Do calories, osmolality, or calcium determine gastric emptying?

To determine whether calories, osmolality, or calcium mediate gastric emptying we employed a standardized radioactive meal in 10 normal human volunteers. A variety of simple and complex sugars, medium-chain fatty acid (MCFA), pectin, and gluten were dissolved in water and ingested with the test meal. The studies were also performed with calcium chloride, EDTA, and an equimolar combination of these chemicals. Results of gastric emptying showed that incremental glucose produced an increase in emptying time with a tendency for emptying time to show a proportionally greater delay with increasing glucose concentrations. Fructose and polyhexose had similar effects to glucose. Pentoses (xylose and arabanose) markedly prolonged gastric emptying when compared with the same amount of glucose. The effect of sucrose and gluten on gastric emptying did not significantly differ from controls. Twenty-five grams MCFA had an effect similar to 50 g glucose. Pectin, a complex carbohydrate, produced a varied effect in different individuals. There was no obvious relationship between osmolality and gastric emptying. Calcium chloride and EDTA prolonged gastric emptying, but the equimolar combination gave values similar to controls. Our findings suggest 1) calories nor osmolality alone determine gastric emptying, 2) both calcium and calcium chelation with EDTA prolong gastric emptying, and 3) a specific food does not necessarily produce the same effect on gastric emptying in different individuals.