Caffeine: Facts and Myths

Caffeine exists everywhere, whether it be soda, coffee, or that new 5-Hour Energy drink that people are talking about.  In fact, more than 80% of Americans consume caffeine regularly.  Caffeinated energy drinks have become so mainstream that companies such as V8 and Ocean Spray are making their own versions in order to stay competitive.  

Here's a rundown on what scientists know about the world's most popular drug.

Fact: Caffeine may help sleep deprivation

In a national survey, about 30% of participants reported averaging 6 hours of sleep or less a night.  In a Roehrs' study of 259 working adults, 15% of them fell asleep within 6 minutes of entering a sleep lab.  Why does caffeine help people who are sleep deprived?  The answer to this has to deal with adenosine.

Adenosine is a natural sedative produced by the brain.  Adenosine levels build up while we are awake, and drop as we sleep.  The direct binding of adenosine to the adenosine receptors is what makes us sleepy.  Caffeine works by temporarily binding to adenosine receptors in the brain.  This prevents adenosine from binding itself to the adenosine receptors (because caffeine is already bound to it, it cannot bind to anything else).

Myth: Caffeine is bad for the heart

This fall, the parents of a 14 year old Maryland girl sued the company who makes Monster Energy drinks because their daughter suffered cardiac arrest after drinking 2 24 oz cans of Monster.  The autopsy of the girl stated "cardiac arrhythmia due to caffeine toxicity", which means the caffeine made worse a heart condition that the girl had.

However, in a study that followed more than 130,000 people for 30 years,they found that drinking coffee didn't increase the risk of cardiac arrhythmia, even among those with existing heart conditions.

Fact: Caffeine can improve physical performance

"Caffeine can improve physical performance in endurance exercise like running, but the effect is less for short bursts of movement such as lifting weights or springing," says Matthew Ganio, who is a professor of kinesiology at the University of Arkansas.

Caffeine helps people last longer during exercise because it prompts the body to burn more of its fat stores instead of the carbohydrates in our muscles.  When the muscles run out of carbohydrate, we get tired.

Matthew Ganio also says "Caffeine also reduces the perception of muscle pain and the perception of how hard we are working, which makes us feel better when exercising and may help us exercise longer."

Myth: Caffeine helps people lose weight

Many companies add caffeine to their weight-loss supplements because it speeds up the metabolic rate, as least for a short period of time.  However, there is little evidence that consuming caffeine leads to significant weight loss or helps people keep weight off.

Fact: Pregnant woman should limit their caffeine intake

The March of Dimes recommends that women who are pregnant or trying to become pregnant consume no more than 200 mg of caffeine a day because the harmful effects of more than that on the fertility, miscarriage, and fetal growth "cannot be ruled out".

The FDA advises women to avoid caffeine-containing foods and drugs if possible, or consume them only sparingly.

Myth: Caffeine increases your blood pressure

While caffeine users may experience a a slight increase in blood pressure, Rob van Dam of the National University of Singapore says "researchers have detected no substantial ink with the development of hypertension in long-term studies of caffeinated coffee intake"


Source: Nutrition Action Magazine December 2012