Moderate Consumption

It would seem that the resolution to the caffeine debate, at least in terms of short-term effects, is simple moderation. Drunk to excess, coffee literally verges on poison; drunk in moderation, it is still the beloved tonic of tradition, a gentle aid to thought, labor, and conversation.

But just how much is enough and how much is too much? No study will commit itself. One can estimate based on inference. Few, if any, studies report negative effects from doses of caffeine under 300 milligrams a day. Since the average cup of coffee (or single serving of espresso) contains about 100 milligrams of caffeine, one could infer from this evidence that anyone should be able to drink about three cups of coffee a day and enjoy the benefits of caffeine with none of the drawbacks. Such a figure assumes, of course, that you do not also consume quantities of cola drinks, chocolate bars, and headache pills. This is a conservative estimate, however. One could infer from other studies that five cups a day is safe for most people. Furthermore, reaction to caffeine varies greatly from individual to individual; some people cannot consume any amount comfortably.

Long-Term Effects

So much for the short-term effects. Researchers in the last 30 years or so have tried to implicate coffee, specifically the caffeine in coffee, in heart disease, birth defects, pancreatic cancer, and a half-dozen other less publicized health problems. So far, the evidence is, at most, inconclusive. Clinical reports and studies continue to generate far more questions than answers, and for every report tentatively claiming a link between caffeine and disease, there are several others contradicting it.

If anything, the medical evidence currently is running in favor of exonerating caffeine rather than further implicating it in disease. Some evidence even points to modest long-term health benefits for coffee drinkers.

One example of the way medical establishment has tended to see-saw on caffeine, condemning on partial evidence then backing off on further evidence, is the purported connection between heavy caffeine intake by pregnant women and birth defects. In the mid-1970s, experiments indicated that the equivalent of 12 to 24 cups of coffee (or equivalent bottles of cola) per day may cause birth defects -- in rats. Although human beings metabolize caffeine differently from rats (and other researchers had questioned some of the conditions of the experiments), the United States Food and Drug Administration issued a widely publicized warning about the possible ill effects of caffeine on the fetus. Subsequently, an analysis by Harvard researchers of coffee drinking among 12,000 women early in their pregnancies failed to find a significant link between coffee intake and birth defects. The upshot of the debate? The official position, if there is one, came from a committee of the National Academy of Sciences, which recommended what common sense dictates, what this book recommends, and what coffee lovers through the ages have argued: Pregnant women, according to the NAS committee, should exercise "moderation" in their intake of caffeine.