Nutrient Directory
What each one does,
and what happens without it.
Every vitamin, the essential minerals and electrolytes, and the macronutrients. Where to find them, what shortage causes, and what too much causes — because for several of these, too much is its own problem.
Not sure where to start?
Pick something you have noticed, and this will show which nutrients list it among their documented deficiency signs. It is an index, not an answer. Every symptom here has many possible causes and most of them are not nutritional — dizziness is far more often blood pressure, the inner ear or a medication than it is iron.
Vitamin A
Fat-soluble vitaminRetinol · Beta-carotene (provitamin A)
Needed to see in dim light — it forms rhodopsin, the pigment in the retina. Also maintains the surface tissues of the eye, gut and airways, and is required for immune function and normal growth.Read moreShow less
Where to find it
Liver · Egg yolk · Butter and cheese · Oily fish · Carrots and sweet potato (as beta-carotene) · Dark leafy greens · Red peppersRead moreShow less
Too little — Xerophthalmia
Night blindness first, then drying of the cornea. Still the leading cause of preventable childhood blindness worldwide. Also raises susceptibility to infection.Most at risk: Rare where food is plentiful. Fat malabsorption — cystic fibrosis, coeliac disease, pancreatic insufficiency — is the usual cause in wealthy countries.Too much
Preformed vitamin A accumulates. Too much causes headache, bone pain, liver damage and hair loss, and — importantly — causes birth defects. Pregnant women should avoid liver and high-dose supplements. Beta-carotene from food does not do this; the body converts only what it needs, though very high intakes turn the skin orange harmlessly.Read moreShow less
How much
900 µg RAE (men) · 700 µg RAE (women)Upper limit: 3,000 µg preformed retinolWorth knowing
Fat-soluble — needs some fat in the meal. Isotretinoin and other retinoid medicines add to the total; do not supplement alongside them.Vitamin B1
Water-soluble vitaminThiamin · Thiamine
Converts carbohydrate into energy, and is needed for nerve and heart muscle function.Where to find it
Pork · Whole grains and fortified cereals · Legumes · Sunflower seeds · TroutToo little — Beriberi · Wernicke–Korsakoff syndrome
Most at risk: Heavy alcohol use above all. Also after bariatric surgery, and with prolonged vomiting.Nerve damage and weakness (dry beriberi) or heart failure and swelling (wet beriberi). In heavy drinkers it causes Wernicke encephalopathy — confusion, unsteadiness and eye movement problems — which is a medical emergency and can become permanent.Read moreShow less
Too much
No known toxicity — excess is excreted.How much
1.2 mg (men) · 1.1 mg (women)Upper limit: None establishedWorth knowing
Destroyed by prolonged heat. Alcohol impairs absorption directly. Loop diuretics increase losses.Vitamin B12
Water-soluble vitaminCobalamin · Cyanocobalamin · Methylcobalamin
Required to make red blood cells, to maintain the myelin sheath around nerves, and to recycle folate.Where to find it
Meat, fish and shellfish · Eggs · Dairy · Fortified plant milks and nutritional yeastToo little — Pernicious anaemia
Most at risk: Vegans and strict vegetarians — it occurs naturally only in animal foods. Also adults over 50, anyone on long-term metformin or acid-blocking medication, and after stomach or bowel surgery.Fatigue and anaemia, then pins and needles, unsteadiness, memory problems and mood change. Nerve damage can become permanent if it goes untreated for long, which is why this one should not be left to guesswork.Read moreShow less
Too much
No known toxicity. Excess is excreted.How much
2.4 µgUpper limit: None establishedStudied for — as a supplement
Corrects the fatigue and anaemia of B12 deficiency. No evidence of benefit in people with normal levels, despite how it is sold.Deficiency causes cognitive symptoms that may not fully reverse if left long. Supplementing people who are not deficient has not been shown to help.Worth knowing
Needs stomach acid and intrinsic factor. Older adults often cannot free it from food protein even though the vitamin is present, so fortified food or supplements work better than more meat. Metformin and proton pump inhibitors both reduce absorption over time.Vitamin B2
Water-soluble vitaminRiboflavin
