A quality multivitamin can help ensure your body gets the vitamins and minerals it needs to thrive. Yes, a balanced diet is still your first line of defense—but since only one in 10 American adults gets enough fruits or vegetables, a daily multivitamin can be key for filling nutrient gaps.

With a dizzying array of multivitamins out there vying for your attention, picking one can be overwhelming. Here, nutritionists share six questions you can ask to simplify the process.

1. Is this multivitamin formulated for my Gender?

It may sound obvious, but it’s important to consider a multi made for your biological gender.

“Men and women vary greatly in their vitamin needs,” say The Nutrition Twins Tammy Lakatos Shames, R.D.N., C.D.N., C.F.T., and Lyssie Lakatos, R.D.N., C.D.N., C.F.T. “For example, women of child-bearing age need additional nutrients, like folic acid.” Menstruating women also need some iron in their multivitamin, since they lose the mineral through their monthly period.

“Men, meanwhile, should not take multivitamins that contain iron, Lakatos and Lakatos Shames add. “For them, higher blood iron levels are linked with increased risk of stroke and heart disease.”

2. Does this multivitamin have a quality seal?

Quality vitamin and supplement brands put their products through rigorous testing—and their packaging sports a third-party-testing or quality seal to prove it.

The Vitamin Shoppe puts all of its own brand products through 320 rigorous quality-assurance steps and verifies ingredient purity and potency through independent, third-party labs. (Check for the quality seal on all of the products.) Other products may sport a USP Verified or NSF International certification seal, says dietitian Lauren Manaker M.S., R.D.N., L.D.

These extra measures ensure you’re getting a high-quality product you can trust.

3. Are there specific nutrients I need to look for in a multivitamin as I age?

Your doctor or nutritionist can provide important insight on your personal nutrition needs as you age. However, people over 50 may want to seek out vitamin B12, in particular.

“Vitamin B12 from food isn’t well-absorbed by up to 30 percent of older adults, as their stomachs become less acidic with aging, says Maggie Moon, M.S., R.D., Los Angeles-based registered dietitian and best-selling author of The MIND Diet.

Related: The Best Skin-Care Supplements For Women Over 50

“The issue is, the liver stores B12 for three to five years,” says Moon. “As a result, deficiency—and related cognitive damage—could develop for years before symptoms occur.”

Talk to your healthcare provider about any other nutrients in particular to look for in your multi.

4. are there nutrients I should limit in my multivitamin?

On the flip side, you may also want to avoid certain nutrients in your multi as you age.

Based on recent diet and lifestyle guidelines to prevent Alzheimer’s disease, you might want to avoid multivitamins that contain iron or copper, especially as you approach and pass middle age.

Iron and copper are essential nutrients. However, some studies suggest that excessive intake—particularly when combined with a diet high in saturated fat—contributes to cognitive problems and increased risk of Alzheimer’s, Moon explains.

5. Do I need (or already take) a prenatal vitamin?

If you’re trying to conceive, or are pregnant or breastfeeding, your doctor has probably already recommended you take a prenatal vitamin, which is specifically formulated for your (and your baby’s) needs.

Related: When Should Women Start Taking Prenatal Vitamins?

In these cases, you don’t need to double up. “If you take a prenatal vitamin, that should take the place of your multivitamin,” says Moon. “The only reason to add more vitamin or mineral supplementation on top of your prenatal is a medical professional specifically advises you to do so.” Women low in vitamin D, for example, may need additional supplementation.

6.  If purchasing a whole-food multivitamin—is it non-GMO?

Choosing a whole-food multivitamin really comes down to personal preference. If you do opt for a whole-food multi, though, consider where it contains GMOs. If you avoid GMOs in foods, you’ll want to avoid them in whole-food vitamins and supplements you take, too.

“Non-GMO supplements are another way to avoid exposure to the herbicide glyphosate,” say Lakatos and Lakatos Shames. “Research suggests long-term exposure to glyphosate is linked to cancer.” (It’s also been linked to liver and kidney damage, and reproductive and developmental issues.)

Look for a Non-GMO Project certification seal to confirm a product is free of GMOs.

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