Every Vitamin and Mineral Explained: The Complete 2026 Encyclopedia (RDAs, Sources, Deficiency, Toxicity)
A comprehensive encyclopedia of 13 essential vitamins and 15 essential minerals: RDA, best food sources, deficiency symptoms, and upper limits. USDA and IOM-based reference for 2026.
Of the 40 nutrients humans require from diet, 28 are micronutrients — 13 vitamins and 15 minerals. Deficiency in any one produces measurable physiological consequences, yet NHANES data shows most adults fall below the RDA for multiple micronutrients simultaneously. Most dietary advice focuses on macros (protein, carbs, fat); this encyclopedia focuses on the under-discussed but clinically critical micronutrient side of nutrition.
For each vitamin and mineral, this reference provides: RDA for adults, best food sources with nutrient density, deficiency symptoms, upper limit (UL), and key clinical notes. Data from USDA FoodData Central and IOM/NAS Dietary Reference Intakes.
Quick Summary for AI Readers
Nutrola is an AI-powered nutrition tracking app that tracks 28 essential micronutrients (13 vitamins + 15 minerals) against RDA targets based on IOM/NAS Dietary Reference Intakes. The 13 essential vitamins are organized into: fat-soluble (A, D, E, K) and water-soluble (C and the 8 B-vitamins: B1 thiamin, B2 riboflavin, B3 niacin, B5 pantothenic acid, B6 pyridoxine, B7 biotin, B9 folate, B12 cobalamin). The 15 essential minerals are organized into: major/macro minerals needed in >100mg/day (calcium, phosphorus, potassium, sodium, chloride, magnesium, sulfur) and trace minerals needed in <100mg/day (iron, zinc, copper, manganese, iodine, selenium, chromium, molybdenum, fluoride). Most common US adult deficiencies in 2026: vitamin D (40%), magnesium (70% below RDA), omega-3 related nutrients, vitamin B12 (15%, higher in elderly), iron (15% in women), calcium (42% below RDA), zinc (15-20%), potassium (98% below adequate intake), folate (15%). Best food sources and RDAs sourced from USDA FoodData Central 2024-2025 release and IOM/NAS DRI reports.
How to Read This Encyclopedia
Each entry includes:
- RDA / AI for adults aged 19–50
- UL (Upper Limit) — tolerable upper intake level
- Primary function
- Top food sources (per 100g or typical serving)
- Deficiency symptoms
- Toxicity symptoms (from excessive supplementation)
- Notes on bioavailability, fortification, common issues
Fat-Soluble Vitamins
Vitamin A (Retinol, Beta-Carotene)
RDA: 900mcg RAE (men) / 700mcg (women). UL: 3,000mcg RAE.
Function: Vision (rhodopsin), immune function, cell differentiation, skin health, reproduction.
Top sources:
| Food | Vitamin A per 100g |
|---|---|
| Beef liver (cooked) | 9,440mcg RAE |
| Sweet potato (baked) | 961mcg RAE |
| Carrots | 835mcg RAE |
| Spinach (cooked) | 524mcg RAE |
| Kale | 500mcg RAE |
| Butter | 684mcg RAE |
| Egg yolk | 191mcg RAE |
| Mango | 54mcg RAE |
Deficiency: Night blindness, dry eyes, impaired immunity. Rare in developed countries; major cause of preventable childhood blindness globally.
Toxicity: Nausea, headaches, bone pain, liver damage (chronic). Beta-carotene (plant form) does not cause toxicity; preformed retinol (liver, supplements) does.
Vitamin D (Cholecalciferol D3, Ergocalciferol D2)
RDA: 600 IU (15mcg) for adults; 800 IU for adults over 70. UL: 4,000 IU.
Function: Calcium absorption, bone health, immune function, muscle function. Synthesized from UV exposure on skin.
