Micronutrients Most Americans Fall Short On — And Food Sources to Consider

Vitamin D is one of the most consistently under-consumed nutrients in the United States, according to data from the National Health and Nutrition Examination Survey (NHANES). The body can produce vitamin D through sun exposure, but factors like geographic location, skin tone, sunscreen use, and time spent indoors all limit synthesis for many people.

Dietary sources of vitamin D are relatively limited, but they include fatty fish such as salmon, trout, and tuna; egg yolks; and fortified foods like cow's milk, some plant-based milk alternatives, and certain breakfast cereals. Beef liver also contains modest amounts. Because food sources alone rarely meet needs for those with low sun exposure, a healthcare provider may recommend checking serum levels and discussing whether supplementation is appropriate for an individual's circumstances.

Calcium is essential for bone integrity, muscle function, and nerve signaling. Despite its prominence in public health messaging, many Americans — particularly adolescent girls, older adults, and those who avoid dairy — do not consistently meet recommended intake levels.

Dairy products remain the most concentrated food sources: milk, yogurt, and cheese each provide substantial calcium per serving. For those who limit or avoid dairy, calcium is also found in fortified plant-based beverages, canned salmon or sardines with bones, firm tofu made with calcium sulfate, and certain leafy greens such as bok choy, kale, and broccoli. It is worth noting that calcium absorption varies by food; spinach and Swiss chard, while nutritious, contain compounds called oxalates that reduce calcium bioavailability.

Potassium supports healthy blood pressure, fluid balance, and proper muscle and nerve function. Federal dietary guidelines have identified potassium as a nutrient of public health concern because inadequate intake is widespread, largely due to low consumption of fruits, vegetables, and legumes relative to processed foods.

Excellent food sources include bananas, oranges, cantaloupe, potatoes (with skin), sweet potatoes, white beans, lentils, spinach, and avocados. Dairy foods and fish also provide meaningful amounts. Increasing potassium through whole foods is generally considered safe for healthy adults, though people with kidney disease or those taking certain medications should consult their healthcare provider before making significant dietary changes, as impaired kidneys may not excrete potassium efficiently.

Magnesium participates in more than 300 enzymatic reactions in the body, including energy production, protein synthesis, and blood glucose regulation. Like potassium, magnesium shortfalls are common and closely tied to low intake of whole plant foods. Heavily processed diets tend to be low in this mineral.

Nuts and seeds — particularly pumpkin seeds, almonds, and cashews — are among the richest sources. Whole grains such as oats, brown rice, and whole wheat bread contribute meaningfully, as do legumes, dark leafy greens, and dark chocolate. Because magnesium is found predominantly in plant-based whole foods, diets that restrict grains or limit vegetables tend to fall short. See our discussion of dietary trade-offs for more context on how certain eating patterns affect mineral intake.

Iron is needed for oxygen transport in the blood and energy metabolism. Iron-deficiency anemia remains one of the most common nutritional deficiencies globally, and certain American subgroups — including women of reproductive age, pregnant individuals, infants, and young children — are at elevated risk of inadequate intake.

Iron comes in two forms: heme iron, found in meat, poultry, and seafood (particularly red meat and oysters), is absorbed more efficiently; non-heme iron is present in plant foods like lentils, kidney beans, tofu, fortified cereals, and spinach. Pairing non-heme iron sources with vitamin C-rich foods — such as adding bell pepper to a lentil dish — enhances absorption. Conversely, calcium and certain compounds in tea or coffee can inhibit absorption when consumed simultaneously. Needs differ substantially by age and sex, so routine monitoring is best done with a healthcare provider.

Vitamin B12 is critical for red blood cell formation, neurological function, and DNA synthesis. It is found almost exclusively in animal-derived foods, making deficiency a real concern for people following vegan or largely plant-based diets, as well as for older adults whose ability to absorb B12 naturally declines with age due to changes in stomach acid production.

Primary food sources include meat, poultry, fish, shellfish, eggs, and dairy products. Nutritional yeast and certain fortified plant-based milks or breakfast cereals provide B12 for those avoiding animal products. People who follow plant-based diets or are over 50 are commonly advised by clinicians to monitor their B12 status, since food choices alone may not be sufficient in these populations. This is one of the clearer cases where supplementation may be warranted — but that determination belongs to a qualified healthcare professional.