If Your Vitamins Are Missing These Ingredients, You're Shopping Wrong


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Have you ever browsed the aisles of your local drugstore or scrolled through Amazon, trying to figure out exactly which supplement is best? You might want to start taking vitamin D, but just looking at all the ones that are for sale out there can seem overwhelming. So you inevitably choose the one with the highest ratings or the coolest-looking bottle or the kind that you've seen on your friend's kitchen counter.

While it can be easy to go with something that's popular or that your friends trust, there are some things to keep in mind when shopping for vitamins. You'll want to be sure that what you're buying is actually effective and safe—because who wants to shell out money for something that isn't going to help you at all?


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And it's important to note that your diet should always come first when it comes to getting those nutrients you need. "It's always best to get your vitamins and minerals from eating a well-balanced, nutrient-dense diet," explains Claire Virga, MS, RDN, of Rooted Wellness. "Most healthy individuals can get everything they need from a balanced diet, and taking lots of different supplements is unnecessary, expensive, and potentially harmful. Always consult your doctor before taking a new supplement."

Plus, taking supplements won't cancel out any poor lifestyle choices or habits. They're not the cure for everything, and they're highly individualized. "If you're not sure whether you're meeting all of your dietary requirements with food alone, throwing in a really well-formulated multivitamin or multi-mineral is not a bad way to go, but it's important to understand that you can't supplement your way out of an unhealthy lifestyle and expect for it to work," says Robin Foroutan, MS, RDN, HHC, a spokesperson for the Academy of Nutrition and Dietetics.

But sometimes, you will need to shop around for supplements. So how can you be sure that what you're putting into your body is going to help? I asked both Virga and Foroutan for their tips on choosing seven common supplements. Again, keep in mind that you should always chat with your doctor before you take something new. These are general recommendations, but your doctor knows your health history best and will be able to give you more personalized suggestions.

Vitamin D

It's probably safe to say that almost everyone has had a vitamin D deficiency before. Virga cites a 2011 study that found 41.6% of U.S. adults had a vitamin D deficiency. "It's almost impossible to get enough vitamin D through diet alone to keep your blood levels in a good range," Foroutan adds. "Because vitamin D really is synthesized by your skin in response to sun exposure."

The nutrient is crucial to our immune system and bone health, so it's important to get your levels checked with your doctor regularly, Virga explains. Decreased levels of vitamin D have been associated with increased risk for certain types of cancer and type 1 diabetes.

What to Look For: "Vitamin D supplements are found in two different forms, D2 (ergocalciferol) and D3 (cholecalciferol)," Virga explains. "Vitamin D3 is the type found in the body and that our bodies produce from UV light. Studies have shown that vitamin D3 is more effective at raising levels of calcifediol, the major circulating metabolite of vitamin D. A 2008 study showed that vitamin D3 supplementation was almost twice as effective at raising serum vitamin D levels as vitamin D2 supplementation among a group of elderly women."


Omega-3s are important for brain and heart health. They can help lower the risk of heart disease by reducing triglyceride levels and raising HDL (good cholesterol) levels. And omega-3 fatty acids can help with inflammation, too.

Virga says that healthy individuals who eat at least two servings of fatty fish (like salmon or tuna) per week may be able to get enough omega-3s through their diet alone. But she recommends that people who have high triglyceride levels, are at risk for heart disease, or are pregnant or breastfeeding talk to their doctors about taking omega-3 supplements.

What to Look For: "When selecting an omega-3 supplement, it is important to pick a supplement that contains a combination of both EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)," Virga recommends. "EPA and DHA are in the biologically active form and can be used readily by the body. They each provide unique health benefits so it's important to look for a supplement that contains both. You may also see supplements that contain ALA (alpha-linolenic acid), which is a form of omega-3 derived from plant-based sources. However, ALA is not in the active form and the conversion to the active form is not very efficient, making an ALA supplement less effective and beneficial for health."

And Foroutan adds that if you are buying fish oil or other essential fatty acids, you should look into the packaging and shipping. "Check that it's not expired because these are delicate oils that could go rancid—that's true for any essential fatty acid," she says. "You want to make sure that you're buying it from a reputable place. If you're buying it in stores or even online, you want to make sure that it's hasn't been sitting in a hot warehouse for days before it shipped out to you."


According to the National Institutes of Health's Office of Dietary Supplements, magnesium plays a role in regulating muscle and nerve function, blood sugar levels, and blood pressure, and making protein, bone, and DNA. Through your diet, you can get magnesium from legumes, nuts, seeds, whole grains, leafy greens, and some milk products.

If you're magnesium-deficient, you might experience symptoms like loss of appetite, vomiting, fatigue, and weakness. And the NIH says that in some severe cases, other signs can include numbness, tingling, muscle cramps, seizures, personality changes, and abnormal heart rhythm.

