Is Caffeine bad for us?

19 02 2013

There has been recent debate over whether caffeine is bad for us both in sporting and non sporting context.

What is caffeine?

1,3,7-trimethylxanthine, also known as caffeine, is the world’s most-consumed natural pharmacologic agent. Caffeine is found in coffee beans, tea leaves, cocoa beans, chocolate, and cola nuts, and its use is incredibly widespread. Did you know that if you consume a large chocolate bar you could see as much as 50mg of caffeine? That is sometimes half a cup of coffee!

In the United States, roughly 9 out of every 10 men and women consume caffeine, averaging 238 mg every day. Upwards of 30% of Americans consume a whopping 600 mg of caffeine daily. About 71% of the caffeine we consume comes from coffee, while 16% comes from tea, and 12% from soft drinks and energy drinks. And we are not alone. Coffee is the most-commonly consumed beverage in the world.

So, let’s acknowledge the obvious. First, just about everyone is consuming caffeine. In fact, because of its ubiquitous availability, caffeine is no longer on the banned substance list of the International Olympic Committee. Second, people everywhere are using it because it does have pharmacologic properties. The fact is it functions as a mild stimulant. As such, it helps wake us up and keeps us going when we feel like throwing in the towel. No surprise, athletes are interested in those very same effects applied to their sport.

cup of freshly brewed black coffee, focus is on the middle bubbles


How exactly does caffeine work? 

Caffeine has a wide range of actions in the human body. Essentially it functions as a stimulant by interfering with the binding of receptors in the body (adenosine to adenosine receptors).

Adenosine is a neuromodulator chemical in the brain, and it works opposite of caffeine in regulating nerve cell activity. It has a calming effect because it slows the activity of nerve cells, whereas caffeine speeds up the activity of cells. Taking hold of the central nervous system, many of us will agree that caffeine intake decreases tiredness, increases alertness, improves mood, enhances concentration, and helps to speed reaction time when making choices.

In terms of a sporting context, for many athletes, a key benefit of caffeine is that it lowers the perception of the intensity or difficulty of the effort. Thus, athletes are able to exercise at a higher intensity for longer, without actually feeling like they’re working harder.



The bad press

Last year headline news read that a fit and healthy runner collapsed and died half a mile from the finish of the London Marathon after taking a ‘performance-enhancing stimulant’. The runner was determined to beat her personal best in the race and decided to take a pre-workout product called Jack3D, a high caffeinated product. As she neared the finish of the race she unfortunately suffered a cardiac arrest and never regained consciousness. The popular sports supplement, now banned, was used to help her once she hit the wall in order to break through it and maximize her performance. Its main active ingredient was an amphetamine-like substance DMAA (dimethylamylamine) which boosts energy and metabolism, but had been banned in the US and Canada after two soldiers died during strenuous training after taking it. Recording a narrative verdict, coroner Dr Philip Barlow said the combination of the DMAA with ‘extensive physical exertion caused cardiac failure which resulted in her death.’

Tolerance of caffeine

Caffeine is one of those products where you can develop a real tolerance or have major diminished responses with repeated doses. If you regularly drink a few cups of strong coffee a day then the chances are the effects will start to lessen with time. One of the main issues with caffeine is that it is addictive. People have been known to suffer from withdrawal symptoms with noticeable ones such as headaches. A study conducted by Evans and Griffiths provided indirect evidence for tolerance development in caffeine. The study provided the clearest evidence to date of complete tolerance development to a central nervous system effect of caffeine in humans.

Should we worry about having too much?

As with everything, it is all about moderation! Although moderate caffeine intake isn’t likely to cause harm, too much can lead to some unpleasant effects. Heavy daily caffeine use — more than 500 to 600 mg a day (around 5-6 cups) — may cause insomnia, nervousness, restlessness, tremors, and irritability.

Some positives of coffee :

  • Lowers risk of cancer – Coffee drinking has been associated with a lower risk of lung, prostate, breast, endometrial, pancreatic, stomach, and colon cancer. Like most studies, there are also some that have shown no benefit from coffee, which could be due to many reasons. But, it seems clear that coffee can be protective and does not increase cancer risk.
  • Lowers risk of heart disease – Coffee intake is highly protective for the cardiovascular system and has been repeatedly found to decrease risk of heart disease and death from a heart attack. In one 15-year study of 41,000 women, drinking up to 3 cups of coffee a day was linked to lower risk of heart failure. Similar results have been shown for men.
  • Improves vascular health – The caffeine in coffee has actually been shown to improve the health of the blood vessels because it increases nitric oxide production in the endothelium (the thin layer of cells that line the interior surface of blood vessels), which improves vascular muscle tone. Coffee also supports healthy arterial pressure, lowering blood pressure over the long-term.
  • Elevates fat burning – The fat loss effect of coffee drinking hasn’t been studied extensively, but one study showed drinking 500 ml of coffee daily for 4 weeks produced 2.5 kg weight loss in overweight subjects. Perhaps more effective, green coffee extract, which comes from the bean before roasting and can be added to any beverage, has been shown to produce significant fat loss.

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