Vitamins & minerals
Recommended intakes, upper limits, roles and food sources for every vitamin and mineral, then the ones athletes get wrong: iron, vitamin D, calcium and antioxidants. Energy, macronutrients, fluids and performance supplements are in nutrition & hydration. Intakes are the US Dietary Reference Intakes as listed on the NIH Office of Dietary Supplements (ODS) fact sheets, for adults 19–50; they are for healthy people, not treatment.
Reading the numbers
| Term | Meaning (ODS) |
|---|---|
| RDA, Recommended Dietary Allowance | daily intake that meets the needs of nearly all (97–98%) healthy people |
| AI, Adequate Intake | set when there isn't enough evidence for an RDA; assumed to be adequate |
| UL, Tolerable Upper Intake Level | maximum daily intake unlikely to cause harm; from food, water and supplements unless noted |
| CDRR | Chronic Disease Risk Reduction intake; used for sodium instead of a UL |
| DV, Daily Value | the single reference amount on US labels (%DV) |
| µg | microgram, also written mcg; 1 mg = 1,000 µg |
"None set" for a UL means there wasn't enough data, not that any amount is safe. A varied diet with enough energy covers active people for most nutrients (ACSM/AND/DC 2016); iron is the main exception (ODS).
Fat-soluble vitamins
Stored in the body, so they build up: the ULs matter most here. Absorbed with dietary fat.
| Vitamin | Men | Women | Pregnancy | UL |
|---|---|---|---|---|
| A | 900 µg RAE | 700 µg RAE | 770 µg RAE | 3,000 µg (preformed retinol only) |
| D | 15 µg (600 IU) | 15 µg (600 IU) | 15 µg | 100 µg (4,000 IU) |
| E | 15 mg | 15 mg | 15 mg | 1,000 mg (supplemental α-tocopherol) |
| K (AI) | 120 µg | 90 µg | 90 µg | none set |
| Vitamin | Main roles | Food sources | Deficiency signs |
|---|---|---|---|
| A | vision in low light, immunity, cell growth, reproduction | liver, dairy, eggs, fish; beta-carotene in sweet potato, carrots, spinach | night blindness, dry eyes (xerophthalmia) |
| D | calcium and phosphorus absorption, bone; a role in muscle is emerging | oily fish, UV-exposed mushrooms, fortified milk and plant milks, eggs; sun on skin | soft bones (osteomalacia): bone pain, weakness |
| E | antioxidant in cell membranes, immune function | wheat-germ oil, sunflower seeds, almonds, vegetable oils | rare: neuropathy, poor coordination, muscle weakness |
| K | blood-clotting proteins, bone proteins | kale, spinach, broccoli, natto (K2) | rare in adults: easy bleeding and bruising |
Water-soluble vitamins
Excess is mostly excreted, so ULs exist for only a few. Needs are the same for athletes; energy-dense diets usually cover the B vitamins.
