Does caffeine stunt your growth?
During a breakfast stop prior to a recent day of skiing, my husband chided our teenage son for requesting coffee, saying that "caffeine stunts your growth." When challenged both my husband and I were obliged to concede that we did not know if there was any scientific backing for this common parental admonition. So we put it to you, Cecil. Does caffeine stunt your growth?
The good news, at least from your son's standpoint, is that I haven't been able to find a single study saying caffeine stunts your growth. The bad news is that I can't find a single study saying it doesn't stunt your growth, either. Although most dispensers of health advice think the danger is a myth, you do find a few zealots intimating that caffeine is an insidious evil. It's tempting to dismiss such views as alarmist, but the truth is we don't have enough hard evidence to rule out much of anything.
Nobody claims caffeine is a health food. The world's most widely used drug, regulated or otherwise, caffeine is a potent stimulant with no nutritional value. It can cause jitters, insomnia, indigestion, and other temporary side effects when consumed in excess and is almost certainly mildly addictive, as Starbucks patrons lining up for their daily hit will attest. Whether it can do more serious harm, though, has yet to be conclusively established. On the subject of caffeine and growth, the most relevant areas of concern are the following:
(1) Caffeine during pregnancy. A sizable body of research suggests that caffeine consumption can harm the fetus. For example, a study published in 2000 in the New England Journal of Medicine says that drinking six or more cups of coffee a day (or otherwise ingesting at least 500 milligrams of caffeine) is linked to a doubling of the risk for miscarriage. A 1980 study commissioned by the Food and Drug Administration found that caffeine fed to pregnant rats caused birth defects and delayed skeletal development in their offspring, leading the agency to urge expectant mothers to avoid the stimulant--advice that has been widely ignored. On the other hand, a 1991 analysis of human-subject data found no association between a mother's caffeine consumption and the height, weight, or head circumference of her newborn; likewise it didn't seem to have any effect on the kid's IQ and attention span, measured at age seven.
(2) Caffeine and calcium. Caffeine is a diuretic and causes calcium to be leached out of bones and excreted. However, the reviews of the medical literature I've seen indicate that the effect is slight and can be readily compensated for with diet. Because caffeine has been implicated as a contributor to osteoporosis in the elderly and other vulnerable populations, though, plenty of folks are worried that the substitution of caffeinated soft drinks for milk during childhood (when the need for calcium is great) might lead to developmental problems.
The key word is "might." One can plausibly argue that caffeine consumption might stunt growth, but as far as I can tell no one has demonstrated that it does, nor have I seen anyone storming the ramparts at the FDA demanding that such research be undertaken. No doubt that's because U.S. children already drink plenty of caffeinated sodas, yet we aren't faced with epidemic numbers of short, spindly kids but rather lots and lots of fat ones.
A small band of caffeine opponents, though, sees the lack of anticaffeine research as evidence of the dread hand of the coffee industry at work. A nutritionist named Stephen Cherniske has written a book entitled Caffeine Blues (1998), in which he blames caffeine for diabetes, ulcers, PMS, stroke, heart disease, etc. (Cherniske also happens to sell a coffee substitute that's supposed to help people kick the caffeine habit.) In a letter published last April in Addiction, researcher Margaret Katholi and her coauthors cite Cherniske's book and go on to mention studies suggesting that "caffeine addiction may be a 'gateway drug,' facilitating more serious addictive habits in some youths." Katholi doesn't claim caffeine stunts growth, but she does think it impairs classroom performance and robs kids of sleep. She's proposed a national "zero caffeine for kids" campaign and demands caffeine labeling on foods and supplements.
Some of the arguments against caffeine are a little far-fetched (today coffee, tomorrow crack cocaine?), and there's no scientific consensus that caffeine is all bad. (Indeed, some of its metabolites may act as antioxidants, and brand-new Harvard research claims that people who drink lots of caffeinated coffee greatly lower their risk of developing diabetes.) Still, the critics' point that sugary caffeinated soft drinks are taking the place of healthier beverages in the typical American kid's diet is well taken — reasonable folk may disagree about whether the caffeine is worse than the sugar, but either way it can only help matters to get those Coke machines out of our grade schools.