Step in your neighborhood pharmacy and you’ll likely find an entire aisle jam-packed with nutritional supplements. With so many choices, how do you know what to buy?

Take your pick. The most expensive brands aren’t necessarily the best. Those discount store knock-offs can be just as good as the popular brands. Just be sure to check the label because those generics may not have the same level of nutrients as the original brand.

Choose a formula that has been USPtested. Testing doesn’t ensure the safety or efficacy of the supplements, but at least you know the supplement contains the ingredients it says it does—and that they are in a bioavailable form.

In most cases, it doesn’t matter if a vitamin comes from natural or synthetic sources. With vitamin E, however, choose a natural form such as RRR-alpha-tocopherol or d-alpha-tocopherol. The opposite is true for folate. Choose folic acid, which is a synthetic formulation more bioavailable than the natural folate found in food.

Consumer smarts. Don’t believe the hype on the label. “Natural” doesn’t necessarily mean “safe.” And words like “advanced,” “complete” or “maximum” can mean anything or nothing. A term such as “high potency” only means most (at least 66%) of the included nutrients have at least 100% of the daily values.

If it sounds too good to be true, it probably is. Steer clear of the snakeoil “miracle” cures. Don’t assume that because a supplement is on the shelf in your pharmacy or supermarket, it’s safe to take. The government doesn’t review or test supplements before they are sold.

Only after a substance is proven to be harmful does the FDA take action to have the substance removed. Be informed before combining supplements with over-the-counter andprescription drugs. For example, vitaminE and ginko biloba thin the blood and can dangerously interact with anticoagulants.

On the other hand, vitamin K can reduce the effectiveness of anticoagulant drugs. Consult with a health professional to be safe.