| Vitamin | Men | Women | Pregnancy | UL |
|---|---|---|---|---|
| C | 90 mg | 75 mg | 85 mg | 2,000 mg (smokers need +35 mg/day) |
| B1 thiamin | 1.2 mg | 1.1 mg | 1.4 mg | none set |
| B2 riboflavin | 1.3 mg | 1.1 mg | 1.4 mg | none set |
| B3 niacin | 16 mg NE | 14 mg NE | 18 mg NE | 35 mg (supplements and fortified food) |
| B5 pantothenic acid (AI) | 5 mg | 5 mg | 6 mg | none set |
| B6 | 1.3 mg | 1.3 mg | 1.9 mg | 100 mg (EFSA 2023: 12 mg) |
| B7 biotin (AI) | 30 µg | 30 µg | 30 µg | none set |
| B9 folate | 400 µg DFE | 400 µg DFE | 600 µg DFE | 1,000 µg (folic acid, not food folate) |
| B12 | 2.4 µg | 2.4 µg | 2.6 µg | none set |
| Vitamin | Main roles | Food sources | Deficiency signs |
|---|---|---|---|
| C | collagen, antioxidant, non-heme iron absorption, immunity | red pepper, orange, kiwifruit, broccoli, strawberries | scurvy: bruising, joint pain, poor wound healing, corkscrew hairs |
| B1 | carbohydrate metabolism, nerves | whole and fortified grains, pork, fish | weight loss, confusion, weakness; beriberi (neuropathy, wasting) |
| B2 | energy metabolism (FAD, FMN) | eggs, organ meat, lean meat, milk, fortified grains | cracked lips and mouth corners, sore throat, skin rash |
| B3 | energy metabolism (NAD, NADP) | poultry, beef, fish, nuts, legumes, grains | pellagra: rash on sun-exposed skin, red tongue, gut upset |
| B5 | coenzyme A, fat and energy metabolism | nearly all foods; beef, chicken, organ meat, whole grains | very rare: burning or numb hands and feet, fatigue |
| B6 | 100+ enzyme reactions, mostly protein and amino-acid metabolism | fish, liver, potatoes, non-citrus fruit, fortified cereal | anemia, cracked lips, sore tongue, depression, confusion |
| B7 | carboxylase enzymes (fat, glucose, amino acids) | organ meat, eggs, fish, meat, seeds, nuts, sweet potato | thinning hair, scaly red rash around face, brittle nails |
| B9 | DNA synthesis, cell division, red blood cells | leafy greens, legumes, asparagus, liver, fortified grains | megaloblastic anemia, mouth ulcers, sore tongue |
| B12 | red blood cells, nerves, DNA | meat, fish, dairy, eggs; fortified cereal and nutritional yeast | anemia, fatigue, numbness and tingling, pale skin |
Raw egg white binds biotin (cooking stops this). Deficiencies of B1, B2, B3, B5 and B7 are rare on a varied diet.
Major minerals
| Mineral | Men | Women | UL | Note |
|---|---|---|---|---|
| calcium | 1,000 mg | 1,000 mg | 2,500 mg | same in pregnancy |
| phosphorus | 700 mg | 700 mg | 4,000 mg | 3,500 mg UL in pregnancy |
| magnesium, 19–30 | 400 mg | 310 mg | 350 mg (supplements only) | pregnancy 350 mg |
| magnesium, 31–50 | 420 mg | 320 mg | 350 mg (supplements only) | pregnancy 360 mg |
| sodium (AI) | 1,500 mg | 1,500 mg | none; CDRR 2,300 mg | cut back if above 2,300 mg (NASEM 2019) |
| potassium (AI) | 3,400 mg | 2,600 mg | none set | pregnancy 2,900 mg |
| chloride (AI) | 2,300 mg | 2,300 mg | 3,600 mg | mostly from salt |
| Mineral | Main roles | Food sources | Deficiency signs |
|---|---|---|---|
| calcium | bone and teeth, muscle contraction, nerves, clotting | dairy, fortified plant milk, calcium-set tofu, sardines with bones, kale | low bone density, osteoporosis, stress fractures |
| phosphorus | bone, ATP, cell membranes | dairy, meat, fish, eggs, nuts, legumes, grains, additives | rare: weakness, bone pain, confusion |
| magnesium | cofactor for 300+ enzymes, muscle and nerve function, energy | pumpkin seeds, almonds, spinach, cashews, black beans | poor appetite, nausea, fatigue; then numbness, cramps, arrhythmia |
| sodium | fluid volume, nerve and muscle signals | salt, bread, processed food | low blood sodium is usually from overdrinking, not diet |
| potassium | nerve and muscle signals, blood pressure | dried apricots, lentils, potatoes, bananas, milk, yogurt | low blood levels come from vomiting, diarrhea or drugs, not diet |
| chloride | fluid balance, stomach acid | salt | rare |
Sweat losses of sodium are covered in nutrition & hydration.
