Effects of short-term low- and high-carbohydrate diets on postprandial metabolism in non-diabetic and diabetic subjects.
OBJECTIVE
Low-fat high-carbohydrate diets raise plasma triacylglycerol (TG) concentrations. To test whether the nature of the carbohydrate affects metabolic responses, we conducted a randomized cross-over study using a short-term, intensive dietary modification.


RESULTS
Eight non-diabetic subjects and four subjects with diet-controlled type 2 diabetes participated. They followed three isoenergetic diets, each for 3 days: high-fat (50% energy from fat), high-starch and high-sugar (each 70% energy from carbohydrate). Normal foods were provided. We measured plasma TG and glucose concentrations, fasting and after a standard test meal, on day 4 following each dietary period. Fasting TG concentrations were greatest following the high-sugar diet (mean+/-SEM for all subjects 1900+/-420micromol/l) and lowest following high-fat (1010+/-130micromol/l) (P=0.001); high-starch (mean 1500+/-310) and high-fat did not differ significantly (P=0.06). There was a greater effect in the diabetic subjects (diet x diabetes status interaction, P=0.008). Postprandial TG concentrations were similarly affected by prior diet (P<0.001) with each diet different from the others (P<or=0.01). The elevation of fasting TG on the high-sugar versus high-fat diet was strongly related to the average fasting TG concentration (P=0.01 across both diabetic and non-diabetic subjects). Fasting glucose concentrations were not affected by prior diet but postprandial glucose concentrations were (P=0.018), with significantly higher values after the high-fat than the high-sugar diet (P=0.03).


CONCLUSIONS
The short-term TG-raising effect of a very low-fat diet is dependent upon the nature of the carbohydrate, with a greater effect of a sugar-rich than a complex-carbohydrate-rich diet.
Culling
K S
KS
Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK.
Neil
H A W
HA
Gilbert
M
M
Frayn
K N
KN
D000328:Adult; D001786:Blood Glucose / Q000032:analysis / Q000378:metabolism*; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000178:diet therapy*; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000145:classification / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D019422:Dietary Sucrose / Q000008:administration & dosage / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005215:Fasting / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D013213:Starch / Q000008:administration & dosage / Q000378:metabolism; D014280:Triglycerides / Q000097:blood*; D055815:Young Adult
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D019422:Dietary Sucrose; D014280:Triglycerides; D013213:Starch