Overview
Minerals are inorganic elements required for human health. They are classified as major minerals (required >100 mg/day) or trace minerals (required <100 mg/day). Minerals serve structural roles (bones, teeth), regulatory functions (nerve conduction, muscle contraction), and enzymatic cofactor roles.
| Property | Major Minerals | Trace Minerals |
|---|---|---|
| Daily requirement | >100 mg/day | <100 mg/day (often in μg range) |
| Body content | >5 g each (typical) | <5 g each (typical) |
| Number | 6 | 9 (essential for humans) |
| Examples | Ca, P, Mg, Na, K, Cl | Fe, Zn, Cu, Mn, I, Se, Cr, Mo, F |
Major Minerals
Calcium (Ca)
| Aspect | Detail |
|---|---|
| Body content | ~1,000-1,200 g (99% in bones and teeth, 1% in blood and cells) |
| RDA (adults 19-50) | 1,000 mg/day |
| RDA (women >50, men >70) | 1,200 mg/day |
| UL | 2,000-2,500 mg/day (from supplements and food combined) |
| Absorption | 25-40% (vitamin D-dependent via TRPV6, increased in deficiency, decreased with age) |
Functions:
| Function | Mechanism |
|---|---|
| Bone structure | Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) provides strength |
| Muscle contraction | Troponin C binding, sarcoplasmic reticulum release |
| Nerve transmission | Neurotransmitter release (presynaptic Ca²⁺ influx) |
| Blood coagulation | Factor IV (cofactor for coagulation cascade) |
| Cell signaling | Intracellular second messenger (calmodulin, PKC) |
| Enzyme regulation | Cofactor for many enzymes |
Food Sources:
| Food | Serving | Calcium (mg) | % DV |
|---|---|---|---|
| Yogurt (plain, nonfat) | 6 oz (170 g) | 300 | 23% |
| Milk (2%) | 1 cup (240 mL) | 293 | 23% |
| Sardines (canned, with bones) | 85 g (3 oz) | 325 | 25% |
| Cheese (cheddar) | 30 g (1.5 oz) | 204 | 16% |
| Fortified orange juice | 1 cup (240 mL) | 349 | 27% |
| Fortified tofu (calcium-set) | ½ cup (126 g) | 434 | 33% |
| Kale (cooked) | 1 cup (130 g) | 177 | 14% |
| Collard greens (cooked) | 1 cup (170 g) | 357 | 27% |
| Broccoli (cooked) | 1 cup (156 g) | 62 | 5% |
| Almonds | ¼ cup (35 g) | 97 | 7% |
| Canned salmon (with bones) | 85 g (3 oz) | 181 | 14% |
Deficiency (Hypocalcemia):
| Condition | Features |
|---|---|
| Osteoporosis | Reduced bone mineral density, increased fracture risk (chronic) |
| Rickets/Osteomalacia | Poor bone mineralization (with vitamin D deficiency) |
| Paresthesias | Perioral numbness, fingertip tingling |
| Tetany | Muscle cramps, carpopedal spasm, Chvostek/Trousseau signs |
| Seizures | Neuromuscular irritability |
| Cardiac arrhythmia | Prolonged QT interval |
Toxicity (Hypercalcemia): Nephrolithiasis (kidney stones), vascular calcification, milk-alkali syndrome, constipation, impaired renal function.
Phosphorus (P)
| Aspect | Detail |
|---|---|
| Body content | ~600-700 g (85% as hydroxyapatite in bone, 15% in soft tissue) |
| RDA (adults) | 700 mg/day |
| UL | 4,000 mg/day (adults) |
| Absorption | 55-70% (active via vitamin D, passive paracellular) |
Functions: Bone mineralization (hydroxyapatite), ATP/ADP energy currency, DNA/RNA backbone, cell membrane phospholipids, acid-base buffer, enzyme regulation (phosphorylation), 2,3-BPG (hemoglobin O₂ affinity).
