See if this sounds familiar: Lately you’ve been doing more and more in less and less time, staying up way too late—and you feel dead tired when the alarm sounds in the morning. Caffeine, in the form of coffee and energy drinks, becomes a crutch for getting through the day. But there’s a catch. Just one “venti” Starbucks coffee packs a 415-mg caffeine jolt— about seven times more than found in a soft drink. At that level, coffee turns into a drug, and you turn into an addict.

What can you do to safely and naturally boost energy levels without resorting to stimulants? The answer lies in enhancing your normal cell biology and consuming more of the nutrients that help your body burn food for energy.

The 70 trillion cells that make up your body all work together to produce energy. Tiny cell structures called mitochondria convert blood sugar and fats to adenosine triphosphate (ATP), the chemical form of energy. In stepping-stone fashion, ATP levels increase through a series of three chemical processes. The following nutrients all help raise ATP and energy levels.

Alpha-lipoic acid

This antioxidant functions as a cofactor in the first two major steps of energy production. Animal and human studies have found that a combination of acetyl-L- carnitine, a slightly different form of the same nutrient, and alpha-lipoic acid can augment energy levels.

Dose: 100–300 mg daily

B vitamins

Although all B vitamins are beneficial, vitamins B1, B2, and B3 (niacin) play critical roles in breaking down food for energy. Some people get a quick energy spike after taking a daily high-potency B-complex vitamin supplement.

Dose: Choose a supplement that contains at least 50 mg each of vitamin B1, B2, and B3. In most formulas, amounts of other B vitamins are relatively consistent. B2 will turn your urine yellow, but that’s the vitamin’s natural color; it’s harmless.

Coenzyme Q10

In the 1970s, Japanese doctors started using this vitamin-like nutrient to treat heart failure, a disease characterized by a lack of energy in heart tissue. Studies have since found that coQ10 supplements improve stamina and energy levels in people who exercise by promoting the final step in energy production. Other studies found coQ10 also heightens energy in people who don’t exercise regularly, as well as in seniors.

Dose: 100–300 mg daily; it takes about three months to reach maximum effect

L-carnitine

This protein constituent transports fats within mitochondria so they can be burned for energy. Many antiseizure drugs, such as valproic acid, interfere with L-carnitine and can zap energy levels. A study of 66 centenarians found that L-carnitine supplements reduce physical and mental fatigue, and increase cognitive function and muscle mass.

Dose: 2,000 mg of L-carnitine or acetyl-L-carnitine; consider taking along with coQ10 for additional benefits. Combining L-carnitine with a high-protein dinner may energize you the next day.

Magnesium

This remarkable mineral participates in more than 300 enzyme reactions. Some of these take place in the energy-generating mitochondria. Like alpha-lipoic acid, magnesium aids glycolysis. Magnesium also bonds with ATP to help activate it, increasing energy.

Dose: 200 mg twice daily

Quercetin

Found in the skins of apples and onions, this antioxidant increases the number of mitochondria in brain and muscle cells, which in turn amplifies your energy-making capacity. In both animal and human studies, quercetin supplements improved endurance. (Cyclist Lance Armstrong is a fan.)

Dose: 1,000 mg daily

Note: It’s a good idea to talk to your health care provider before starting a new supplement.