Last reviewed on 11 September 2026.
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That arithmetic explains a pattern Indian doctors see constantly. Indian studies have repeatedly found low B12 in a large share of adults, and the problem is consistently worse among vegetarians. This post covers where vegetarians can get B12, how to tell whether you are short, how the test is read, and what actually corrects a deficiency.
What is vitamin B12, and why does the body need it?
Vitamin B12, or cobalamin, is a water-soluble vitamin the body needs to make healthy red blood cells, to copy DNA, and to keep the insulating sheath around nerves intact. Absorption is unusually complicated. Stomach acid first releases B12 from food, and a protein made in the stomach, called intrinsic factor, then carries it to the far end of the small intestine, where it is absorbed. A problem at any step, from low stomach acid to gut disease, can cause deficiency even when intake looks adequate.
How much vitamin B12 does an adult need each day?
About 2 to 2.5 mcg a day for most adults. ICMR-NIN's Nutrient Requirements for Indians (2020) places its adult values in this range, and most requirement tables raise the figure a little for pregnancy and breastfeeding. The US figure of 2.4 mcg is similar. These are tiny amounts, measured in micrograms, or millionths of a gram. The liver also holds a store that can last a few years, which is why a diet low in B12 can take years to produce symptoms, and why a normal result at 25 does not settle the question at 45.
Which vegetarian foods contain vitamin B12?
Milk, curd, buttermilk, paneer, cheese and eggs are the only natural vegetarian sources. According to USDA FoodData Central, cow's milk carries roughly 0.4 to 0.5 mcg per 100 mL, so a 250 mL glass gives about 1 mcg. Plain curd sits in a similar range per 100 g. A large egg provides around 0.4 to 0.5 mcg, most of it in the yolk. Paneer varies with the milk and the method used, and published figures for it are too inconsistent to quote with confidence.
| Food | Roughly how much B12 |
|---|---|
| Cow's milk | about 0.4 to 0.5 mcg per 100 mL |
| A 250 mL glass of milk | about 1 mcg |
| Plain curd | a similar range per 100 g |
| One large egg | around 0.4 to 0.5 mcg, most of it in the yolk |
| Paneer | published figures vary too much to quote with confidence |
Figures as reported by USDA FoodData Central. Repeated boiling costs milk some of its B12.
Can a lacto-vegetarian get enough B12 from dairy alone?
In theory yes, in practice often not. Reaching 2 to 2.5 mcg from dairy would take something like two glasses of milk plus a generous bowl of curd every day, eaten consistently for years. Many adults drink milk only in tea, and boiling milk repeatedly, as Indian kitchens tend to, destroys some of its B12. So a vegetarian who takes little dairy, or who has other risk factors, can drift into deficiency despite a diet that looks sensible on paper.
What should vegans and people who avoid dairy do?
Vegans need fortified foods or a supplement, because without dairy or eggs there is no dependable dietary source at all. In India, B12 is added to some breakfast cereals, plant milks and packaged foods. FSSAI's +F logo marks products fortified under its standards, though the logo alone does not tell you which nutrients were added, so read the nutrition panel for the B12 figure per serving.
Is there any plant source of vitamin B12?
No plant food is a reliable source of active vitamin B12. Spirulina is often sold as one, but most of what it contains is a pseudo-B12 analogue that the human body cannot use, and it may register on some laboratory assays and give a false impression. Fermented idli and dosa batters, pickles and mushrooms contain at most trace amounts. Nutritional yeast counts only if it has been fortified; the unfortified kind has almost none, as the guide to what nutritional yeast is explains.
What are the signs of vitamin B12 deficiency?
The early signs are vague: tiredness, weakness, breathlessness on the stairs and pale skin, which are the effects of anaemia. Nerve symptoms follow, or sometimes come first: pins and needles in the hands and feet, numbness, unsteady balance, and changes in memory, concentration and mood. A sore, smooth, red tongue and mouth ulcers are classic clues. Blood tests may show megaloblastic anaemia, where red cells are fewer and abnormally large. Nerve damage left untreated for long can become permanent, which is the main reason to test rather than wait.
Why do metformin and acidity tablets lower B12?