Food Sources: Dairy (milk, yogurt, cheese), meat, poultry, fish, eggs, nuts, beans, lentils, whole grains (phytate-bound), processed foods (phosphate additives).
Deficiency (Hypophosphatemia): Muscle weakness, osteomalacia, hemolytic anemia (↓ 2,3-BPG, ↑ O₂ affinity), impaired ATP synthesis, neurological dysfunction. Seen in: refeeding syndrome, renal phosphate wasting, chronic antacid use, alcohol use disorder.
Toxicity (Hyperphosphatemia): Soft tissue calcification (calcium phosphate deposition), secondary hyperparathyroidism (chronic kidney disease). Note: phosphorus additives in processed foods contribute to excessive intake in the Western diet.
Magnesium (Mg)
| Aspect | Detail |
|---|---|
| Body content | ~24 g (50-60% in bone, 30-40% in muscle/soft tissue, 1% in blood) |
| RDA (adults) | Men: 400-420 mg/day; Women: 310-320 mg/day |
| UL | 350 mg/day (from non-food sources — magnesium salts) |
| Absorption | 30-50% (enhanced by vitamin D, reduced by phytates) |
Functions:
| Function | Mechanism |
|---|---|
| ATP stabilization | Mg²⁺ binds ATP (Mg-ATP is the active substrate) |
| Enzyme cofactor | >300 enzymes (including all ATP-requiring enzymes, kinases) |
| DNA/RNA synthesis | Polymerase stabilization |
| Muscle relaxation | Antagonist to calcium — regulates excitation-contraction coupling |
| Nerve transmission | NMDA receptor blockade, GABA receptor modulation |
| Structural | Component of hydroxyapatite (bone) |
| Heart rhythm | Stabilizes cardiac membrane, potassium channel function |
Food Sources:
| Food | Serving | Magnesium (mg) | % DV |
|---|---|---|---|
| Pumpkin seeds | ¼ cup (30 g) | 190 | 45% |
| Almonds | ¼ cup (35 g) | 105 | 25% |
| Spinach (cooked) | 1 cup (180 g) | 157 | 37% |
| Black beans (cooked) | 1 cup (172 g) | 120 | 29% |
| Cashews | ¼ cup (35 g) | 87 | 21% |
| Peanuts | ¼ cup (35 g) | 65 | 15% |
| Avocado | 1 medium (200 g) | 58 | 14% |
| Banana | 1 medium (118 g) | 32 | 8% |
| Salmon (cooked) | 85 g (3 oz) | 26 | 6% |
| Dark chocolate (70-85%) | 30 g | 64 | 15% |
| Yogurt (plain) | 6 oz (170 g) | 24 | 6% |
Deficiency (Hypomagnesemia):
| Feature | Description |
|---|---|
| Neuromuscular | Tremor, tetany, Chvostek/Trousseau signs, seizures |
| Cardiac | Arrhythmia (ventricular tachycardia, torsades de pointes), prolonged QT |
| Metabolic | Hypokalemia (refractory to K⁺ replacement), hypocalcemia (↓ PTH) |
| Other | Anorexia, nausea, apathy, weakness, depression |
Risk groups: Alcohol use disorder (↑ renal excretion, ↓ intake), diuretic use, type 2 diabetes (↑ renal excretion), GI losses (Crohn’s, celiac), proton pump inhibitor use (long-term), older adults.
Toxicity (Hypermagnesemia): Rare (occurs with renal failure or massive supplementation). Symptoms: nausea, lethargy, hypotension, bradycardia, loss of reflexes, respiratory depression, cardiac arrest.
