouldn’t spoil a good news story, but we have previously mentioned the presence of toxic acrylamide and furan especially in coffee. Now the European Food Safety Authority has published a new opinion on furan confirming the previous suspicion that furan in food could be harmful to health. Based on animal studies they concluded that liver damage and liver cancer are the most critical health effects.
Although the average intake of food containing furan indicates a low health concern for most consumers, for high consumers exposure is up to three times what would be considered of low concern for public health.
The most exposed group of people are infants, mainly through consumption of ready-to-eat jarred or canned foods. Exposure in other population groups is mainly from consumption of grain-based foods and, here you have it, coffee, depending on age and consumer habits.
The highest concentrations of furan were found in whole roasted coffee beans, with a mean value of 4,579 µg/kg. High mean concentrations of furan were also found in ground roasted coffee (2,361 µg/kg) and instant coffee powder (310 µg/kg). This should be compared to mean values ranging from not detected to 57 µg/kg for most other foods.
All is not lost
There is a serious anomaly between the observational findings that coffee consumption is associated with a lower risk of liver damage, while on the contrary animal studies link the presence of furan in the diet to liver damage. And coffee provides the highest exposure to furan in adults.
What’s to give?
As bad as the concentrations of furan seem to be in solid coffee samples, in preparing the coffee beverage there is both a dilution and an evaporative loss of furan down to typical concentrations of about 60 µg/L in the final beverage. Still bad for heavy coffee drinkers.
But there is more.
Coffee contains a complex mixture of bioactive compounds benefiting health.
It contributes a large proportion of the daily intake of dietary antioxidants, greater than tea, fruit, and vegetables. Chlorogenic acid is the most abundant antioxidant in coffee; though it is degraded by roasting, alternative antioxidant organic compounds are formed. Caffeine also has significant antioxidant effects.
Cafestol and kahweol induce enzymes involved in carcinogen detoxification and stimulation of intracellular antioxidant defence, contributing towards an anticarcinogenic effect.
These antioxidant and anti-inflammatory compounds are likely to be responsible for the beneficial associations between coffee consumption and liver health, and might neutralise the effects of furan.