If you feel like the drugstore’s vitamins and supplements section is constantly expanding, you’re not imagining it. The global dietary supplements market is expected to grow about nine percent between 2021 and 2028 to be worth a whopping $128 billion. With so many options to choose from (fish oil! omega-3s! vitamin A!), it’s getting harder and harder to be a discerning consumer. Are those green horse pills hocked by your friendly neighborhood influencer actually life-changing? Do you really need to supplement all of the B vitamins?

While supplement labels may lure you into buying purchasing with big promises like “stress reduction” and “better sleep,” it’s important to be skeptical and do some preliminary research to see if a certain ingredient actually delivers on said promises. The U.S. Food and Drug Administration (FDA) does not approve vitamins and supplements; it simply inspects manufacturing practices and steps in if a certain supplement becomes a public health concern. So some companies make dubious claims and get away with it. One recent consumer review found that 46 percent of supplements don’t keep their lofty promises.

Basically, it pays to be a Skeptical Susan when you’re perusing the supplement aisle of the drugstore. But to make things a bit easier, we talked to registered dietitian and supplement researcher Anne Danahy, RDN, founder of Craving Something Healthy, and “Kelly LeVeque, holistic health coach and NOW Wellness Expert,” to spill on what supplements you should consider adding to your cart—and how to determine whether a product is actually right for you.

3 questions to ask yourself when you’re considering supplementation

1. Could I get this vitamin from my diet instead of taking a supplement?

Dietitians are a big fan of telling you to “eat your vitamins,” and Danahy is no exception. “[Everyone] should consider whether there are gaps in their diet that can be filled with food before turning to supplements,” says Danahy. “The nutrients in whole foods are present in balanced amounts and as part of a whole package with protein, carbs, healthy fats, fiber, antioxidants, etc. All of these work synergistically in your body, so always start with a well-balanced diet.” Basically, most people should try upping their intake of certain foods before resorting on a pill to make up the difference.

That said, certain people might struggle to meet their needs through diet alone, whether it’s due to a health condition (like Celiac disease) or their particular eating plan. Vegans, for example, have more limited sources of brain-boosting B12 since it’s most commonly found in animal foods. In cases like these, supplementation can be incredibly helpful to close nutritional gaps. Pregnant people should also take a folic acid supplement and other prenatal vitamins to support their baby’s development and reduce the risk of birth defects.

2. What is sparking your interest in this particular supplement?

Maybe you’ve heard that 5-HTP can help you calm the heck down when you’re majorly stressing or that melatonin can support a good night’s sleep. While there often is some evidence to support these touted benefits, it’s essential to make sure you’re addressing lifestyle factors that may also contribute to these issues, says Danahy. If work keeps you busy around the clock, for instance, can you try stress-management strategies like exercise, meditation, gardening, or reading before reaching for a supplement? If the answer is “no,” that’s totally fine—but the question is worth asking.

3. What can my family history tell me about what supplements may benefit me?

“Even if someone is in good health, I’d recommend assessing their risk for certain health conditions because of their lifestyle or family history,” says Danahy. “For example, someone with a family history of heart disease and blood pressure that’s starting to creep up may want to think about omega-3 fish oil, beetroot powder, or certain antioxidants.”

If this sounds like you, ask your doctor what they think about supplementation based on your personal family history. This isn’t a one-size-fits-all situation.

The 4 supplements to take, according to a dietitian and a nutritionist

1. Vitamin D

According to Danahy, most folks could benefit from vitamin D. “It’s hard to get enough from your diet unless you eat a lot of salmon, egg yolks, and fortified milk,” she says. “This is also a vitamin that most people aren’t deficient in, but many people have suboptimal levels.” Vitamin D has many essential functions, including helping your body absorb calcium (which is critical for bone health), reducing inflammation, and promoting mental well-being. In other words, it’s pretty darn important—and worth thinking about.

Daily recommended intake: 600-800 IUs per day (15-20 mcg).

2. Omega-3s

If you’re living and breathing right now, you’ve probably heard the hype surrounding omega-3s. “Omega-3 or fish oil is another one I often recommend for middle age-plus. It can help reduce blood pressure and triglycerides, but I also like it because it supports cognitive health and has anti-inflammatory effects,” says Danahy. She caveats that eating food sources of omega-3s—like salmon, sardines, and fatty fish two to three times per week—will still be a better option than supplementation.

Daily suggested intake: 1.1 grams for women; 1.6 grams for men (for reference, a 2-ounce serving of farmed salmon contains about 1.5 grams of omega-3s)

3. Magnesium

“[Magnesium] is involved in more than 300 biochemical reactions in your body, so it helps support everything from bones and muscles to glucose and blood pressure to DNA and RNA synthesis,” says Danahy. “You can take it anytime, but some people feel it helps them relax in the evening if they take it after dinner.” The mineral is also essential for heart health because it supports nerve, cell, and muscle health. She recommends magnesium glycinate, a form of magnesium that’s slightly easier for the body to absorb. (FYI, magnesium appears in foods including spinach, black beans, and almonds.)

Daily suggested intake: 310-360 milligrams per day for women (depending on age and pregnancy), and 400-420 milligrams for men (depending on age).

4. A multivitamin

LeVeque, for one, is a big fan of the multivitamin to cover all your bases. They can be a good way of consuming a variety of macro and micronutrients without paying for individual vitamins.

There’s a caveat, though: Multivitamins come in many varieties, so you will need to consult a doctor, dietitian, or other trust health professional about which blend makes sense for you based on factors like your age, diet, current medications, and whether or not you’re pregnant. Harvard Health recommends reading the label and choosing one that contains your daily recommended allowance of its various vitamins and minerals and features the United States Pharmacopeia (USP) seal of approval on the label (an indication of the purity and strength of a given vitamin). And beware of common multivitamin side effects, like GI distress.

Daily suggested intake: Varies per vitamin.

Long story short: Supplements aren’t nearly as straightforward as they seem. So if you have lingering questions, make sure to check in with your primary care doctor. There’s no use in spending big at the drugstore if it’s not making a significant impact on your everyday health and well-being.