Sodium (Na)
| Aspect | Detail |
|---|---|
| Body content | ~100 g (mainly extracellular fluid, bone) |
| AI (adults) | 1,500 mg/day (adequate intake) |
| CDC/USDA recommendation | <2,300 mg/day (upper limit) |
| Upper limit (IOM) | 2,300 mg/day (1,500 mg/day for high-risk groups) |
| UL | 2,300 mg/day |
| Average US intake | ~3,400 mg/day (well above recommendations) |
Functions: Extracellular fluid volume maintenance (major extracellular cation), blood pressure regulation, nerve impulse generation (action potentials via voltage-gated Na⁺ channels), nutrient transport (SGLT1, sodium-coupled transporters), acid-base balance.
Food Sources: Table salt (NaCl), processed foods (bread, cold cuts, pizza, soup, fast food, canned vegetables, condiments), cheese, olives, soy sauce.
| Food | Serving | Sodium (mg) |
|---|---|---|
| Table salt | 1 tsp (6 g) | 2,300 |
| Soy sauce | 1 tbsp (15 mL) | 878 |
| Ham (deli) | 85 g (3 oz) | 1,040 |
| Chicken noodle soup (canned) | 1 cup (252 g) | 790 |
| Dill pickle | 1 medium (65 g) | 785 |
| Pizza (cheese, chain) | 1 slice | 640 |
| White bread | 2 slices | 230-460 |
Deficiency (Hyponatremia): Nausea, headache, confusion, seizures, coma (serum Na⁺ <135 mEq/L). Risk groups: endurance athletes (overhydration), SIADH, diuretics, adrenal insufficiency, excessive sweating.
Toxicity (Hypernatremia): Thirst, lethargy, confusion, seizures (serum Na⁺ >145 mEq/L, common in older adults with impaired thirst mechanism).
Potassium (K)
| Aspect | Detail |
|---|---|
| Body content | ~150 g (98% intracellular, 2% extracellular) |
| AI (adults) | 3,400 mg/day (men); 2,600 mg/day (women) |
| UL | Not established (no tolerable UL from food) |
| Average US intake | ~2,500 mg/day (below recommendations) |
Functions: Intracellular fluid volume maintenance (major intracellular cation), membrane potential (resting membrane potential), nerve conduction and muscle contraction (repolarization), blood pressure regulation (vasodilation, natriuresis), acid-base balance, glycogen and protein synthesis.
Food Sources: Fruits (bananas, oranges, cantaloupe, apricots), vegetables (potatoes, sweet potatoes, spinach, tomatoes, avocados), beans, lentils, dairy, fish, meat.
| Food | Serving | Potassium (mg) |
|---|---|---|
| Potato (baked, with skin) | 1 medium (173 g) | 926 |
| Sweet potato (baked) | 1 medium (114 g) | 542 |
| Avocado | 1 medium (200 g) | 975 |
| Spinach (cooked) | 1 cup (180 g) | 839 |
| Banana | 1 medium (118 g) | 422 |
| Salmon (cooked) | 85 g (3 oz) | 326 |
| Yogurt (plain, nonfat) | 6 oz (170 g) | 330 |
| White beans (canned) | ½ cup (130 g) | 595 |
| Tomato juice | 1 cup (240 mL) | 527 |
| Orange juice | 1 cup (240 mL) | 443 |
Deficiency (Hypokalemia): Muscle weakness, fatigue, cramps, constipation, cardiac arrhythmia (U waves on ECG, ventricular ectopy), hypertension (chronic). Risk groups: diuretic treatment, vomiting/diarrhea, licorice (glycyrrhizic acid), hyperaldosteronism.
Toxicity (Hyperkalemia): Muscle weakness, paresthesias, cardiac arrhythmia (peaked T waves, widened QRS, sine wave, asystole). Risk groups: renal failure, ACE inhibitors/K⁺-sparing diuretics, adrenal insufficiency, massive cellular release (crush injury, tumor lysis).
