Caffeine remains the world’s most widely used but least understood psychoactive drug with regard to its overall impact on public health. We know that caffeine has both desirable and undesirable effects. These effects are well documented in the medical research and widely accepted by consumers. Yet most, if not all, of the often-cited research dating back to the 1970s focus only on a narrow range of short-term effects associated with caffeine rather than its overall impact on us.
Too much of the published research, in my opinion, has focused on short-term athletic and cognitive performance and too little on long-term work performance and public health. The most often cited evidence in connection with negative effects actually relates to withdrawal symptoms rather than the effect of the drug itself; these are not the same issue! Other reports are hopelessly confusing. We can find well-considered studies, for example, that caffeine is associated with a lower incidence of depression and other studies associating the drug with higher incidence of depression. How do we weigh the positive against the negative? The scientific research, taken as a whole, has been unsatisfactory and unfulfilling from a consumer’s perspective.
I’m not aware of any analysis that effectively weighs the positive effects against the negative effects on long-term health and performance under a range of human experiences. Further, there does not seem to have been any successful attempts to isolate the impact of caffeine from the larger negative factors of chronic sleep deprivation, lack of exercise, and other stress factors that likely combine to produce negative effects on long-term health and performance.
We need more information that isolates the impact of caffeine and weighs the positive and negative effects. For now, I’ll just stick with the position “everything in moderation”.