Lactose Intolerance

Lactose intolerance occurs when the body does not produce enough lactase, the enzyme needed to break down lactose, the natural sugar found in milk and dairy products, in the small intestine. Undigested lactose passes into the colon, where it is fermented by gut bacteria, producing gas and drawing water into the bowel, which causes the characteristic digestive symptoms. Lactase production naturally declines after infancy in most of the world's population, and this decline is especially common among people of African, Asian, and Hispanic descent, meaning a large proportion of Nigerian adults have some degree of lactose intolerance, even though it may go unrecognised as the specific cause of their digestive symptoms. It is distinct from a milk protein allergy, which involves the immune system and can be far more serious.

Symptoms typically appear 30 minutes to two hours after consuming lactose-containing foods, and severity depends on how much lactase is deficient and how much lactose is consumed: • Bloating and abdominal distension • Abdominal cramping or pain • Gas (flatulence) • Diarrhoea, often watery • Nausea, occasionally with vomiting, particularly after large amounts of dairy Symptoms are generally dose-dependent: small amounts of dairy may be tolerated without issue, while larger amounts trigger noticeable symptoms.

Lactose intolerance results from insufficient lactase enzyme production in the small intestine. The most common form, primary lactose intolerance, is a natural, genetically programmed decline in lactase production after infancy, common in most of the world's population outside regions with a long history of dairy farming. Secondary lactose intolerance can develop temporarily after an intestinal infection, injury, or surgery that damages the lining of the small intestine, and usually improves once the underlying gut lining heals.

• African, Asian, or Hispanic ancestry, where the genetic decline in lactase production after infancy is most common • Premature birth, since lactase levels rise late in pregnancy • Increasing age, as lactase levels continue to decline over the lifespan in genetically predisposed individuals • Conditions that damage the small intestine, such as coeliac disease, Crohn's disease, or a recent gastrointestinal infection (for secondary lactose intolerance)

• Chronic digestive discomfort if the diagnosis is unrecognised and dairy intake continues unmanaged • Reduced calcium and vitamin D intake if dairy is avoided entirely without adequate substitution, which can affect bone health over time • Unnecessary dietary restriction or missed diagnosis if symptoms are mistaken for other gastrointestinal conditions such as irritable bowel syndrome

Lactose intolerance itself, when due to the natural genetic decline in lactase, cannot be prevented, but symptoms are very manageable: • Limit or space out dairy intake to amounts your body tolerates, rather than eliminating it entirely, since many people can tolerate small amounts • Choose lower-lactose dairy products, such as hard cheeses and yoghurt, which contain less lactose than milk • Lactase enzyme supplements, taken before consuming dairy, can prevent symptoms • Lactose-free milk and dairy alternatives provide nutritional substitutes without triggering symptoms • If avoiding dairy significantly, ensure adequate calcium and vitamin D intake through other foods or supplementation