Despite providing a variety of health benefits, vegetarian and predominantly plant-focused diets don’t generally provide all the nutrients your body needs.^1,2 If you’re not eating a wide variety of plant-based and animal-based foods on a daily basis, a good multivitamin can help supplement the vitamins and minerals your diet may be lacking.

Specific nutrients vegetarians should pay attention to

B12

Vitamin B12 is required for DNA synthesis, healthy neurological function, and the manufacturing of red blood cells that carry oxygen to our cells.³ Consequently, if you’re deficient in B12, your cells may not receive the necessary amount of oxygen they need to function. A B12 deficiency is linked to anemia, neurological issues, low energy levels, and overall weakness.^4–6 In other words, a B12 deficiency can leave you feeling tired and sluggish—something none of us can afford these days. Because our bodies do not make B12, we must obtain it from food sources (primarily animal products such as eggs, dairy, and red meat) and/or supplements. Although there are plant-based sources that naturally contain B12 (shitake mushrooms, spirulina, nori) or are fortified with B12 (nutritional yeast, soy milk, meat substitutes), because these options are less prevalent than animal-derived sources, vegetarians are at particularly high risk for B12 deficiency.⁷

Calcium

Calcium plays a pivotal role in many bodily processes, including heartbeat regulation, the regulation of heart rate and rhythm, muscle contraction, nerve impulse transmission, blood clotting, and  building strong bones and teeth.⁸ Over time, a calcium deficiency can lead to low bone mineral density, an increased risk of  fractures and osteopenia, and—if left untreated—osteoporosis.⁹ Calcium must also come from our diet and is mainly found in dairy products, dark leafy greens, almonds, and soybeans (fortified soymilk, tofu, and tempeh). Although many of these sources are plant-based, research indicates that many vegetarians and vegans have difficulty meeting their calcium needs and may be at a greater risk of calcium deficiency than non-vegetarians.¹⁰

Iron

Like B12, iron plays a major role in red blood cell production, particularly in the formation of hemoglobin, which transports oxygen from the lungs to other parts of the body.¹¹ Iron comes in two forms: heme iron (which can be found in animal-derived foods like meat, poultry, and fish) and nonheme iron (commonly found in fortified cereals and plant-based foods like beans, legumes, and dark leafy greens). It is important to note that the amount of iron your body actually absorbs from these sources is typically low (ranging from 2 to 35%) and will depend on the type of iron consumed along with other dietary factors.¹¹ Heme iron is moderately bioavailable and other dietary factors have minimal effect on its absorption (roughly 15-35% is absorbed), the bioavailability of non-heme iron is lower and can be strongly affected by the consumption of certain foods (roughly 2-20% is absorbed).¹¹

Foods that can inhibit iron absorption include those rich in calcium (dairy products), phytates (grains, nuts, sesame seeds, soybeans) and polyphenols (black tea, coffee, red wine, dark chocolate, cocoa powder).  On the flip side, foods high in vitamin C can actually enhance iron absorption.¹¹ (Which is why squeezing some lemon over your spinach salad or topping your iron-fortified cereal with sliced strawberries are great ways to enhance flavor and build up your iron stores!) It’s important to keep these things in mind as even mild forms of iron deficiencyhave been linked to cognitive and functional impairment, increased risk of disease, and pregnancy complications for both Mom and baby.¹¹ This is especially important for vegetarians, given that the low bioavailability of iron in plant-based foods generally puts them at an increased risk for iron deficiency.¹¹

Zinc

Zinc contributes to a number of important bodily processes, including building up our immune system’s defenses, combating oxidative stress and apoptosis, and aiding in whole-body homeostasis.¹² However, a vegetarian or plant-based diet typically contains more phytate-rich foods (grains, nuts, sesame seeds, soybeans), which are the main inhibitors of zinc absorption.¹³ Zinc absorption is generally low in humans (only 33%!) and even lower for individuals who eat a diet with a high phytate to zinc ratio.¹⁴ Ways to decrease the phytate content in foods (and their effects on zinc absorption) is by soaking nuts, seeds, and legumes overnight, consuming fermented foods (tempeh, miso), and choosing sprouted grains.¹⁵ However, a recent review of 26 studies found that dietary zinc intakes and zinc blood levels were lower in populations that follow vegetarian diets compared with non-vegetarian populations.¹⁶ So even if you’re taking measures to reduce the phytate content in your plant-based foods, it’s best to supplement with zinc to ensure you’re getting the appropriate daily amount. 

Vitamin D

This one isn’t exclusive to vegetarians—everyone should be concerned about their vitamin D intake. Among its many functions, vitamin D provides support for cardiovascular functions, immune activity, a healthy pregnancy, and bone, muscle, and brain health.¹⁷

Unfortunately, recent research indicates that roughly 50% of Americans are deficient in vitamin D, which can lead to significant health consequences.¹⁷ Although this deficiency is not specific to a vegetarian diet, most individuals (including vegetarians) would benefit from supplementing their vitamin D intake regularly.

Taking a daily multivitamin can help fill gaps

While a vegetarian or plant-focused diet can provide you with higher amounts of vitamins and minerals, it also eliminates certain animal-derived foods that contain more bioavailable forms of particular nutrients. Fortunately, taking a daily multivitamin with the right nutrients can help fill in some of those gaps, and help you reach your long-term health goals. But remember, multivitamins are called “supplements” because they are meant to supplement your diet; not replace or substitute for a balanced diet.