Fatigue is most commonly linked to iron deficiency because iron is essential for hemoglobin and oxygen delivery. When iron stores fall, reduced oxygen transport can cause easy tiredness, shortness of breath on exertion, and palpitations. But fatigue is not exclusive to iron. Magnesium supports energy metabolism and neuromuscular function, and low intake may contribute to weakness over time. Electrolyte disturbances (potassium/sodium) can also produce generalized weakness—especially with sweating, diarrhea, or diuretic use. Zinc deficiency may indirectly affect vitality via appetite, immunity, and recovery. Clinically, a broader work-up is often more useful than chasing a single mineral: CBC, iron studies, basic electrolytes, and—when indicated—thyroid and B-vitamins.\n\nSource note: NIH ODS fact sheets on iron and magnesium (functions and deficiency symptoms).