Jun 04 2010
Have you had your coffee yet today? Do you feel that caffeine is helpful, perhaps even necessary, to being alert and energetic? You may want to reconsider regular use of caffeine.
Caffeine is one of the most, if not the most, commonly consumed drugs among humans. A 2005 extensive survey found that 87% of Americans consume caffeine regularly, with an average intake of 193 mg per day.
The most common sources of caffeine are coffee (71%), soft drinks (16%), and tea (12%). Other sources include chocolate, over-the-counter medications (like headache or cold medications), and dietary supplements. Caffeine derives from the coffee bean, cocoa bean, kola bean, and the guarana fruit.
While many people feel that caffeine is a performance enhancing substance, the evidence has been largely against this notion, if somewhat mixed. But a recent large study strongly supports the evidence against any true cognitive or alertness benefit for caffeine.
The study authors looked at 162 non/low caffeine users and 217 medium/high caffeine users. They were also interested in the effects of specific genetic variants, ADORA2A and ADORA1 polymorphism, that render people more sensitive to certain caffeine effects. They had participants refrain from caffeine use then challenged them with increasing doses of caffeine or placebo, and assessed their anxiety, alertness and headaches.
They found that caffeine withdrawal (giving placebo to high caffeine users) caused increased headaches and decreased alertness. This is no surprise and supports prior research. In my own practice I see a great deal of caffeine withdrawal headaches and can sometimes “cure” patients just by having them stop their daily caffeine use.
When regular caffeine users were given caffeine this simply returned them to their baseline, and did not enhance their alertness. Non caffeine users saw no benefit from taking caffeine.
Caffeine also caused anxiety in non caffeine users, especially those with certain genetic variants. However, it did not increase anxiety in regular users, who therefore seem to be tolerant to the anxiety-producing effects of caffeine – even if they had the susceptible gene variants.
The take home is that regular use of caffeine produces no benefit to alertness, energy, or function. Regular caffeine users are simply staving off caffeine withdrawal with every dose – using caffeine just to return them to their baseline. This makes caffeine a net negative for alertness, or neutral at best if use is regular enough to avoid any withdrawal.
Meanwhile, regular caffeine use (even without withdrawal) can increase blood pressure, worsen headaches, cause palpitations, insomnia, and jitteriness. Intermittent use can also increase anxiety, although this study showed regular users become tolerant to this effect.
I am not trying to be down on caffeine, just report the research. This research also shows that caffeine is generally safe, and while it does increase blood pressure (a risk factor for heart disease) caffeine is not an independent risk factor for heart disease itself. There is also evidence that regular caffeine use (perhaps just coffee use) decreases the risk of Type 2 diabetes. Pregnant women should avoid caffeine because of potential effects on fetal growth and spontaneous abortion. Migraneurs should also avoid caffeine as it can worsen a migraine syndrome.
But if you do not have any specific medical condition that caffeine can exacerbate, regular moderate caffeine use appears to be safe. Just don’t fool yourself into thinking it is helping you stay alert or function better.
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