Vitamin D test: normal levels, deficiency symptoms and where to get it

Vitamin D keeps your bones and muscles strong, and low levels are very common. Here's how to read your 25-OH vitamin D result and what actually raises it.

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Quick answer

What is a normal vitamin D level?

Vitamin D is measured as 25-hydroxyvitamin D. Below 20 ng/mL (50 nmol/L) is deficient and below 12 ng/mL (30 nmol/L) is severely low. Most experts consider 20 ng/mL or more enough for bone health, and many labs print 30 to 100 ng/mL as the reference range. Above about 50 ng/mL brings no extra benefit, and very high levels can be harmful.

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Health information, not medical advice. Your doctor knows your full picture; ask them about your result.

Range chart

Vitamin D levels chart

25-hydroxyvitamin D (25-OH D, the usual vitamin D test). ng/mL × 2.5 = nmol/L. Your lab's range on the report is the one to compare with.

Resultng/mLnmol/LWhat it usually means
Severely lowBelow 12Below 30Raises the risk of soft bones (rickets in children, osteomalacia in adults). Needs treatment.
Deficient12 to 1930 to 49Too low for healthy bones. Usually treated.
Insufficient20 to 2950 to 74Enough for most people by IOM standards; some labs and experts prefer 30 or more.
Sufficient30 to 5075 to 125A healthy level for bones and muscles.
HighAbove 50Above 125No extra benefit. Usually from supplements; worth reviewing the dose.
Too highAbove 150Above 375Risk of vitamin D toxicity and high calcium. Needs a doctor.

Many labs print 30 to 100 ng/mL as "normal". Guidelines differ on whether 20 or 30 ng/mL is enough, but they agree that below 12 is too low and that going above 50 doesn't help.

Foods with vitamin D

Approximate amounts from the NIH Office of Dietary Supplements. Very few foods are rich in it, which is why sunlight and sometimes supplements matter.

FoodTypical servingVitamin D (about)
Cod liver oil1 tablespoon1,360 IU (34 mcg)
Salmon, cooked85 g (3 oz)570 IU (14 mcg)
Mushrooms grown under UV light½ cupabout 360 IU (9 mcg)
Fortified milk1 cupabout 120 IU (3 mcg)
Fortified breakfast cereal1 servingabout 80 IU (2 mcg)
Tuna, canned in water85 g (3 oz)40 IU (1 mcg)
Egg yolk1 large egg44 IU (1 mcg)

The general daily intake reference is 600 IU (15 mcg) for adults up to 70 and 800 IU (20 mcg) over 70. Treating a deficiency uses higher doses that your doctor sets.

What does vitamin D do?

Vitamin D helps your gut absorb calcium and phosphate, the minerals that build and keep bones and teeth strong. It also keeps muscles working well and plays a part in the immune system.

Your skin makes vitamin D when it's exposed to sunlight (UVB rays), and a smaller amount comes from food. The liver turns it into 25-hydroxyvitamin D, which is what the blood test measures, because it shows your stores over the past few weeks. The kidneys then make the active form.

Vitamin D2 and D3 both raise your level; D3 (cholecalciferol), the kind your skin makes, tends to raise it a little more and last a little longer. The test is often written as 25-OH vitamin D, vitamin D total or vitamin D3 test.

What does low vitamin D mean?

Low vitamin D is very common, including in sunny countries, because many people spend most daylight hours indoors. You're more likely to run low if you:

  • spend little time outdoors, cover most of your skin, or live far from the equator in winter
  • have darker skin, which makes less vitamin D from the same sunlight
  • are older, as skin makes less with age
  • are overweight, as vitamin D is stored in fat
  • are pregnant or breastfeeding, or an exclusively breastfed baby
  • have coeliac disease, inflammatory bowel disease, liver or kidney disease, or have had weight-loss surgery
  • take some medicines, such as some anti-seizure medicines or long-term steroids

Signs of low vitamin D are often vague or absent. They can include tiredness, bone or back pain, aching or weak muscles (especially climbing stairs or getting up from a chair), muscle cramps, low mood and getting ill often. Over time, low levels thin the bones (osteoporosis), and severe deficiency softens them: rickets in children and osteomalacia in adults.