Central to energy production in every cell, and needed to activate vitamins B6 and folate.Where to find it
Milk and yoghurt · Eggs · Liver · Almonds · Mushrooms · Fortified cerealsToo little — Ariboflavinosis
Cracks at the corners of the mouth, a sore magenta tongue, sore throat and sensitivity to light.Most at risk: People avoiding dairy, heavy drinkers, and during pregnancy.Too much
No known toxicity. Turns urine bright yellow, which is harmless and often mistaken for a problem.How much
1.3 mg (men) · 1.1 mg (women)Upper limit: None establishedWorth knowing
Destroyed by light — which is why milk is no longer sold in clear glass.Vitamin B3
Water-soluble vitaminNiacin · Nicotinic acid · Nicotinamide
Forms NAD and NADP, the coenzymes that drive several hundred metabolic reactions. Also involved in DNA repair.Where to find it
Meat, poultry and fish · Peanuts · Whole grains · Mushrooms · Fortified cerealsToo little — Pellagra
Most at risk: Heavy alcohol use, severe malnutrition, and some rare metabolic disorders.The classic four Ds — dermatitis on sun-exposed skin, diarrhoea, dementia and, untreated, death. Historically endemic where maize was the staple, because its niacin is bound and unavailable unless treated with lime.Read moreShow less
Too much
Nicotinic acid causes intense flushing, itching and headache above about 50 mg. Sustained high doses can damage the liver. The doses once used for cholesterol are prescription territory, not self-treatment.Read moreShow less
How much
16 mg NE (men) · 14 mg NE (women)Upper limit: 35 mg from supplementsWorth knowing
The body can make a little from tryptophan, which is why protein intake affects requirements. High doses affect blood sugar and uric acid.Vitamin B5
Water-soluble vitaminPantothenic acid
Forms coenzyme A, which is required to metabolise fats, carbohydrate and protein, and to make hormones.Where to find it
Almost everything — the name is Greek for "from everywhere" · Chicken and beef · Avocado · Mushrooms · Sunflower seeds · Whole grainsRead moreShow less
Too little
Effectively unknown outside of experimental starvation studies, where it caused burning feet and fatigue.Most at risk: Nobody eating any reasonable diet.Too much
No known toxicity. Very high doses may cause diarrhoea.How much
5 mgUpper limit: None establishedVitamin B6
Water-soluble vitaminPyridoxine · Pyridoxal-5-phosphate
Involved in over a hundred enzyme reactions, most of them in protein metabolism. Needed to make haemoglobin and several neurotransmitters, including serotonin and GABA.Where to find it
Chickpeas · Tuna and salmon · Poultry · Bananas · Potatoes · Fortified cerealsToo little
Anaemia, cracked lips, a swollen tongue, low mood, confusion, and a weakened immune response.Most at risk: Kidney disease, autoimmune conditions, heavy alcohol use.Too much
One of the few water-soluble vitamins with real toxicity. Sustained high doses cause peripheral neuropathy — numbness and loss of coordination — which may not fully reverse. Harm has been reported below the official limit.Read moreShow less
How much
1.3 mg · rising to 1.7 mg (men) and 1.5 mg (women) over 50Upper limit: 100 mgStudied for — as a supplement
Well supported for nausea in pregnancy and recommended in obstetric guidelines, often combined with doxylamine. One of the better-evidenced entries here.Some trial support for premenstrual symptoms. Take care with dose — high intakes cause nerve damage.Worth knowing
Reduces the effectiveness of levodopa when taken without carbidopa. Some medicines deplete it, including isoniazid.Vitamin B7
Water-soluble vitaminBiotin · Vitamin H
A coenzyme in fat and carbohydrate metabolism, and in gene regulation.Where to find it
Egg yolk · Liver · Nuts and seeds · Salmon · Sweet potatoToo little
Thinning hair, a scaly red rash around the eyes and mouth, and neurological symptoms. Rare.Most at risk: People eating raw egg white regularly — avidin in it binds biotin. Also pregnancy and some genetic disorders.Too much
No toxicity, but a genuine practical hazard: high-dose biotin supplements interfere with many laboratory blood tests, including thyroid and troponin assays. That has caused missed heart attacks. Tell any doctor ordering blood tests if you take it.Read moreShow less
How much
30 µgUpper limit: None establishedWorth knowing
Raw egg white blocks absorption; cooking destroys the avidin. Distorts immunoassay blood tests — stop several days before testing.Vitamin B9
