title: A randomised four-intervention crossover study investigating the effect of carbohydrates on daytime profiles of insulin, glucose, non-esterified fatty acids and triacylglycerols in middle-aged men.
abstract: Postprandial concentrations of glucose, insulin and triacylglycerols (TG) correlate to risk for CHD. Carbohydrates affect many metabolites that could have a potential effect on cardiovascular risk factors. The objective of the present study was to examine, using a randomised prospective study, the acute (day 1) and ad libitum medium-term (day 24) effects of four diets: a high-fat diet (HIGH-FAT; 50 % fat, >34 % monounsaturated fatty acids); a low-glycaemic index (GI) diet (LOW-GI; high-carbohydrate, low-GI); a high-sucrose diet (SUCROSE; high carbohydrate increase of 90 g sucrose/d); a high-GI diet (HIGH-GI; high-carbohydrate, high-GI). Daytime profiles (8 h) (breakfast, lunch and tea) of lipid and carbohydrate metabolism were completed during day 1 and day 24. Seventeen middle-aged men with one or more cardiac risk factors completed the study. There was no change from day 1 or between diets in fasting glucose, lipids or homeostatic assessment model (HOMA) on day 24. The HIGH-FAT compared with the three high-carbohydrate diets was associated with lower postprandial insulin and glucose but higher postprandial TG and non-esterified fatty acids (NEFA). There was a significant increase in the 6 h (15.00 hours) TG concentration (day 1, 2.6 (sem 0.3) mmol/l v. day 24, 3.3 (sem 0.3) mmol/l; P<0.01) on the SUCROSE diet. Postprandial HOMA (i.e. incremental area under the curve (IAUC) glucose (mmol/l per min)xIAUC insulin/22.5 (mU/l per min)) median changes from day 1 to day 24 were -61, -43, -20 and +31 % for the HIGH-FAT, LOW-GI, SUCROSE and HIGH-GI diets respectively. The HIGH-GI percentage change was significantly different from the other three diets (P<0.001). Despite being advised to maintain an identical energy intake there was a significant weight change (-0.27 (sem 0.3) kg; P<0.02) on the LOW-GI diet compared with the SUCROSE diet (+0.84 (sem 0.3) kg). In conclusion the HIGH-FAT diet had a beneficial effect on postprandial glucose and insulin over time but it was associated with higher postprandial concentrations of TG and NEFA. Conversely the HIGH-GI diet appeared to increase postprandial insulin resistance over the study period.
authors.affiliation: Nutrition and Dietetic Research Group, Hammersmith Hospital, Du Cane Road, London W12 0HS, UK.
authors.forename: Audrey E
authors.initials: AE
authors.lastname: Brynes
authors.forename: C
authors.initials: C
authors.lastname: Mark Edwards
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Ghatei
authors.forename: Anne
authors.initials: A
authors.lastname: Dornhorst
authors.forename: Linda M
authors.initials: LM
authors.lastname: Morgan
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Bloom
authors.forename: Gary S
authors.initials: GS
authors.lastname: Frost
mesh_terms: D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D014280:Triglycerides / Q000097:blood*
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides