Dr. Prabhat AryaMD · Internal Medicine
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Vitamin D, B12 and folate, how low is low.

Low vitamin D and low B12 are two of the most common findings on Indian health checks. Most are easy to correct. A few, especially a low B12 with numb feet or memory trouble, need a doctor soon.

Reviewed by Dr. Prabhat Arya, MBBS, MD (Internal Medicine)

Reviewed · Next review · Sources: MedlinePlus, Testing.com, NHS

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Read this first.

Go by the range printed on your own report. The ranges here are typical adult ranges, and labs use different cut-offs, especially for vitamin D. Check the unit: vitamin D is usually in ng/mL in India; if your report says nmol/L, divide by 2.5 to get ng/mL. For B12, if your report says pmol/L, multiply by 1.36 to get pg/mL.

A low vitamin D is very common in India, even in sunny places, because many people spend the day indoors and cover up outdoors. On its own, without bone pain or a low calcium, it is not urgent.

A low B12 is common in vegetarians and in people on metformin or acid-reducing medicines. It matters more than vitamin D because, left untreated for long, it can damage nerves for good.

Read these with your blood count (CBC): a high MCV or low haemoglobin with a low B12 or folate shows the deficiency is already affecting your blood. If you take supplements, note it when you compare with your last report.

Every value, one by one.

25-OH Vitamin D (25-hydroxy vitamin D, total)

The stored form of vitamin D, which the body needs for strong bones and muscles

Typical adult range Most Indian labs: below 20 ng/mL deficient; 20–30 insufficient; 30–100 sufficient

High usually means
Almost always from too much supplement: high-strength weekly sachets, capsules or injections taken for longer than planned, or several products together. Very high levels raise blood calcium, which can cause thirst, passing a lot of urine, constipation, nausea, confusion and kidney stones.
Low usually means
Too little sun on bare skin, darker skin, covering up, staying indoors, extra weight, older age, kidney or liver disease, gut problems that affect absorption, and some epilepsy medicines. Many people with low vitamin D feel nothing; others notice aching bones, muscle weakness or tiredness.
Usually nothing to worry about when
It is 20–30 ng/mL and you feel well: more sun and diet, or a modest supplement, is usually enough. Many experts consider 20 ng/mL and above adequate for most adults.
See a doctor when
It is below 12 ng/mL, or low with bone pain, muscle weakness, a fracture after a minor fall, or a low calcium or high ALP on other tests: see a doctor within a few weeks. Above 100 ng/mL: stop vitamin D supplements and see a doctor this week to check your calcium.

Vitamin B12 (cobalamin)

A vitamin from animal foods (milk, curd, eggs, meat, fish) needed for nerves and for making blood

Typical adult range About 200–900 pg/mL (labs vary, for example 197–771 or 211–911)

High usually means
Usually B12 tablets or injections, including those in multivitamins. If you take none, a high B12 is occasionally a sign of liver disease or a blood condition, and is worth mentioning at your next check-up.
Low usually means
A vegetarian diet with little milk or curd, or a vegan diet. Long-term metformin for diabetes, and acid-reducing medicines (such as pantoprazole or omeprazole) taken for months, lower absorption. Others: pernicious anaemia (the immune system stops the stomach absorbing B12), stomach or bowel surgery, coeliac disease, and regular alcohol.
Usually nothing to worry about when
It is 200–300 pg/mL (borderline) and you have no tingling, numbness, memory or balance problems and a normal blood count. Your doctor may advise diet changes or a supplement, and a repeat or an extra test (methylmalonic acid or homocysteine) if you have symptoms.
See a doctor when
It is below 200 pg/mL: see a doctor within a few weeks to start treatment and find the cause. Low or borderline with tingling or numbness in the hands or feet, unsteady walking, memory problems, low mood, or a sore red tongue: see a doctor this week, because nerve damage can become permanent if treatment is delayed.

