The minerals most worth paying attention to are calcium, magnesium, iron, zinc, and iodine, because these are the ones people most commonly fall short on through diet alone. Global modeling data published in The Lancet Global Health estimates that 68% of the world’s population doesn’t get enough iodine from food, 66% falls short on calcium, and 65% doesn’t get enough iron. Whether you personally need a supplement depends on your diet, your life stage, and what’s actually missing.
The Minerals Your Body Needs
Your body uses minerals to build bone, carry oxygen, fire nerve signals, regulate your heartbeat, and produce hormones and enzymes. They split into two categories based on how much you need.
Macrominerals are needed in larger quantities: calcium, magnesium, potassium, phosphorus, sodium, chloride, and sulfur. Most people get plenty of sodium, phosphorus, and chloride from a typical diet without trying. Calcium, magnesium, and potassium are the ones that tend to run low.
Trace minerals are needed in tiny amounts: iron, zinc, selenium, iodine, copper, manganese, fluoride, and molybdenum. Iron and zinc deficiencies are widespread globally, while deficiencies in manganese, molybdenum, and copper are rare in people eating a varied diet.
Which Ones Most People Lack
If you eat a reasonably varied diet and still suspect gaps, these five minerals deserve the closest look:
- Calcium: Critical for bones, muscle contraction, and nerve signaling. Adults need about 1,000 mg per day (1,200 mg for women over 50 and men over 70). Dairy, fortified plant milks, canned sardines with bones, and leafy greens like kale are the richest food sources.
- Magnesium: Involved in over 300 enzyme reactions, including energy production, blood sugar regulation, and sleep. Women need 310 to 320 mg per day; men need 400 to 420 mg. Nuts, seeds, dark chocolate, and whole grains are good sources, but many people still fall short.
- Iron: Carries oxygen in your blood. Women of reproductive age need 18 mg per day due to menstrual losses, while men and postmenopausal women need only 8 mg. Red meat, lentils, spinach, and fortified cereals are top sources.
- Zinc: Supports immune function, wound healing, and taste perception. Women need 8 mg daily; men need 11 mg. Oysters are the single richest source, followed by beef, chickpeas, and pumpkin seeds.
- Iodine: Essential for thyroid hormone production. Iodized salt, seafood, and dairy are the primary sources, and people who use non-iodized specialty salts or eat little seafood are at higher risk of falling short.
Why Diet Alone Can Fall Short
Even with a balanced diet, modern food may contain fewer minerals than it once did. Research tracking nutrient density over the past 50 to 70 years has found significant declines in fruits and vegetables: calcium content dropped 16 to 46%, iron fell 24 to 32%, magnesium declined 16 to 35%, and zinc dropped 27 to 59%. One analysis noted that 80% of this nutritional dilution happened in just the last 30 to 40 years, likely driven by intensive farming practices that prioritize yield over nutrient density.
This doesn’t mean food is useless. Whole foods still provide minerals in forms your body absorbs well, bundled with fiber and other nutrients that supplements can’t replicate. But it does explain why some people eating “healthy” diets still show low levels on blood work.
Life Stages That Change Your Needs
Pregnancy and breastfeeding increase the need for iron, calcium, and iodine substantially. Iron demands rise because blood volume expands by nearly 50%, and iodine needs increase to support fetal brain development. Most prenatal vitamins are formulated with these in mind, though they often contain insufficient calcium (you may still need dietary sources or an additional supplement).
After menopause, calcium becomes more important because declining estrogen accelerates bone loss. The recommended intake rises to 1,200 mg per day for women over 50. Magnesium remains equally important in older adults, supporting both bone density and cardiovascular function.
Vegetarians and vegans face higher risk for iron and zinc shortfalls because the plant-based forms of these minerals are harder for the body to absorb. Eating vitamin C-rich foods alongside iron-rich plants (like squeezing lemon over lentils) can significantly improve uptake.
How Minerals Interact With Each Other
Minerals don’t work in isolation, and taking too much of one can interfere with another. Copper, zinc, and iron are a classic example: high-dose zinc supplements can deplete copper over time, and excess iron can reduce zinc absorption. This is one reason blanket megadosing is risky.
Calcium and magnesium can compete for absorption when taken in large doses at the same time. If you supplement both, splitting them into separate doses (one in the morning, one in the evening) can help. Iron is best absorbed on its own or with vitamin C, and taking it alongside calcium or with coffee or tea reduces how much you absorb.
Choosing the Right Form
The form a mineral comes in affects how well your body absorbs it and what side effects you might experience. Magnesium is the most common example. Magnesium glycinate and magnesium citrate are both well absorbed, with up to 90% absorption in the intestine, and uptake begins about one hour after you take them. But they serve slightly different purposes. Glycinate is better suited for sleep and anxiety support because it pairs magnesium with an amino acid that has calming properties. Citrate is more useful for constipation relief because it draws water into the intestines, and it also shows benefits for migraines and leg cramps.
For iron, look for forms labeled “gentle” or chelated if you’re prone to stomach upset, as basic iron sulfate commonly causes nausea and constipation. For calcium, calcium citrate absorbs well without food, while calcium carbonate (the cheaper option) needs to be taken with a meal to absorb properly.
When and How to Take Them
There’s no single best time of day to take minerals. The most important factor is consistency. That said, a few practical rules help:
- Iron: Best absorbed on an empty stomach or with a small amount of vitamin C-rich food. Avoid taking it with dairy, coffee, or tea.
- Calcium: Take with food for better absorption (especially calcium carbonate). Split doses of 500 mg or less, since your body can’t absorb large amounts at once.
- Magnesium: Can be taken any time. Many people prefer bedtime, especially with glycinate, since it may support relaxation and sleep.
- Zinc: Best absorbed with food to avoid nausea. Don’t take it at the same time as iron.
If you take thyroid medication, space mineral supplements at least four hours apart, because calcium and iron in particular can block the medication’s absorption.
When Supplementing Can Backfire
More is not better with minerals. Selenium, for instance, has a tolerable upper limit of 255 micrograms per day for adults. Going beyond that regularly can cause hair loss, brittle nails, and nerve damage. Iron is particularly dangerous in excess because the body has no efficient way to shed it, and accumulation can damage the liver and heart. The European Food Safety Authority has noted there isn’t even enough data to set a safe upper limit for iron, which speaks to how carefully intake should be managed.
High-dose zinc (above 40 mg per day over weeks) can suppress immune function, the opposite of what most people take it for. And excess calcium from supplements (though not from food) has been linked in some research to increased cardiovascular risk.
The safest approach is to get a blood test to identify actual deficiencies before supplementing, then use targeted doses to fill specific gaps rather than taking large amounts of everything.