Harvard Health

Do you feel tired or run-down? Do you lack the energy you used to have? If so, you're part of a large group. Fatigue is one of the most common problems patients report to their doctors. As many as 14 percent of men and 20 percent of women say they feel "frequently fatigued," and in a survey of more than 17 million older people, ages 51 and up, 31 percent reported the symptom of fatigue.

Go to the store, and you'll see a multitude of vitamins, herbs, and other supplements touted as energy boosters. Some are even added to soft drinks and other foods for this purpose. Especially popular are supplements containing ginkgo biloba, ginseng, guarana, chromium picolinate, vitamin B12, DHEA, coenzyme Q10, and creatine. Even ephedra, which was banned by the U.S. Food and Drug Administration several years ago, remains available on the Internet.

There's little or no scientific evidence to support the claims for most of these substances. The fact is, the only pill that'll boost your energy is one containing a stimulant, such as caffeine, and the effects of these stimulants wear off within hours. The same holds true for drinks touted as energy boosters. Most contain a combination of vitamins, as much caffeine as a cup of coffee, and lots of sugar.

Popularity of energy drinks soars

Looking for energy from a bottle? You're not alone. So-called energy drinks have become the fastest selling category in the beverage industry. Most popular among the 18-to-34 age group, energy drinks grew in sales by 240 percent from 2004 to 2009 in the United States, to an annual total of $7.6 billion.

But there's really no magic formula here. What gives these drinks their jolt is good old-fashioned caffeine. Caffeine content varies widely among energy drinks. Many contain as much or more caffeine as a cup of coffee, along with loads of sugar. A 2007 Consumer Reports analysis, which tested 12 popular energy drinks, found that the amount of caffeine varied from 50 to 145 milligrams (mg) per cup (8 ounces). But the bulk of these drinks -- nine of the 12 -- contained between 75 and 85 mg of caffeine per cup. As a point of comparison, the researchers reported that coffee has roughly 100 mg of caffeine per cup, while 12 ounces of Coca-Cola has 35 mg.

Energy drinks also contain a mix of herbs and substances that are marketed as "energy boosters," such as those discussed in this report, which haven't actually been proven to increase energy unless the drinks also contain caffeine.

Some medical experts are concerned that individuals, particularly young people, may steadily consume too many of these drinks -- and that so much caffeine, a diuretic, can contribute to dehydration. Public health experts have also raised concerns about the growing sales of energy drinks containing both alcohol and caffeine, prompting the FDA to warn manufacturers that caffeine is an "unsafe additive" to an alcoholic beverage. Caffeine can mask a person's level of intoxication, the FDA said. It's important to tell your doctor if you are taking any supplements. Some interact with other drugs.

Supplements (including herbs, vitamins, and other substances) aren't subject to quality control by the U.S. government. The FDA doesn't regulate their content, purity, or effectiveness. It's up to the individual manufacturers to police the purity and content of their own products.

Here's a look at some substances commonly touted as energy boosters:

1. Ginkgo biloba.

Derived from the maidenhair tree, ginkgo biloba has been used for centuries in Chinese medicine and is now a common dietary supplement in Western countries. Its effects on cognition (thinking), mood, alertness, and memory have been the subject of many studies, but many of those studies have not been of high quality. A 2007 Cochrane Collaboration review found evidence too weak to conclude that ginkgo biloba improved cognition in people with Alzheimer's disease. Other studies suggest ginkgo biloba may improve some aspects of mood, including alertness and calmness, in healthy subjects. Regarding memory, evidence is conflicting.

2. Ginseng.

This is a relatively safe and popular herb, said to reduce fatigue and enhance stamina and endurance. Data from human studies are sparse and conflicting. Some studies report that ginseng improves mood, energy, and physical and intellectual performance. Other research concludes it doesn't improve oxygen use or aerobic performance, or influence how quickly you bounce back after exercising.

3. Guarana.

This herb induces a feeling of energy because it's a natural source of caffeine. But consuming a lot of guarana, especially if you also drink coffee and other caffeinated beverages, could ultimately lower your energy by interfering with sleep.

4. Chromium picolinate.

This trace mineral is widely marketed to build muscle, burn fat, and increase energy and athletic performance, but research has not supported these claims.

5. Vitamin B12.

Some people take vitamin B12 by injection or pills as a way to get a quick energy burst, but most experts attribute any results to the placebo effect. Unless you have a B12 deficiency, taking shots or supplements is unlikely to make a difference.

6. DHEA.

Sometimes marketed as a "fountain of youth," this naturally occurring hormone is said to boost energy as well as prevent cancer, heart disease, and infectious disease -- among other things. The truth is that DHEA has no proven benefits and some potentially serious health risks, such as lowering levels of healthy HDL cholesterol and increasing levels of testosterone, which can encourage acne and facial hair growth in women. Some research shows DHEA can damage the liver. Because this hormone is related to estrogen and testosterone, there is also concern that it may increase the risk for breast and prostate cancers. It's wise to avoid taking DHEA until further research clarifies its side effects.

7. Coenzyme Q10.

This enzyme is found in mitochondria, the energy factories of our cells. Supplements have been shown to improve exercise capacity in people with heart disease and may do the same in people with rare diseases that affect the mitochondria. One small European study in 2009 suggested that people with chronic fatigue syndrome might benefit from supplementation with coenzyme Q10, but more research is needed on this topic.

8. Creatine

Another compound produced by the body; it is largely found in muscle. It is widely sold as a supplement. Taken as a supplement, there is evidence that it can build muscle mass and improve athletic performance requiring short bursts of muscle activity (like sprinting). However, there's little evidence that it can do the same in older adults, or that it can reduce a feeling of fatigue in anyone. While no adverse effects of taking creatine in the doses recommended on the bottle (typically 2 to 3 grams per day) have been established, there are very few studies of sufficient size and duration to allow confidence about the lack of adverse effects.

9. Ephedra.

Although this product was banned by the FDA in 2004 because of major safety concerns, including increased risk of heart attack and stroke, it remains available for sale on the Internet. Any effectiveness ephedra may have in terms of boosting energy probably results from two substances it contains -- ephedrine and pseudoephedrine -- which may increase alertness. There is no safe amount of ephedra you can consume. If you want to boost your energy by stimulating your central nervous system, a cup of coffee or another caffeinated beverage will work just as well. - From Harvard Special Report: Boosting Your Energy

 

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Health - Vitamins, Herbs And Supplements: Do 'Energy Boosters' Really Work?