Getting all the vitamins and minerals you need from the food you eat can be challenging for anyone—no matter what diet you follow. Not sure where you might come up short? In a 2009 research review, the Academy of Nutrition and Dietetics (formerly the American Dietetic Association) identified important nutrients of concern to vegans and vegetarians: omega-3 fatty acids, vitamins B12 and D, calcium, zinc, iron, and iodine. Supplements can help fill in the gaps should your menu be lacking, but before navigating the aisles, read on for what to look for—and what to avoid—when seeking veg-friendly options. Omega-3s Two omega-3 fatty acids—eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—promote overall health, including normal brain function and a healthy heart, and may contribute to strong bones and a lower risk for diabetes. GETTING ENOUGH? Fish is the primary food source of EPA and DHA. Plants contain the most basic type of omega-3, alpha-linolenic acid (ALA), which is found in abundance in chia, ground flaxseeds, flax oil, and walnuts, and in trace amounts in soybeans and tofu. Although your body can convert ALA into EPA and DHA, it may not produce enough: studies show that compared to omnivores, vegans and vegetarians tend to have lower blood levels of both EPA and DHA. VEG FACTOR: Look for fish-free omega-3 supplements that deliver either DHA or a combination of EPA and DHA made from microalgae (the same stuff fish eat to get their omega-3s). If you're pregnant or breast-feeding, consider talking to your physician about supplementing with DHA, especially important for the brain and central nervous system, to support the healthy development of your baby. Vitamin B12 Everyone needs vitamin B12 for healthy nerves and blood—a deficiency can cause serious and irreversible nerve damage, fatigue, and anemia. GETTING ENOUGH? B12 is produced by the gut bacteria in animals, and substantial amounts are found naturally only in animal foods. Eggs and dairy provide some B12, but not as much as meat and fish. You can alternatively turn to B12-fortified breakfast cereals, plant-based milks, meat substitutes, and nutritional yeast such as Red Star Vegetarian Support Formula. The National Institutes of Health recommends supplemental B12 for everyone over age 50—vegetarians and omnivores alike—since your body loses the ability to absorb B12 from foods as you get older. The recommended intake is only 2.4 micrograms (2.8 micrograms if you're breast-feeding), but there's no harm in upping that amount, since your body can safely store excess B12. VEG FACTOR: B12 in supplements is not animal-derived, but it could be packed in non-veg gelatin capsules, so check the label. You can also get your daily dose of B12 from a multivitamin. Vitamin D In addition to helping your body absorb calcium for stronger bones, the sunshine vitamin supports a robust immune system. Shortages have been linked to greater likelihood of depression, high blood pressure, and cancer. GETTING ENOUGH? You can generate vitamin D on your own by getting direct sunlight, but using sunscreen or covering up your skin stops the process. Many Americans—veg or not—may lack sufficient vitamin D, which can be hard to get from food alone. Food sources include mushrooms exposed to UV rays and fortified products such as dairy and nondairy milks, orange juices, and breakfast cereals. VEG FACTOR: There are two forms of vitamin D. D2, derived from yeast, is typically used in fortified foods, while D3, traditionally made from lanolin in sheep's wool, is arguably more absorbable. Fortunately, more and more vegan vitamin D3 options—sourced from lichen instead of lanolin—are popping up on the market. Calcium Essential for bone health, calcium helps lower risk of bone fractures, especially in older people. To absorb calcium, you also need vitamin D. GETTING ENOUGH? Dairy gets the most attention, but greens such as kale, collards, and cabbage also have highly absorbable calcium. Fortified plant milks, orange juices, and tofu are good plant-based sources too. If you don't consume a few servings a day, however, you could require a calcium boost. What's more, some greens, such as spinach, beet greens, and Swiss chard, contain oxalates, substances that inhibit calcium absorption. (Oxalates break down when greens are cooked.) Multivitamins may include enough calcium for your needs; if not, you can take a separate supplement, which might be paired with vitamin D or magnesium to help your body assimilate the nutrients. Supplements should provide only the amount missing from food—calcium overload can be toxic. The RDA for calcium is 1,000 milligrams daily for women up to age 50 and men up to age 70. The safe upper limit is 2,500 milligrams daily for men and women up to age 50, and 2,000 milligrams daily after age 50. VEG FACTOR: Calcium in most supplements comes from mineral deposits, but watch out for calcium derived from bone meal or oyster shell. Multivitamin A multivitamin is a convenient way to add overall insurance to your diet. In addition to calcium and vitamins D and B12, it often contains essential nutrients such as zinc, iodine, and iron that you may be missing. GETTING ENOUGH? There's plenty of immune-boosting zinc in nuts and seeds, but absorption may be blocked by phytates in whole grains and legumes. Likewise, iodine, important for thyroid health, can be found in iodized table salt (not sea salt or kosher salt) and sea veggies, but soybeans, cruciferous veggies, and sweet potatoes can interfere with iodine's absorption. Iron, too, can be tricky: women who have not reached menopause may need extra iron, which is lost during monthly periods. Eating iron-rich leafy green veggies and beans along with vitamin C-rich foods aids iron absorption. Note: If you get enough iron and calcium from other sources, look for formulas that leave these out. Too much can be harmful. VEG FACTOR: Stick with multivitamins labeled "vegan" or "vegetarian." Some contain digestive enzymes and probiotics, often called friendly bacteria, which enhance digestion and absorption of nutrients from both supplements and foods. Keep an eye out for the following on supplement labels: GELATIN The most common non-veg ingredient to look for. Many otherwise vegetarian supplements are rendered non-vegetarian by the presence of a gel cap. You want the ones delivered in V-caps or veggie caps. Gelatin is also found in some gummy vitamins. LANOLIN The source of most vitamin D3 supplements. Derived from sheep's wool, lanolin is vegetarian but not vegan. STEARIC ACID An additive that prevents supplement ingredients from caking during the manufacturing process. It might be derived from animals or plants (look for "vegetable source" in the ingredients list).