Trace minerals are essential nutrients your body needs in very small amounts, specifically less than 100 milligrams per day. Despite these tiny quantities, they play outsized roles in everything from carrying oxygen through your blood to regulating your thyroid. There are nine widely recognized essential trace minerals: iron, zinc, selenium, iodine, copper, manganese, chromium, fluoride, and molybdenum.
How Trace Minerals Differ From Major Minerals
Minerals in nutrition fall into two categories based on how much your body requires daily. Major minerals (sometimes called macrominerals) are needed at levels above 100 mg per day. This group includes calcium, potassium, magnesium, sodium, phosphorus, and sulfur. Trace minerals, also called microminerals, are needed below that 100 mg threshold. The distinction is purely about quantity, not importance. A deficiency in a trace mineral can be just as serious as a deficiency in a major one.
The Nine Essential Trace Minerals
Each trace mineral serves a specific set of functions. They generally fall into three broad categories: oxygen transport, metabolic catalysis (helping chemical reactions happen), and hormone production.
Iron
Iron is the trace mineral your body needs in the largest amount. It’s the core component of hemoglobin, the protein in red blood cells that binds and carries oxygen to every tissue in your body. Adult men need about 10 mg per day, while premenopausal women need around 15 mg per day due to menstrual blood loss. After menopause, women’s needs drop to match men’s. Red meat, shellfish, lentils, spinach, and fortified cereals are all reliable sources. Iron deficiency is the most common mineral deficiency worldwide, causing fatigue, difficulty concentrating, spoon-shaped nails, and impaired wound healing.
Zinc
Zinc is involved in over 300 enzymatic reactions. It supports immune function, wound healing, DNA synthesis, and your senses of taste and smell. Adult men need about 15 mg per day, women about 12 mg. Oysters contain more zinc per serving than any other food, but beef, crab, beans, and nuts are also good sources. Low zinc levels can cause hair loss, skin rashes, ridged nails, and a dulled sense of taste and smell.
Iodine
Your thyroid gland uses iodine to produce hormones that regulate metabolism, growth, and brain development. The recommended intake for adults is 150 micrograms per day. Iodized salt is the most common source in many countries, along with seaweed, dairy, and seafood. Iodine deficiency leads to fatigue, weight changes, mood disturbances, and in severe cases, an enlarged thyroid gland (goiter). During pregnancy, inadequate iodine can impair fetal brain development.
Selenium
Selenium works as a component of antioxidant enzymes that protect cells from damage. It also plays a direct role in thyroid hormone metabolism, helping convert inactive thyroid hormone into its active form. Adults need 55 to 70 micrograms per day. Brazil nuts are extraordinarily rich in selenium; just one or two nuts can meet your daily requirement. Fish, meat, eggs, and whole grains also contribute. Low selenium causes persistent fatigue and can weaken immune defenses.
Copper
Copper helps form red blood cells, maintain nerve cells, and support your immune system. It’s also essential for building connective tissue and acts as part of your body’s antioxidant defense system. Liver, shellfish, nuts, seeds, and dark chocolate are good dietary sources. Copper deficiency can cause fatigue, trouble concentrating, mood changes like anxiety or irritability, and changes in hair color or texture.
Manganese
Manganese supports bone formation, blood clotting, and the metabolism of carbohydrates and amino acids. It also contributes to antioxidant enzymes that protect cells, particularly in mitochondria. Whole grains, nuts, leafy vegetables, and tea are common sources. The European Food Safety Authority sets a safe daily intake level of 8 mg for adults. Deficiency is rare but can manifest as skin rashes and impaired wound healing.
Chromium
Chromium appears to enhance the action of insulin, the hormone that moves sugar from your blood into your cells. Its exact mechanism is still debated, but people with low chromium may experience difficulty with blood sugar regulation and trouble concentrating. Broccoli, grape juice, whole grains, and meat contain small amounts.
Fluoride
Fluoride strengthens tooth enamel and makes it more resistant to acid attacks from bacteria. It also promotes the remineralization of early tooth decay. Most people get fluoride through treated drinking water, toothpaste, and tea. The safe intake level for adults is about 3.3 mg per day.
Molybdenum
Molybdenum is a cofactor for enzymes that break down certain amino acids and toxins. Deficiency is extremely rare because the body needs only tiny amounts, and it’s found in legumes, grains, and organ meats. The upper safe intake for adults is 0.6 mg per day.
What Blocks or Boosts Absorption
Getting enough trace minerals from food isn’t just about what you eat. It also depends on what else you eat at the same time. Several naturally occurring plant compounds can bind to minerals in your digestive tract and prevent them from being absorbed.
Phytate, found in whole grains, legumes, nuts, and seeds, is one of the strongest inhibitors. It chelates (binds tightly to) iron, zinc, copper, and calcium, forming complexes your body can’t break down. Tannins, the compounds that give tea and red wine their astringent taste, also inhibit iron, copper, and zinc absorption. In one study of healthy adults, drinking tea with an iron-fortified meal reduced iron absorption by 37%, but drinking that same tea an hour after the meal had no effect. Oxalates in foods like spinach and rhubarb primarily block calcium but can affect other minerals too.
The good news: vitamin C is a powerful counterbalance. Adding vitamin C-rich foods to a meal can offset much of the inhibitory effect of phytate and tannins. As little as 30 mg of vitamin C (roughly the amount in half an orange) can neutralize the iron-blocking effect of tannins. Fermentation also breaks down phytate, which is why fermented foods like sourdough bread and tempeh deliver minerals more efficiently than their unfermented counterparts.
How Much Is Too Much
Because trace minerals are needed in such small amounts, the gap between “enough” and “too much” can be narrow. Each mineral has what’s called a tolerable upper intake level, the maximum daily amount from all sources (food, water, and supplements combined) that’s unlikely to cause harm.
For adults, the European Food Safety Authority sets upper limits at 25 mg per day for zinc, 255 micrograms for selenium, 600 micrograms for iodine, and 0.6 mg for molybdenum. Iron’s upper safe intake level is set at 40 mg per day. Exceeding these levels occasionally isn’t dangerous, but chronic excess can cause real problems. Too much iron causes gastrointestinal distress and, over time, can damage the liver and heart. Excess zinc interferes with copper absorption, potentially creating a secondary deficiency. Too much selenium causes brittle nails, hair loss, and garlic-scented breath.
For most people eating a varied diet, toxicity from food alone is unlikely. The risk comes primarily from high-dose supplements, especially those marketed as multi-mineral formulas where several trace minerals may approach or exceed safe levels simultaneously. If you’re already eating a reasonably balanced diet that includes whole grains, vegetables, protein sources, and some seafood, you’re likely getting adequate amounts of all nine essential trace minerals without supplementation.
Who’s Most at Risk for Deficiency
Certain groups face a higher risk of falling short. Premenopausal women are vulnerable to iron deficiency because of monthly blood loss. Pregnant women need more iron, iodine, and zinc to support fetal development. Vegetarians and vegans may struggle with iron and zinc because plant-based forms of these minerals are less bioavailable than animal-based forms, and plant-heavy diets tend to be higher in phytate.
People with digestive conditions that reduce nutrient absorption, such as celiac disease or inflammatory bowel disease, are also at elevated risk. Older adults sometimes absorb minerals less efficiently and may eat less varied diets. In these situations, targeted supplementation of a specific mineral, guided by blood work, is more effective and safer than taking a broad-spectrum trace mineral supplement.