CAFFEINE AND STRESS

CAFFEINE AND STRESS

Caffeine increases some of the normal stress responses because it increases the amount of adrenaline that is active in the body under stress­ful circumstances. Thus, it seems that caffeine users who find themselves under stress (or who use caffeine even more during stressful periods to work more effectively) may experience more of the effects that stress can produce. Adrenaline release increases blood pressure during stress, and the caffeine-induced rise adds to this. Thus, caffeine and stress together lead to greater bodily stress responses than either does alone.

CAFFEINE AND PANIC ATTACKS

In some people, caffeine can contribute to the experience of panic attacks, which generally come on suddenly and involve powerful feelings of threat and fear. The experience can be very debilitating for a brief period of time. It seems that caffeine is more likely to bring on panic attacks in people who have had them previously. However, relatively high doses of caffeine (greater than 700 milligrams) have been reported to lead to panic attacks in people who have never experienced them.

ENHANCEMENT OF PHYSICAL PERFORMANCE

Caffeine can slightly enhance physical endurance and delay fatigue asso­ciated with vigorous exercise in some people. One way that caffeine might accomplish this is by releasing fats into the blood for use as energy, enabling the body to conserve its other energy stores (in the form of stored sugars), thus allowing the athlete to sustain physical activity for a longer period of time. Caffeine may also help muscle performance during physical exercise, although the way this happens is not clear. What we do know is that caffeine dilates the bronchioles, making it easier for air to pass into the lungs. This would seem to have a beneficial effect on certain types of physical performance. Still, the most thorough studies of well-trained athletes are inconclusive. In some cases there appear to be performance-enhancing effects, and in others there are none. So the jury

remains out.

Two words of caution, though, for those who use caffeine for this pur­pose. Because caffeine causes an increased loss of water through urine production, a person exercising on caffeine may become dehydrated more rapidly during long periods of exercise such as distance running or cycling. This caution is particularly important for hot-weather exercisers. The other concern is the effects of caffeine on heart rate and heart rhythms. Strenuous exercise obviously stresses the heart, so a person with cardiovascular disease could experience problems while using caffeine to promote physical performance.

People who worry about their weight might be interested in the issue of fat metabolism. Products based on the supposed ability of caffeine and theophylline to "burn fat" include a theophylline cream placed on the market several years ago that was supposed to melt fat away. Just rub it on the offending fat pad! Unfortunately, the effectiveness of this treat­ment hasn't been established (one big problem is probably getting the theophylline through the skin and into the fat cells).

Likewise, there is tremendous interest in whether a combination of caf­feine and exercise can help to promote the burning of fat as fuel for weight loss. Fat cells really do have adenosine receptors, and xanthines really can cause a small release of stored fat, so some foods that include caffeine have been sold as fat burners. However, the scholarly research on these prod­ucts has demonstrated only small weight-loss effects. Coffee and its cous­ins may prove to be a useful part of weight-loss programs in the future, but at this point nothing "melts" fat except old-fashioned exercise and a healthy diet.