Find out what they are and their best sources—food or supplements.

Find out what they are and their best sources-food or supplements.

Are you getting the nutrients you need? If you are striving for a balanced diet based on the USDA's MyPlate model (whole grains, lean proteins and lots of veggies), you likely are. Still, there are instances when even the healthiest eater should consider taking a vitamin or mineral in supplement form. Listed here are the nutrients we need (and may not be getting enough of) and their best sources: food or supplements. (Be sure to consult your health-care provider before deciding to take any nutritional supplements.)

Vitamin A: Leafy greens and orange vegetables supply loads of beta carotene, which your body converts to vitamin A: half a sweet potato (11,000 IU) or a large carrot (12,028 IU) will cover your bases. If you eat a healthy diet, you probably don't need supplemental vitamin A, but a multivitamin/mineral that delivers no more than 100% of the Daily Value (check the Supplement Facts panel) won't hurt.

Vitamin C: One red bell pepper (152 mg) or a large orange (98 mg), and you're done for the day. Recommended intake is 90 mg. Other great sources: broccoli (51 mg, 1/2 cup, cooked), strawberries (85 mg, 1 cup).

Vitamin D: When UV rays hit our skin (sans sunblock), we make this "sunshine" vitamin-but often not enough of it. The Institute of Medicine (IOM) recently upped recommended intakes in a 2011 report, concluding "available scientific evidence supports a key role of calcium and vitamin D in skeletal health." Older people, people with dark skin and people who live in areas where stretches without a sunny day are common (e.g., the Northeast) should supplement with a multivitamin/mineral or calcium with vitamin D that supplies 600 IU (or up to 2,000 IU, say many experts, citing studies linking D deficiency to numerous health issues, including cancer, cardiovascular disease, depression and dementia). Choose a product with the D3 form-or "cholecalciferol" in the ingredients list-as it's absorbed much better than vitamin D2, or "ergosterol."

Vitamin E: It's one of the more difficult nutrients to get through diet alone, but you can help meet your daily needs (15 mg) by eating these healthful foods: sunflower seeds (7 mg, 1 oz.), almonds (7 mg, 1 oz.), canola oil (2 mg, 1 Tbsp.), olive oil (2 mg, 1 Tbsp.). When diet falls short, a 100% DV multivitamin will help fill the gap.

Vitamin K: You'll have no problem reaching the recommended intake (90 mcg for women, 120 for men)-and then some-if you eat leafy greens, such as kale (531 mcg, 1/2 cup cooked) and chard (286 mcg, 1/2 cup cooked). If you're taking blood thinners, talk with your doctor before taking a multi that includes vitamin K: it can interfere with the meds.

Folic Acid: Women who might become pregnant need 400 mcg (100% DV) of this B vitamin in supplemental form (e.g., part of a prenatal multivitamin/mineral). These women-and everyone else-should also eat a diet rich in folate. Good sources: lentils (179 mcg, 1/2 cup), chickpeas (141 mcg, 1/2 cup) and green vegetables, including asparagus (134 mcg, 1/2 cup cooked).

Vitamin B12: Plentiful in meats, seafood, dairy and eggs, B12 isn't found in plant-based foods; vegans should supplement. If you're over 50, the IOM recommends getting B12 in a supplement (a multivitamin/mineral works just fine): production of stomach acid, which you need to extract the vitamin from food, declines with age.

Calcium: Three to four servings of low-fat dairy-skim milk (299 mg, 1 cup), yogurt (488 mg, 1 cup), low-fat cheese (176 mg, 1.5 oz.)-will deliver your recommended daily dose (1,000 mg if you're 50 or younger; 1,200 mg, 50+). When diet falls short, take a separate 500 mg supplement (calcium is too bulky to fit all you need into a multi). Clinical trials show that, in combination with vitamin D, calcium supplements improve bone density and reduce fracture risk in postmenopausal women.

Iron: Many premenopausal women don't meet the recommended intake (18 mg) and would benefit from a multi that supplies 100% DV. Men and postmenopausal women who take a multivitamin/mineral should pick one with 10 mg or less of the mineral: too much can cause constipation or lead to iron overload for those genetically susceptible to storing too much. Good sources: clams (24 mg, 3 oz.), lentils (3 mg, 1/2 cup), beef (2 mg, 3 oz.). Heme iron from animal sources is better absorbed than the plant-based nonheme form. Vitamin C makes nonheme iron more absorbable (so throw some C-rich salsa on those lentils).

Magnesium: A diet rich in whole grains, nuts, leafy greens and low-fat dairy should easily supply the IOM's recommendation. Good sources: almonds (76 mg, 1 oz.), spinach (78 mg, 1/2 cup cooked), beans and lentils (35-60 mg, 1/2 cup), bulgur (29 mg, 1/2 cup) and yogurt (47 mg, 1 cup).

Zinc: Healthy people don't need much to meet their needs: 11 mg for men, 8 mg for women. (If you take a multivitamin/mineral, make sure the supplement doesn't exceed the recommended dose for zinc: the UL [tolerable upper intake level, or highest level thought to be safe] is 40 mg, and too much zinc can cause the body to lose copper, which it needs to make important enzymes.) Lean beef and shellfish are excellent sources: 3 oz. of crab supplies nearly half the DV (5 mg). Good plant sources: nuts and legumes.

Selenium: You can meet your needs by eating poultry, shellfish (crab and shrimp each have 40 mcg per 3 oz.) and whole grains, such as brown rice (19 mcg, 1 cup) and whole-wheat bread (23 mcg, 2 slices). Brazil nuts are a super source: one nut may have as much as 100 mcg.

Potassium: Get your fill of this mineral-which helps maintain normal blood pressure- by consuming plenty of produce.

The rest: You're probably already meeting your recommended intakes for thiamin (B1), riboflavin (B2), niacin (B3), B6, biotin, pantothenic acid, iodine, manganese, molybdenum, chloride, phosphorus, chromium.