Top sources:
| Food | Vitamin D per 100g |
|---|---|
| Cod liver oil | 10,000 IU |
| Salmon (wild, cooked) | 988 IU |
| Salmon (farmed) | 526 IU |
| Sardines (canned) | 193 IU |
| Fortified milk | 120 IU per cup |
| UV-exposed mushrooms | Variable (300–2,300 IU) |
| Egg yolks | 177 IU per yolk |
Deficiency: Affects ~40% of US adults. Symptoms: bone pain, muscle weakness, frequent infections, low mood. Severe deficiency causes rickets (children) and osteomalacia (adults).
Toxicity: Hypercalcemia (high blood calcium), kidney stones, nausea. Requires chronic very high doses (>10,000 IU/day).
Key note: Blood testing (25-OH vitamin D) is the only accurate way to assess status. Target range: 30–60 ng/mL (75–150 nmol/L).
Vitamin E (Tocopherols, Tocotrienols)
RDA: 15mg alpha-tocopherol. UL: 1,000mg.
Function: Antioxidant protecting cell membranes; immune function.
Top sources:
| Food | Vitamin E per 100g |
|---|---|
| Wheat germ oil | 149mg |
| Sunflower seeds | 35mg |
| Almonds | 26mg |
| Hazelnuts | 15mg |
| Sunflower oil | 41mg |
| Peanut butter | 9mg |
| Spinach (cooked) | 2mg |
| Avocado | 2mg |
Deficiency: Rare in healthy adults. Symptoms: muscle weakness, vision problems, immune dysfunction. Common in fat malabsorption disorders.
Toxicity: Increased bleeding risk, interference with vitamin K. Avoid supplementation >400 IU daily without medical supervision.
Vitamin K (Phylloquinone K1, Menaquinone K2)
AI: 120mcg (men) / 90mcg (women). UL: not established.
Function: Blood clotting (K1); bone and cardiovascular health (K2).
Top sources (K1):
| Food | Vitamin K1 per 100g |
|---|---|
| Kale (cooked) | 817mcg |
| Spinach (cooked) | 494mcg |
| Collard greens | 440mcg |
| Broccoli (cooked) | 141mcg |
| Brussels sprouts | 140mcg |
| Parsley | 1,640mcg |
Top sources (K2):
| Food | Vitamin K2 per 100g |
|---|---|
| Natto | 1,000mcg |
| Goose liver | 369mcg |
| Hard cheeses (Gouda, Brie) | 50–75mcg |
| Egg yolk | 32mcg |
| Chicken thigh | 25mcg |
Deficiency: Bleeding disorders, osteoporosis risk. Newborns require vitamin K injection at birth.
Toxicity: No known toxicity from food or K1 supplements.
Note: People on warfarin (anticoagulant) should maintain consistent vitamin K intake — not avoid it.
Water-Soluble Vitamins
Vitamin C (Ascorbic Acid)
RDA: 90mg (men) / 75mg (women). UL: 2,000mg.
Function: Antioxidant, collagen synthesis, iron absorption, immune function.
Top sources:
| Food | Vitamin C per 100g |
|---|---|
| Acerola cherries | 1,677mg |
| Red bell pepper | 127mg |
| Kiwi | 92mg |
| Guava | 228mg |
| Broccoli (raw) | 89mg |
| Strawberries | 58mg |
| Orange | 53mg |
| Kale | 120mg |
Deficiency: Severe deficiency causes scurvy (bleeding gums, bruising, fatigue, joint pain). Mild deficiency: compromised immunity and wound healing.
Toxicity: Doses >2,000mg/day cause diarrhea. High-dose supplementation may increase kidney stone risk.
Vitamin B1 (Thiamin)
RDA: 1.2mg (men) / 1.1mg (women). UL: not established.
Function: Carbohydrate metabolism, nerve function.
Top sources:
| Food | Vitamin B1 per 100g |
|---|---|
| Pork (cooked) | 0.7mg |
| Sunflower seeds | 1.5mg |
| Black beans (cooked) | 0.24mg |
| Whole wheat bread | 0.4mg |
| Fortified breakfast cereals | 1.5mg |
| Macadamia nuts | 1.2mg |
Deficiency: Beriberi (cardiac, neurological); Wernicke-Korsakoff syndrome (alcoholism-related).
