Caffeine: Good for Athletes, Bad for Babies
Literally, it was just days ago that I devoted an entire newsletter to caffeine, and yet here again, it's back in the news. Two recent studies add fuel to the debate over whether or not caffeinated beverages are nectar or poison.
The first, out of the Universities of Leicester and Leeds in England a few months ago, provides yet more evidence that caffeine in almost any amount and from any source puts pregnant mothers at risk for giving birth to low-weight babies. The researchers followed 2,645 pregnant women and found that those who consumed 159 mg of caffeine daily -- the equivalent of just over a cup of coffee -- increased their risk of having a lower birth weight baby by 20 percent. The risk jumped to 50 percent for those drinking the equivalent of about 1.5 large cups (200 to 299 mg daily). The more caffeine the women consumed, the greater the risk. Again, the caffeine came from a variety of sources and in fact, most of the women in the study -- 62 percent -- got their caffeine from tea (remember -- the study took place in England; also, note that you have to drink double the amount of tea to get the equivalent amount of caffeine contained in coffee).
The cup-a-day effect led to average fetal weight reductions ranging from 1.2 to two ounces in the first trimester, up to 2.8 ounces in the second trimester, and as much as 3.14 ounces in the last trimester. Those women who metabolized caffeine the fastest saw the greatest impact on fetal weight. The study authors concluded that women should reduce caffeine intake both before and during pregnancy, since even these small reductions in birth weight can be dangerous for infants who already are small.
Numerous earlier studies found similar effects, although at least one found no association between caffeine intake and low birth weight and another found that reducing caffeine intake in the second half of pregnancy didn't affect birth weight at all. Most studies, though, have found reduced fetal weight, as well as links between fetal caffeine exposure and hyperactivity, ADD, behavioral problems, and smaller head circumference.
But the news isn't all bad for those who crave caffeine in the morning, providing they aren't pregnant women. A study just came out showing that by drinking a few cups of coffee before exercising (or getting caffeine from any source), you might avoid the muscle pain that typically accompanies a tough workout. The benefit applied both to regular caffeine consumers and to those who usually avoided caffeine. The researchers believe that caffeine may block a chemical that activates pain receptors in cells in response to inflammation.
The subjects in the study took pills containing caffeine (equivalent to the amount found in almost three cups of coffee) before a high-intensity workout on an exercise bike. Those who took the pills experienced a significant reduction in pain in their quadraceps.
Researcher Robert Motl commented, "If you go to the gym and you exercise and it hurts, you may be prone to stop doing that because pain is an aversive stimulus that tells you to withdraw. So if we could give people a little caffeine and reduce the amount of pain they're experiencing, maybe that would help them stick with that exercise."
Could Starbucks be filling prescriptions for thigh pain in the near future? If so, those prescription cappuccinos would need a warning label advising that pregnant women had better steer clear...unless you're looking for babies capable of staying up all night and cramming for exams from the day they're born.