Coffee consumption might be beneficial after all (Photo: uzagaku – Flickr)
Apologies for the association, but this post is about a possible diuretic that potentially might improve your brain function according to recent research. We are talking about the assumed effects of consuming coffee and similar beverages. You would have thought that by now the effects of caffeine and related methylxanthine compounds on the human body would be clear. But there are still conflicting opinions in the literature. From mainly negative reporting of gastric ulcers and cardiovascular disease, the situation changed when in 2008 a Harvard-led study reported finding no detrimental effects of consuming up to six cups of coffee a day using 130,000 study subjects.
Caffeine, with the full chemical name of 1,3,7-trimethylxanthine, and the related methylxanthines theobromine and theophylline, can be found naturally in the leaves, seeds, and fruits of more than 60 plants, including coffee, tea leaves, kola nuts, guarana, and cocoa beans. Coffee is one of the most widely consumed beverages in the world, and the most commonly consumed psychoactive drug with a production of about 7.4 million tons per year.
The people of Finland are among the biggest coffee consumers in the world. Finns consume an average of 12 kilograms of coffee per capita yearly or 4-5 large cups a day, which is over twice the amount of most other Europeans. Only tiny Luxembourg exceeded this number, with an average consumption of close to 17 kg per year. It might have been expected that countries like Italy or France would be at the top of coffee consumption charts with their famous high quality coffees. However, the French and the Italians only consume an average of 5 kg of coffee per year, slightly higher than the 4 kg in the USA.
Influence on memory
It is clear that caffeine is a psychoactive stimulant drug that influences brain chemistry. It mimics adenosine by binding to adenosine receptors and thus blocking the effects of adenosine, which happens to be to slow down nerve impulses and cause drowsiness. So the brain becomes more alert. Caffeine also increases the levels of dopamine in the brain, which improves the feeling of well-being and mood. But what about memory? Here it is not so clear with studies of short-term and long-term memory showing positive, negative, and no effects at all. The research consensus seems to indicate a slight overall inhibitory effect, reducing the capacity of our short-term memory and working memory. Bad luck!
Improved performance in the elderly (Photo: Lucia Whittaker – Flickr)
However, the situation is much more positive for the elderly. For most older adults, memory performance depends on the time of day, with performance being optimal early in the morning and declining during the late afternoon hours. In a study by Ryan and co-workers from the University of Arizona, adults over the age of 65 who considered themselves “morning types” were tested twice over an interval of 5 to 11 days, once in the morning and once in the late afternoon. Participants consumed either coffee with caffeine or decaffeinated coffee at both sessions. Participants who consumed decaffeinated coffee showed a significant decline in memory performance from morning to afternoon. In contrast, those who consumed caffeine showed no decline in performance from morning to afternoon. The results suggested that time-of-day effects may be mediated by nonspecific changes in the level of arousal.
And the diuretic effects?
A review of the available literature suggests that acute consumption of 250-300 mg of caffeine, or 2-3 cups of coffee, results in a short-term stimulation of urine output in individuals who have been deprived of caffeine for a period of days or weeks. However, regular coffee consumption quickly leeds to a tolerance and the diuretic effect is much diminished. But we shouldn’t forget the detrusor muscles in the bladder that help determine capacity limits and outputs and might deteriorate with age. Caffeine happens to relax detrusor muscles causing an urgency to urinate. This indirectly compounds the diuretic effects of caffeine. So it might be that the title is correct after all for the elderly.
But there is more
And in even better news, in 2009 researchers in Finland and Sweden reported results from a study that followed over 1,400 people over 20 years, and found that those who drank 3 to 5 cups of coffee a day in their midlife years had a 65% lower chance of developing dementia and Alzheimer’s disease compared with those who reported drinking no coffee at all or only occasionally. This was supported when researchers from the University of South Florida and the University of Miami, published a paper in June 2012 describing how they monitored the memory and thinking processes of 124 people, aged 65 to 88, and found all those with higher blood levels of caffeine (mostly from drinking coffee) avoided the onset of Alzheimer’s disease in the following four years. The same researchers had previously shown that caffeine consumption could reduce blood levels of the beta-amyloid protein that forms into plaques in the brains of people with Alzheimer’s.
Caffeine can hinder degenerative brain changes (Photo:alles-schlumpf – Flickr)
Further, a research team led by Professor Freund from the University of Illinois suggested that caffeine consumption could help to ease cognitive decline and lower the risks of developing Alzheimer’s disease by blocking inflammation in the brain. The team found that mice given caffeine had lower inflammatory markers and recovered the ability to form memories after hypoxia 33% faster than those not given caffeine.
For Parkinson’s Disease, another neurodegenerative disorder, it appears there is also a link between higher coffee consumption and decreased risk. And like Alzheimer’s, this also seems to be due to caffeine, but it is less clear how it works. One study from the University of North Dakota in the USA, suggested that it might be due to an effect of caffeine that preserves the blood-brain-barrier. The findings were supported by a meta-analysis of 26 studies that suggested an inverse association between tea drinking and the chance of developing Parkinson’s disease. For every increase of 300 mg per day in caffeine intake, they found a drop of 24% in the relative risk of developing Parkinson’s.
Possible health claims
The European Food Safety Authority (EFSA) has received several health claims in relation to products containing caffeine. It has rejected claims that cocoa can enhance mood and that black tea can help focus attention because of insufficient evidence presented. However, claims in relation to what was summarised as alertness and attention after consumption of coffee, guarana or caffeine got the thumbs up by the EFSA Panel on Dietetic Products, Nutrition and Allergies. First the Panel considered that increased alertness and increased attention might both be a beneficial physiological effects. Then, in weighing the evidence, the Panel considered that there was good consensus on the role of caffeine in increasing alertness, measured as speed of reaction times, and increasing attention, measured by a range of psychometric tasks, in healthy individuals of both sexes, at doses of at least 75 mg.
On the basis of the data presented, the Panel concluded that a cause and effect relationship has been established between the consumption of caffeine and increased alertness and attention. In order to bear the claim, a product should contain at least 75 mg caffeine per serving. However, the Panel could not refrain from issuing a warning that for children consumption of a dose of 5 mg/kg body weight could result in transient behavioural changes, such as increased arousal, irritability, nervousness or anxiety. In relation to pregnancy and lactation, they stated that moderation of caffeine intake, from whatever source, is advisable.
So how much coffee do you need?
Two daily cups of coffee might be enough (Photo: antwerpenR – Flickr)
It is quite difficult to figure out how much caffeine is consumed from a regular cup of coffee. Cup sizes differ from country to country. For instance, in the USA, coffee is typically served in a 240 ml cup, which is twice the amount of a typical European serving. The caffeine concentration also varies depending on the beans, how they are roasted, and how the coffee is prepared. A restaurant-style serving of Espresso in a 30ml cup can contain from 40 to 75 mg of caffeine. Even a decaffeinated Espresso can contain up to 15 mg of caffeine.
On the other hand, a 240 ml cup of generic instant coffee can contain any amount from 27 to 173 mg of caffeine, while a Starbucks Pike Place 480 ml cup of brewed coffee contains 330 mg of caffeine. A moderate intake of caffeine is probably around 300 mg per day. This is roughly 3 to 4 cups of ground roasted coffee or 5 cups of instant coffee. So 1-2 cups of coffee a day should easily qualify for the health claim.
By the way, tea has about half as much caffeine as coffee in case you are a tea drinker.