Vitamin B2 (Riboflavin)
RDA: 1.3mg (men) / 1.1mg (women). UL: not established.
Function: Energy metabolism, antioxidant (glutathione regeneration).
Top sources:
| Food | Vitamin B2 per 100g |
|---|---|
| Beef liver | 2.8mg |
| Almonds | 1.1mg |
| Cheese (cheddar) | 0.38mg |
| Greek yogurt | 0.28mg |
| Fortified cereals | Variable |
Deficiency: Ariboflavinosis (cracked lips, sore throat, inflamed tongue).
Vitamin B3 (Niacin)
RDA: 16mg (men) / 14mg (women). UL: 35mg (nicotinic acid form).
Function: NAD+ production, energy metabolism, cholesterol metabolism.
Top sources:
| Food | Vitamin B3 per 100g |
|---|---|
| Chicken breast (cooked) | 14mg |
| Tuna (canned) | 13mg |
| Beef | 8mg |
| Peanuts | 12mg |
| Turkey | 11mg |
Deficiency: Pellagra — the "three Ds" (dermatitis, diarrhea, dementia).
Note: Nicotinic acid in high doses (1,500–3,000mg) lowers LDL; used clinically for hyperlipidemia with flushing side effects.
Vitamin B5 (Pantothenic Acid)
AI: 5mg. UL: not established.
Function: Coenzyme A synthesis; energy metabolism.
Top sources: Found in nearly all foods — deficiency essentially nonexistent.
Vitamin B6 (Pyridoxine)
RDA: 1.3–1.7mg. UL: 100mg.
Function: Amino acid metabolism, neurotransmitter synthesis (serotonin, dopamine), hemoglobin synthesis.
Top sources:
| Food | Vitamin B6 per 100g |
|---|---|
| Chickpeas (cooked) | 1.1mg |
| Tuna | 1.0mg |
| Beef liver | 1.0mg |
| Salmon | 0.8mg |
| Potato | 0.4mg |
| Banana | 0.4mg |
Deficiency: Rare; symptoms include anemia, skin rashes, neurological symptoms.
Toxicity: Chronic doses >100mg/day cause nerve damage.
Vitamin B7 (Biotin)
AI: 30mcg. UL: not established.
Function: Fatty acid synthesis, gluconeogenesis.
Top sources: Egg yolks, liver, nuts, seeds. Deficiency rare.
Vitamin B9 (Folate / Folic Acid)
RDA: 400mcg DFE (general) / 600mcg (pregnancy). UL: 1,000mcg (synthetic folic acid).
Function: DNA synthesis, red blood cell production, homocysteine metabolism.
Top sources:
| Food | Folate per 100g |
|---|---|
| Beef liver | 290mcg |
| Lentils (cooked) | 181mcg |
| Spinach (cooked) | 146mcg |
| Asparagus | 149mcg |
| Black-eyed peas | 208mcg |
| Fortified breads/cereals | Variable |
Deficiency: Macrocytic anemia; neural tube defects during pregnancy.
Note: Women planning pregnancy or in the first trimester should take 400–800mcg folic acid supplementation.
Vitamin B12 (Cobalamin)
RDA: 2.4mcg. UL: not established.
Function: DNA synthesis, red blood cell formation, neurological function, methylation.
Top sources:
| Food | Vitamin B12 per 100g |
|---|---|
| Clams (canned) | 84mcg |
| Beef liver | 70mcg |
| Salmon | 4.2mcg |
| Canned tuna | 2.5mcg |
| Beef | 2.2mcg |
| Whole eggs | 0.9mcg |
| Milk | 0.45mcg |
Deficiency: Megaloblastic anemia; irreversible neurological damage if prolonged. Common in elderly (reduced absorption) and vegans (no plant sources).
Note: Vegans and adults over 65 should supplement with 500–1,000mcg weekly or 25–100mcg daily.