Water-soluble vitaminFolate · Folic acid (the supplement form)
Required to make and repair DNA and to divide cells — so it matters most where cells divide fastest, including in a developing embryo.Where to find it
Dark leafy greens · Legumes and lentils · Asparagus · Avocado · Fortified flour and cereals · LiverToo little — Megaloblastic anaemia
Most at risk: Anyone who could become pregnant, heavy drinkers, coeliac disease, and people on methotrexate.Large immature red cells, fatigue, mouth ulcers and irritability. In early pregnancy, shortage causes neural tube defects such as spina bifida — which is why flour is fortified in Canada and why supplementation is advised before conception.Read moreShow less
Too much
High folic acid can mask B12 deficiency by correcting the anaemia while nerve damage continues unchecked. That is the main reason for the upper limit.How much
400 µg DFE · 600 µg in pregnancyUpper limit: 1,000 µg from supplementsStudied for — as a supplement
Studied alongside B12 and B6 for lowering homocysteine. The homocysteine falls; the clinical benefit has been harder to demonstrate.Worth knowing
Folic acid from supplements and fortified food is absorbed better than natural folate. Methotrexate, some anticonvulsants and sulfasalazine all interfere with it.Vitamin C
Water-soluble vitaminAscorbic acid
Required to make collagen, which is why deficiency shows in skin, gums and wound healing. Also an antioxidant, helps recycle vitamin E, and greatly increases absorption of plant iron.Read moreShow less
Where to find it
Peppers · Citrus fruit · Strawberries and kiwi · Broccoli and Brussels sprouts · Blackcurrants · PotatoesToo little — Scurvy
Most at risk: Smokers need more. Also people eating very restricted diets, and heavy drinkers.Bleeding gums, bruising, poor wound healing, corkscrew hairs, joint pain and profound fatigue. The disease that killed more sailors than combat, and the reason the vitamin was found at all.Read moreShow less
Too much
Excess is excreted, but large doses cause diarrhoea and stomach cramps, and raise the risk of kidney stones in susceptible people.How much
90 mg (men) · 75 mg (women) · +35 mg for smokersUpper limit: 2,000 mgStudied for — as a supplement
The clearest negative result in this directory. Regular supplementation does not prevent colds in the general population — the Cochrane review is unambiguous. It shortens them very slightly, by around 8% in adults, and only if taken continuously beforehand rather than started when symptoms appear.Read moreShow less
Required for collagen synthesis; healing is impaired in deficiency and restored by correcting it.Worth knowing
Absorption falls sharply above about 200 mg at a time — splitting doses is better than one large one. Greatly increases non-haem iron absorption, which matters both to vegetarians and to people with haemochromatosis, who should be careful.Vitamin D
Fat-soluble vitaminCholecalciferol (D3) · Ergocalciferol (D2) · The sunshine vitamin
Lets the gut absorb calcium and phosphorus, which is why it governs bone strength. Also acts on muscle and immune cells. Made in the skin from UVB sunlight rather than obtained mainly from food.Read moreShow less
Where to find it
Oily fish — salmon, mackerel, sardines · Egg yolk · Fortified milk and plant milks · Cod liver oil · UV-exposed mushroomsRead moreShow less
Too little — Rickets (children) · Osteomalacia (adults)
Soft, deforming bones in children; bone pain and muscle weakness in adults. Milder shortage is common and often silent.Most at risk: Anyone at Canadian latitudes between October and March — the sun is too low to make any. Also darker skin, covered skin, older adults, and people who are housebound. Health Canada recommends a supplement for adults over 50.Too much
Only from supplements, never from sun. Excess raises blood calcium, causing nausea, confusion, kidney stones and kidney damage. Case reports of harm generally involve doses well above the upper limit taken for months.Read moreShow less
How much
600 IU (15 µg) · 800 IU (20 µg) over 70Upper limit: 4,000 IU (100 µg)Studied for — as a supplement
Well established with calcium for preventing rickets and osteomalacia, and for reducing fracture risk in older people who are deficient or housebound. Trials in people who already have adequate levels have been largely negative.Read moreShow less