Folate (folic acid, serum)

A B-vitamin from green leafy vegetables, dals and fruit, needed for making blood and in early pregnancy

Typical adult range Above about 4 ng/mL (labs vary; many print 3–17 ng/mL)

High usually means
Usually folic acid tablets or fortified foods. Harmless in itself, but high folate can hide the blood signs of a low B12, which is why the two are tested together.
Low usually means
A diet low in vegetables and dals, regular alcohol, pregnancy and breastfeeding, coeliac disease and other gut problems, and some medicines (methotrexate, and some epilepsy medicines such as phenytoin). Serum folate also dips for a few days after poor eating, so one low result may need a repeat.
Usually nothing to worry about when
It is just below the range after a few days of poor appetite, and your blood count is normal.
See a doctor when
It is low with anaemia or a high MCV: see a doctor within a few weeks; the B12 must be checked before folic acid is started. If you are pregnant or planning a pregnancy, you should be taking folic acid every day from before you conceive until 12 weeks of pregnancy, whatever your result: if you are not, ask your doctor this week.

Results that go together.

PatternsTypical, not certain
When you seeIt usually means
Low B12 with high MCV and low haemoglobinB12 deficiency anaemia. Needs treatment and a search for the cause, including pernicious anaemia, especially if your diet does not explain it or the B12 stays low despite treatment.
Low B12 in someone on metforminCommon after some years on metformin. Do not stop metformin; your doctor can add B12. Yearly B12 checks are sensible on long-term metformin.
Low folate with high MCV, normal B12Folate deficiency: often diet or alcohol. Easy to treat once B12 is confirmed normal.
Low vitamin D with low calcium and high ALPThe bones are short of vitamin D (osteomalacia). Needs proper treatment and a recheck; see a doctor within a few weeks.
High MCV with normal B12 and folateLook for other causes: alcohol, an underactive thyroid, liver disease or medicines. See thyroid tests and liver tests.

Get help today if

  • Taking vitamin D supplements and now very thirsty, passing a lot of urine, vomiting, very constipated, or confused or drowsy: go to hospital today for a calcium test.
  • Low B12 with new weakness of the legs, falls, loss of control of the bladder or bowels, or sudden confusion: go to hospital today.
  • Low B12 or folate with haemoglobin below 7 g/dL, or with breathlessness at rest, chest pain or fainting: go to hospital today; with chest pain or fainting, call 112.

Call 112 or go to the nearest emergency department. Ambulance: 108 (102 in some states).

Read more.

Questions people ask.

  1. Is vitamin D of 15 ng/mL very low?

    It is in the deficient range on most Indian reports, and common. It is not an emergency. It usually needs a course of vitamin D advised by your doctor, more sun on bare arms and legs, and a recheck after about three months. If you have bone pain, muscle weakness or a recent fracture, see a doctor within a few weeks.

  2. What B12 level is dangerous?

    There is no single number. Below 200 pg/mL needs treatment. What makes it urgent is symptoms: tingling or numbness, unsteady walking or memory problems mean see a doctor this week, even if the level is only borderline.

  3. Why is my B12 low when I eat well?

    B12 comes almost only from animal foods, so a vegetarian diet with little milk and curd often runs short. Metformin, acid-reducing medicines taken for months, and pernicious anaemia, where the stomach cannot absorb B12, cause it even with a good diet.

  4. My vitamin B12 is high. Is that a problem?

    Usually not: it is most often from B12 tablets, injections or multivitamins. If you take none, mention it at your next check-up so your liver tests and blood count can be looked at.

  5. Can I take vitamin D and B12 without testing?

    Modest doses are generally safe, but the high-strength weekly sachets and injections can push vitamin D too high if taken for too long. Test first, take the course your doctor advises, and recheck.

Where this can be checked

These are trusted general sources. The advice on this page is Dr. Arya’s, written for patients in India. Ranges differ between labs: go by the range printed on your own report.

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Dr. Prabhat Arya · MBBS, MD (Internal Medicine)