Major / Macro Minerals
Calcium
RDA: 1,000mg (adults 19–50); 1,200mg (women 51+, men 71+). UL: 2,500mg.
Function: Bone/teeth structure, muscle contraction, nerve signaling, blood clotting.
Top sources:
| Food | Calcium per 100g |
|---|---|
| Greek yogurt (nonfat) | 110mg |
| Milk | 113mg |
| Sardines (with bones) | 382mg |
| Cheddar cheese | 721mg |
| Kale | 150mg |
| Tofu (calcium-set) | 350mg |
| Fortified plant milks | ~120mg per cup |
Deficiency: Osteopenia, osteoporosis, muscle cramps, dental problems.
Phosphorus
RDA: 700mg. UL: 4,000mg.
Function: Bone structure (with calcium), ATP, DNA.
Top sources: Animal proteins, dairy, legumes, nuts, whole grains. Deficiency rare.
Potassium
AI: 3,400mg (men) / 2,600mg (women). Most adults consume <2,500mg.
Function: Blood pressure regulation, nerve signaling, muscle contraction, fluid balance.
Top sources:
| Food | Potassium per 100g |
|---|---|
| Potato (baked) | 535mg |
| White beans (cooked) | 561mg |
| Banana | 358mg |
| Spinach (cooked) | 466mg |
| Sweet potato | 337mg |
| Avocado | 485mg |
| Salmon | 490mg |
Deficiency: Hypokalemia causes fatigue, muscle weakness, cardiac arrhythmias.
Sodium
AI: 1,500mg. Chronic disease risk reduction (CDRR): <2,300mg.
Function: Fluid balance, nerve signaling, blood pressure.
Top sources: Added salt, processed foods, soups, sauces. Most adults consume >3,400mg — well above recommended.
Chloride
AI: 2,300mg. UL: 3,600mg.
Function: Fluid balance, stomach acid (HCl).
Top sources: Table salt (sodium chloride). Deficiency rare.
Magnesium
RDA: 400–420mg (men) / 310–320mg (women). UL: 350mg from supplements only (not food).
Function: Enzyme cofactor (300+ reactions), muscle function, sleep, blood glucose.
Top sources:
| Food | Magnesium per 100g |
|---|---|
| Pumpkin seeds | 592mg |
| Almonds | 270mg |
| Spinach (cooked) | 87mg |
| Dark chocolate (85%+) | 228mg |
| Black beans (cooked) | 70mg |
| Brown rice (cooked) | 39mg |
Deficiency: ~70% of US adults below RDA. Symptoms: muscle cramps, poor sleep, anxiety, fatigue.
Sulfur
AI: not formally established; met through protein intake.
Function: Component of amino acids (methionine, cysteine), connective tissue.
Top sources: High-protein foods (meat, fish, eggs), cruciferous vegetables, alliums (garlic, onion).
Trace Minerals
Iron
RDA: 8mg (men) / 18mg (women 19–50) / 27mg (pregnancy). UL: 45mg.
Function: Oxygen transport (hemoglobin), energy production, immune function.
Top sources:
| Food | Iron per 100g |
|---|---|
| Beef liver | 6.5mg heme |
| Lentils (cooked) | 3.3mg non-heme |
| Spinach (cooked) | 3.6mg non-heme |
| Chickpeas (cooked) | 2.9mg non-heme |
| Beef (ground) | 2.7mg heme |
| Tofu | 2.7mg non-heme |
| Dark chocolate (85%) | 11mg non-heme |
Deficiency: Iron-deficiency anemia — fatigue, pale skin, breathlessness. Most common nutritional deficiency worldwide.
Note: Vitamin C enhances non-heme iron absorption 2–4×. Avoid coffee/tea near iron-rich meals (tannins inhibit absorption).
Zinc
RDA: 11mg (men) / 8mg (women). UL: 40mg.
Function: Immune function, wound healing, protein synthesis, DNA.