Trace minerals
| Mineral | Men | Women | Pregnancy | UL |
|---|---|---|---|---|
| iron | 8 mg | 18 mg | 27 mg | 45 mg |
| zinc | 11 mg | 8 mg | 11 mg | 40 mg |
| copper | 900 µg | 900 µg | 1,000 µg | 10,000 µg |
| selenium | 55 µg | 55 µg | 60 µg | 400 µg |
| iodine | 150 µg | 150 µg | 220 µg | 1,100 µg |
| manganese (AI) | 2.3 mg | 1.8 mg | 2.0 mg | 11 mg |
| chromium (AI) | 35 µg | 25 µg | 30 µg | none set |
| molybdenum | 45 µg | 45 µg | 50 µg | 2,000 µg |
| fluoride (AI) | 4 mg | 3 mg | 3 mg | 10 mg |
| Mineral | Main roles | Food sources | Deficiency signs |
|---|---|---|---|
| iron | hemoglobin, myoglobin, energy enzymes | heme: red meat, oysters, liver; non-heme: fortified cereal, lentils, tofu, spinach | fatigue, weakness, poor concentration and endurance, anemia |
| zinc | immunity, enzymes, wound healing, growth | oysters, beef, pumpkin seeds, dairy, beans | poor immunity, hair loss, diarrhea |
| copper | iron metabolism, connective tissue, energy enzymes | shellfish, nuts, seeds, organ meat, whole grains, chocolate | anemia, frequent infections; often caused by excess zinc |
| selenium | selenoproteins: thyroid hormone, antioxidant enzymes | Brazil nuts, seafood, meat, eggs, grains | rare; Keshan heart disease in low-selenium regions |
| iodine | thyroid hormones | cod, seaweed, dairy, eggs, iodised salt | goitre, hypothyroidism |
| manganese | enzyme cofactor (e.g. superoxide dismutase); carbohydrate and fat metabolism | whole grains, shellfish, nuts, legumes, tea | not firmly established |
| chromium | may enhance insulin action (mechanism unclear) | meat, grains, fruit, vegetables, nuts, brewer's yeast | not reported in healthy people |
| molybdenum | part of the molybdopterin enzyme cofactor | legumes, whole grains, nuts, liver | not seen on normal diets |
| fluoride | tooth enamel, resists decay | fluoridated water, tea | tooth decay |
Units and conversions
Labels now use µg or mg; older labels and many supplements still use IU.
| Nutrient | Conversion (ODS) |
|---|---|
| vitamin D | 1 µg = 40 IU; 1 IU = 0.025 µg; so 25 µg = 1,000 IU |
| vitamin A, retinol | 1 IU = 0.3 µg RAE |
| vitamin A, supplemental β-carotene | 1 IU = 0.3 µg RAE |
| vitamin A, dietary β-carotene | 1 IU = 0.05 µg RAE |
| vitamin A, dietary α-carotene, β-cryptoxanthin | 1 IU = 0.025 µg RAE |
| vitamin E, natural (RRR-α-tocopherol) | 1 IU = 0.67 mg; 1 mg = 1.49 IU |
| vitamin E, synthetic (all-rac) | 1 IU = 0.45 mg; 1 mg = 2.22 IU |
| blood 25(OH)D | 1 ng/mL = 2.5 nmol/L; 1 nmol/L = 0.4 ng/mL |
| ferritin | 1 ng/mL = 1 µg/L |
All amounts in µg (RAE, DFE) or mg (NE). Folic acid on an empty stomach counts double (1 µg DFE = 0.5 µg). A mixed diet giving 900 µg RAE is anywhere from 3,000 to 36,000 IU of vitamin A, depending on the source.
Athlete priorities
Supplements don't improve performance unless they fix a deficiency (ACSM/AND/DC 2016). The nutrients worth checking are iron, vitamin D and calcium.