Can vitamin D be too high?

Yes, but almost only from taking too much in supplements. You can't get too much from sunlight, and food rarely provides much.

Levels above about 50 ng/mL (125 nmol/L) bring no further benefit. Above about 150 ng/mL (375 nmol/L), vitamin D can push blood calcium too high. Signs include thirst, passing a lot of urine, nausea and vomiting, constipation, tiredness, confusion and, in time, kidney stones or kidney damage.

High-dose vitamin D is widely sold and sometimes taken for months without a test. If you take it, check with your doctor how long to continue and when to retest.

How do you get vitamin D from sunlight and food?

Sunlight is the main source for most people. Short, regular exposure of the face, arms and legs to midday sun on most days, without sunscreen and without burning, helps the skin make vitamin D. How long you need depends on your skin tone, where you live and the season: lighter skin may need 10 to 15 minutes, darker skin longer. Sun through a window doesn't work, and long, unprotected exposure raises the risk of skin cancer, so never let your skin burn.

Food helps a little: oily fish (salmon, mackerel, sardines), cod liver oil, egg yolks, mushrooms grown under UV light, and foods with vitamin D added, such as some milks, plant milks, yoghurts, cereals and cooking oils. Vegetarians and vegans usually rely on sunlight, fortified foods and, when needed, supplements.

Do you need to fast for a vitamin D test?

  • It's a small blood sample from a vein. No fasting is needed unless other tests at the same visit need it.
  • The test to ask for is 25-hydroxyvitamin D (25-OH D). The "1,25-dihydroxy" test is a different, specialist test.
  • If you take vitamin D, keep taking it as usual unless your doctor says otherwise, and tell the lab the dose.
  • Levels are usually lower at the end of winter and higher at the end of summer.
  • Results usually come back within one to two days.

Who should get a vitamin D test?

Healthy adults without symptoms don't usually need routine vitamin D tests; the Endocrine Society's 2024 guideline advises against routine testing for most people under 75. Testing makes sense if you:

  • have bone pain, muscle weakness, frequent falls or a fracture from a minor fall
  • have osteoporosis or are being treated for it
  • have conditions that affect absorption (coeliac disease, IBD, weight-loss surgery) or liver or kidney disease
  • take medicines that lower vitamin D
  • are taking high-dose vitamin D, to check the level isn't too high
  • are recovering from treatment, usually about 3 months after starting, when the level has settled

How can you raise low vitamin D?

  • Get some sun safely: short, regular outdoor time on most days, without burning.
  • Eat foods with vitamin D: oily fish, eggs, UV-grown mushrooms and fortified milk, cereals or oils.
  • Supplements: follow your doctor's plan. Treating a deficiency uses higher doses for a set time, and the right dose depends on your level, weight and health. Don't take high-dose vitamin D for months without a test; too much raises calcium and can harm the kidneys.
  • Calcium matters too: dairy, fortified plant milks, ragi, sesame, leafy greens and tofu help vitamin D build bone.
  • Recheck after about 3 months of treatment, as your doctor advises.

When to see a doctor

Book a visit

  • Your vitamin D is below 12 ng/mL (30 nmol/L): see a general physician within 1 to 2 weeks to plan treatment and check calcium.
  • It's below 20 ng/mL (50 nmol/L) and you have bone pain, muscle weakness or frequent falls: see a general physician within 2 to 4 weeks.
  • It's above 100 ng/mL (250 nmol/L), or you've taken high-dose vitamin D for months without a test: see a doctor within a week to check calcium and review the dose.
  • You're pregnant, breastfeeding or caring for a baby and unsure about vitamin D: ask your doctor or midwife at the next visit.

Get emergency help now (call your local emergency number) if someone has:

  • confusion, severe vomiting, extreme thirst and weakness, or an irregular heartbeat while taking high-dose vitamin D (possible high calcium)
  • muscle spasms, tingling around the mouth or a fit, especially with known very low vitamin D or calcium

A vitamin D number on its own is never an emergency. These signs are.

