Are You Taking The Wrong Vitamins?

From magnesium to multis to D, C, and E, how do you know which ones to take? Not all are created equal. Some formulas contain less active forms of the vitamin—meaning you're probably not getting the full benefit—while others may be too potent or contain things you just don’t need.

Here's how to sort through all the label mumbo-jumbo to make the most of your vitamin-popping routine.

More than half of Americans pop a multi. If that’s how your doc wants you to start your day, follow these three tips: 

1. Choose one with no more than 2500 IUs of preformed vitamin A, says Tieraona Low Dog, MD, Prevention advisor and fellowship director at the Arizona Center for Integrative Medicine. Too much retinol, the active form of A (it will say "palmitate" or "acetate" on the label) has been linked to bone loss and increased risk of hip fractures, finds a review of 20 studies from UCLA. 

2. Look for one containing natural vitamin E (d-alpha tocopherol) because your body doesn’t absorb synthetic E (dl-alpha tocopherol) as effectively.

3. Unless you’re menstruating or pregnant, avoid formulas with iron. Not only do older women not need extra iron, a 2011 study in JAMA Internal Medicine that looked at women around age 60 found that iron supplements were associated with a 10% increased risk of mortality.

D isn’t always easy to get from food (unless you eat enough fatty fish and fortified dairy and cereals), but you need 600 IU a day. So if you’re taking a supplement, Dr. Low Dog says to choose one containing D3 (cholecalciferol). A recent study in The Journal of Clinical Endocrinology & Metabolism found that D3 is far more effective in raising blood levels of D than D2 (ergocalciferol). One catch? If you’re vegan, you’ll want to read the label carefully. Most cholecalciferol is derived from fish oil, so you’ll need to take a newer vegan D3 made from a plant compound called lichen; one option is Nordic Naturals' Vitamin D3 Vegan ($22, nordicnaturals.com).

There are times when your doctor may recommend an iron supplement—if you’re menstruating or have anemia, for example. But iron can wreak havoc on your GI system, including constipation and upset stomach. Avoid those unpleasant side effects by choosing a food-based iron supplement (Dr. Low Dog likes Mega Food Blood Builder). Bonus if it contains vitamin C to help boost iron absorption. In general, women under 50 need 18 mg of iron a day, while those over 50 need 8 mg.

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If you’re a woman, chances are you’ve been told to take a calcium supplement if you’re not getting enough though your diet; in fact, more than 50% of women pop calcium, according to a Journal of Nutrition study. But there are two things you need to know:

1. Avoid supplements boasting "calcium lactate" and "calcium gluconate" because these are two less concentrated forms of calcium, finds a study in Nutrition in Clinical Practice. Two main (and more ideal) forms of calcium are "citrate" and "carbonate." Carbonate tends to cost less and contains more calcium so you don’t have to take multiple pills (like you might with citrate), but you do have to take it with a meal. It also may cause bloating and constipation. If you’re prone to those digestive woes, then citrate will be your best bet. 

2. Your body can only absorb so much calcium at one time. On the supplemental facts panel on the back of the bottle, you’ll see an amount of “elemental calcium” listed (it’s simply the amount of calcium in the supplement). You don’t want to take more than 500 mg of elemental calcium at once, says Victoria Drake, PhD, manager of the micronutrient information center at the Linus Pauling Institute at Oregon State University. That means if you’re taking 1,000 mg per day—women up to age 50 should get 1,000 mg per day; those over 50 need 1,200 mg—you should take one pill twice a day. (Check out these food sources of calcium to meet your daily needs.)

Omega-3 supplements have gained mega popularity for good reason, having been associated with improving heart health, relieving arthritis symptoms, and even helping prevent skin cancer. And the supplement you're taking is probably fine. “Most of our omega-3 supplements in the US are actually pretty good quality,” says Dr. Low Dog.

Choose a supplement with 500 to 800 mg EPA and 300 to 500 mg DHA. On the label (look on the front of the bottle), it should say “molecularly distilled”—that’s your clue that the oil went through a process to remove heavy metals and contaminants. If you’re avoiding fish, look for supplements labeled “fish-free” or “vegetarian,” which are commonly derived from omega 3-rich algae. 

There isn’t an official recommendation for fish oil, but if you don’t have heart disease, the American Heart Association says you can get all the omega-3s you need from eating oily fish like salmon and tuna twice a week. If you have heart disease, your doctor may recommend getting up to one gram of EPA and DHA daily. (Vegetarian? Here's how to get enough omega-3s.)

Over age 50? Research shows you might not absorb B12 from foods as well as you used to. Plus, if you're taking metformin to treat diabetes, you're probably not getting as much B12 as you need, as the Rx interferes with B12 absorption. That’s where a supplement comes in. Dr. Low Dog recommends 250 to 500 mcg of the methylcobalamin form of B12, the form most readily available to the body. Most women need 2.4 mcg daily.

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Probiotics may improve GI health and even positively impact your mood and immunity, research shows. That’s because probiotics colonize good bacteria in your gut. While there's no RDA for probiotics, many people take them to improve their body’s balance. Go for a supplement that lists several species of bacteria, such as Lactobacillus and Bifidobacterium. Also scan the label to make sure the formula contains a prebiotic, like inulin or fructo-oligosaccharides (FOS); these feed probiotics so they can thrive in your gut, boosting the supplement’s effectiveness. 

Taking in the 2 to 2½ cups a day of fruits and veggies the USDA recommends provides about 200 mg of vitamin C—above the current daily recommendation that adult women get 75 mg. But because vitamin C plays such an important role in your body (it helps with the growth and repair of tissue, wound healing, and bone maintenance), the Linus Pauling Institute recommends that you get more: at least 400 mg a day, says Drake. She recommends 500 mg, broken up into two separate 250 mg doses, one in the AM and PM. For even better absorbability, go for a slow-release formula, suggests a recent review study on vitamin C, published in the journal Nutrients. Look for “sustained release” or “time-release” on the label.

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Migraines and menstrual cramps are just two of the reasons you might be taking extra magnesium. You can find them in many different forms, like magnesium oxide, citrate, glycinate, and others. Women over age 30 need 320 mg of magnesium daily, so taking a dose of 300 to 500 mg of citrate or glycinate is your best bet, advises Dr. Low Dog. For one, these forms are less likely to cause diarrhea. Plus, citrate is a soluble form of the mineral, and thus well absorbed. In a UK study that compared citrate with two other forms of magnesium (amino-acid chelate and oxide), taking citrate for 60 days boosted blood levels of the mineral the most.

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