What to Look For: There are different types of magnesium supplements for different purposes, so it all depends on your specific needs. Foroutan says that magnesium citrate and magnesium oxide are normally used for regularity and constipation. "Then, there's magnesium glycinate, and that one is better absorbed," she explains. "So that's the form that I would recommend if we do some blood testing and it shows that their magnesium mineral levels are low because that one is better absorbed. And then there's magnesium threonate. That one is more for brain function and mood. So if I'm using it for neurotransmitter reasons or somebody who's high-stress and I want them to chill out, magnesium threonate would be a more appropriate one."


Virga says that it's common for women in their reproductive years to experience an iron deficiency because of menstruation. Also, women's iron needs increase during pregnancy and lactation as well. 

According to The Cleveland Clinic, iron helps prevent anemia and boosts resistance to infection. You can get iron in your diet through red meats, poultry, fish, beans, spinach, tofu, and lentils, to name a few foods.

What to Look For: Virga explains that iron supplements come in many forms, and you'll see different types of iron listed on the ingredients labels, which can be confusing. Some common forms are ferrous sulfate, ferrous gluconate, ferric citrate, and ferric sulfate.

"Iron supplements are known to cause GI upset and side effects like constipation, diarrhea, and nausea," she says. "Constipation is one of the main complaints I hear from clients taking iron supplements, which is why I often recommend iron supplements containing ferrous bisglycinate, a form of ferrous iron that has been shown to be effective at reducing the risk for iron deficiency in pregnant women and causes fewer GI issues, including constipation."

Vitamin B12

B12 plays an important role in red blood cell formation, brain function, nerve health, and DNA synthesis, Virga says. Some symptoms of a vitamin B12 deficiency are weakness and fatigue; light-headedness or dizziness; heart palpitations or rapid heart rate; shortness of breath; nausea or poor appetite; weight loss; diarrhea; and constipation.

The tricky thing about vitamin B12, though, is that you can only get it through animal-based foods, so vegetarians and vegans will have to take supplements. Additionally, Virga says those over the age of 50 may also need to take a vitamin because the stomach stops producing enough hydrochloric acid to support optimal B12 absorption as we age.

What to Look For: "When you're looking for supplements, there are a lot of different forms of B12," Foroutan says. "The cheapest and most common is called cyanocobalamin. It is not great. It's not well utilized by your cells. So a better one to use is hydroxocobalamin or methylcobalamin."


Folate is a B vitamin that is needed to produce healthy red blood cells and create energy from the foods that we eat, according to Virga. The vitamin becomes even more important when you're trying to conceive or are pregnant, as inadequate consumption during the first six weeks of pregnancy can lead to neural tube defects.

Folate can be found in a lot of different foods like leafy greens, fruits, nuts, beans, seafood, eggs, meat, poultry, and grains. According to the NIH, spinach, liver, asparagus, and brussels sprouts are foods with the highest folate levels.

What to Look For: "Folic acid is a synthetic form of folate you'll find in most supplements and fortified foods," Virga says. "Once we consume folic acid, our bodies must convert it to the active form of folate, methylfolate. Many individuals possessing a MTHFR gene variant may be unable to efficiently convert folic acid into the active form, which can be dangerous, especially during pregnancy when folate needs are increased. Since MTHFR gene variants are quite common and many people are unaware they have a variant unless they’ve undergone genetic testing, I recommend that you look for a folate supplement that contains the active form, L-methylfolate. This ensures that your body can use the folate you are taking in from the supplement."


Biotin is a B vitamin that plays a role in the metabolism of fatty acids, glucose, and amino acids, plus histone modifications, gene regulation, and cell-signaling, according to the NIH. Foods that contain biotin include meats, eggs, fish, seeds, nuts, and some vegetables like sweet potatoes.

Many people take it to support hair, skin, and nails. "If you're losing hair, there might be a problem, so you should see a doctor," Foroutan says. "You have to make sure your thyroid's okay; you have to make sure that you don't have an unusual nutritional deficiency; stress levels might be out of whack. That's the first place to start, so go to the doctor. If all things check out clear, a biotin supplement is a reasonable thing to try. It works the best if you're actually deficient in biotin."

What to Look For: "With the dosing, if it's for hair and nail health, I would recommend at a minimum people take 5 milligrams," Foroutan says. "The bottle usually has biotin listed as micrograms, so 5000 micrograms is 5 milligrams. Anywhere between 5 and 10 milligrams is an appropriate dose for hair, skin, and nails."


This article is provided for informational purposes only and is not intended to be used in the place of advice of your physician or other medical professionals. You should always consult with your doctor or healthcare provider first with any health-related questions.

Managing Editor

Sarah is lifestyle writer and editor with over 10 years of experience covering health and wellness, interior design, food, beauty, and tech. Born and raised in Los Angeles, she attended New York University and lived in New York for 12 years before returning to L.A. in 2019. In addition to her work on THE/THIRTY and Who What Wear, she held editor roles at Apartment Therapy, Real Simple, House Beautiful, Elle Decor, and The Bump (sister site of The Knot). She has a passion for health and wellness, but she especially loves writing about mental health. Her self-care routine consists of five things: a good workout, “me” time on the regular, an intriguing book/podcast/playlist to unwind after a long day, naps, and decorating her home.