Widely trialled and largely disappointing — most randomised trials find no effect on mood in people who are not deficient. Low vitamin D is common in people who are unwell, which may be a consequence rather than a cause.Read moreShow less
Worth knowing
Fat-soluble. Taking it with the largest meal of the day improves absorption. Some anticonvulsants, corticosteroids and weight-loss medicines reduce levels.Vitamin E
Fat-soluble vitaminAlpha-tocopherol
The main fat-soluble antioxidant in cell membranes, protecting the fats in them from oxidation. Also has a role in immune function.Where to find it
Sunflower seeds · Almonds and hazelnuts · Vegetable oils · Avocado · Spinach · WheatgermToo little
Very rare from diet. When it occurs it causes nerve and muscle damage — loss of coordination, weakness, and eventually retinal damage.Most at risk: Almost exclusively people with fat malabsorption or rare genetic disorders of fat transport.Too much
High-dose supplements increase bleeding risk and have been associated with higher all-cause mortality in some analyses. There is no reason to take large doses.How much
15 mgUpper limit: 1,000 mg from supplementsWorth knowing
Fat-soluble. Adds to the effect of warfarin and other anticoagulants.Vitamin K
Fat-soluble vitaminPhylloquinone (K1) · Menaquinone (K2)
Required to make several clotting factors — the K is for Koagulation. Also activates proteins that bind calcium into bone.Where to find it
Kale, spinach and other dark greens · Broccoli and Brussels sprouts · Vegetable oils · Natto and fermented foods (K2) · Hard cheeses (K2)Read moreShow less
Too little
Easy bruising and prolonged bleeding. Rare in adults; newborns are given vitamin K at birth because they are born with very little.Most at risk: Newborns, people with fat malabsorption, and those on long courses of antibiotics.Too much
No known toxicity from food or supplements.How much
120 µg (men) · 90 µg (women)Upper limit: None establishedWorth knowing
Fat-soluble. Gut bacteria make some K2. Directly opposes warfarin. Anyone on warfarin should keep their intake steady rather than avoiding greens — sudden changes in either direction destabilise INR.Calcium
Major mineralNinety-nine per cent of it is structural — bone and teeth. The remaining one per cent runs muscle contraction, nerve signalling and blood clotting, and the body will strip bone to keep that fraction steady.Read moreShow less
Where to find it
Dairy · Fortified plant milks · Tinned sardines with bones · Tofu set with calcium · Kale and bok choy · AlmondsToo little
Most at risk: Postmenopausal women, people avoiding dairy without replacing it, and those with coeliac disease.Blood levels stay normal at the expense of the skeleton, so shortage shows as reduced bone density over years rather than symptoms now. Severe acute low calcium causes muscle cramps and tingling.Read moreShow less
Too much
Supplemental excess causes constipation and kidney stones, and can interfere with iron and zinc absorption. Some evidence links high supplemental — not dietary — calcium to cardiovascular risk.Read moreShow less
How much
1,000 mg · 1,200 mg for women over 50 and men over 70Upper limit: 2,500 mgStudied for — as a supplement
Reduces fracture risk with vitamin D in older adults, particularly those in care. Benefit in younger healthy adults with adequate intake is much less clear, and high-dose supplements have their own risks.Read moreShow less
Worth knowing
Needs vitamin D. Absorbed better in doses of 500 mg or less at a time. Reduces absorption of iron, zinc and several antibiotics — separate them by two hours.Copper
Trace mineralNeeded to use iron, to form connective tissue, and for nerve function and energy production.Where to find it
Liver · Oysters and shellfish · Dark chocolate · Cashews and sesame · MushroomsToo little
Anaemia that does not respond to iron, low white cell count, bone abnormalities, and nerve damage.Most at risk: People taking high-dose zinc for long periods, and after bariatric surgery.Too much
Nausea and liver damage. Wilson disease causes accumulation regardless of intake.How much
900 µgUpper limit: 10 mgWorth knowing
High zinc intake blocks it — the commonest cause of copper deficiency in practice.Iodine
