To B12 Or Not To B12? Why Blind Supplementation Can Do More Harm Than Good

For Arnav Mehta, exhaustion was both the result and the reward of an always-on life. “It became a form of self-adulation,” says the Mumbai-based financial analyst. That was until it began dragging him down, a malaise no amount of sleep could shake off.

The popular verdict was “burnout”, but Mehta’s AI confidant suggested, “B12 deficiency.” Self-prescribed B12 supplements offered little relief. A self-ordered blood test came back borderline, revealing nothing of consequence to the 31-year-old. “A doctor identified a thyroid condition much later as the probable cause,” he recalls.

Mehta did what many Indians do with persistent fatigue: silence the symptom but spare the sickness. And B12 is often a perfect alibi.

B12 deficiency is widely recognised as a major public health concern in India with known haematological, neurological, obstetric and other consequences across age groups. Although not nationally representative, a 2021 review of Indian studies involving different populations and diagnostic criteria estimated that about 53% of participants were B12-deficient — 48% of adults and 57% of those under 18. A 2026 review in Frontiers in Nutrition describes this as among the highest rates reported worldwide. Other studies have reported high prevalence among vegetarians, pregnant women and older adults.

While diagnostic thresholds may vary, on a standard blood test, a B12 level of 300 pg/mL or above is generally considered normal, 200–299 pg/mL is borderline, and below 200 pg/mL is deficient. According to the 2026 Workforce Health Index, data from annual health check-ups arranged through the insurance broker Loop showed that 73.9% of employee B12 test reports were below 300 pg/mL. Across all test reports, including employees and covered family members, 35% were borderline and 34.5% were deficient.

Supply conundrum

Humans cannot synthesise B12 and must obtain it through animal-source foods (such as milk, eggs, meat and fish), fortified foods or supplements. B12 deficiency may result from inadequate dietary intake. The other cause could be impaired nutrient absorption due to insufficient secretion of a stomach protein called intrinsic factor, gastrointestinal disorders and surgery, or long-term use of medications such as metformin or proton-pump inhibitors.

“Certain gut microbes can produce vitamin B12,” says Dr. R. Hemalatha, former Director, ICMR–National Institute of Nutrition, Hyderabad. “However, the extent to which it contributes to human nutritional requirements remains unclear.” Some bacteria involved in food fermentation can also produce vitamin B12, she adds, but their amounts and bioavailability vary considerably. “We need more research to understand whether traditional fermented foods contribute meaningfully to B12 intake.” Fortified foods, she notes, can help improve B12 intake.

“B12 deficiency can go unnoticed because people tend to dismiss the symptoms as everyday tiredness or stress,” observes Dr. Vaishali Lokhande, Senior Consultant — General Medicine, Apollo Hospitals, Navi Mumbai. “If you are constantly feeling tired or weak, experiencing dizziness, mouth ulcers, a sore tongue, tingling or numbness in your hands and feet, or even difficulty with memory or balance, it is worth getting your B12 levels checked.”

B12 deficiency can affect both the blood and nervous system. “It can lead to anaemia, neurological disturbances and cognitive problems,” says Dr. Hemalatha. “Anaemia reduces the blood’s oxygen-carrying capacity, causing fatigue, weakness and breathlessness, particularly during physical exertion.”

Symptoms can be tricky, though. For example, B12 deficiency can cause nerve-related symptoms such as tingling, numbness, poor balance and difficulty walking, even when haemoglobin levels are normal and there is no anaemia. “Low vitamin B12 levels,” says Dr. Hemalatha, “may not always cause noticeable symptoms, while symptoms such as fatigue, numbness or memory problems, which may suggest B12 deficiency, can have other causes.”

Experts caution that severe B12 deficiency, if left untreated for too long, can even result in permanent damage to the nervous system.

Innocent until tested

A serum B12 test is usually the first step in identifying a deficiency, says Dr. Lokhande, but the report alone may not tell the full story. “We also need to look at the patient’s symptoms and medical history,” she says. “If B12 levels are borderline or do not match the symptoms, additional tests such as MMA or homocysteine may be recommended to understand whether the body is getting enough usable B12.” However, not everyone needs these tests, she clarifies. “The key is to identify the deficiency and start appropriate treatment early.”

According to Dr. Amrita Ghosh, Consultant Diabetologist at Fortis Cdoc Hospital, New Delhi, oral tablets are sufficient for most people with mild deficiency. “Sublingual preparations have not been shown to be significantly better than regular tablets,” she says. “Injections are usually recommended in severe deficiency, neurological symptoms or absorption problems.” The duration depends on the cause. “Some people may need supplements for a few months, while those with persistent dietary deficiency or absorption problems may need them long-term,” she says.

Dr. Ghosh is concerned about the growing tendency among Indians to blindly take B12 supplements without finding out why they have symptoms. “People often start taking them for tiredness, hair fall or general weakness, assuming that B12 will solve the problem,” she says.

Being a water-soluble vitamin, B12 does not generally accumulate to toxic levels like fat-soluble vitamins A and D. “However, unnecessary high-dose supplementation without medical advice is not recommended,” Dr. Hemalatha says.

Dr. Ghosh agrees. “B12 is generally a safe vitamin, and there is no established upper limit for its intake. But taking unnecessarily high doses does not offer any extra benefit if your levels are already adequate,” she says. “Occasionally, supplements can cause acne-like skin eruptions or allergic reactions.”

As in Mehta’s case, it is important not to mistake a symptom for a diagnosis.

Published on: Sunday, November 15, 2026, 07:25 AM IST