Malabsorption

Malabsorption occurs when the gut fails to absorb nutrients properly — from coeliac disease, pancreatic insufficiency, inflammatory bowel disease, small intestinal bacterial overgrowth (SIBO), or bariatric surgery. Hallmark signs are unintentional weight loss despite eating, pale greasy stools that float, bloating, and deficiency symptoms like fatigue (iron, B12) or easy bruising (vitamin K). Treatment targets the underlying cause: a strict gluten-free diet for coeliac, enzyme replacement for pancreatic insufficiency. Supplements correct deficiencies but do not fix absorption itself, and self-diagnosing risks missing coeliac disease, which must be tested before removing gluten.

Evidence synthesis: Malabsorption is a consequence of underlying pathology rather than a disease itself, so supplementation evidence is condition-specific. Vitamin B12 deficiency is well documented after gastric surgery and in pancreatic disease, where oral or intramuscular replacement effectively restores levels. Fat-soluble vitamin (A, D, E, K) deficiency occurs in any cause of steatorrhoea. Iron deficiency is common in coeliac disease even without anaemia. The evidence strongly supports targeted replacement based on measured deficiencies rather than blind supplementation, and equally strongly supports treating the root cause - enzyme replacement for pancreatic insufficiency, gluten elimination for coeliac disease, antibiotics for SIBO.