Countless products, conflicting studies ‑- deciding which supplements to swallow can be confusing, to say the least. We asked our experts in the field to weigh in on which pills pack the biggest punch for healthy women in their 20s and 30s. Check out what these pros profess.

Susan Trimbo, PhD, senior vice president of scientific affairs for GNC
"The most prudent thing is to take a multivitamin," says Trimbo. Look for a brand name so you know that it's a quality product. Then it comes down to whether you want something comprehensive or a basic multivitamin that's more on the conservative side. Trimbo likes very comprehensive, high-potency products, which tend to pack more B vitamins and can include botanicals like green tea. Every woman should probably be taking a calcium supplement, as well, says Trimbo. Any kind of calcium is a step in the right direction, but Trimbo prefers calcium citrate malate, which in studies is shown to be absorbed well by the body. Other considerations include a fiber supplement and cranberry for urinary-tract health.

Barbara Levine, PhD, clinical associate professor of nutrition in medicine at Weill Cornell Medical College
Folic acid is important in preventing birth defects, so you need to get that in a "multi" if you're planning a family. Also, "go back to your multi for vitamin E," says Levine, who recommends sticking to 100 to 150 percent of the recommended daily amounts and getting most of your nutrients from food. Products labeled "stress formula" often contain more B vitamins, "but vitamins won't help you through emotional stress," she says. "Don't go overboard ‑- otherwise you're going to have expensive urine." Vitamins won't give you energy, either, she warns. Only calories can do that. Many of us are deficient in calcium, so pop a supplement with vitamin D unless you're getting four to five servings of dairy a day. Omega-3 polyunsaturated fatty acids, particularly DHA, are also high on Levine's list of must-take supplements: "[They] are very important for women planning on getting pregnant because babies need them for cognitive function and visual acuity. They can also help ward off postpartum depression." Levine recommends a DHA supplement that's derived from algae.