According to conventional wisdom, coffee is solely a drink for adults.
Kids rarely complain—after all, it’s an acquired taste, and a bitter cup of java isn’t exactly irresistible to a young child’s palate.
But the idea that kids can’t have coffee has nothing to do with taste; it’s based on the well-known assertion that coffee stunts growth. It sounds plausible, for some reason, but is it really based in science?
Possibly, but the effect is likely overstated. At one point, scientists believed that caffeine affects calcium absorption, preventing the body from using the mineral effectively. Heavy caffeine consumption was even thought to be a risk factor for osteoporosis. More recent studies have prompted a reversal on this position, however.
Caffeine doesn’t seem to meaningfully affect calcium absorption, according to a 1992 study published in the Journal of Bone and Mineral Research.
“High caffeine consumption has been proposed as a risk factor for osteoporotic fracture, but the evidence associating high caffeine intake with low bone density is inconsistent,” wrote the study’s authors, noting that caffeine intake doesn’t seem to be an important osteoporosis risk factor.
A cup of coffee probably won’t stop a growing body from growing.
But that doesn’t make caffeine a good dietary addition for younger kids.
“There are lots of things we can’t do because we’re not old enough or mature enough,” said Kevin Shannon, MD, a professor of pediatric cardiology and director of pediatric arrhythmia at the Mattel Children’s Hospital of the University of California, Los Angeles, in an interview with TODAY. “Caffeine should probably be added to that list.”
That’s not because of the stimulant’s purported growth-stunting capabilities but its effect on the cardiovascular system. A 2014 study from the University of Buffalo’s School of Public Health and Health Professions showed that a moderate amount of caffeine can increase blood pressure and slow heart rates in young children.
The slow heart rates occur because the heart is forced to compensate for rising blood pressure. The effect is reversed at high caffeine dosages.
Caffeine can also contribute to insomnia and other sleep disorders, which may actually have an effect on growth. It’s a diuretic, so it can cause dehydration in large amounts, and it can cause jitters, headaches, gastrointestinal distress, and withdrawal symptoms.
These symptoms are often more pronounced in kids, since a relatively small amount of caffeine has a greater effect on a smaller body.
“Caffeine is absorbed in every body tissue,” wrote Marcie Schneider, MD, adolescent medicine physician and a former member of the American Academy of Pediatrics Committee on Nutrition, for Live Science. “It increases your heart rate and it increases your blood pressure. Caffeine changes your body temperature and your gastric juices. It changes how attentive you are, and can really cause trouble in terms of sleep.”
Schneider also provided an alternate hypothesis for the “coffee stunts your growth” belief.
“Caffeine is a stimulant, and therefore it may change their appetite,” she wrote. “Adolescents gain half of their adult weight in their teenage years. If caffeine curbs their appetite in some way it could affect their growth.”
While that sounds completely plausible, we should note that we couldn’t find direct evidence to back up that assertion.
Unfortunately, kids are drinking quite a bit of caffeine, although they rarely get their fix from coffee. A 2010 study published in the journal Pediatrics found that 75 percent of children consume caffeine on a daily basis. Most of that comes from sodas, chocolate, and energy drinks.
Parents also frequently mistake energy drinks for sports drinks, which is problematic; many energy drinks have much more caffeine per serving than coffee or soda. Some also contain taurine, which neutralizes some of the negative effects of caffeine, potentially allowing children to consume even more of the drinks.
Sodas, energy drinks, and blended coffee drinks also have high amounts of sugar. High-sugar diets are linked to obesity and malnutrition in kids, so parents should certainly try to cut out unnecessary sugars wherever possible.
Some doctors say that ideally, children shouldn’t consume any caffeine.
“I think there is no place for caffeine in a child’s diet until they become young adults, at age 18,” said Jessica Lieb, registered dietitian at the Children’s Hospital of Pittsburgh of the University of Pittsburgh Medical Center. “And even in adults, it’s important to be really careful. As in all things, caffeine should be consumed in moderation.”
For some families, a “no caffeine” rule is impractical, but most experts say that parents should establish some limits.
The Canadian government suggests a maximum recommended intake of 45 milligrams per day for children aged 4 to 6. For reference, a 12-ounce diet cola contains roughly 45 milligrams, and a typical cup of coffee contains about 95 milligrams.
The bottom line: Young kids shouldn’t have coffee. Older teenagers can probably gradually add caffeine to their diets with few ill effects. Provided that they couple their coffee with a balanced breakfast after a good night’s sleep, their bodies should grow just fine.