Vitamin deficiency blood tests, at home

No fasting required for vitamin D or B12 tests. If you're combining with a lipid profile or fasting sugar, then 8–12 hours of fasting is needed.

Sun exposure (15–20 min daily on bare arms and face), foods like fatty fish, egg yolk, and fortified milk, plus a daily supplement (1000–2000 IU for maintenance, 60,000 IU/week for 6–8 weeks to correct deficiency under medical supervision).

Not without a test. Some vegetarians have surprisingly good B12 levels if they consume dairy, fortified foods or take occasional supplements. A blood test gives certainty. Vegans without supplementation are almost always deficient.

Serum iron fluctuates daily and reflects recent intake. Ferritin reflects your body's iron stores — a much more reliable indicator. Low ferritin with normal haemoglobin means iron deficiency without anaemia, often catching the problem before it gets serious.

Discontinue B12 supplements 24–48 hours before the blood draw — recent doses can temporarily inflate the reading and mask true deficiency. Vitamin D supplements don't affect short-term test accuracy as much.