The effects of ginseng, ephedrine, and caffeine on cognitive performance, mood and energy

A variety of claims regarding the purported energy-enhancing properties of nutritional supplements and food constituents have recently been made. It a ppears that the supplements most frequently associated with such assertions are ginseng, ephedrine, and caffeine. Claims of increased energy are diffi cult to evaluate objectively because their meaning is not usually defined o r specified. Often it is not clear whether the claims refer to physical or mental energy or both. Furthermore, an agreed upon scientific definition of either physical or mental energy enhancement does not exist. In spite of o bvious differences in what the term physical energy, as opposed to mental e nergy implies, there is no clear scientific consensus on whether there is a difference between the two types of energy. Because the substances in ques tion have been anecdotally associated with improvements in both physical an d mental performance, their effects on both functions will be discussed, bu t with an emphasis placed on cognitive function and mood. Of the three subs tances discussed, caffeine's effects on cognitive and physical function, mo od, and energy are best understood. If is clear that this food/drug enhance s these functions when administered in moderate doses. Ephedrine may also e nhance certain physical and mental functions related to "energy," but the e vidence that ginseng has such properties is exceedingly weak.