(FORTUNE Magazine) – THANKS TO THE LUNKHEADS OVER AT Major League Baseball and the shenanigans of USA Track and Field, performance-enhancing drugs have gotten a bad name. Let's look at this for a minute. Isn't better performance what we're all searching for? Does anyone really strive for average performance or--worse--outright deterioration? I think not. But it's paradoxical to assume that in an attempt to improve things, you'd choose to ingest something harmful, like steroids or epo or the latest designer drug cooked up for power lifters in some back-alley lab in Belgium. No smart person would do this. Rather, what you'd want is the new generation of fine-tuned products that actually benefit the body--the micronized, optimized, cutting-edge stuff that helps stave off the inevitable stresses of life, especially urban business life. I'm talking about intelligently working all the angles to make sure the engine runs better than ever (even at higher mileage), not puffing up your muscles, shrinking your testicles, or thickening your brow bone.

For 20 years I've competed seriously at sports--mostly swimming, but I also dabbled in cycling and running. Along the way I began my business career and learned the extent to which mental and emotional stress take a very physical toll. Over time I've felt the changes: fatigue setting in faster, recovery taking longer, little pains cropping up, things just not feeling as sharp as they used to. I detest these feelings. Fighting them with every tool I could get my hands on seemed the thing to do, so I experimented with supplements that promised to help. Some did; most didn't. Unlike Big Pharma, the supplement industry has managed to evade strict FDA oversight. Making grandiose promises is standard practice, yet most of the claims are untested, subjective, and of dubious merit. Coaches, trainers, doctors, other athletes--everyone had a pet theory and a prescription about how to perform better. I tried them all. I'm talking about over-the-counter products--no prescriptions, nothing too harsh, nothing illegal. Some people call them nutraceuticals; some call them nootropics (after the Greek words noos and tropos, which together mean "acting on the mind"); some call them plain old vitamins; others call them drugs. Everyone, however, calls them big business: In 2003, estimated revenue for the dietary-supplement industry was $19.8 billion.

In the end my ideal selection came down to a mere handful. As you read through this list, please remember that everyone's biochemistry is different. Each of us is a unique and complicated machine, and what works for me may not work for you. (In fact, some supplements can hurt you.) So the first rule of performance enhancement is this: Listen to your body. If a supplement doesn't suit you, stop taking it. And it goes without saying that if you have a heart problem or any other health issue, or currently are using medication, talk to a doctor first.

Workout tonic [C][D][E][H]

Proendorphin was created by the St. Louis company Nutraceutics, a three-generation clan of pharmacologists, to help athletes train harder and recover faster. This orange powder, until recently available only through doctors, is a high-grade blend of B vitamins, kola nitida (an organic caffeine), ginseng, and other nutrients, carefully processed to ensure the highest level of absorption and potency. In general there are two problems with your average vitamin supplement. First, if it comes in a giant, horse-choking pill, it's likely to slip through your system largely undigested. And then there's the often crummy quality of the base ingredients. "We pay $100 per kilo for our ginseng," says Brett Cherry, Nutraceutics' sales manager. "Meanwhile, at trade shows people come up to us all the time offering ginseng for $6 per kilo."

I mix up a water bottle of Proendorphin and drink it during swim practice. On bleary afternoons I'll drink a packet and suddenly be interested in completing even the most deadly chore. As a stimulant that doesn't make you jittery, it's an excellent alternative to coffee. Also, Proendorphin is the best hangover cure I've ever tried.

Juice for your joints [A][F]

Glucosamine and chondroitin are known as a remedy for joint pain, but few have heard of MSM. Which is too bad, because MSM rocks. It's a natural form of sulfur used by the body to build bone, connective tissue, and muscle. In a perfect world your supply would be found entirely in fresh fruits and vegetables. These days, however, food isn't that trustworthy, and minerals are so depleted that we need to supplement. In my experience with a balky shoulder and occasional knee pain, MSM works quickly and powerfully to eliminate pain, with zero side effects. Friends I've turned on to it have witnessed the same result. (One of them referred to it as magic.) Often it's sold in a blend with glucosamine; for me it works better solo. Bonus: Sometimes referred to as "the beauty mineral," MSM feeds skin and hair.

