Coffee: friend or foe?
Written by Dr. Josie Fullerton, Postdoctoral Research Associate at the Institute of Cardiovascular & Medical Sciences, University of Glasgow.
For many, coffee is an essential part of their daily routine. We get up, put the kettle on, and have a cup of strong coffee before starting our working day. Unsurprisingly, coffee is one of the most widely consumed drinks across the globe. But is coffee good or bad for you?
Previous research has shown that coffee may have a combined positive and negative effect on our health. For example, coffee can slow disease progression in the liver, such as fibrosis. Yet, for those who suffer with anxiety, coffee can increase the likelihood of panic attacks.
Although caffeine is the most widely recognised ingredient of coffee, it only contributes to 2-3% of the total ingredients of coffee. We should be mindful that coffee contains other compounds such as sugars and carbohydrates, and we are discussing the combined effects of these when discussing the health impact of coffee.
The Research
Scientists at the University of Southampton led by Dr Robin Poole, have looked at the evidence for associations between coffee and various health outcomes. They reviewed all available evidence to determine the current understanding of the effect of coffee on our health – this is called an ‘umbrella review’.
The Results
This review of 201 papers reported that coffee consumption appears to reduce the incidence of cancer (specifically liver, prostate and endometrial), skin cancers (melanoma and non-melanoma), as well as type 2 diabetes, depression, and metabolic syndromes. Furthermore, the incidence of neurodegenerative diseases, such as Alzheimer’s disease and Parkinson’s disease, appeared to be reduced. As with previous reports, the review reported clear reduced incidence of liver conditions, as fibrosis, cirrhosis, and liver cancers. This may be due to the presence of antioxidants in caffeine. It should be noted the health benefits do not increase with increased intake of coffee – in other words, the health benefits level off after 3-4 cups of coffee a day.
Although not all the outcomes of coffee were positive. The research showed that in pregnant women, coffee is associated with premature labour, miscarriage, low birth weight, and the increased risk of childhood leukaemia. Previous studies have shown that the action of caffeine is doubled in pregnancy, therefore the effect per cup is much higher in pregnant women. Furthermore, caffeine can easily cross the placenta where it will reach the baby, which may account for these damaging health effects.
Media coverage
We have previously reported on media coverage of research around coffee consumption. Not surprisingly this review was picked up by the media, as coffee consumption spans the globe. The Guardian reported on ‘The truth about caffeine: how coffee really effects our bodies’, stating that over 2 billion cups of coffee is consumed per day. Encouragingly, this article discusses the action of coffee, how quickly it can act, but also the action of caffeine on the bodies central nervous system and its links with anxiety. When discussing Dr Poole’s work, The Guardian quotes the published literature that the intake of coffee is generally positive for our health.
The Guardian article does not discuss the findings relating to pregnancy – only quoting that the NHS has an upper caffeine limit for pregnant women, stated on the NHS webpage as 200mg/day (approximately two mugs of coffee). This point was probably left out on purpose as the impact of coffee in pregnancy requires further research – however, it currently leans towards having the potentially for harmful effects.
Take-home message
Overall, this paper and the media coverage states that the consumption of coffee is more often associated with positive health effects, with the largest reduction in risk for those who have 3-4 cups of coffee a day. However, as always, more research is required, but I’ll not be putting my coffee cup down any time soon.
researchtheheadlines.org 