Vitamin D and B12 Deficiency in India: Symptoms, Tests and Treatment

Two deficiencies turn up on Indian blood reports more than any others, and both are handled badly in opposite directions: vitamin D is over-treated with sachets taken for years, and B12 is under-recognised while it quietly damages nerves. This guide explains who is at risk, what the deficiencies actually feel like, which tests to ask for, and how each is treated properly.

Why is vitamin D deficiency so common in a sunny country?

Vitamin D is made in the skin when it is exposed to midday ultraviolet B. Indians are deficient because that exposure rarely happens. Work is indoors, travel is covered, clothing covers the arms and legs, and the darker the skin the more exposure is needed. Air pollution filters ultraviolet in the cities. Diet contributes very little unless foods are fortified. Studies across India find 70 to 90 percent of people tested have levels below 20 ng/mL. Sunscreen, often blamed, makes almost no difference in real use.

The consequences are bone and muscle: aches in the lower back, hips and thighs, weakness climbing stairs, fatigue, and in the long term softened bones in adults and rickets in children. Claims that vitamin D prevents cancer, heart disease, infections and depression have largely not held up in trials of supplementing people who were not deficient. Correcting a real deficiency helps; mega-dosing a normal level does not.

Why is B12 deficiency so common in Indians?

Vitamin B12 is found in animal foods. Vegetarians, who are a large share of the population, get some from milk and curd and very little otherwise. Absorption also falls with age, with acidity medicines such as omeprazole and pantoprazole taken long term, with metformin for diabetes, after weight-loss or stomach surgery, and with an autoimmune condition called pernicious anaemia. Surveys of apparently healthy Indians find deficiency in a third to a half of people, and higher in vegetarians.

B12 is needed for nerves and for making blood cells. Deficiency causes tiredness, breathlessness on exertion and a large-cell anaemia; tingling and numbness in the feet and hands, unsteadiness, and in advanced cases weakness and memory or mood changes; a sore red tongue and recurrent mouth ulcers. The nerve damage can become permanent if the deficiency is prolonged, which is why it should not be dismissed as weakness or stress.

What do the symptoms look like side by side?

Fatigue alone does not distinguish anything; it is the commonest symptom of almost every condition and of ordinary life. That is why testing matters.

Which tests to ask for

For vitamin D, ask for 25-hydroxy vitamin D, not 1,25-dihydroxy vitamin D, which is a different test that is often normal even in deficiency. Below 20 ng/mL is deficient, 20 to 30 insufficient, 30 to 100 adequate.

For B12, ask for serum vitamin B12. Below about 200 pg/mL is deficient; 200 to 300 is a grey zone in which the deficiency may still be real. In the grey zone, or when symptoms are strongly suggestive, methylmalonic acid or homocysteine confirms it; both rise when cells are short of B12. A complete blood count shows whether the red cells are enlarged, and folate is usually checked alongside because the two are treated together.

Tests in India cost a few hundred to a thousand rupees each and are available at every large laboratory. Test before you treat, so you know where you started and can confirm you have got there.

How vitamin D is treated safely

The standard Indian course for deficiency is 60,000 IU of cholecalciferol once a week for eight weeks, taken with a meal that contains some fat. After that, or from the start for insufficiency, a maintenance dose of 1,000 to 2,000 IU daily, or 60,000 IU once a month, keeps the level stable. Recheck the level after three months. Calcium is not automatically needed; dietary calcium from milk, curd, ragi and greens is usually enough unless intake is poor.

Sunlight remains the free option: 15 to 30 minutes of midday sun on the arms and legs a few times a week produces a useful amount in lighter Indian skin and needs longer in darker skin. Morning or evening sun and sun through glass do almost nothing for vitamin D, whatever the forwarded messages say.

How B12 is treated

Oral B12 at 1,000 to 2,000 micrograms daily corrects most deficiencies, including many caused by poor absorption, because a small fraction is absorbed regardless of stomach function. Injections of 1,000 micrograms, given several times in the first weeks and then monthly or as directed, are used when there are neurological symptoms, when the level is very low, in pernicious anaemia and when oral treatment fails. Nerve symptoms may take months to improve and improve most when treatment starts early. Folate is often corrected at the same time; B12 must be replaced first or alongside, because folate alone can worsen the nerve damage.

Vegetarians who are deficient once will usually need an ongoing maintenance dose, or reliable fortified foods, because the diet that caused the deficiency has not changed. Long-term users of metformin or acid-suppressing medicines should have B12 checked every year or two.

Who should be tested?

Anyone with the symptoms above. Vegetarians and vegans, at least once. People on metformin or long-term acidity medicines. Pregnant women and those planning pregnancy, because B12 deficiency affects the baby. Older adults. People with unexplained anaemia, tingling or memory change. Women who cover most of the skin and indoor workers, for vitamin D. Children with delayed walking, bow legs or recurrent fractures.

When to see a doctor

See a doctor rather than self-treating if you have tingling, numbness, unsteadiness, memory problems or anaemia, because B12 deficiency with nerve involvement needs prompt and properly dosed treatment. See a doctor if bone pain is severe, if you have kidney disease or kidney stones before taking vitamin D, if you have been taking high-dose vitamin D for months, or if a course of treatment has not improved your symptoms. Deficiency is a diagnosis to confirm and treat, not a label for tiredness.