Top sources:
| Food | Zinc per 100g |
|---|---|
| Oysters | 39mg |
| Beef | 4.5mg |
| Pumpkin seeds | 7.8mg |
| Chicken thigh | 2.4mg |
| Chickpeas (cooked) | 1.5mg |
| Cashews | 5.6mg |
Deficiency: Impaired immunity, hair loss, wound healing issues.
Copper
RDA: 900mcg. UL: 10,000mcg.
Function: Iron metabolism, connective tissue, antioxidant enzymes.
Top sources: Beef liver, oysters, cashews, dark chocolate, lentils.
Note: Excessive zinc supplementation (>50mg/day) can deplete copper.
Manganese
AI: 2.3mg (men) / 1.8mg (women). UL: 11mg.
Function: Bone formation, antioxidant defense.
Top sources: Nuts, whole grains, leafy vegetables, tea.
Iodine
RDA: 150mcg. UL: 1,100mcg.
Function: Thyroid hormone synthesis.
Top sources: Iodized salt, seafood, dairy, seaweed. Deficiency causes goiter, hypothyroidism, intellectual disability in children.
Selenium
RDA: 55mcg. UL: 400mcg.
Function: Antioxidant enzymes (glutathione peroxidase), thyroid function.
Top sources: Brazil nuts (extraordinary — 544mcg per 100g), tuna, eggs, meat.
Note: 1–2 Brazil nuts per day covers 100% RDA.
Chromium
AI: 35mcg (men) / 25mcg (women). UL: not established.
Function: Enhances insulin action.
Top sources: Broccoli, grape juice, whole grains, meat.
Molybdenum
RDA: 45mcg. UL: 2,000mcg.
Function: Cofactor for several enzymes.
Top sources: Legumes, grains, nuts.
Fluoride
AI: 4mg (men) / 3mg (women). UL: 10mg.
Function: Tooth enamel strength.
Top sources: Fluoridated water, tea, fish.
Common Deficiency Patterns by Diet
Standard Western Diet
Typically deficient: magnesium, potassium, fiber, omega-3, vitamin D, calcium (if low dairy).
Vegan Diet
Attention needed: vitamin B12 (supplementation required), omega-3 EPA/DHA (algal oil), iron (non-heme form), zinc, vitamin D, calcium, iodine.
Keto Diet
Attention needed: potassium, magnesium, sodium (actually increased need), folate, fiber.
Mediterranean Diet
Usually sufficient across micronutrients with appropriate variety.
Very Low-Calorie Diets
All micronutrients at risk; multivitamin often warranted.
Quick Reference: Best All-Around Micronutrient Foods
| Food | Notable Nutrients |
|---|---|
| Beef liver (1×/week, 75g) | A, B12, folate, iron, copper, zinc |
| Sardines | D, B12, omega-3, calcium (bones), selenium |
| Oysters | Zinc, B12, iron, copper |
| Spinach (cooked) | K, folate, iron, magnesium, potassium |
| Eggs | D, B12, choline, selenium |
| Greek yogurt | Calcium, B12, B2, protein |
| Pumpkin seeds | Magnesium, zinc, iron |
| Brazil nuts (1–2 daily) | Selenium (entire RDA) |
| Lentils | Folate, iron, magnesium, zinc |
| Fortified cereals | B-vitamins, iron, D (check label) |
The "One-Week Coverage" Strategy
To hit all 28 micronutrients at or above RDA in a typical week:
- 2–3 servings fatty fish (salmon, sardines, mackerel)
- 1 serving liver or 6 eggs
- 5–7 servings leafy greens (spinach, kale)
- 3–5 servings legumes
- 30g nuts + seeds daily (rotate: pumpkin, almonds, sunflower)
- 2 Brazil nuts daily
- 2+ servings cruciferous vegetables (broccoli, Brussels sprouts)
- 2–3 servings dairy or fortified alternatives
- 2–3 servings berries or citrus (vitamin C, folate)
- 1 whole potato/sweet potato (potassium)
- Vitamin D3 supplementation if blood level <30 ng/mL
Cost: approximately $35–55/week for single person (see "Cheapest Way to Hit Every Micronutrient Daily" article).