Trace mineralIts only job is thyroid hormone — and thyroid hormone sets the metabolic rate of every cell, and governs brain development before birth.Where to find it
Iodised salt · Seaweed — extremely variable, kelp can be excessive · Cod and haddock · Dairy · EggsToo little — Goitre · Congenital iodine deficiency
Most at risk: People using only non-iodised sea or rock salt, vegans, and pregnancy.Thyroid enlargement, fatigue, weight gain and cold intolerance. In pregnancy, shortage causes irreversible intellectual disability in the child — historically the world’s leading preventable cause.Read moreShow less
Too much
Too much also causes thyroid dysfunction — both over- and underactivity. Kelp supplements can contain wildly variable and sometimes enormous amounts. This is a nutrient where more is emphatically not better.Read moreShow less
How much
150 µg · 220 µg in pregnancyUpper limit: 1,100 µgWorth knowing
Interacts with thyroid medication and lithium.Iron
Trace mineralHaem iron (animal) · Non-haem iron (plant)
Carries oxygen — it sits at the centre of haemoglobin in blood and myoglobin in muscle. Also needed for energy production and immune function.Where to find it
Red meat and liver · Shellfish · Legumes and lentils · Tofu · Fortified cereals · Dark leafy greens · Pumpkin seedsToo little — Iron deficiency anaemia
Most at risk: Menstruating women, pregnancy, vegetarians and vegans, endurance athletes, and anyone with gut bleeding — which is why unexplained iron deficiency in men and older women is investigated.The most common nutritional deficiency in the world. Fatigue, breathlessness, pallor, cold hands, brittle nails, and sometimes a craving for ice or dirt. Affects concentration long before anaemia appears on a blood test.Read moreShow less
Too much
Iron supplements are a leading cause of fatal poisoning in young children — keep them locked away. In adults, excess causes constipation and nausea; in haemochromatosis it accumulates and damages the liver, heart and pancreas. Do not supplement without knowing your levels.Read moreShow less
How much
8 mg (men) · 18 mg (menstruating women) · 27 mg in pregnancyUpper limit: 45 mgStudied for — as a supplement
Resolves fatigue reliably where the fatigue is caused by iron deficiency, and trials show benefit even before full anaemia. It does nothing for fatigue in people whose iron is normal, and taking it without knowing is how people end up with iron overload.Read moreShow less
Worth knowing
Plant iron is absorbed poorly — vitamin C alongside it improves that substantially, while tea, coffee and calcium taken with the meal reduce it. Reduces absorption of levothyroxine and several antibiotics — separate by four hours.Magnesium
Major mineralA cofactor in more than three hundred enzyme systems, including energy production, protein synthesis, muscle and nerve function, and blood glucose control.Where to find it
Pumpkin seeds · Almonds and cashews · Spinach · Black beans · Dark chocolate · Whole grainsToo little
Most at risk: Type 2 diabetes, heavy alcohol use, long-term diuretics or proton pump inhibitors, and older adults.Muscle cramps and twitching, fatigue, irritability, and in severe cases abnormal heart rhythms. Mild shortage is common and easily missed, because blood levels stay normal while tissue stores fall.Read moreShow less
Too much
Supplements cause diarrhoea long before anything worse — magnesium is a laxative, which is what milk of magnesia is. Dangerous accumulation happens only with kidney impairment.How much
400–420 mg (men) · 310–320 mg (women)Upper limit: 350 mg from supplements only — food is not limitedStudied for — as a supplement
Trials of magnesium for migraine prevention are modestly positive and it appears in several clinical guidelines as an option. Effect sizes are small.Small trials in older adults report improved sleep. The evidence is thin and often quoted more confidently than it deserves.Frequently taken for cramps. Trials in older adults and in pregnancy have mostly found no benefit over placebo.Worth knowing
Citrate and glycinate forms are absorbed better than oxide, which is mostly laxative. Reduces absorption of some antibiotics and bisphosphonates — separate them.Manganese
Trace mineralA cofactor in bone formation, wound healing and antioxidant enzymes.Where to find it
Whole grains · Nuts · Leafy greens · Tea · LegumesToo little
