Effects of Carbohydrate Meals of Varying Consistency on Gastric Myoelectrical Activity

TGHC Ferdinandis, AS Dissanayake, HJ De Silva
Correspondence: Dr T G H C, himanif@hotmail.com

ABSTRACT
Background There is at present no agreement on the type of test meal to be used when performing EGG. To our knowledge the response of the stomach to high carbohydrate isocaloric meals of different consistencies has not been formally assessed.
Aim To study 1) the effects of high carbohydrate meals of varying consistency on EGG activity; and 2) the effects of increasing the calorie content of a meal without changing its consistency and composition on the postprandial EGG.
Subjects Eighteen healthy volunteers, six males (age: 21-35 year, weight: 45-60 kg) and 12 females in the follicular phase of the menstrual cycle (age: 24-30 years, weight: 45-55 kg).
Methods Following an overnight fast subjects were given three high carbohydrate, low fat, isocaloric meals (165-170 kcal) of different consistencies (solid, semisolid, liquid), on three separate days in a random order. The liquid and semisolid meals were equal in volume (200 ml) while the volume of the solid meal was smaller. One hour EGG recordings were done in the fasting and fed states in each subject. As a second step, ten of the above volunteers (taken randomly) were given the solid test meal on a separate day after increasing the calorie content of the meal to 350 kcal.
Results The power of the EGG at the dominant frequency significantly increased after solid (175 kcal meal: fasting 49 +/- 12 dB vs. fed 57 +/- 13 dB; p < 0.05, 375 kcal meal: fasting 48.5 +/- 12.9 dB vs fed 58.1 +/- 11.7 dB) and semisolid (fasting 50 +/- 12 dB vs. fed 55 +/- 13; P < 0.05). The increase in power was not significantly different when fed with solids and semisolids. There was no statistically significant change in EGG power during the first 15 or 60 minutes after the liquid meal. Feeding showed no significant effect on the dominant frequency and the percentage of 2-4 cpm waves of the EGG with any of the three types of test meals.
Conclusion Solid and semisolid meals high in carbohydrate and low in fat are capable of inducing a significant increase in the EGG power in normal subjects. Isocaloric solid and semisolid meals have similar effects on gastric slow wave activity. EGG appears unaffected by the liquid meal. Therefore only an increase in the power of the EGG can be regarded as normal if a high carbohydrate solid or a semisolid meal is given as the test meal when performing an EGG.

Keywords: Electrogastrography, test meal consistency, gastric myoelectrical activity
Singapore Med J 2002; 43(11): 579-582