Objective:To investigate glycaemic and satiating properties of potato products in healthy subjects using energy-equivalent or carbohydrate-equivalent test meals, respectively.Subjects and setting:Thirteen healthy subjects volunteered for the first study, and 14 for the second. The tests were performed at Applied Nutrition and Food Chemistry, Lund University, Sweden.Experimental design and test meals:All meals were served as breakfast in random order after an overnight fast. Study 1 included four energy-equivalent (1000 kJ) meals of boiled potatoes, french fries, or mashed potatoes; the latter varying in portion size by use of different amounts of water. The available carbohydrate content varied between 32.5 and 50.3 g/portion. Capillary blood samples were collected during 240 min for analysis of glucose, and satiety was measured with a subjective rating scale. Study 2 included four carbohydrate-equivalent meals (50 g available carbohydrates) of french fries, boiled potatoes served with and without addition of oil, and white wheat bread (reference). The energy content varied between 963 and 1534kJ/portion. Capillary blood samples were collected during 180 min for analysis of glucose, and satiety was measured using a subjective rating scale.Results:Study 1: boiled potatoes induced higher subjective satiety than french fries when compared on an energy-equivalent basis. The french fries elicited the lowest early glycaemic response and was less satiating in the early postprandial phase (area under the curve (AUC) 0-45 min). No differences were found in glycaemic or satiety response between boiled or mashed potatoes. Study 2: french fries resulted in a significantly lower glycaemic response (glycaemic index (GI)=77) than boiled potatoes either with or without addition of oil (GI=131 and 111, respectively). No differences were found in subjective satiety response between the products served on carbohydrate equivalence.Conclusions:Boiled potatoes were more satiating than french fries on an energy-equivalent basis, the effect being most prominent in the early postprandial phase, whereas no difference in satiety could be seen on a carbohydrate-equivalent basis. The lowered GI for french fries, showing a typical prolonged low-GI profile, could not be explained by the fat content per se.Sponsorships:The Swedish Agency for Innovation Systems (Project No P11900-3 A) and Oresund Starch Profiles (OSP).European Journal of Clinical Nutrition advance online publication, 28 February 2007; doi:10.1038/sj.ejcn.1602677.
