Symptoms related to LI appear 30 min to 2 h after consumption
of food products containing lactose. Related symptoms include
bloating, cramping, flatulence and loose stool and some reports
also suggest that they lead to irritability bowel syndrome
(Joachim 1999; Vesa et al. 2000). The rate of LI varies in the
population and the rate of incidence of LI in different ethnic
races worldwide is provided in Table 1 (Scrimshaw and Murray
1988; de Vrese et al. 2001).