Extremely rare in people. Reported effects include poor bone growth and skin changes.Most at risk: Effectively nobody eating a normal diet.Too much
Inhaled manganese — an occupational exposure in welding and mining — causes a Parkinson-like neurological condition. Dietary excess is not the concern.How much
2.3 mg (men) · 1.8 mg (women)Upper limit: 11 mgPhosphorus
Major mineralPhosphate
Builds bone alongside calcium, forms the backbone of DNA, and makes ATP — the molecule cells actually spend as energy.Where to find it
Dairy · Meat and fish · Nuts and seeds · Legumes · Cola drinks (as additives)Too little
Very rare. Causes bone pain, weakness and loss of appetite.Most at risk: Severe malnutrition, refeeding after starvation, and heavy alcohol use.Too much
Excess matters mainly in kidney disease, where it accumulates and pulls calcium from bone. Phosphate additives in processed food are absorbed far more readily than natural phosphorus.Read moreShow less
How much
700 mgUpper limit: 4,000 mgPotassium
ElectrolyteThe main positive ion inside cells. Sets the electrical gradient that lets nerves fire and muscles — including the heart — contract. Works against sodium to regulate blood pressure and fluid balance.Read moreShow less
Where to find it
Potatoes with skin · Beans and lentils · Bananas · Leafy greens · Tomato and orange juice · Yoghurt · SalmonToo little — Hypokalaemia
Muscle weakness and cramps, constipation, fatigue, and — if severe — dangerous heart rhythm disturbances.Most at risk: People on loop or thiazide diuretics, prolonged vomiting or diarrhoea, and eating disorders.Too much
From food, essentially none in healthy people — the kidneys excrete the excess. In kidney disease, or with potassium-sparing diuretics and ACE inhibitors, it accumulates and high blood potassium can stop the heart. Potassium supplements are genuinely dangerous in the wrong person.Read moreShow less
How much
3,400 mg (men) · 2,600 mg (women)Upper limit: None from foodStudied for — as a supplement
Increasing dietary potassium lowers blood pressure, and the World Health Organization recommends it for that reason. Food rather than supplements — potassium tablets can be dangerous, particularly with kidney disease or certain heart medicines.Read moreShow less
Worth knowing
ACE inhibitors, ARBs and potassium-sparing diuretics all raise levels. Do not supplement while on them without medical advice.Selenium
Trace mineralForms the selenoproteins, including glutathione peroxidase — the body’s main antioxidant defence — and is required to activate thyroid hormone.Where to find it
Brazil nuts — one or two supply a full day · Tuna and sardines · Eggs · Whole grains · Sunflower seedsToo little — Keshan disease
A form of heart muscle disease seen where soils are selenium-poor, notably parts of China. Also causes muscle weakness and impaired immunity.Most at risk: People in low-selenium regions, kidney dialysis, and severe gut disease.Too much
The margin between enough and too much is narrow. Excess causes garlic breath, hair and nail loss, and nerve damage. Eating a large handful of Brazil nuts daily can genuinely reach that.Read moreShow less
How much
55 µgUpper limit: 400 µgSodium
ElectrolyteSalt (sodium chloride)
The main positive ion outside cells. Governs fluid balance, blood volume and blood pressure, and is needed for nerve transmission.Where to find it
Table salt · Bread and processed foods — where most intake actually comes from · Cured meats · Cheese · Sauces and stockToo little — Hyponatraemia
Most at risk: Almost nobody eating normally. Deficiency is a medical situation, not a dietary one.Rare from diet. Occurs with prolonged heavy sweating replaced by water alone, some medicines, or drinking excessive water — causing headache, confusion, seizures. Endurance athletes are the classic case.Read moreShow less
Too much
The realistic problem for nearly everyone. High intake raises blood pressure and, over decades, stroke and heart disease risk. Most of it arrives in processed food rather than the salt cellar.Read moreShow less
How much
1,500 mg adequate intakeUpper limit: 2,300 mg suggested limit — most people eat well above thisZinc
Trace mineralA cofactor for hundreds of enzymes. Central to immune function, wound healing, taste and smell, and DNA synthesis.Where to find it
Oysters — by far the richest source · Beef and lamb · Pumpkin seeds · Chickpeas and lentils · Cashews · Whole grainsToo little
