A supplement that promises to give you a day's worth (or more!) of whatever vitamin or mineral you need sounds like a guarantee for better health, right? But before you stock up on zinc, vitamin D, and iron—to name a few—it’s worth looking at whether you truly need to supplement your diet.
Experts agree that it’s best to nourish your body with whole foods, and that for the most part, people can get the nutrients they need from a varied and balanced diet.
“It’s best to go with whole foods first, not only because it encourages you to have variety in your diet, but because we generally better absorb vitamins and minerals when they come from whole foods,” says Heather Caplan, RD, host of the RD Real Talk podcast and co-founder of the Lane 9 Project.
And those labels that boast a supplement can give you 300% of your recommended intake? Don’t fall for it, says Caplan. Our bodies aren’t designed to absorb more than we need at any given time. “Supplements can become expensive things that we excrete anyway,” she says.
That being said, there are some special cases in which you may benefit from popping a pill. Talk to your doctor if anything below sounds like you, and, if you decide to try a supplement, look for brands that have been vetted by a third party. Supplements aren’t as well regulated as prescription meds, so Caplan recommends brands that have been verified by the nonprofit United States Pharmacopeia, marked by a USP label.
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You have anemia
Anemia is a condition in which your body doesn’t have enough red blood cells to transport oxygen, often leaving you feeling weak or fatigued. Often, people with anemia are low in iron and vitamin B12.
“Taking an iron supplement can help your body build iron stores faster than if you were trying to get them just from food,” says Caplan. “If you were able to increase your iron stores from food in the first place, you probably wouldn’t be experiencing anemia.”
She points out that being deficient in iron isn’t usually related to diet, but instead, from blood loss, menstruation, childbirth, and even physical activity, like long-distance running, because of the toll it can take on your body.
While adding a supplement can up your iron stores, increasing your dietary sources of iron will also help–and it will encourage a more balanced diet. There are two types of iron sources: heme and non-heme. Heme iron comes from animal products—the best being red meat; non-heme iron is found in plant sources, like beans and lentils, and, of course, spinach.
If you’ve been diagnosed with osteoporosis, your bones are weak, fragile, and at risk of fracture. You may need to add a calcium and vitamin D supplement—they’re often combined into one pill to increase absorption—to make sure you’re getting enough to keep your bones strong.
Vitamin D is one nutrient that’s hard to get through diet alone. Dietary sources include fish, eggs, some mushrooms, cheese, and fortified foods like orange juice. Your body also makes vitamin D when exposed to sunlight.
Folic acid is the most important nutrient the little person you’re growing needs, as it helps prevent brain and spine birth defects. In fact, it’s so important that doctors and dietitians recommend taking a prenatal supplement with folic acid when you’re trying to conceive so it’s already in your system when you become pregnant.
Caplan points out that it can also be a good idea for pregnant women to take iron, because your iron needs almost double during pregnancy.
Pregnant women may also benefit from taking a fish oil supplement, she says. Your body can’t make omega-3 fatty acids, so you have to get them from food or supplements. Increasing your fatty fish intake is one way to up your omega-3s (not to mention healthy fat and lean protein), but fish oil is often added to prenatal supplements to support a baby’s cognitive development.
For people with celiac disease, eating gluten, a protein found in wheat, damages the small intestine. When the small intestine is inflamed, nutrients like B vitamins may not be fully absorbed. Upon diagnosis, doctors may recommend that people suffering from celiac disease take B vitamin supplements.
Once you settle in to your gluten-free diet and inflammation of the intestine has gone down, you likely will no longer need a supplement. Caplan recommends eating a variety of foods like gluten-free oats and quinoa to maintain a healthy level of B vitamins.
While non-heme iron is found in plant sources, it’s the heme iron in animal products that’s best absorbed by your body. Caplan says it’s worth getting an annual blood test done to determine if your iron levels warrant a supplement if you don't eat meat.
Vitamin B12, on the other hand, is only found in animal products and fortified foods.
“The general recommendation is for vegans and vegetarians to take a supplement for B12, but some don’t, and they may find they’re doing okay,” Caplan says.
If people following a vegan diet aren’t eating much soy—tofu, soy milk, edamame—they may be at risk of not getting enough calcium, too, Caplan says.