TOLERANCE TO THE DAILY INGESTION OF 2 CUPS OF MILK BY INDIVIDUALS CLAIMING LACTOSE-INTOLERANCE

We reported previously that consumption of one cup of milk (240 mL) pe r day produced negligible symptoms in lactase-nonpersistent (LNP) indi viduals self-described as being severely lactose intolerant. We hypoth esized that such LNP individuals could also tolerate two cups of milk per day if taken in two widely divided doses with food, and that psych ologic factors play a role in perceptions of lactose intolerance. The Minnesota Multiphasic Personality Inventory 2 (MMPI-2) was administere d to 19 LNP subjects self-described as markedly lactose intolerant (S- LNP), 13 LNP subjects who denied lactose intolerance (A-LNP), and 10 l actase-persistent individuals who believed they were lactose intoleran t (S-LP). Symptoms were recorded when LNP subjects ingested 240 mL reg ular or lactose-hydrolyzed milk twice daily for 7 d in a double-blind crossover study. The results showed that neither LNP group had a signi ficant increase in symptoms (P < 0.05) during the regular compared wit h the lactose-hydrolyzed milk periods. However, S-LNP subjects reporte d significantly greater gaseous symptoms than did the A-LNP subjects d uring both treatment periods. The MMPI-2 showed a high score on the '' lie'' validity scale for S-LNP subjects. We conclude that LNP subjects tolerate two cups of milk per day without appreciable symptoms. S-LNP subjects have underlying flatulence that is misattributed to lactose intolerance. MMPI-2 results were of questionable validity because of t he high rate of dissimulation by LNP subjects.