Vitamin Deficiencies and Chronic Fatigue: The Tests Worth Doing

Nutrition 2026-06-05 5 min read Medically reviewed by The Cure Cabin doctors

A tired man resting his head in his hands — Persistent, unexplained fatigue can signal an underlying deficiency.

"I sleep enough but I'm always tired." It's one of the most common complaints in any clinic — and one of the most under-investigated. Before fatigue is attributed to stress or a busy life, three deficiencies epidemic in India deserve a blood test: vitamin D, vitamin B12 and iron.

Vitamin D — the sunshine paradox

Despite abundant sun, an estimated 70–90% of urban Indians are deficient — indoor lives, pollution and darker skin (which needs longer sun exposure) all contribute. Beyond fatigue, low D causes muscle aches, low mood, frequent infections and bone pain. Test 25-OH vitamin D; deficiency needs proper prescribed dosing followed by a maintenance plan, not an occasional random sachet.

Fresh vegetables — Vegetables, eggs and dairy help correct the most common deficiencies.

Vitamin B12 — the vegetarian blind spot

B12 comes almost entirely from animal foods, making deficiency very common in vegetarians — and in anyone on long-term acidity medication or metformin, which reduce absorption. Symptoms build slowly: fatigue, brain fog, low mood, and eventually tingling or numbness in hands and feet (a sign it's affecting nerves — don't wait for this). Dairy helps but often isn't enough; supplementation is cheap, safe and effective.

Iron — especially for women

More than half of Indian women are anemic, largely from iron deficiency — menstrual losses plus low dietary iron absorption. Fatigue, breathlessness on stairs, hair fall, brittle nails, cold hands and craving ice are classic. Test hemoglobin plus ferritin (iron stores) — ferritin can be low, causing symptoms, before hemoglobin drops. Pair iron-rich foods with vitamin C, and keep tea/coffee an hour away from iron-rich meals — tannins block absorption.

Test, don't guess

Multivitamins bought blind are the wrong answer: they under-dose what you're deficient in and waste money on what you're not. The right sequence is simple — test the specific markers, correct with proper therapeutic dosing, re-test in 3 months, then maintain. If levels are corrected and fatigue persists, that's genuinely useful information too: it points the investigation toward thyroid, sleep quality, blood sugar or mood — each fixable once found.

This article is for education, not medical advice. For diagnosis and treatment personalized to you, consult a qualified doctor.