You eat a balanced diet, for the most part. You chomp on five nutritious servings of ripe fruits and cruciferous veggies every day—so you’re OK on the vitamins and minerals front, right? Not necessarily, reports the Ecologist (March 2008). In recent years, the soil in which farmers grow our foods has become so depleted of basic nutrients that produce simply isn’t as nourishing as it used to be.

Supplements can serve as a savvy backup to your everyday diet. The trick is taking the right ones, the right way. Not all pills and capsules are created equal, and labels are often little help: Every bottle claims to be the most complete, the most digestible, the best choice for men or for women. (Does anyone really benefit from 3,000 times the recommended daily intake of vitamin C?)

The first thing to keep in mind, reports Natural Solutions (April 2008), is that price doesn’t necessarily correlate with quality, so resist the temptation to err on the side of the expensive bottle. Look for vitamins in sufficient amounts, covering the recommended daily intake without going overboard. The magazine recommends 500 milligrams of vitamin C for a day’s dosage; excess water-soluble vitamins just pass through in urine anyhow—which is why vitamins are sometimes dismissed as a way to make expensive pee. For your body to use the vitamins, the pill must also dissolve properly. To test your vitamin, float one cup of white vinegar in a bowl of water heated to about 98 degrees. Drop in your pill, and gently shake the vinegar cup every five minutes. The pill should dissolve in 30 minutes to an hour.

Natural vitamins, which are derived from plant, food, or animal sources, are not necessarily better than synthetic ones. The main concern is bioavailability, or how well your body can make use of the nutrients. Vitamins C and B6, for example, are equally bioavailable in natural and synthetic forms, which is good news for anyone who enjoys the taste of chalky vitamin C chews. Fat-soluble vitamin E, however, is more bioavailable when it is derived from a natural source.