Which Vitamins You Are Missing: Signs and What Tests
Reviewed by the LabReadAI medical team
"I'm always tired, my hair is falling out, my nails break — I must be missing some vitamins." The urge to take "something for energy" is understandable, but taking vitamins blindly is pointless and sometimes harmful. Let's break down how to tell which vitamins you are missing: by signs and, above all, by tests — because only blood can truly show a deficiency.
Why "Taking Vitamins Just in Case" Is Not the Best Path
Deficiency signs are non-specific (fatigue can come from iron, B12 or the thyroid), and an excess of some vitamins (A, D in large doses) is harmful. So it is wiser not to guess but to check key markers and replace what is genuinely lacking.
Common Signs of Low Vitamins and Minerals
| Sign | What to check first |
|---|---|
| Fatigue, weakness, pallor | iron/ferritin, B12, vitamin D |
| Hair loss, brittle nails | ferritin, vitamin D, zinc |
| Frequent colds | vitamin D, zinc |
| Numbness, tingling, anaemia | vitamin B12, folate |
| Bone aches, low mood | vitamin D |
| Bleeding gums | vitamin C |
Signs only hint where to look — a test confirms the deficiency.
What Tests to Run for Vitamins and Minerals
A sensible baseline: vitamin D (25-OH), vitamin B12, ferritin (iron stores), folate, and as indicated — zinc, magnesium, a complete blood count. Convenient as one package — the vitamin panel. The most common deficiencies are vitamin D and iron: covered in vitamin D deficiency and iron deficiency anaemia.
The Most Common Deficiencies
- Vitamin D — deficiency is very common, especially in winter; affects bones, immunity, mood.
- Iron/ferritin — a frequent cause of fatigue and hair loss, especially in women.
- B12 and folate — important for blood and the nervous system; B12 deficiency is common in older people and vegans (see vitamin B12 deficiency).
What to Do After the Tests
Replace exactly what is low, in an adequate form and dose, and recheck later. Do not prescribe yourself high doses "by eye": some vitamins are toxic in excess. The dose and form are chosen from the results and your condition.
To understand your tests and which vitamin is actually low, upload the form (PDF or photo) to the vitamin and supplement matching by tests service: the AI will explain the markers and point out what is lacking. This helps but does not replace a doctor.
This article is informational. Prescribing supplements is the doctor's job.
For informational purposes only
This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Please consult a healthcare professional for medical guidance.