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Energy Supplements: Stimulants

  • Caffeine
  • Herbal sources of caffeine and related compounds like guarana, yerba mate, and kola nut
  • Green tea (also a source of caffeine)
  • Capsaicin (red pepper)
  • Asian Ginseng
  • Bitter Orange (specifically, the ingredient synephrine)

If you’re feeling groggy after lunch, what you really want is a stimulant. And for all the exotic herbs and amino acids sold as energy supplements, one of the most potent stimulants is also the most familiar: caffeine.

“Caffeine is a common ingredient in just about any product marketed for energy enhancement,” says Coates. And while an energy drink might have 25 other ingredients, the one you really feel is likely to be caffeine. “The amount of caffeine just swamps everything else,” Coates tells WebMD.

So how does caffeine work? “Caffeine and similar compounds do step up the metabolism temporarily,” says Roger Clemens, PhD, spokesman for the Institute of Food Technologists. “That can make people feel better.”

Shao says that there’s pretty good evidence that caffeine can temporarily improve mental focus and, in athletes, help stave off exhaustion.

Although some products are seen as natural alternatives to caffeine, many actually contain caffeine itself or similar chemical substances that have similar effects. These include kola nut, yerba mate, and guarana. Green tea also provides a dose of caffeine and a related compound, theophylline, as well as the antioxidant epigallocatechin gallate (EGCG). It is possible that, because of these specific compounds, green tea may have unique effects on mental and physical energy.

Asian ginseng is not a caffeine derivative, but it may also serve as a mild stimulant. Will it help boost energy? There’s a lot of historical use of the different species of ginseng as tonics, says Coates. And a fair amount of scientific evidence exists for the three main “ginseng” species and their effects on psychological and physical health. For example, the effects of Siberian ginseng (eleutherococcus senticosus, often just called eleuthero) were studied in the Russian cosmonauts. The results indicated that there may be some benefit to stamina and “physical” energy. Capsaicin -- the ingredient that makes chili peppers hot -- is also sometimes used for its purported stimulant properties, but more for a metabolic boost than for obvious improvements in physical or mental energy.

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