Iron
| Point | Detail | Source |
|---|---|---|
| who is at risk | female, endurance and vegetarian athletes, regular blood donors | ACSM/AND/DC 2016 |
| how common | ~15–35% of female and ~5–11% of male athlete groups | Sim et al. 2019 |
| why athletes lose more | menstruation, foot-strike haemolysis, sweat, gut bleeding (NSAIDs), hepcidin after exercise lowers absorption | ODS; ACSM/AND/DC 2016 |
| energy link | ~6 mg iron per 1,000 kcal eaten, so dieting cuts iron | ACSM/AND/DC 2016 |
| needs | intense exercise may raise needs by 30–70%; aim above the RDA (over 18 mg women, over 8 mg men) | ODS; ACSM/AND/DC 2016 |
| ferritin | under 30 µg/L suggests deficiency, under 10 µg/L anemia (general population) | ODS |
| athlete ferritin cut-offs | no agreement; suggestions run from under 10 to under 35 µg/L | ACSM/AND/DC 2016 |
| ferritin caveat | rises with inflammation, so a "normal" result can hide low stores | ODS |
| sports anemia | early-training hemoglobin dip from plasma expansion; harmless | ACSM/AND/DC 2016 |
| treatment time | reversing iron-deficiency anemia takes 3–6 months | ACSM/AND/DC 2016 |
| Absorption tip | Detail | Source |
|---|---|---|
| pair non-heme iron with vitamin C or meat | both raise absorption | ODS |
| keep tea, coffee and cocoa away from iron meals | polyphenols cut absorption 50–90%; black tea 79–94% | Hurrell et al. 1999 |
| separate calcium and iron supplements | calcium may reduce heme and non-heme absorption | ODS |
| take supplements in the morning | absorption was higher after a morning run than in the evening | McCormick et al. 2019 |
| timing around hard sessions | ACSM advises against taking iron right after strenuous exercise (hepcidin); newer data favor within ~30 min of a morning session, before hepcidin peaks at ~3 h | ACSM/AND/DC 2016; Peeling et al. 2023 |
| alternate-day dosing | single morning doses on alternate days absorbed better than daily doses in iron-depleted women | Stoffel et al. 2017 |
Vitamin D
| Point | Detail | Source |
|---|---|---|
| status marker | serum 25(OH)D | ODS |
| NASEM cut-offs | under 30 nmol/L deficient; 30–50 inadequate; ≥ 50 adequate; over 125 possible harm | ODS |
| sports cut-offs | insufficiency 50–75 nmol/L, deficiency under 50; targets of 80–125 nmol/L suggested | ACSM/AND/DC 2016 |
| vitamin D winter | no skin synthesis Nov–Feb at 42°N (Boston), Oct–Mar at 52°N (Edmonton) | Webb et al. 1988 |
| higher risk | above ~35° latitude, indoor training, dark skin, early or late training, full cover or sunscreen | ACSM/AND/DC 2016 |
| UK advice | 10 µg/day in autumn and winter | NHS |
| performance | fixing deficiency matters; vitamin D is not an ergogenic aid | ACSM/AND/DC 2016 |
| test if | past stress fracture, bone or joint injury, muscle pain or weakness, overtraining signs, little sun | ACSM/AND/DC 2016 |
Calcium, bone and REDs
Low energy availability, and in women menstrual disruption, raise the risk of low bone density and stress fractures; low calcium adds to it (ACSM/AND/DC 2016). For athletes with low energy availability or menstrual dysfunction the joint statement advises 1,500 mg/day calcium and 1,500–2,000 IU/day vitamin D, alongside fixing energy intake. See energy availability and a doctor for missed periods or bone stress injuries.
Magnesium and cramps
| Claim | Evidence |
|---|---|
| magnesium prevents exercise cramps | no trials in exercise-associated cramps (Cochrane 2020) |
| magnesium prevents night cramps (older adults) | unlikely to help, moderate-certainty evidence (Cochrane 2020) |
| cramps mean low magnesium | cramps are a late sign of real deficiency, after appetite loss and fatigue (ODS) |
| magnesium supplements are harmless | diarrhea is common, especially with oxide, carbonate, chloride and gluconate (ODS) |
AIS lists magnesium (as oxide) in Group C: evidence not supportive.