Love weed [E][G][H]

The main ingredient of Testron SX, Tribulus terrestris, is a weed. The best crop grows in Bulgaria, and for centuries Eastern European and Asian civilizations have hoarded it for themselves. You can't blame them. This botanical comes with impressive claims and, as far as I'm concerned, delivers on them: It sparks libido, brightens mood, and acts as an all-round energy tonic. In my experience, the first item on that list is what you really notice. Tribulus stimulates the body's production of luteinizing hormone, which regulates sex drive. Look around the health-food store: There are entire aisles devoted to male potency. Most of the products are packed with low-quality stimulants and yohimbe, an herb that, when I took it, produced truly terrifying mood swings. In general, I look for a boost that doesn't come with a fierce backlash. This supplement will warm you up, not fling you overhead and then drop you onto cement.

Urban defense [A][B][C][E]

Juvenon tackles a universal problem: stress. Everyone knows that pressure-filled workdays, toxic environments, and bad habits exact a physical toll, but stress comes in devious packages. It seems deeply unfair that exercise, undeniably a good habit, also causes stress on a cellular level. The result is free radicals, rogue molecules that rampage through cells causing oxidation, which in turn disrupts molecular structure (think rusty car). A class of nutrients known as antioxidants helps repair (and for that matter, prevent) the damage. Vitamins C and E and beta carotene are the big three, but a substance called alpha lipoic acid is also popular among athletes. ALA doesn't just protect energy-producing mitochondria and DNA from free-radical damage; it also seems to boost the potency of other antioxidants. Meanwhile, at the University of California at Berkeley, renowned biochemist Bruce Ames discovered that stacking ALA with the amino acid acetyl-L-carnitine resulted in an even more effective formula, and a rejuvenating one, given that cell wear and tear is the definition of aging. I take these two nutrients (packaged together in Juvenon) to help recover from hard workouts, and though there are no huge, pyrotechnic effects I can point to--no bursts of energy or Dorian Gray--type drama --when I don't take it, I miss it.

Fuel for cells [A][B][C][D]

Not nearly as alien as its name, nicotinamide adenine dinucleotide, or NADH, is a coenzyme, the active form of vitamin B3. Your body comes equipped with a supply and doles it out in proportion to the amount of activity going on in any given cell. For instance, heart tissues work overtime and therefore receive plenty. One problem: The innate source dwindles over time. A naturopathic doctor recommended NADH, and though it's expensive, for me at least it's worth the cash. NADH is the body's most potent antioxidant. It cleans up messes. And who doesn't need that (especially after a five-course business dinner with three bottles of wine, followed by four hours of sleep and an overseas flight)?

Brain food [A][C][E][H]

Immodestly touted by its marketers as "the highest-quality brain-power powder on the market," Choline Cocktail II, for my money, delivers on its hype. The ingredient list is impressive--a tonic for the gray matter--and it's synergistic, meaning that these substances work more effectively when taken together. It includes phosphatidylserine, a phospholipid that nourishes nerve tissue, neurons, and cell membranes. Now the brain is complicated, and I'm no neurobiologist, but phosphatidylserine is one of the few supplements to have undergone rigorous scientific testing, at Stanford and elsewhere, that showed it's effective as a memory enhancer and brain protector.

It's accompanied in the mix by the brain antioxidant ginkgo biloba; DMAE, a concentration-bolstering supplement; and choline, a vitamin-like compound that can be absorbed through the blood-brain barrier, the body's defense against harmful substances getting into mission control. The brain loves choline, using it to maintain cell membranes and build the neurotransmitter acetylcholine (low acetylcholine is a distinguishing feature in Alzheimer's patients). This powder also contains a passel of vitamins, the heart-protecting enzyme CoQ10, and guarana, a naturally occurring form of caffeine. Choline Cocktail won't supercharge your workouts, but it's a lovely antidote to the four o'clock doldrums and a thoughtful thing to do for your body's hardest-working organ.

Turbo-heart [E][G][H]

Vivaxyl is another performance drink mix from the maker of Proendorphin. The two products share a similar recipe with one big difference: Each packet of Vivaxyl contains 2,800 milligrams of the amino acid arginine. This specific dosage--no more, no less, according to the company--promotes nitric-oxide release, a process that has an impressive résumé. (Three doctors won a Nobel in 1998 for discovering it.) The process does everything short of giving you a neck massage: It's great for your heart, revs up circulation, combats fatigue, strengthens the immune system, and contributes to better erectile function. As if that's not enough, I find that the Vivaxyl mix brightens my mood. This is a mellower drink than Proendorphin--the arginine seems to cut the stimulant quotient--making it perfect for days when a long meeting's on the agenda rather than a long workout. ■