By: David Robson
The world's most popular psychoactive substance, caffeine, enjoys unprecedented popularity as a stimulating beverage in the form of coffee, tea and in a wide range of "energy drinks," the latter of which are hitting the market in rapid succession.
Even drinks targeted at younger markets, such as Mountain Dew and Coke, contain reasonable levels of caffeine - enough to warrant concern from various health authorities.
In the USA alone, the equivalent of 168mg of coffee per person, or a cup and a half for each of its 275 million inhabitants, is consumed every day. Of course, many drink significantly more than this. Given caffeine is a drug, which makes it an addictive substance, are we getting too much of a good thing when we insist on our several morning coffees, and other caffeine containing products throughout the day?
It is hard to say exactly what the long term consequences of sustained caffeine use are, but one thing is fairly obvious: society in general, it seems, has formed a reliance on this 'worlds most preferred drug of choice' and its energizing effects.
How Does Caffeine Stimulate The Body? Caffeine stimulates the body by activating the sympathetic branch of the central nervous system (CNS), which leads to an increased heart rate, improved blood flow and blood pressure to the muscles, a release of glucose by the liver and a decreased blood flow to the skin and inner organs.
The CNS is stimulated by the hormone epinephrine (adrenaline), which is released from the pituitary gland, usually in response to a perceived threat.
An effect called competitive inhibition, which causes an interruption to a pathway that normally serves to regulate nerve conduction (by suppressing post-synaptic potentials), occurs when caffeine, which is structurally very similar to the molecule adenosine, binds to the surface of adenosine receptors without actually activating them.
Adenosine plays an important role in sleep and wakefulness. Caffeine, by attaching to the adenosine receptors, prevents an over-accumulation of adenosine in the cells and, as a result negates its sleep promoting effects. This process is what ultimately causes the release of epinephrine and central nervous system stimulation.
Viewed in this light, caffeine could be described as a substance that thwarts one of the main processes by which the nervous system is calmed, not an energy producer in it own right.
Also, in our cells we have a molecule called cyclic AMP (a molecule that acts as a second messenger, which carries signals from the cell surface to proteins within the call) that serves as a messenger in the epinephrine release process. Caffeine causes Cyclic AMP to store in the cells, thus blocking its removal. This, in turn, intensifies and prolongs the actions of epinephrine.
Caffeine acts as an erogenic (it improves ones capacity for physical and mental work) based on its previously described effects, as well as the actions of its various metabolites (smaller molecules that serve various biological functions as products of metabolism). Caffeine's metabolites and their respective actions follow:
1. Theobromine:
Theobromine increases oxygen and nutrient flow to the brain, serving as a vasodilator.
2. Theophylline:
Theophylline relaxes the smooth muscles (most notably the bronchioles) and increases heart rate efficiency.
3. Paraxanthine:
Paraxanthine aids lipolysis (the breakdown of fat for energy).
Caffeine's Uses With its popularity soaring, caffeine in it many guises is being used for reasons other than pure enjoyment. Let us take a look at the various ways caffeine is used.
1. As An Athletic Performance Enhancer.
Caffeine is widely used in the athletic community as an erogenic aid. It has been reported as having such positive effects on sports performance as increased energy levels, reaction times and alertness, and improvements in endurance. Experts believe that caffeine causes the muscle cells to utilize proportionally greater amounts of fat than would otherwise be used under normal conditions.
The fatty acids released from the muscles - in the presence of caffeine - to sustain endurance work, are thought to have a muscle-glycogen sparring effect. Thus, glycogen can be used more readily during the latter stages of an event or workout, and the athlete will be able to train longer due to the utilization of the larger fatty acid energy stores.
2. To Improve Mental Acuity:
Another of caffeine's erogenic effects is its ability to heighten metal acuity and improve cognitive function. It has been shown that 75-150mg of caffeine will elevate neural activity in several parts of the brain, which assists with the completion of simple intellectual tasks - for example: relatively passive, automatic, data-driven tasks such as performing simple arithmetic, and auditory reaction time.
Although caffeine can help with more complex tasks (logical and numerical reasoning, complicated arithmetic and reading comprehension), this often hinges on the personality of the user and a series of other factors including time of the day and immediate environment. However, many people report positive benefits in taking caffeine before mental tasks such as studying for a test.
Caffeine is believed to aid memory. It is speculated that because caffeine plays a role in adrenaline (norepinephrine) production in the brain, and adrenaline, due to its fight or flight function, can improve memories for important and shocking events memory in other areas is enhanced with caffeine intake.
3. To Improve Body Composition:
To lose fat, many are turning to caffeine in its most common form, coffee, or as a supplement to hasten lipolysis, or the breakdown of adipose tissue. Caffeine's metabolite paraxanthine mobilizes fatty acids to be used as fuel in place of glycogen. Caffeine is also thought to increase the thermogenic effect of food, which helps with total energy expenditure and weight loss. It is also thought to suppress appetite. Many of the weight loss supplements on the market today list caffeine as a key ingredient.
. As Therapy:
Caffeine is widely used as a pain reliever, primarily as a way to treat headache (one such product is Excedrin, which also contains acetaminophen and aspirin). As mentioned, caffeine works as a vasodilator, thus helping to increase blood flow to the brain to negate the painful effects of a headache.
Caffeine is also used to stimulate breathing in newborn babies with apnea (cessation of breathing) due to premature birth or surgery. Additionally, caffeine can be used in cases where breathing is depressed (such as when one overdoses with heroin or other opiates). Given its dilating effects on airways, caffeine is also thought to be useful in the treatment of asthma, with some studies finding modest benefits.
Is Caffeine Addictive? Caffeine is an addictive drug that operates on the same pathways that cocaine, heroin and amphetamines use to produce feelings of energy through the stimulation of the central nervous system. Although milder than any of these other stimulating drugs, caffeine causes addiction in many: those who feel they cannot function without their morning coffee, and/or who need several cups throughout the day are probably addicted - a term, caffeinism, has even been coined to explain the abuse of caffeine.
With caffeine addiction, the body becomes oversensitive to a neurotransmitter in the brain called adenosine, when caffeine intake is reduced. This results in a rapid drop in blood pressure, and resultantly, an excess of blood in the head, and thus the commonly reported withdrawal headache associated with a reduction in caffeine. This signals addiction.
Caffeine withdrawal may appear within 12 to 24 hours after the final cup of coffee or other caffeine product. In addition to headache, symptoms can include fatigue, nausea, drowsiness, irritability and anxiety. Extreme cases may produce depression and diminished motivation and concentration levels.
As with many drugs, caffeine has a tolerance affect in that the more that is used, the lower the sensitivity one will have to it. This reduction in sensitivity means that as time passes, more will be needed to get the same effects. A good rule for those wanting to enjoy the performance effects of caffeine, without having to consume mass quantities, is to use it sparingly. In other words, use it when needed, rather than on a continual bases.
It is worth noting that if an athlete wants to use caffeine as an erogenic aid, for a sporting event or training session, it is best they abstain from it for 48 hours prior. When the body has built up a tolerance to its effects (in those who take in at least three cups of coffee per day), caffeine will probably not provide a significant glycogen sparing effect.
Conclusion Caffeine is the worlds most widely used drug for several reasons: it provides a stimulating effect which often forms a reliance on its use, gives the user physical and mental benefits, is contained in many popular products, and is used for medical and therapeutic purposes.
It has been said that if caffeine consumption were to end tomorrow, 70% of the world's productivity would decline markedly; such is the widespread dependence we have for it. In light of its popularity and reported benefits, caffeine use in moderation may not necessarily be a bad thing. Just exercise caution, and enjoy.