Poor wound healing, frequent infections, hair loss, loss of taste and smell, and in children, stunted growth.Most at risk: Vegetarians and vegans — phytates in grains and legumes bind it. Also alcohol use, gut disease, and pregnancy.Too much
Sustained high intake causes copper deficiency, which produces anaemia and nerve damage. Zinc nasal sprays have caused permanent loss of smell and should be avoided entirely.How much
11 mg (men) · 8 mg (women)Upper limit: 40 mgStudied for — as a supplement
Zinc lozenges started within a day of symptoms shorten a cold by roughly a day in meta-analyses. Started later they do nothing, and the doses used cause nausea and a lingering taste in many people.Read moreShow less
Improves healing where zinc is deficient. No benefit shown in people with normal levels.Worth knowing
Soaking, sprouting and fermenting grains and legumes reduces phytate and improves absorption. Competes with copper and iron. Reduces absorption of some antibiotics.Carbohydrate
CarbohydrateSugars · Starch
The body’s preferred fuel, and the only fuel the brain uses in quantity under normal conditions.Where to find it
Whole grains · Potatoes and root vegetables · Fruit · Legumes · Dairy (lactose)Too little
Not essential in the strict sense — the body can make glucose from protein and fat. Very low intake causes fatigue, constipation and bad breath as ketones rise.Most at risk: Not a deficiency seen in practice.Too much
Excess free sugar contributes to tooth decay, weight gain and metabolic problems. Whole-food carbohydrate behaves quite differently from refined sugar.How much
130 g minimum for brain function · 45–65% of energy typicallyUpper limit: None; free sugars suggested under 10% of energyFats
FatLipids · Omega-3 · Omega-6
Energy storage, cell membrane structure, hormone production, and the transport of vitamins A, D, E and K. Two fatty acids — linoleic and alpha-linolenic — are essential and must be eaten.Read moreShow less
Where to find it
Oily fish — the useful long-chain omega-3s · Olive oil · Nuts and seeds · Avocado · Flax and chia (short-chain omega-3) · EggsRead moreShow less
Too little
Rare. Dry scaly skin, poor wound healing, and in infants, impaired growth and vision.Most at risk: Very low-fat diets, fat malabsorption conditions.Too much
Fat is energy-dense, so excess contributes to weight gain. Industrial trans fats raise cardiovascular risk and are now largely banned in Canada.How much
20–35% of energy · omega-3: 1.6 g (men), 1.1 g (women)Upper limit: None as such; trans fats should be as low as possibleStudied for — as a supplement
Omega-3 supplements lower triglycerides reliably. Their effect on cardiovascular events has been repeatedly trialled with mostly disappointing results — eating fish appears to do better than taking the capsules.Read moreShow less
Trials of EPA-rich omega-3 in depression are mixed, with some positive results in people already on treatment.Worth knowing
Conversion of plant omega-3 to the long-chain forms in fish is poor — under 10% — so fish or algae oil is not interchangeable with flax. High-dose fish oil increases bleeding risk alongside anticoagulants.Fibre
CarbohydrateSoluble fibre · Insoluble fibre
Not digested by us — it feeds gut bacteria, adds bulk, slows glucose absorption and binds bile acids. Soluble and insoluble types do different jobs.Where to find it
Legumes · Whole grains and oats · Fruit with skin · Vegetables · Nuts and seedsToo little
Constipation, and over time a less diverse gut microbiome. Low intake is associated with bowel disease and cardiovascular risk.Most at risk: Most people in North America — average intake is roughly half the recommendation.Too much
Rapid increases cause bloating, wind and discomfort. Increase gradually and with enough fluid.How much
38 g (men) · 25 g (women)Upper limit: None establishedStudied for — as a supplement
Soluble fibre improves constipation and IBS symptoms and appears in mainstream guidelines. Insoluble fibre can make IBS worse, which is why the type matters more than the amount.Worth knowing
Very high intakes can bind minerals such as iron and zinc. Can slow absorption of medicines — separate psyllium and similar from tablets.Protein
ProteinAmino acids