Chloride (Cl)
| Aspect | Detail |
|---|---|
| Body content | ~100 g (mainly extracellular fluid) |
| AI (adults) | 2,300 mg/day |
| UL | 3,600 mg/day |
| Functions | Gastric acid (HCl), chloride-bicarbonate exchange (RBCs, pancreas, ileum), immune defense (neutrophil myeloperoxidase), fluid balance |
Food Sources: Table salt (NaCl), seaweed, olives, rye, tomatoes, lettuce, processed foods. Obtained primarily as sodium chloride.
Deficiency (Hypochloremia): Metabolic alkalosis (associated with vomiting, diuretics).
Toxicity (Hyperchloremia): Metabolic acidosis (associated with excess saline infusion, renal tubular acidosis).
Trace Minerals
Iron (Fe)
| Aspect | Detail |
|---|---|
| Body content | 3-4 g (women: 2.5 g, men: 4 g) |
| RDA (adults 19-50) | Men: 8 mg/day; Women: 18 mg/day |
| RDA (pregnancy) | 27 mg/day |
| RDA (>50 years) | 8 mg/day (both sexes — women stop menstruating) |
| UL | 45 mg/day |
| Absorption | ~5-15% (dietary factors affect significantly — heme iron 25%, non-heme 1-20%) |
| Body distribution | Hemoglobin (65%), myoglobin (10%), ferritin/hemosiderin (20-25%), transferrin (<1%) |
Types of Dietary Iron:
| Type | Sources | Absorption | Regulated by |
|---|---|---|---|
| Heme iron (Fe²⁺) | Meat, fish, poultry (from hemoglobin/myoglobin) | 15-35% | Less regulated (heme carrier protein 1) |
| Non-heme iron (Fe³⁺) | Plants, dairy, eggs, supplements | 1-22% | Highly regulated (DMT1, ferroportin, hepcidin) |
Factors Affecting Non-Heme Iron Absorption:
| Enhancer | Inhibitor |
|---|---|
| Vitamin C (ascorbic acid) — reduces Fe³⁺ to Fe²⁺ | Phytates (grains, legumes, nuts) |
| Meat, fish, poultry (“meat factor”) | Tannins (tea, coffee) |
| Organic acids (citric, malic, lactic) | Calcium (dairy, supplements) |
| Egg protein (phosvitin) | |
| Polyphenols (red wine, cocoa) | |
| Soy protein |
Hepcidin Regulation (Master Iron Regulator):
| State | Hepcidin | Effect |
|---|---|---|
| Iron replete / inflammation | ↑ | ↓ Ferroportin → ↓ Iron absorption and release from stores |
| Iron deficiency / hypoxia | ↓ | ↑ Ferroportin → ↑ Iron absorption and release from stores |
| Anemia of chronic disease | ↑ | Functional iron deficiency (iron trapped in stores) |
Food Sources:
| Food | Serving | Iron (mg) | Type | % DV |
|---|---|---|---|---|
| Beef liver (cooked) | 85 g (3 oz) | 5.8 | Heme | 32% |
| Oysters (cooked) | 85 g (3 oz) | 7.8 | Heme | 43% |
| Beef sirloin (cooked) | 85 g (3 oz) | 2.0 | Heme | 11% |
| Chicken liver | 85 g (3 oz) | 10.8 | Heme | 60% |
| Fortified breakfast cereal | 1 serving | 18 | Non-heme | 100% |
| Spinach (cooked) | 1 cup (180 g) | 6.4 | Non-heme | 36% |
| Lentils (cooked) | 1 cup (198 g) | 6.6 | Non-heme | 37% |
| Kidney beans (cooked) | 1 cup (177 g) | 5.2 | Non-heme | 29% |
| Pumpkin seeds | ¼ cup (30 g) | 4.3 | Non-heme | 24% |
| Tofu (firm) | ½ cup (126 g) | 3.4 | Non-heme | 19% |
| Dark chocolate (70-85%) | 30 g | 3.4 | Non-heme | 19% |
Deficiency (Iron Deficiency Anemia):
| Stage | Marker Changes |
|---|---|
| Stage 1 (Iron depletion) | ↓ Serum ferritin (<30 ng/mL) |
| Stage 2 (Iron-deficient erythropoiesis) | ↓ Transferrin saturation (<16%), ↑ TIBC (total iron-binding capacity) |
| Stage 3 (Iron deficiency anemia) | ↓ Hemoglobin (<12 g/dL women, <13 g/dL men), microcytic (↓ MCV), hypochromic (↓ MCH) |
