Dark chocolate, red wine, and coffee –should you consume them while pregnant? It’s pretty hard to tell from the news these days. Dark chocolate is pushed frequently, often because of a study presented showing an improved circulation through the uterus and fetus in women who eat chocolate regularly. Coffee and wine also are encouraged frequently, the reasoning for all three foods relating compounds called polyphenols, many of which are anti-oxidants, so the work against the disease process. But then you’ll also hear news reports highlighting studies concluding that chocolate, wine, or coffee will harm you, or harm your fetus.
How can we resolve this conflict? One approach is simply to appreciate that studies comparing health outcomes with various factors often reveal correlations between two things, but without one thing being the cause of another. There is a joke among epidemiologists, for instance, that application of statistics demonstrates that everybody in Miami is born Latino and dies Jewish.
Another approach is to look very closely at the details of what is being compared. Concerning chocolate, for instance, there was a study suggesting that chocolate, and also herbal teas, orange and certain other foods containing antioxidant polyphenols, could promote closure of the ductus arteriosis, an opening between the fetal pulmonary artery and aorta that allows high pressure blood to move directly into systemic circulation, bypassing the fetal lungs. Normally, the ductus arteriosis closes after birth, but if it closes during fetal life that causes pulmonary hypertension and problems with the heart’s right ventricle. The study found that chocolate could thus be harmful to a fetus during the third trimester, but this doesn’t mean that chocolate earlier in pregnancy is doing harm. Since studies on food in pregnancy do not always compare trimesters, this hints at one way to resolve the conflict.
When you look at all studies on antioxidant foods together, there is not a clear picture on whether their effect in pregnancy is overall good, bad, or neutral. However, chocolate, red wine, and coffee are also in the news because they contain a compound called resveratrol, which activates proteins in the body called sirtuins. The resveratrol-sirtuin system has been a subject of research but it is very early in the game. Several laboratory animal studies have shown promise, but there have been no long-term studies in humans even not related to pregnancy. Then there is the added complication that red wine contains not just resveratrol, but alcohol too. So, as with many health claims about food, there is a whole lot of uncertainty in the realm of chocolate, coffee, and red wine. They are probably fine in moderation. A couple of cups of coffee per day is probably fine, but then there is a problem with ‘moderation’ meaning different things to different people. Moderate wine consumption is not two glasses per day; when you’re pregnant it could be more like a half a glass, or less. Moderate chocolate is not five candy bars, but much less. And so, if you’re really into these foods talk with your doctor, especially as you approach the final trimester.