Supplies the twenty amino acids used to build everything structural and functional — muscle, enzymes, antibodies, hormones. Nine of them cannot be made by the body and must come from food.Read moreShow less
Where to find it
Meat, fish and eggs · Dairy · Legumes and lentils · Tofu and tempeh · Nuts and seeds · Whole grainsToo little — Kwashiorkor · Marasmus
Muscle wasting, swelling, poor wound healing, hair and skin changes, and weakened immunity. Severe forms are diseases of famine.Most at risk: Older adults, who need more than younger adults and often eat less. Also illness, recovery from surgery, and very restricted diets.Too much
Well tolerated in healthy people. In established kidney disease, high intake accelerates decline — which is where the general "protein harms kidneys" idea comes from, and it does not apply to healthy kidneys.Read moreShow less
How much
0.8 g per kg body weight minimum · 1.0–1.2 g/kg is often suggested for older adultsUpper limit: None establishedWorth knowing
Plant proteins are individually incomplete but combine perfectly well across a day — the old "combining at every meal" advice was overturned decades ago.Water
OtherHydration
Around 60% of body weight. The medium every reaction happens in, the transport for nutrients and waste, and the mechanism of temperature control.Where to find it
Drinking water · Tea and coffee — yes, they count · Fruit and vegetables · Soups and milkToo little — Dehydration
Thirst, dark urine, headache, fatigue and poor concentration. Older adults lose the thirst signal, which is why dehydration is common and easily missed in them.Most at risk: Older adults, hot weather, illness with fever or vomiting, and endurance exercise.Too much
Drinking far more than the kidneys can excrete dilutes blood sodium and causes hyponatraemia — confusion, seizures, and occasionally death. It has killed marathon runners and people attempting water-drinking challenges.Read moreShow less
How much
3.7 L total (men) · 2.7 L (women), including water from foodUpper limit: None establishedStudied for — as a supplement
Dehydration is a recognised headache trigger, though trials of drinking more as a treatment are small.
How to read this.
Deficiency diseases are settled fact rather than opinion — scurvy is what vitamin C was discovered through, and pellagra and rickets were solved the same way. That is why these entries can be direct in a way a herb directory cannot.
More is not better. Several of these do real harm in excess — vitamin A causes birth defects, B6 causes nerve damage that may not reverse, iron supplements are a leading cause of fatal poisoning in small children, and selenium has a narrow margin between enough and too much. Every entry says what too much looks like, because that is the half most directories leave out.
Reference intakes are adult figures and vary with age, sex and pregnancy. Each entry links to the NIH Office of Dietary Supplements fact sheet, which is the standard reference and goes into far more depth than we do.
The symptom lookup is a fixed index, not a chatbot, and that is deliberate. Ask a language model “I feel dizzy, what am I missing?” and it will name a nutrient confidently every time. A lookup can honestly return nothing — which is often the true answer.
Please read
This directory is educational information published by Arkanic Healing Studio. It is not medical or dietetic advice, it does not diagnose, treat, cure or prevent any disease, and it is not a substitute for care from a doctor, pharmacist or registered dietitian.
Nothing here is personalised to you. Reference intakes are adult figures and vary with age, sex, pregnancy, medication and medical conditions. Listing a symptom against a nutrient means that symptom appears among that nutrient’s documented deficiency signs — it does not mean you are deficient, and most causes of most symptoms are not nutritional.
Do not start a supplement on the strength of this page. Several nutrients here cause real harm in excess, some interact with prescription medicines, and a few are genuinely unwise to take without knowing your blood levels first. If something is worrying you, please see your doctor — a blood test costs you nothing here and answers the question properly.
We sell no supplements and have no commercial interest in what you take. Content is compiled from public reference sources including the NIH Office of Dietary Supplements, which every entry links to.