The glycaemic index values of foods containing fructose are affected by metabolic differences between subjects.
OBJECTIVE
Glycaemic responses are influenced by carbohydrate absorption rate, type of monosaccharide absorbed and the presence of fat; the effect of some of these factors may be modulated by metabolic differences between subjects. We hypothesized that glycaemic index (GI) values are affected by the metabolic differences between subjects for foods containing fructose or fat, but not for starchy foods.


METHODS
The GI values of white bread (WB), fruit leather (FL) and chocolate-chip cookies (CCC) (representing starch, fructose and fat, respectively) were determined in subjects (n=77) recruited to represent all 16 possible combinations of age (< or =40, >40 years), sex (male, female), ethnicity (Caucasian, non-Caucasian) and body mass index (BMI) (< or =25, >25 kg/m2) using glucose as the reference. At screening, fasting insulin, lipids, c-reactive protein (CRP), aspartate transaminase (AST) and waist circumference (WC) were measured.


RESULTS
There were no significant main effects of age, sex, BMI or ethnicity on GI, but there were several food x subject-factor interactions. Different factors affected each food's area under the curve (AUC) and GI. The AUC after oral glucose was related to ethnicity, age and triglycerides (r 2=0.27); after WB to ethnicity, age, triglycerides, sex and CRP (r 2=0.43); after CCC to age and weight (r 2=0.18); and after FL to age and CRP (r 2=0.12). GI of WB was related to ethnicity (r 2=0.12) and of FL to AST, insulin and WC (r 2=0.23); but there were no significant correlations for CCC.


CONCLUSIONS
The GI values of foods containing fructose might be influenced by metabolic differences between -subjects, whereas the GI of starchy foods might be affected by ethnicity. However, the proportion of variation explained by subject factors is small.
Wolever
T M S
TM
Glycemic Index Laboratories, Inc., Toronto, Ontario, Canada. thomas.wolever@utoronto.ca
Jenkins
A L
AL
Vuksan
V
V
Campbell
J
J
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D019540:Area Under Curve; D001219:Aspartate Aminotransferases / Q000097:blood; D001835:Body Weight / Q000502:physiology; D001939:Bread; D002097:C-Reactive Protein / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism*; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism*; D005006:Ethnicity; D005260:Female; D005632:Fructose / Q000008:administration & dosage; D005947:Glucose / Q000008:administration & dosage; D038321:Glycemic Index / Q000208:ethnology / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D013213:Starch / Q000008:administration & dosage; D014280:Triglycerides / Q000097:blood; D055815:Young Adult
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D007328:Insulin; D014280:Triglycerides; D005632:Fructose; D013213:Starch; D002097:C-Reactive Protein; D001219:Aspartate Aminotransferases; D005947:Glucose