Antioxidant megadoses
| Study | Dose | Result |
|---|---|---|
| Gomez-Cabrera et al. 2008 | 1 g/day vitamin C, endurance training | less mitochondrial biogenesis; hampered endurance adaptations |
| Paulsen et al. 2014 | 1,000 mg vitamin C + 235 mg vitamin E, 11 weeks running | no change in VO₂max, but blunted mitochondrial signaling |
| same group, strength study | same doses, 10 weeks lifting | smaller strength gains in arm curls; similar muscle growth |
Exercise-induced free radicals are part of the training signal. Get antioxidants from fruit and vegetables, don't megadose around training (AIS lists vitamin E in Group C, vitamin C in Group B), and stay under the ULs.
Absorption interactions
| Pair | Effect | Practical | Source |
|---|---|---|---|
| vitamin C + non-heme iron | raises absorption | fruit or peppers with plant-iron meals | ODS |
| meat, fish, poultry + non-heme iron | raises absorption | small portion of meat with beans or grains | ODS |
| tea, coffee, cocoa + iron | cuts non-heme absorption 50–90%; milk doesn't prevent it | drink them between meals, not with iron-rich ones | Hurrell et al. 1999 |
| phytate (grains, beans) + iron, zinc | reduces absorption | why vegetarians need 1.8× the iron and absorb less zinc | ODS |
| calcium + iron | may reduce both heme and non-heme | take calcium and iron supplements apart | ODS |
| iron supplement ≥ 25 mg + zinc supplement | less zinc absorbed | separate them | ODS |
| high zinc + copper | zinc blocks copper; ~50–60 mg/day for weeks lowers copper status | stay under the 40 mg zinc UL | ODS |
| vitamin D + calcium | low vitamin D status cuts calcium absorption | fix vitamin D first | ODS |
| oxalate (spinach) + calcium | 5% absorbed from spinach vs 27% from milk | count dairy, tofu, kale, not spinach | ODS |
| calcium dose size | 36% of a 300 mg dose absorbed vs 28% of 1,000 mg | split supplements into doses of 500 mg or less | ODS |
| calcium carbonate | needs stomach acid | take carbonate with food; citrate any time | ODS |
| dietary fat + vitamins A, D, E, K | needed for absorption | take fat-soluble supplements with a meal | ODS |
| high folic acid + B12 | fixes the anemia but not the nerve damage of B12 deficiency | check B12 status if taking high-dose folic acid | ODS |
| vitamin K + warfarin | vitamin K counters the drug | don't change greens or vitamin K supplements suddenly; tell your doctor | ODS |
| iron + levothyroxine or levodopa | iron lowers drug absorption | take at different times | ODS |
Toxicity and upper limits
Food alone rarely exceeds a UL; supplements, fortified foods and "stacking" several products do.
