Difficulty digesting maltose, the disaccharide sugar composed of two glucose units, effectively a form of disaccharide intolerance. It results from deficiency of the intestinal enzyme maltase-glucoamylase, which normally splits maltose during digestion. Undigested maltose passes to the colon, where bacteria ferment it, causing bloating, gas, abdominal pain, and diarrhoea after eating malt-containing foods such as beer, malted cereals, and some confectionery. Congenital deficiency is rare; more often, low enzyme activity accompanies general gut disorders. Diagnosis uses breath tests or dietary challenge, and management involves limiting maltose-rich foods while ensuring the overall diet remains balanced and enjoyable.