Common Nutrient Gaps in American Diets and the Foods That Fill Them

Potassium plays a central role in regulating blood pressure, fluid balance, and muscle function. Despite its importance, surveys such as the NHANES data analyzed in the Dietary Guidelines for Americans consistently identify it as a nutrient most US adults fall short on.

The gap is largely a fruit-and-vegetable problem. Bananas are well known for potassium, but they're not even close to the top sources. Cooked white beans, lentils, baked potatoes (with skin), spinach, and sweet potatoes all deliver substantially more per serving. Canned tomato products — including paste and sauce — are also concentrated sources that fit easily into everyday cooking.

Calcium is critical for bone density, nerve signaling, and muscle contraction — and it's not only a concern for older adults. Many younger Americans, particularly those who limit dairy, consume well below the recommended amounts.

Dairy foods (milk, plain yogurt, cheese) remain among the most bioavailable sources, meaning the body absorbs a high proportion of the calcium they contain. For those who avoid dairy, fortified plant-based milks, canned sardines and salmon with edible bones, firm tofu made with calcium sulfate, and cooked bok choy or kale are practical alternatives. Note that while spinach contains calcium, its high oxalate content reduces absorption significantly.

Vitamin D supports calcium absorption, immune regulation, and bone health. It is synthesized when skin is exposed to sunlight — but factors including indoor lifestyles, sunscreen use, geographic latitude, and skin pigmentation mean that many Americans cannot rely on sun exposure to meet their needs year-round.

Food sources are limited but important: fatty fish (salmon, mackerel, sardines), egg yolks, and beef liver contain natural vitamin D. Fortified foods — particularly cow's milk, many plant-based milks, and some breakfast cereals — are where most Americans actually get the majority of their dietary vitamin D. If you're concerned about your status, a healthcare provider can order a blood test to assess your levels before any supplementation decisions are made.

Magnesium is involved in over 300 enzymatic reactions, including energy production, protein synthesis, and blood glucose regulation. It's found primarily in plant foods — which is consistent with the general pattern of low intake in diets heavy in processed and refined foods.

Pumpkin seeds are one of the most concentrated food sources of magnesium available. Other reliable options include almonds, cashews, black beans, edamame, whole-grain bread, and cooked spinach. Choosing whole grains over refined grains makes a meaningful difference here, since much of the magnesium in grain is found in the bran and germ — components stripped out during refining.

Fiber consistently ranks among the most under-consumed nutrients in the US diet. It supports digestive regularity, feeds beneficial gut bacteria, helps moderate blood sugar responses after meals, and contributes to satiety. Both soluble fiber (found in oats, legumes, and some fruits) and insoluble fiber (found in wheat bran, vegetables, and whole grains) play important roles.

The practical strategy is straightforward: eat more whole plant foods and fewer refined ones. Legumes — lentils, chickpeas, black beans — are among the most fiber-dense foods widely available at any price point. For a deeper look at why the fiber gap is so wide and how to address it day to day, see our guide to dietary fiber.

Vitamin A supports vision, immune function, and cell growth. It exists in two main dietary forms: preformed vitamin A (retinol), found in animal products, and provitamin A carotenoids (most notably beta-carotene), found in colorful plant foods. The body converts beta-carotene to vitamin A as needed.

Orange and deep-yellow vegetables are the easiest visual cue: sweet potatoes, carrots, butternut squash, and red bell peppers are all rich in beta-carotene. Among animal sources, beef liver is exceptionally concentrated — a small portion can meet multiple days' worth of need. Dark leafy greens like spinach and kale also contribute, despite their green color masking the carotenoids present.