Coffee is a worldwide phenomenon. Despite absolutely no requirement for it in the human diet, millions of us use it every day. After observing the huge milk and sugar filled cups of a certain coffee chain a venture capitalist famously remarked “it’s all about warm milk and a bottle” his colleague observing “If I could put a nipple on it, I’d be a multimillionaire”. We need it, we love it, we can’t get enough of it.
Why? What does it do? What is very likely happening to you this minute at your desk?
Living on your nerves
Having left your mug (actually it also works if taken as pills or as gum) caffeine is rapidly absorbed from the gastrointestinal tract into the bloodstream. It is then metabolised by the liver. Peak plasma concentration is reached in approximately an hour.
Caffeine is a neurotoxin alkaloid. It stops insects eating plants. It works by being a very similar shape to adenosine, a nucleotide which is very important in energy transfer and neurotransmission. Adenosine inhibits nerve firing because it prevents the release of excitatory neurochemicals such as serotonin and acetylcholine.
Caffeine settles into the adenosine receptors in the surface of neurons and in doing so, prevents adenosine itself from getting in there. Therefore no receptor activation can occur and the effect is just the opposite. With no adenosine in place to tranquilise the nerve, excitory neurochemicals will be released. Blood vessels constrict in your head and neck, the rate of nerve firing increases, your blood pressure and heart rate may rise and you experience a renewed interest and vigour when it comes to your Excel document.
Your higher cognitive function is now improved. Even what you can see is enhanced. The stimulation of nerves which use acetylcholine to send their messages affects a variety of areas in the body and brain. The visual cortex is one such area and drinking coffee causes an enhancement in our ability to process the shape, colour and location of visual objects.
Caffeine helps you remember
Caffeine improves subjective memory. That is you think you remember things better. Thankfully it also improves both recall and to a small effect also memory retention. Strangely it seemed to do so best at lower doses, possibly because at higher does you are too busy dancing around the room.
Significantly, the caffeine intake had to be administered post-task, if given before it could actually inhibit memory retention. So it appears that whilst a coffee may help you when writing the minutes of the important morning call, it won’t help you much before going into yet another important meeting.
Acetylcholine is important for memory storage and indeed elderly people show a greater memory benefit after caffeine intake following that in older people there is a decline in brain acetylcholine levels. So make a coffee for the Director too.
After the Christmas party
Caffeine has been shown to reverse some of the performance effects of ethanol. Hurrah! However you need more than just the one cup. A reasonably high caffeine dose of 300mg was able to reverse the detrimental effects of ethanol on a recall memory task. This is about 3 cups of brewed coffee. It also reduces the sedative effects, at least for a while, partly because you think you feel more awake.
Unfortunately it has no effect on that special type of dizziness. Nor can it erase photographs off the internet. Sorry.
Caffeine may stop you getting fat
The gym culture of the modern office place has led to the explosion of body building supplements onto the market. Amongst these are the “Fat Burners”, sold with the promise to raise metabolic rates, help you burn through your flabby areas and become more attractive to the opposite sex. Almost all of these contain caffeine.
Caffeine increases lipid mobilization (increases plasma free fatty acids) and also increases fat oxidation (its oxidative disposal). Free fatty acid turnover doubled after caffeine ingestion due to a large increase in fatty acid oxidation and recycling. Oxidation especially seems to increase synergistically in the presence of adrenaline, so it may well be of use to you when on that exercise bike.
Caffeine was also found to increase resting energy expenditure, partly through the action of the sympathetic nervous system (such as increased heart rate, blood pressure, plasma adrenaline etc. A bonus when sitting at your desk.
Even seasoned caffeine abusers were found to benefit from these effects, so a normal caffeine intake did not cause much tolerance. There is real potential for a use for caffeine as a means of helping loss of body fat and maintenance of body weight.
Just how addictive is it?
Dopamine release is a well published action of cocaine. And indeed dopamine is also released when caffeine binds to its adenosine receptor. Happily caffeine does not work in quite the same way as other stimulatory drugs. Despite the desperate, joyless faces that queue at your local Starbucks every morning it actually has quite a low addictive potential.
This is because the dopamine released by the action as caffeine acts on different areas of the brain. The dopamine released by the action of cocaine acts within the region known as the accumbens nucleus. You might know this better as the “pleasure centre” of the brain, since it plays a role in reward, laughter, pleasure and of with that also aggression, fear and addiction.
Caffeine, due to its preferred choice of adenosine receptor, releases dopamine in the brain which binds to an area in the medial prefrontal cortex. Here it exerts its cognitive enhancing and pyschostimulatory effects happily without turning us into hardcore drug addicts.
Why does going cold turkey hurt?
You’ve spent some time, possibly years, inhibiting adenosine. If you then choose to deprive your body of its caffeine it becomes very sensitive to the adenosine which is now able to do its job. Blood pressure drops quickly with the result that there is an excess of blood in the head. Not surprisingly, you get a headache.
What happens when you have too much?
Caffeine in normal usage (that’s about 4 cups of instant a day by the way) is widely regarded to be safe. However there are cautions to be made. Caffeine raises blood pressure and can cause anxiety. These effects are especially prolonged in people who are not regular caffeine users. Those of you who are already stressed executives, who suffer from diagnosed hypertension, might not benefit from a further increase in blood pressure and should seek to limit the number of espressos that you drink.
Pregnant women also are advised to take it easy, with a recommended intake of no more than two cups of instant coffee (about 200mg of caffeine). This is due to a possible correlation between caffeine intake and low birth weight and a slight increased risk of miscarriage.
In general, don’t overdo it. Too much caffeine can cause a range of symptoms, from nausea, shakiness and headache to rapid arrhythmias, agitation and convulsions.
What else is in my coffee other than the caffeine?
Coffee is much more than just the caffeine. In fact is contains as many as 1500 chemical substances.
Coffee contains its fair share of micronutrients such as potassium, magnesium, vitamin E and niacin. Two or three coffees can provide half the recommended dose of niacin (otherwise known as Vitamin B3) which is important for the conversion of food to energy and also for skin and nerves.
Coffee also contains antioxidants that may protect biological molecules and membranes from oxidative damage. Melanoidins in instant coffee have been shown to inhibit the mutagenicity of known carcinogens. Coffee contains chlorogenic acid, long touted as a potent antioxidant which may slow the release of glucose into the bloodstream. The role of coffee in Type 2 diabetes is still disputed with some studies showing a protective effect and others suggesting a worsening of the condition. Just don’t add sugar to your drink.
Without the added sugar, the drink is even good for your teeth. Trigonelline as well as caffeine and chlorogenic acid seem to interfere with the tooth damaging bacteria Streptococcus mutans and prevent it from causing cavities.
It is Christmas, and so what better way to finish this article than with some coffee-related winter indulgence.
- Vodka Espresso (for a more interesting office lunch):
- 1 Measure of good vodka
- 1 Measure Kahlua or other coffee liqueur
- 1oz of espresso
Prepare a martini glass; shake all the ingredients with ice; strain into the prepared glass; and drink to your enhanced cognition!