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Questions people ask

  • A vitamin D test measures 25-hydroxyvitamin D (25-OH D) in your blood, the form that shows how much vitamin D your body has stored over the past few weeks. It's also called the vitamin D3 test, vitamin D total or 25-OH vitamin D. It helps find deficiency and checks whether supplements are working.

  • Below 20 ng/mL (50 nmol/L) is deficient and below 12 ng/mL (30 nmol/L) is severely low. 20 ng/mL or more is enough for most people by Institute of Medicine standards, and many labs print 30 to 100 ng/mL as normal. Above about 50 ng/mL brings no extra benefit.

  • Many people have no symptoms. When they appear, they include tiredness, bone or back pain, aching or weak muscles (especially with stairs or standing up), muscle cramps, low mood and frequent infections. Severe, long-standing deficiency softens bones, causing rickets in children and osteomalacia in adults.

  • Mostly too little sun on the skin: spending most of the day indoors, covering up, darker skin, older age, or winter far from the equator. Being overweight, pregnancy, coeliac disease, inflammatory bowel disease, liver or kidney disease, weight-loss surgery and some medicines also lower it.

  • Few foods have much. The best are cod liver oil, oily fish such as salmon, mackerel and sardines, egg yolks, mushrooms grown under UV light, and foods with vitamin D added, such as some milks, plant milks, yoghurts, cereals and cooking oils. For most people, sunlight is still the main source.

  • Short, regular exposure of the face, arms and legs to midday sun on most days helps, without sunscreen and without burning. Lighter skin may need 10 to 15 minutes; darker skin needs longer. Sun through glass doesn't work. Never let your skin burn, as that raises the risk of skin cancer.

  • Yes, almost always from high-dose supplements, not from sunlight or food. Very high levels (above about 150 ng/mL) can raise blood calcium, causing thirst, frequent urination, nausea, vomiting, confusion and, over time, kidney damage. If you take high-dose vitamin D, ask your doctor how long to continue and when to retest.

  • Vitamin D3 (cholecalciferol) is the form your skin makes from sunlight and is found in animal foods; vitamin D2 (ergocalciferol) comes from plants and fungi. Both raise your vitamin D level, and D3 tends to raise it a little more. The blood test measures both together as 25-hydroxyvitamin D.

  • No. You can eat and drink normally before a vitamin D test. If other tests are done at the same time, such as fasting glucose or a lipid profile, follow the fasting instructions for those. If you take vitamin D supplements, keep taking them unless your doctor says otherwise.

  • With treatment your doctor sets, levels usually rise over 6 to 12 weeks, which is why a recheck is usually done about 3 months after starting. Symptoms such as aches and tiredness can take a few months to improve. Keeping the level up afterwards often needs regular sun, food sources and sometimes a smaller daily supplement.

  • Routine tests aren't usually needed for healthy adults. Testing makes sense with bone pain, muscle weakness, frequent falls, a fracture from a minor fall, osteoporosis, absorption problems such as coeliac disease, liver or kidney disease, some long-term medicines, or when taking high-dose vitamin D.

  • Yes. Vitamin D helps your gut absorb calcium from food, and without enough of it your body can't build or keep strong bones however much calcium you eat. That's why bone-health advice usually pairs the two: enough vitamin D, and calcium from dairy, fortified plant milks, ragi, sesame, leafy greens or tofu.

Other tests explained

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Sources

  1. MedlinePlus: Vitamin D test
  2. NIH Office of Dietary Supplements: Vitamin D fact sheet
  3. NHS: Vitamin D
  4. Institute of Medicine: Dietary reference intakes for calcium and vitamin D (2011)
  5. Endocrine Society: Vitamin D for the prevention of disease guideline (2024)
  6. Demay MB et al. Vitamin D for the prevention of disease: an Endocrine Society guideline. J Clin Endocrinol Metab 2024

Updated . Health information, not medical advice. Your doctor knows your full picture; ask them about your result.