Lactose intolerance is a clinical condition characterised by the presence of gastrointestinal signs and symptoms secondary to consumption of food substances containing lactose. It is the deficiency of lactase due to primary or econdary causes that is associated with presence of GI symptoms. Lactase deficiency results in increased osmotic load which increases the intestinal water content. Also, lactose is readily fermented by the colonic microbiome leading to production of short chain fatty acids and gas [mainly hydrogen (H2), carbon dioxide (CO2), and methane (CH4)] causing the clinical syndrome of abdominal cramps, bloating, diarrhoea, and flatulence (Figure 1).