Both interfere with absorption. Long-term metformin, the most widely prescribed diabetes medicine in India, is linked with falling B12 levels, and diabetes guidelines advise periodic B12 checks for people who take it. Proton pump inhibitors such as omeprazole and pantoprazole, and older acid-reducing drugs, lower the stomach acid needed to free B12 from food. Neither is a reason to stop the medicine. A vegetarian with diabetes on metformin, or anyone on acid tablets for years, has two risks stacked together and should ask the prescribing doctor about a test.
How is vitamin B12 deficiency tested?
With a serum B12 blood test, often ordered alongside a complete blood count. Reference ranges vary between laboratories, but many Indian reports print something close to 200 to 900 pg/mL. As a rough guide, a result below about 200 pg/mL is low, and 200 to 300 pg/mL is borderline. Some labs report in pmol/L instead, where 200 pg/mL is roughly 148 pmol/L. Serum B12 is an imperfect marker, because it measures all the B12 in the blood rather than the portion cells can use, so a borderline result with symptoms may call for a second test.
What do MMA and homocysteine results add?
They show whether the body is actually short of B12 at the level of the cells. Methylmalonic acid (MMA) and homocysteine both build up when B12 is lacking, so raised values alongside a borderline serum B12 point towards true deficiency. MMA is the more specific of the two, because homocysteine also rises with low folate, kidney problems and some medicines. Which test to add is the doctor's decision, based on your symptoms and the first result.
How is a B12 deficiency treated?
A doctor treats it, usually with high-dose oral B12 or a course of injections. High-dose tablets work even when absorption is poor, because a small fraction of a large dose crosses the gut wall without needing intrinsic factor. Injections are preferred when deficiency is severe, when nerves are affected, or when a condition such as pernicious anaemia blocks absorption entirely. Methylcobalamin and cyanocobalamin are both used in India, and both correct deficiency. The dose, the route and how long to continue depend on the cause, so this is not a supplement to guess at.
From a suspicion to a settled level
Notice the pattern, not one symptom
Tiredness and breathlessness on the stairs, or pins and needles, numbness, poor balance and a sore, smooth tongue.
Count the risk factors
A vegetarian or vegan diet, years on metformin or acid tablets, gut disease or gut surgery all push the odds up.
Get the blood test
Serum B12, usually with a complete blood count, and MMA or homocysteine added when the first result is borderline and the symptoms fit.
Let the doctor pick the route
High-dose tablets work even when absorption is poor. Injections are preferred when deficiency is severe, nerves are affected, or absorption is blocked entirely.
Then use food to hold the level
Dairy, eggs and fortified foods keep a corrected level up. They do not rescue a deficiency, and nerve symptoms settle more slowly than the numbers.
How can you increase B12 levels quickly?
Only supplements or injections, taken under a doctor's supervision, raise B12 quickly; food cannot. Injections can lift blood levels within days, and high-dose tablets take somewhat longer. Symptoms improve more slowly than the numbers, and nerve symptoms may take months to settle. Diet matters for keeping levels up afterwards, not for rescue. Anyone with numbness, balance problems or memory changes should see a doctor promptly rather than trying to eat their way out of a deficiency.
Does B12 deficiency cause anaemia like iron deficiency does?
It causes anaemia, but a different kind. Iron deficiency makes red cells small and pale, while B12 or folate deficiency makes them large and immature. Indian vegetarians can have both at once, and the two can partly mask each other on a blood count. Taking folic acid alone can correct the anaemia of B12 deficiency while nerve damage quietly continues, which is why the cause needs pinning down first. For the iron side of the plate, the anaemia diet chart covers Indian meals in detail.
Building B12 into a vegetarian day
A glass of milk at breakfast, a bowl of curd with lunch and a glass of masala chaas in the afternoon make a realistic dairy pattern, adding up to perhaps 1.5 to 2 mcg. A plate of curd rice or an egg adds more. This is a sound base, not a guarantee, and it does nothing for someone whose absorption is impaired. Plant-based eating done well means knowing exactly where the gaps are, and NNWA's six-week Plant-Based Nutrition course gives a module each to key micronutrients and to supplements and gaps, for 10,999 rupees.
The short answer
Vitamin B12 comes from bacteria, reaches vegetarians only through dairy, eggs, fortified foods and supplements, and runs low in a large share of Indian adults. Dairy helps but often falls short. If you are vegetarian, and especially if you take metformin or acidity tablets or have symptoms, get tested. If you are vegan, plan for fortified foods or a supplement from the start.