RAISING MILK ENERGY CONTENT RETARDS GASTRIC-EMPTYING OF LACTOSE IN LACTOSE-INTOLERANT HUMANS WITH LITTLE EFFECT ON LACTOSE DIGESTION

Lactose digestion improves when the energy content of a meal is raised , perhaps due to delayed gastric emptying; however, this has not been demonstrated directly. It is not known whether lactose-intolerant subj ects should consume full-fat or high energy milk instead of half-skimm ed milk. In this study, breath (CO2)-C-13 and hydrogen (H-2) measureme nts were combined to assess simultaneously the effect of increasing mi lk energy content on gastric emptying, digestion, and tolerance of lac tose. On two separate days, 11 adult lactose maldigesters ingested, in the fasting state, a single dose of 710 kJ half-skimmed milk or 1970 kJ high energy milk. Both contained 18 g lactose and were supplemented with 100 mg C-13-glycine for breath (CO2)-C-13 measurement. For 6 h a fter milk ingestion, samples of expired breath were collected, and sub jects scored their symptoms on a four-grade questionnaire. Gastric emp tying was measured from excretion of breath (CO2)-C-13. The mean gastr ic emptying half-time was significantly longer after ingestion of high energy milk than after half-skimmed milk (84 +/- 4 vs. 64 +/- 4 min, P = 0.004). The mean area under the breath H-2 excretion curve measure d for 6 h was 330 +/- 61 mu L/L after subjects consumed high energy mi lk vs. 470 +/- 82 mu L/L after they consumed half-skimmed milk (P = 0. 07). Mean symptom scores did not differ after ingestion of the two mil ks, but only two subjects experienced disturbing symptoms after high e nergy milk ingestion compared with five subjects after ingestion of ha lf-skimmed milk (P = 0.56). Although ingestion of high energy milk del ayed the gastric emptying of lactose for significantly longer than the ingestion of half-skimmed milk (P < 0.01), it did not lead to signifi cant improvement in symptoms and reflected only a trend toward improve d lactose digestion (P = 0.07), as measured by the area under the brea th H-2 excretion curve. These results indicate that it is not benefici al for most lactose-intolerant subjects to replace consumption of half -skimmed milk by milk with a higher energy content.