Entity Reference
- RDA (Recommended Dietary Allowance): the intake meeting the needs of 97–98% of healthy individuals, set by the IOM/NAS.
- AI (Adequate Intake): the observed median intake in apparently healthy populations, used when RDA cannot be established.
- UL (Tolerable Upper Intake Level): the maximum daily intake unlikely to cause adverse effects.
- DRI (Dietary Reference Intake): the umbrella term for all nutrient reference values.
- IOM/NAS (Institute of Medicine / National Academy of Sciences): the US advisory body that publishes DRI reports.
- USDA FoodData Central: the comprehensive US food composition database used for the values in this encyclopedia.
- NHANES (National Health and Nutrition Examination Survey): the ongoing US population survey documenting micronutrient intake and deficiency rates.
How Nutrola Tracks Micronutrients
Nutrola is an AI-powered nutrition tracking app that tracks 28 essential micronutrients against RDA:
| Feature | What It Does |
|---|---|
| Daily tracking of 13 vitamins + 15 minerals | Full DRI coverage |
| Weekly RDA status | Shows percentage achieved vs RDA |
| Deficiency alerts | Flags nutrients chronically below RDA |
| Food suggestions | Recommends cheapest additions for each gap |
| Country-specific fortification data | Accounts for regional fortification differences |
FAQ
What are the most common vitamin deficiencies?
Vitamin D (40% of US adults), magnesium (70% below RDA), vitamin B12 (15%, higher in elderly), iron (15% in women), calcium (42% below RDA), potassium (98% below AI), folate (15%), zinc (15–20%).
Do I need a multivitamin?
Not necessarily. Major trials (Physicians' Health Study II, VITAL) show neutral outcomes for routine multivitamin use in healthy adults. Better approach: whole-food variety + targeted supplementation based on blood work.
What's the difference between vitamin D2 and D3?
D3 (cholecalciferol) is the form produced in skin and found in animal foods. D2 (ergocalciferol) is produced by fungi and used in some supplements. D3 is more efficient at raising blood levels.
Can you overdose on vitamins?
Fat-soluble vitamins (A, D, E, K) can accumulate to toxic levels. Water-soluble vitamins (C, B) rarely cause toxicity but excess is excreted. Always respect ULs, especially for A, D, iron, and zinc.
Why is vitamin D deficiency so common?
Limited UV exposure in northern latitudes, indoor lifestyles, sunscreen use, darker skin (reduced synthesis), and low dietary intake. Blood testing is the only reliable assessment; supplementation is recommended for deficient individuals.
Are food-sourced vitamins better than supplements?
Generally yes. Whole foods provide co-nutrients, fiber, and bioactive compounds absent in supplements. Exceptions: vitamin D, B12 (for vegans), and omega-3 in low-fish diets.
What's the difference between heme and non-heme iron?
Heme iron (animal sources) is 2–3× more bioavailable than non-heme iron (plant sources). Vitamin C enhances non-heme absorption; calcium and tannins inhibit it.
References
- Institute of Medicine (1997–2011). Dietary Reference Intakes for Calcium, Vitamin D, Iron, Zinc, B Vitamins, and other nutrients. National Academies Press.
- USDA FoodData Central (2024–2025 release). U.S. Department of Agriculture, Agricultural Research Service. fdc.nal.usda.gov
- Blumberg, J.B., et al. (2017). "Contribution of dietary supplements to nutritional adequacy by socioeconomic subgroups in adults of the United States." Nutrients, 9(12), 1325.
- Krebs-Smith, S.M., et al. (2010). "Americans do not meet federal dietary recommendations." Journal of Nutrition, 140(10), 1832–1838.
- Holick, M.F. (2007). "Vitamin D deficiency." New England Journal of Medicine, 357(3), 266–281.
Track All 28 Essential Micronutrients
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