| Symptom | Description |
|---|---|
| Fatigue, weakness | Reduced oxygen delivery |
| Pallor | Reduced hemoglobin |
| Dyspnea on exertion | Cardiopulmonary compensation |
| Pica | Craving for ice (pagophagia), dirt (geophagia), starch (amylophagia) |
| Restless legs syndrome | Associated with low ferritin |
| Koilonychia | Spoon nails (chronic iron deficiency) |
| Glossitis, cheilitis | Tongue and lip inflammation |
| Plummer-Vinson syndrome | Upper esophageal web (rare) |
Risk Groups: Menstruating women, pregnancy, infants/toddlers (rapid growth), adolescents, vegetarians/vegans, blood donors, GI bleeding (peptic ulcer, colon cancer, NSAIDs), malabsorption (celiac, atrophic gastritis, gastric bypass).
Toxicity (Iron Overload):
| Condition | Mechanism |
|---|---|
| Hereditary hemochromatosis | HFE gene mutation (C282Y) — increased iron absorption |
| Hemosiderosis | Repeated transfusions, excessive supplementation, chronic liver disease |
| Secondary iron overload | β-thalassemia major, sideroblastic anemia (ineffective erythropoiesis → increased absorption) |
Toxicity symptoms: Organ damage (liver cirrhosis, cardiomyopathy, diabetes mellitus, arthropathy, hypogonadism), bronze skin pigment.
Zinc (Zn)
| Aspect | Detail |
|---|---|
| Body content | 1.5-2.5 g |
| RDA (adults) | Men: 11 mg/day; Women: 8 mg/day |
| Pregnancy | 11 mg/day |
| Lactation | 12 mg/day |
| UL | 40 mg/day |
| Absorption | 20-40% (phytates inhibit, animal protein enhances) |
Functions: Catalytic cofactor for >300 enzymes (alcohol dehydrogenase, alkaline phosphatase, superoxide dismutase, RNA polymerase, metalloproteinases), structural role (zinc finger proteins — gene transcription), immune function (T-cell development, NK cell activity), wound healing, cell division and growth, neurological function, sense of taste and smell (gustin).
Food Sources:
| Food | Serving | Zinc (mg) | % DV |
|---|---|---|---|
| Oysters (cooked) | 85 g (3 oz) | 74 | 493% |
| Beef (cooked) | 85 g (3 oz) | 5 | 33% |
| Crab (cooked) | 85 g (3 oz) | 4.7 | 31% |
| Pork (cooked) | 85 g (3 oz) | 3 | 20% |
| Chicken (dark meat) | 85 g (3 oz) | 2.4 | 16% |
| Pumpkin seeds | ¼ cup (30 g) | 2.2 | 15% |
| Cashews | ¼ cup (35 g) | 1.9 | 13% |
| Chickpeas (cooked) | 1 cup (164 g) | 2.5 | 17% |
| Yogurt | 6 oz (170 g) | 1.2 | 8% |
| Hemp seeds | 3 tbsp (30 g) | 3.0 | 20% |
Deficiency:
| Feature | Description |
|---|---|
| Growth retardation | Stunting in children (developing countries) |
| Hypogonadism | Delayed sexual maturation, hypogonadotropic hypogonadism |
| Impaired immunity | ↑ Infection risk (recurrent respiratory/GI infections) |
| Hair loss | Alopecia |
| Diarrhea | Chronic, persistent |
| Impaired wound healing | Poor epithelialization |
| Dysgeusia/hyposmia | Impaired taste and smell |
| Acrodermatitis enteropathica | Genetic zinc malabsorption (periorificial dermatitis) |
| Nocturnal vision impairment | Zinc required for retinoid metabolism |
Risk groups: Vegetarians/vegans (phytates reduce absorption), pregnancy/lactation (↑ requirement), infants/children (rapid growth), older adults (↓ absorption, ↑ medication use), GI disease (Crohn’s, ulcerative colitis, short bowel), sickle cell disease (↑ urinary loss), alcohol use disorder.
