It's hard not to feel overwhelmed in the vitamin aisle, with dozens of products claiming to boost energy, ease stress, and even extend your life. 

Sorting through the mix can be tricky, but it's worth the effort. Since we don't always maintain perfect health on all fronts, certain supplements can help fill in the gaps. What's more, research suggests that some can reduce your risk of chronic illnesses.

But don't assume that any supplement gives you a free pass when it comes to your lifestyle. "Achieving optimal health really means eating a wholesome, varied diet; exercising regularly; and managing stress -- not popping pills," says Brent Bauer, M.D., director of the Mayo Clinic's Complementary and Integrative Medicine Program in Rochester, Minnesota.

So, along with maintaining healthy habits, consider including these four supplements in your daily regimen.

Multivitamin
Given multivitamins' recent bad press -- a large study showed they did not help prevent cancer or heart disease in postmenopausal women -- you might be wondering if your one-a-day is worth it. Our experts say it is. "Unless you eat a perfect diet of whole foods, it's worth taking a multivitamin to cover your nutritional bases," says Victoria Maizes, M.D., executive director of the Tucson-based Arizona Center for Integrative Medicine. Multivitamins typically contain a range of nutrients that people often need more of, such as vitamins C and E, the B vitamins, and zinc. Some studies have shown a link between multivitamin use and better health.

But remember that no vitamin can compensate for poor lifestyle choices: "If you tend to think, 'I can smoke, eat fast food, and never exercise, but as long as I take my vitamins, I'm good to go,' you're wrong," says Bauer.

How to take: Seek a product with 400 mcg of folic acid and vitamins B6 and B12, says Maizes. It should offer vitamin C (about 200 mg), natural vitamin E (400 IU), and selenium (200 mg). Look for vitamin A as mixed carotenes, not as retinol, which has been linked to an increased risk of fractures.