Vitamin D deficiency is one of the most common findings in routine blood work in India — and one of the most frequently dismissed.
Patients are told their levels are low, given a supplement, and sent home with no explanation of what low Vitamin D actually does to the body or how long correction takes.
It matters more than most people realise: Vitamin D affects immunity, muscle strength, bone density, mood, energy levels, and how well the thyroid and hormonal system function.
Deficiency in B12 and iron are similarly widespread in the Indian population and similarly underexplained.
This surprises most people. The issue isn't lack of sun — it's lack of the right kind of sun exposure at the right time of day. Most urban Indians spend their daylight hours indoors, in vehicles, or under glass, which blocks UV-B rays (the type responsible for Vitamin D synthesis). Darker skin tones also require longer sun exposure to produce the same amount of Vitamin D as lighter skin. The result is that Vitamin D deficiency is extremely common in India across all age groups, regardless of geography.
Lab reports flag deficiency at different cut-offs depending on the laboratory, which creates a lot of confusion. Most labs mark anything above 20 ng/mL as "sufficient" — but many clinicians now aim for levels above 30 ng/mL rather than just clearing the lab's minimum threshold. If you're experiencing fatigue, muscle weakness, bone pain, or frequent infections and your Vitamin D is in the 20–30 range, it is worth treating even if the report says "normal."
A few possibilities. First, the dose may be insufficient — supplementation requirements vary widely depending on how low your baseline was. Second, Vitamin D works in tandem with other nutrients, particularly Vitamin K2 and magnesium. Third, there may be another deficiency alongside the Vitamin D — B12 deficiency, iron deficiency anaemia, and thyroid dysfunction all cause similar fatigue symptoms and frequently coexist with low Vitamin D. A proper review of all these together is more useful than chasing one number.
Different cause, similar symptoms. B12 deficiency in India is common for two main reasons: vegetarian and vegan diets (B12 is found almost exclusively in animal products), and long-term use of metformin (the most common diabetes medication, which reduces B12 absorption). Symptoms — fatigue, tingling in hands and feet, memory issues, mood changes — often overlap with Vitamin D deficiency, which is why testing for both together makes sense. B12 deficiency, if severe and untreated, can cause nerve damage that isn't always fully reversible, so it's worth catching early.
For Vitamin D, tablets and sachets work well for most people. For Vitamin B12, it depends on the severity and the cause. Patients on metformin or those with absorption issues may do better with injections initially. Your doctor will advise based on your levels, symptoms, and what's driving the deficiency — there's no universal answer.
Not always, but iron deficiency is the most common cause of anaemia in India — particularly in women of reproductive age. Anaemia means your haemoglobin is low; iron deficiency is one reason that happens, but not the only one. B12 deficiency and chronic disease can also cause anaemia with a different mechanism and a different treatment. This is why a proper workup looks at ferritin and B12 alongside haemoglobin — haemoglobin alone doesn't tell you why it's low. Iron supplements taken without knowing the cause, or taken incorrectly, often don't work — absorption is affected by tea, coffee, calcium, and timing relative to meals.
Vitamin D deficiency is frequently found alongside thyroid dysfunction and PCOD in women. [See Thyroid Disorders & Women's Health →]
A comprehensive preventive health checkup is the most reliable way to identify Vitamin D, B12, and other deficiencies before symptoms appear. [See Preventive Health & Lifestyle Disorders →]
Dr. Shalini Joshi, MD (USA) is a Senior Consultant in Internal Medicine at Fortis Hospital, Bannerghatta Road, Bengaluru.
Evening consultations are available at Akshaya Nagar, South Bangalore.
Video consultations are available for patients across India.
Corporate wellness talks available on request.
Specialising in diabetes, obesity, thyroid disorders, and preventive health.