Toxicity: GI distress (nausea, vomiting, epigastric pain) — acute; copper deficiency (chronic high doses — Zn induces metallothionein which reduces Cu absorption), impaired immune function at very high doses. Upper limit: 40 mg/day.
Copper (Cu)
| Aspect | Detail |
|---|---|
| Body content | 50-120 mg |
| RDA (adults) | 900 μg/day |
| UL | 10,000 μg/day (10 mg/day) |
Functions: Cofactor for cuproenzymes — cytochrome c oxidase (electron transport chain), superoxide dismutase (antioxidant), dopamine β-hydroxylase (catecholamine synthesis), lysyl oxidase (collagen/elastin crosslinking), ceruloplasmin (iron oxidation, copper transport).
Food Sources: Beef liver, oysters, cashews, sunflower seeds, almonds, lentils, mushrooms, dark chocolate, potatoes.
Deficiency: Anemia (↓ ceruloplasmin → impaired iron transport), neutropenia, osteoporosis (↓ lysyl oxidase), Menkes disease (genetic copper malabsorption — severe neurological degeneration, kinky hair).
Toxicity: Wilson’s disease (genetic — copper accumulation in liver and brain, Kayser-Fleischer rings, cirrhosis, neuropsychiatric symptoms).
Manganese (Mn)
| Aspect | Detail |
|---|---|
| Body content | 10-20 mg |
| AI (adults) | Men: 2.3 mg/day; Women: 1.8 mg/day |
| UL | 11 mg/day |
Functions: Cofactor for arginase (urea cycle), glutamine synthetase (brain), superoxide dismutase (Mn-SOD, mitochondrial antioxidant), glycosyltransferases (proteoglycan synthesis), pyruvate carboxylase (gluconeogenesis).
Food Sources: Mussels, nuts (hazelnuts, pecans), brown rice, pineapple, spinach, legumes, whole grains, tea, black pepper.
Deficiency: Extremely rare. Impaired growth, skeletal abnormalities, impaired glucose tolerance, dermatitis.
Toxicity: Manganism (neurological syndrome resembling Parkinson’s — dystonia, bradykinesia, gait disturbance) — seen primarily in occupational exposure (welding, mining) and total parenteral nutrition.
Iodine (I)
| Aspect | Detail |
|---|---|
| Body content | 15-20 mg (70-80% in thyroid) |
| RDA (adults) | 150 μg/day |
| Pregnancy | 220 μg/day |
| Lactation | 290 μg/day |
| UL | 1,100 μg/day |
Functions: Iodine is essential for thyroid hormone synthesis — T₄ (thyroxine, 4 iodine atoms) and T₃ (triiodothyronine, 3 iodine atoms). Thyroid hormones regulate metabolism, growth, neurological development.
