Many Americans prescribe themselves a minimum of one cup of coffee or tea a day in order to remain alert, but new research suggests that stopping use may have deleterious effects, but more importantly that caffeine was no more useful than a placebo.

Scientists at University of Vermont and Johns Hopkins found that when daily caffeine users stopped consuming the chemical, blood flow was reduced in the brain, a likely cause of withdrawal symptoms such as fatigue or reduced alertness, and were matched with participants reports of those same effects.

They also found that people on placebos reported similar experiences to those on caffeine over the course of the study.

"In contrast to what most of us coffee lovers would think, our study showed no difference between when the participant was maintained on chronic placebo and when the participant was stabilized on chronic caffeine administration," said lead author Dr Stacey Sigmon. "What this means is that consuming caffeine regularly does not appear to produce any net beneficial effects, based on the measures we examined."

Those looking to maintain alertness may find that vitamin supplements, especially for those who do not get enough in their daily diet, may help to alleviate some feelings of lethargy by enabling the body to better process nutrients.