| Nutrient | UL (adults) | Excess causes | Source |
|---|---|---|---|
| vitamin A (retinol) | 3,000 µg | liver damage, birth defects, headache, blurred vision; beta-carotene only yellows skin, but high-dose supplements raised lung cancer risk in smokers | ODS |
| vitamin D | 100 µg (4,000 IU) | high blood calcium, kidney damage, arrhythmia; usually from supplements | ODS |
| vitamin E | 1,000 mg (supplements) | bleeding; 400 IU/day for years raised prostate cancer risk in men | ODS |
| vitamin C | 2,000 mg | diarrhea, nausea, cramps | ODS |
| niacin | 35 mg (supplements) | skin flushing | ODS |
| vitamin B6 | 100 mg (US); 12 mg (EFSA 2023) | sensory neuropathy, loss of coordination | ODS |
| folic acid | 1,000 µg | can mask B12 deficiency | ODS |
| iron | 45 mg | nausea, constipation; overdose above 20 mg/kg is dangerous | ODS |
| zinc | 40 mg | nausea; copper deficiency, lower HDL cholesterol, weaker immunity at ≥ 50 mg | ODS |
| selenium | 400 µg | selenosis: hair and nail loss, garlic breath, metallic taste | ODS |
| magnesium | 350 mg (supplements) | diarrhea, nausea, cramping | ODS |
| calcium | 2,500 mg | constipation, possibly kidney stones | ODS |
| iodine | 1,100 µg | thyroid problems, goitre | ODS |
| manganese | 11 mg | neurotoxicity | ODS |
| fluoride | 10 mg | skeletal fluorosis (joint pain, stiffness) | ODS |
Vegetarian and vegan gaps
| Nutrient | Why | Fix | Source |
|---|---|---|---|
| B12 | only animal foods contain it naturally | fortified foods or a supplement; this one is not optional for vegans | ODS |
| iron | non-heme only; phytate | needs are 1.8× the RDA (about 14 mg men, 32 mg women); pair with vitamin C | ODS |
| zinc | phytate in legumes and grains lowers absorption | legumes, nuts, seeds, whole grains daily | ODS |
| iodine | main sources are seafood, dairy and eggs | iodised salt (¼ tsp ≈ 78 µg); seaweed varies widely | ODS |
| calcium | no dairy | fortified plant milk, calcium-set tofu, kale, bok choy | ODS |
| vitamin D | few plant sources | UV mushrooms, fortified plant milk; supplement in winter | ODS |
| omega-3 (EPA, DHA) | ALA from plants converts poorly | ALA AI 1.6 g men, 1.1 g women from flax, soy, canola; algal oil gives 100–300 mg DHA | ODS |
| creatine | lower muscle creatine | vegetarians tend to respond more to supplements | ODS |
Food first, supplements and third-party testing
| Principle | Detail | Source |
|---|---|---|
| food first | a varied diet with enough energy covers micronutrients; supplements don't help performance unless fixing a deficiency | ACSM/AND/DC 2016 |
| single nutrients | for a clinically confirmed need, e.g. iron for iron-deficiency anemia | ACSM/AND/DC 2016 |
| multivitamin | may suit athletes whose diet lacks energy or variety | ACSM/AND/DC 2016 |
| regulation | US supplements need no approval before sale; the maker is responsible for safety and label claims | ODS |
| contamination | ~15% of 600+ products tested contained undeclared prohibited substances | IOC 2018 |
| bodybuilding products | among the most often adulterated (steroids, SARMs) | ODS |
| third-party testing | Informed Sport (tests every batch), NSF Certified for Sport, BSCG | ODS; Informed Sport |
| no guarantee | testing lowers the risk but can't remove it; a contaminated product can still cause a positive test and a ban | IOC 2018; ODS |
Watch for: why a food-first approach comes first, and how contaminated supplements lead to positive tests.
Recipes
Should I supplement?
Run through this before buying anything. Stop at the first "no".
- Is there a reason? A blood test or diagnosis (low ferritin, low 25(OH)D), a diet that excludes a source (vegan B12), or a life stage (pregnancy folate). "Tired" alone isn't a reason; get checked.
- Can food fix it? Try the food table below first, unless a doctor says otherwise.
- Is the dose safe? Add food, fortified foods and every product together and stay under the UL.
- Any interactions? Medicines (warfarin, levothyroxine), other supplements (iron vs calcium vs zinc).
- Is it tested? Choose Informed Sport or NSF Certified for Sport if you compete or are drug-tested.
- Is there evidence? AIS Group A medical supplements: iron, calcium, vitamin D, zinc, folate.
- Will you retest? Set a date (iron courses in studies run about 8 weeks) and stop when the need ends.
