Lactose maldigestion and milk intolerance in healthy Greek schoolchildren.

The prevalence of lactose maldigestion in Greek adults is 75% but the age at which the lactase activity starts declining is not known. The prevalences of lactose maldigestion and intolerance were investigated in 150 randomly selected Greek children 5-12 y old by using breath-hydrogen analysis after ingestion of lactose (2 g/kg body wt, maximum 50 g) or 0.240 L of milk. Prevalence of lactose maldigestion increased with age (y = -7.30 + 6.49x, r = 0.88, P = 0.004), being 29.4% and 80.0% at ages 5 and 12 y, respectively. Before testing, the reported prevalences of milk-related symptoms by children with high and low lactose-digestion capacity were 21.1% and 39.7% (chi 2 = 5.96, P = 0.015), respectively. However, the corresponding prevalences of lactose intolerance after ingestion of milk were 7.3% and 8.6% (chi 2 = 0.1, P = 0.72) and only three children had a delta H2 greater than or equal to 20 ppm postprandially. Although intestinal lactase activity declines before age 5 y and many Greek children report milk-related symptoms, true malabsorption and intolerance of lactose after a glass of milk is rarely seen at this age.