Fatigue gets all the attention and tells you almost nothing. The symptoms genuinely worth noticing are the ones specific enough to point somewhere.
A sore, smooth tongue
NIH ODS lists glossitis of the tongue among B12 deficiency symptoms. It is far more specific than tiredness, and it is the kind of thing people notice but do not think to mention at an appointment.
The NHS similarly includes a sore and red tongue and mouth ulcers among symptoms of B12 or folate deficiency anaemia.
Numbness and tingling in hands and feet
NIH ODS documents these neurological changes, with an important caveat: they "can occur without anemia, so early diagnosis and intervention is important to avoid irreversible damage." The combination of specificity and potential permanence makes this the symptom least worth waiting out.
Difficulty seeing in low light
NIH ODS identifies night blindness as the first sign of vitamin A deficiency, caused by low rhodopsin levels in the retina. Few other conditions produce exactly this.
Easy bruising and bleeding gums
NIH ODS describes capillary fragility and connective tissue weakness in scurvy — which is what shows up as bruising from minor contact and gums that bleed when brushing.
Why specificity matters more than severity
A mild but specific symptom often carries more diagnostic information than severe fatigue. If you have noticed any of the above, they are worth naming explicitly at an appointment rather than folding into a general description of feeling unwell.
Our free assessment asks about these specific symptoms directly.
References
- NIH ODS — Vitamin B12
- NIH ODS — Vitamin A
- NIH ODS — Vitamin C
- NHS — Vitamin B12 or folate deficiency anaemia
This article summarizes published guidance from the sources linked above. It is general information, not medical advice, and it cannot tell you whether you personally have a deficiency. Only a clinician ordering the right test can do that. If you have symptoms that concern you, speak to a doctor.