A day of food that covers the micronutrients
Per-serving values from the ODS fact sheets; the right-hand column is the share of the adult RDA or AI.
| Food | Serving | Main micronutrients | Share of target |
|---|---|---|---|
| fortified breakfast cereal | 1 serving | iron 18 mg | 100% (women) |
| milk, fortified | 240 mL | calcium 299 mg, iodine 84 µg (nonfat); vitamin D 2.9 µg (2%) | 30%, 56%, 19% |
| orange | 1 medium | vitamin C 70 mg | 78–93% |
| Greek yogurt, plain | ¾ cup | iodine 87 µg | 58% |
| salmon, cooked | 85 g (3 oz) | vitamin D 14.2 µg (sockeye); B12 2.6 µg (Atlantic) | 95%; 108% |
| spinach, boiled | ½ cup | folate 131 µg DFE, magnesium 78 mg | 33%, 19–25% |
| sweet potato, baked | 1 whole | vitamin A 1,403 µg RAE | over 100% (beta-carotene; no UL issue) |
| red pepper, raw | ½ cup | vitamin C 95 mg | over 100% |
| lentils, boiled | 1 cup | iron ~6 mg, potassium 731 mg | 33% (women), 21–28% |
| beef sirloin | 85 g (3 oz) | zinc 3.8 mg | 35–48% |
| pumpkin seeds | 28 g (1 oz) | magnesium 156 mg, zinc 2.2 mg | 37–50%, 20–28% |
| almonds | 28 g (1 oz) | vitamin E 6.8 mg, magnesium 80 mg | 45%, 19–26% |
| Brazil nut | 1 nut | selenium ~70–90 µg | over 100%; a handful exceeds the UL |
| kale, raw | 1 cup | vitamin K 113 µg | 94–126% |
Swap salmon for 2 eggs plus UV mushrooms, and beef for extra seeds and legumes, on meat-free days.
Iron-absorption meal
A plant-iron dinner built to be absorbed. Values from ODS.
| Part | Choice | Iron | Why |
|---|---|---|---|
| base | lentils, 1 cup boiled | ~6 mg | non-heme iron |
| greens | spinach, ½ cup boiled | 3 mg | non-heme iron, folate |
| protein | tofu, firm, ½ cup (or 85 g beef: 2 mg, part heme) | 3 mg | meat also raises non-heme absorption |
| vitamin C | red pepper ½ cup in the dish plus an orange | – | 165 mg vitamin C raises absorption |
| drinks | water with the meal; tea or coffee between meals | – | polyphenols cut absorption 50–90% |
| calcium | yogurt or calcium supplement at another meal | – | calcium competes |
| total | ~12 mg | 67% of women's RDA before absorption |
Supplement only if bloods show deficiency; take it in the morning with vitamin C and no tea, coffee or dairy.
Vitamin D winter plan
For someone above ~40° latitude (e.g. the UK, northern US, Canada) who trains outdoors in summer.
No skin synthesis: Oct-Mar at ~52°N (UK, Canada)
Nov-Feb at ~42°N (Boston)
Food salmon 85 g = 14.2 µg; UV mushrooms ½ cup = 9.2 µg;
fortified milk 240 mL ≈ 3 µg; egg = 1.1 µg
Supplement D3 10 µg (400 IU) per day UK NHS minimum
15 µg (600 IU) US RDA
25-50 µg (1,000-2,000 IU) general-population maintenance
(IOC 2018; no athlete guideline yet)
Ceiling 100 µg (4,000 IU) per day, food + supplements
Test 25(OH)D in late winter if injured, ill often,
or indoors a lot; aim ≥ 50 nmol/L (NASEM),
80-125 nmol/L suggested for athletes (ACSM)
Deficient? high-dose correction only under a doctorTake it with a meal that contains fat. Stop at the end of March unless a test says otherwise.
Vegan athlete gap checklist
Tick every line daily or weekly; any gap is a reason to add a fortified food or a tested supplement.
- B12: fortified foods at 2+ meals or a supplement; check the label, don't guess.