Food Sources:
| Food | Serving | Iodine (μg) | % DV |
|---|---|---|---|
| Seaweed (dried) | 1 g (1/4 sheet) | 16-2,984 (variable) | 11-1,989% |
| Cod (cooked) | 85 g (3 oz) | 99 | 66% |
| Iodized salt | 1.5 g (¼ tsp) | 88 | 59% |
| Milk (cow’s) | 1 cup (240 mL) | 85 | 57% |
| Yogurt (plain) | 6 oz (170 g) | 75 | 50% |
| Egg (hard-boiled) | 1 large | 26 | 17% |
| Shrimp (cooked) | 85 g (3 oz) | 35 | 23% |
| Tuna (canned) | 85 g (3 oz) | 17 | 11% |
Deficiency:
| Condition | Description |
|---|---|
| Goiter | Thyroid gland enlargement (compensatory TSH increase) |
| Hypothyroidism | Fatigue, weight gain, cold intolerance, constipation, dry skin |
| Cretinism (fetal/neonatal) | Irreversible intellectual disability, growth retardation (if deficiency in pregnancy) |
| Impaired cognitive development | Even mild deficiency in childhood reduces IQ |
| Congenital hypothyroidism | If iodine deficiency during pregnancy (prevented by newborn screening) |
Risk groups: Pregnant/lactating women, individuals in regions with iodine-deficient soil (mountainous areas, flood-prone regions), vegans/vegetarians (no iodized salt, no seafood), individuals avoiding iodized salt.
Toxicity: Iodine-induced hyperthyroidism (Jod-Basedow phenomenon), hypothyroidism (Wolff-Chaikoff effect), goiter.
Selenium (Se)
| Aspect | Detail |
|---|---|
| Body content | 14-20 mg |
| RDA (adults) | 55 μg/day |
| UL | 400 μg/day |
Functions: Selenoproteins — glutathione peroxidases (GPX, antioxidant — H₂O₂ → H₂O), thioredoxin reductases (redox regulation), iodothyronine deiodinases (T₄ → T₃ conversion), selenoprotein P (selenium transport), selenoprotein S (ER stress response).
Food Sources: Brazil nuts (one nut: ~95 μg), tuna, halibut, sardines, shrimp, beef, turkey, chicken, eggs, brown rice, sunflower seeds.
Deficiency (rare except in Keshan disease regions): Keshan disease (cardiomyopathy — selenium-deficient soil in China), Kashin-Beck disease (osteoarthropathy), ↓ immune function, impaired thyroid function (↓ deiodinase activity).
Toxicity (Selenosis): Garlic breath odor, nail brittleness, hair loss, GI disturbance, neurological symptoms (peripheral neuropathy).
Chromium (Cr)
| Aspect | Detail |
|---|---|
| Body content | 0.4-6 mg |
| AI (adults) | Men: 35 μg/day; Women: 25 μg/day |
| UL | Not established |
Functions: Chromium potentiates insulin action (chromodulin — enhances insulin receptor tyrosine kinase activity). Evidence for role in glucose metabolism is mixed; newer research questions essentiality.
Food Sources: Broccoli, grape juice, whole wheat bread, brewer’s yeast, turkey breast, apples, potatoes.
Deficiency: Controversial and rarely documented. Potential impaired glucose tolerance, insulin resistance (seen in total parenteral nutrition pre-Cr supplementation). Chromium supplements for diabetes show inconsistent results (some benefit in glycemic control, but average effect is small).
Toxicity: Very low from food; occupational hexavalent chromium (Cr⁶⁺) is carcinogenic and nephrotoxic.
Molybdenum (Mo)
| Aspect | Detail |
|---|---|
| Body content | 5-10 mg |
| RDA (adults) | 45 μg/day |
| UL | 2,000 μg/day |
Functions: Cofactor for sulfite oxidase (sulfite → sulfate), xanthine oxidase (purine catabolism → uric acid), aldehyde oxidase.
Food Sources: Legumes (lentils, beans, peas), whole grains, nuts, milk, eggs, leafy vegetables.
Deficiency: Extremely rare (case reports in specific genetic deficiency — sulfite oxidase deficiency). Molybdenum cofactor deficiency: severe neurological impairment, neonatal seizures.
Toxicity: Not reported from food; animal studies show gout-like symptoms and impaired reproduction.
Fluoride (F)
| Aspect | Detail |
|---|---|
| Body content | 2-3 g (mainly bones, teeth) |
| AI (adults) | Men: 4 mg/day; Women: 3 mg/day |
| UL | 10 mg/day |
Functions: Dental caries prevention (incorporation into hydroxyapatite → fluorapatite — more acid-resistant), bone mineralization.
