Helena Elmståhl

A Low Glycemic Index Diet Does Not Affect Postprandial Energy Metabolism but Decreases Postprandial Insulinemia and Increases Fullness Ratings in Healthy Women

At present, it is difficult to determine whether glycemic index (GI) is an important tool in the prevention of lifestyle diseases, and long-term studies investigating GI with diets matched in macronutrient composition, fiber content, energy content, and energy density are still scarce. We investigated the effects of 2 high-carbohydrate (55%) diets with low GI (LGI; 79) or high GI (HGI; 103) on postprandial blood profile, subjective appetite sensations, energy expenditure (EE), substrate oxidation rates, and ad libitum energy intake (EI) from a corresponding test meal (LGI or HGI) after consuming the diets ad libitum for 10 wk. Two groups of a total of 29 healthy, overweight women (age: 30.5 ± 6.6 y; BMI: 27.6 ± 1.5 kg/m(2)) participated in the 10-wk intervention and a subsequent 4-h meal test. The breakfast test meals differed in GI but were equal in total energy, macronutrient composition, fiber content, and energy density. The LGI meal resulted in lower plasma glucose, serum insulin, and plasma glucagon-like peptide (GLP)-1 and higher plasma glucose-dependent insulinotropic polypeptide concentrations than the HGI meal (P ≤ 0.05). Ratings of fullness were slightly higher and the desire to eat something fatty was lower after the test meal in the LGI group (P < 0.05). Postprandial plasma GLP-2, plasma glucagon, serum leptin, plasma ghrelin, EE, substrate oxidation rates, and ad libitum EI at lunch did not differ between groups. In conclusion, postprandial glycemia, insulinemia, and subjective appetite ratings after a test meal were better after 10-wk ad libitum intake of a LGI compared to a HGI diet. EE and substrate oxidation rates were, however, not affected. These findings give some support to recommendations to consume a LGI diet.

Glucose and insulin responses to porridge and gruel meals intended for infants

Objective:The objective was to determine the glycaemic index (GI) and insulinaemic index (II) of some common products intended for infants; that is, three commercial porridges and one gruel. Also, the influence of added fruit components to porridge on postprandial metabolic responses was studied by comparing corresponding data with a matched model product without fruit.Design:The volunteers were served the test products in random order following an overnight fast. A white bread was included as a reference product. Capillary blood samples were collected before and during 3 h after the meals.Setting:The study was performed at the Department of Applied Nutrition and Food Chemistry, Lund University, Sweden.Subjects:A total of 10 healthy volunteers, six men and four women, aged 24–41 y, with normal body mass indices, were recruited.Results:The GIs (67–75) of the commercial porridges and gruel were significantly lower than for the white bread reference (P<0.05). In contrast, the GI (79) of the model product (porridge without fruit) could not be distinguished from the reference. The IIs (112–149) for the commercial products and model products, respectively, were not significantly different from the reference.Conclusions:The commercial porridges and gruel gave unexpectedly low GIs. In contrast, high IIs were noted. The inconsistency between GI and II could probably be explained by the insulinotrophic effect of the milk component in the products. The fruit and fruit juice added to some of the products had only minor effect on postprandial glycaemia.Sponsorship:The Swedish Council for Forestry and Agricultural Research.