- Iron: legumes, tofu, fortified cereal daily, always with a vitamin C food; ferritin tested regularly, especially if female or running high mileage.
- Zinc: beans, nuts, seeds and whole grains daily.
- Iodine: iodised salt at home or a supplement; limit seaweed snacks (iodine varies).
- Calcium: 3 servings of fortified plant milk (299 mg per 240 mL) or calcium-set tofu (253 mg per ½ cup), plus low-oxalate greens (kale, bok choy).
- Vitamin D: supplement through winter; fortified plant milk the rest of the year.
- Omega-3: ALA from flaxseed (2.35 g per tbsp), chia (5.06 g per 28 g) or canola oil; consider algal oil for EPA and DHA.
- Protein and energy: enough total food and protein; check energy availability if weight or periods change.
- Creatine: worth considering for lifters (3–5 g/day); see nutrition & hydration.
References
- NIH ODS: Health professional fact sheets (opens in a new tab): RDA, AI, UL, roles, food sources, deficiency and toxicity for every nutrient; the source of truth for this sheet
- NIH ODS: Vitamin A (opens in a new tab), Vitamin D (opens in a new tab), Vitamin E (opens in a new tab), Folate (opens in a new tab), Niacin (opens in a new tab): IU, RAE, DFE and NE conversions
- NIH ODS: Iron (opens in a new tab), Calcium (opens in a new tab), Zinc (opens in a new tab), Magnesium (opens in a new tab): absorption interactions
- NIH ODS: Dietary supplements for exercise and athletic performance (opens in a new tab): iron in athletes, antioxidants, regulation, third-party certifiers
- NASEM: DRI table, elements (RDA/AI) (opens in a new tab) and ULs, elements (opens in a new tab): sodium, chloride and potassium values, chloride UL
- NASEM: Sodium and potassium DRIs (2019) (opens in a new tab): the sodium CDRR of 2,300 mg
- EFSA: Tolerable upper intake level for vitamin B6 (2023) (opens in a new tab): the 12 mg/day UL
- Thomas, Erdman and Burke: Nutrition and Athletic Performance, ACSM/AND/DC (2016) (opens in a new tab): iron, vitamin D, calcium and antioxidants for athletes
- Sim et al.: Iron considerations for the athlete (2019) (opens in a new tab): prevalence, hepcidin
- Peeling, Sim and McKay: Iron deficiency in athletes, GSSI SSE (2023) (opens in a new tab): supplement timing and dosing
- McCormick et al.: Morning versus afternoon exercise and iron absorption (2019) (opens in a new tab): morning absorption
- Stoffel et al.: Iron absorption on consecutive versus alternate days (2017) (opens in a new tab): alternate-day dosing
- Hurrell, Reddy and Cook: Inhibition of non-heme iron absorption by polyphenol beverages (1999) (opens in a new tab): tea and coffee
- Webb, Kline and Holick: Season and latitude and vitamin D3 synthesis (1988) (opens in a new tab): vitamin D winter
- NHS: Vitamin D (opens in a new tab): UK 10 µg autumn and winter advice
- Maughan et al.: IOC consensus statement on dietary supplements (2018) (opens in a new tab): vitamin D dosing, contamination rate
- Mountjoy et al.: 2023 IOC consensus statement on REDs (opens in a new tab): energy availability and bone health
- Garrison et al.: Magnesium for skeletal muscle cramps, Cochrane (2020) (opens in a new tab): cramp evidence
- Paulsen et al.: Vitamin C and E supplementation hampers adaptation to endurance training (2014) (opens in a new tab) and Gomez-Cabrera et al.: Vitamin C decreases mitochondrial biogenesis (2008) (opens in a new tab): antioxidant megadoses
- AIS: Sports Supplement Framework (opens in a new tab): Groups A to D
- Informed Sport (opens in a new tab) and NSF Certified for Sport (opens in a new tab): batch-tested supplement registers