Food Sources: Fluoridated water (0.7 ppm), tea, fish (sardines with bones), fluoridated toothpaste (topical).
Deficiency: Increased dental caries risk.
Toxicity (Fluorosis): Dental fluorosis (mottling of enamel — excessive intake during tooth development in children; characterized by white/brown staining), skeletal fluorosis (bone pain, stiffness, calcification of ligaments — seen with very high levels, endemic in some regions).
Electrolyte Balance
| Electrolyte | Primary Role | Normal Serum Range | Regulating Hormones |
|---|---|---|---|
| Sodium (Na⁺) | Extracellular fluid volume, blood pressure | 135-145 mEq/L | Aldosterone (retention), ANP (excretion), ADH (water) |
| Potassium (K⁺) | Membrane potential, cardiac rhythm | 3.5-5.0 mEq/L | Aldosterone (excretion), insulin (cellular uptake) |
| Calcium (Ca²⁺) | Muscle contraction, signaling | 8.5-10.5 mg/dL (total), 4.5-5.5 mg/dL (ionized) | PTH (↑), vitamin D (↑), calcitonin (↓) |
| Magnesium (Mg²⁺) | Enzyme cofactor, neuromuscular | 1.7-2.2 mg/dL | PTH, vitamin D (↑ absorption), aldosterone (↓ reabsorption) |
| Phosphate (PO₄³⁻) | Energy metabolism, bone | 2.5-4.5 mg/dL | PTH (↓ reabsorption), vitamin D (↑ absorption) |
| Chloride (Cl⁻) | Fluid balance, gastric acid | 98-106 mEq/L | Linked to sodium regulation |
Mineral Interactions
| Interaction | Mechanism | Clinical Significance |
|---|---|---|
| Iron and vitamin C | Ascorbic acid enhances non-heme iron absorption (Fe³⁺ → Fe²⁺) | Take iron supplements with vitamin C |
| Iron and calcium | Calcium inhibits both heme and non-heme iron absorption | Separate iron-rich meals and calcium supplements |
| Zinc and copper | High zinc intake → metallothionein → binds copper → ↓ Cu absorption | Caution with long-term high-dose zinc (>40 mg/day) |
| Calcium and magnesium | Compete for absorption; high calcium may reduce Mg absorption | Balance in supplementation |
| Sodium and potassium | Antagonistic effects on blood pressure | High K⁺ attenuates Na⁺-induced hypertension |
| Iron and tea/coffee | Tannins (polyphenols) chelate non-heme iron | Avoid tea/coffee within 1 hour of iron-rich meals |
| Phytates and zinc/iron | Phytic acid chelates minerals | Soak, sprout, leaven, or cook grains/legumes to reduce phytates |
Key Takeaways
- Major minerals (Ca, P, Mg, Na, K, Cl) are required >100 mg/day; trace minerals (Fe, Zn, Cu, Mn, I, Se, Cr, Mo, F) are required in mg or μg amounts
- Calcium, phosphorus, and magnesium are critical for bone health; 99% of body calcium is in bone
- Sodium and potassium jointly regulate blood pressure — increase potassium while decreasing sodium
- Iron deficiency is the most common nutrient deficiency worldwide (2 billion affected), especially in women and children
- Iodine deficiency is the leading preventable cause of intellectual disability worldwide
- Zinc is essential for immune function and growth; deficiency affects 2 billion people globally
- Selenium is a critical antioxidant (glutathione peroxidase); Brazil nuts are the richest source
- Fluoride from fluoridated water and toothpaste significantly reduces dental caries
- Mineral interactions (e.g., zinc-copper, iron-calcium, iron-phytate) affect absorption and should be considered in supplementation
- Sodium intake averages 3,400 mg/day in the US; the recommendation is <2,300 mg/day