John Evans | QOL Quality of Life
Coffee has become ubiquitous, but we still seem confused as to whether it is something we should avoid in our diet or actively embrace for its health benefits. What does the research say? Can we really draw any reliable conclusions?
There are several negative health outcomes typically associated with regular coffee consumption. These include high blood pressure, insomnia, palpitations, arrhythmia, gastrointestinal upset, dehydration and diarrhoea. How valid are these associations and how much coffee is required to produce these effects?
Most of these effects are associated with the caffeine contained in coffee. Caffeine acts on the CNS (Central Nervous System) to increase secretion of adrenaline which results in an increased heart rate and blood pressure. This stimulation (caffeine is often described as a stimulant) also results in greater alertness, greater fatty acid utilisation (yes caffeine can help us to burn fat) and cortisol production. One shot of about 30 – 50ml of espresso typically contains about 63 mg of caffeine, so a double espresso delivers about 125mg of caffeine.
A 2011 study published in the American Journal of Clinical Nutrition reported that for hypertensive individuals (those with diagnosed high blood pressure) a dose of 200-300mg of caffeine caused blood pressure to rise for up to 3 hours. The same review also looked at longer-term coffee consumption but concluded that it had no significant impact on chronic blood pressure or risk of cardiovascular disease.
One reason for coffee’s previous association with ill health was because many studies were not adjusted for the harmful effects of smoking. This means that as a significant proportion of coffee drinkers also smoke the higher risk of certain conditions in coffee drinking populations is reflective of smoking, rather than coffee related health risks (the health risks of smoking being long proven). With the exclusion of smoking related factors in more contemporary studies a different picture seems to be emerging.
Two large scale reviews, one European and a separate US study looked at the relationship between how much coffee people drink and mortality. Both these studies were published in the journal Annals of Internal Medicine and reported in The Independent last year (2017).
The European study included more than 450,000 people. Researchers found men who drank the highest amounts of coffee had a 12% overall reduced risk of death at follow-up from causes including cancer and cardiovascular, digestive and respiratory conditions.
A further detailed review published in the BMJ (British medical Journal) also indicated mild health benefits from coffee drinking. Normal levels of coffee drinking (2-4 cups daily) were associated with no negative health benefits other than in pregnant women. Coffee drinking benefits were particularly strong relating to liver health. A lower risk of Parkinson’s disease, depression and Alzheimer’s disease was also indicated.
These benefits rather than being associated with caffeine, are believed to arise from the high concentration of antioxidant polyphenols which are also present in coffee. These complex substances (see side panel) look set to be the subject of future study.
While we can be cautiously enthusiastic about our coffee drinking we should note that the quality of coffee and whether you take it black, milky or go for a caramel latte topped with cream will play some part in determining how it effects your system and overall nutritional value.
The recent health trend for devotees of The Paleo diet is for “bulletproof” Coffee. This unlikely blend of coffee, butter and coconut oil (or ideally a medium chain triglyceride) is favoured for giving a caffeine kick with an abundant supply of fatty acids. A potent energy giving mix not to everyone’s taste and one that may not always make the gentlest transition through your digestive system.
If you continue to consume a beverage that gives you abdominal cramps and diarrhoea, then you are perhaps your own worst enemy. In general, however, the research suggests no negative outcomes over the long term for gastrointestinal health and a lower risk of conditions like gallbladder disease.
While science seems to indicate at least moderate health benefits from coffee there is the caveat that more research is needed. We should remember individual response to and tolerance of caffeine will be different. It is wise to learn the lessons of your own experience.
If you sit reading this piece bleary eyed and jittery at 2 am while chugging down another espresso, then perhaps switch to a glass of water. If on the other hand you sit in a sunlit riverside café with the perfect cup and the world is good, then drink on.
What are Polyphenols?
Polyphenols are naturally occurring compounds found in plants and are generally involved in defence against ultraviolet radiation or pathogens.
In the last decade, there has been much interest in the potential health benefits of plant polyphenols in the diet. Coffee contains high concentrations of polyphenols. Analysis of research suggests that there is strong evidence that long term consumption of diets rich in plant derived polyphenols may offer protection against conditions such as cancer, diabetes, osteoporosis, cardiovascular diseases, stroke and neurodegenerative diseases.
