Ask A Nutritionist! (Nov/Dec 2007) - The Caffeine Buzz


“I drink 4 cups of coffee and about three cans of diet cola per day. How much does caffeine assist or impede an athlete’s performance?”

Caffeine is one of the world’s most widely used behaviourally active drugs that is legal and unregulated in most jurisdictions, though caffeine is a former banned substance by the International Olympic Committee (IOC).  Surveys indicate that in North America 90% of adults consume caffeine daily.

As a nutritionist, I advise people about the downside to consuming caffeine daily, whether in the form of coffee, tea, cola, energy drinks, chocolate, and some over-the-counter medications.  Chronic daily use of caffeine can cover up a sluggish colon, lead to anxiety, headaches, insomnia and even fatigue.  Physical dependence on the drug is possible, even in quantities of one cup per day.  Consuming caffeine with meals can lead to incomplete digestion and compromised absorption of key vitamins and minerals such as calcium.  And caffeine is one more chemical that the liver has to detoxify.  The amount of caffeine necessary to produce effects varies from person to person depending on body size and degree of tolerance to caffeine.

Caffeine is also a diuretic, meaning it increases urine production and can lead to dehydration.  While some the literature suggests that caffeinated beverages and water affect the body’s water balance similarly during exercise, caffeine consumed apart from exercise still has a diuretic effect.

How much is too much? Health Canada recommends consuming no more than 400mg of caffeine per

day for healthy adults, less than 300mg for pregnant or lactating women and fewer than 85mg for children aged 10-12. One 8 oz cup of coffee has roughly 150mg of caffeine, and 12oz of cola has about 35 mg meaning if you are consuming 4 cups of coffee and 3 cans of cola you’d be ingesting around 700mg of caffeine daily, considerable more than the recommended limit.

What about Athletic Performance? There appears to be a general consensus in the research findings that caffeine improves continuous exercise to exhaustion for endurance activities, such as the marathon.  There is also some research to suggest that caffeine can be used as a performance enhancer in shorter events.   These ergogenic effects of caffeine consumption, however, seem to decrease with habitual use.

However, even though caffeine appears to help improve athletic performance, improved training and optimal nutrition can also help you to obtain your athletic goals, naturally.

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