Insulin-sensitizing effects of dietary resistant starch and effects on skeletal muscle and adipose tissue metabolism.
BACKGROUND
Resistant starch may modulate insulin sensitivity, although the precise mechanism of this action is unknown.


OBJECTIVE
We studied the effects of resistant starch on insulin sensitivity and tissue metabolism.


METHODS
We used a 4-wk supplementation period with 30 g resistant starch/d, compared with placebo, in 10 healthy subjects and assessed the results by using arteriovenous difference methods.


RESULTS
When assessed by euglycemic-hyperinsulinemic clamp, insulin sensitivity was higher after resistant starch supplementation than after placebo treatment (9.7 and 8.5 x 10(-2) mg glucose x kg(-1) x min(-1) x (mU insulin/L)(-1), respectively; P = 0.03); insulin sensitivity during the meal tolerance test (MTT) was 33% higher (P = 0.05). Forearm muscle glucose clearance during the MTT was also higher after resistant starch supplementation (P = 0.03) despite lower insulin concentrations (P = 0.02); glucose clearance adjusted for insulin was 44% higher. Subcutaneous abdominal adipose tissue nonesterified fatty acid (NEFA; P = 0.02) and glycerol (P = 0.05) release were lower with resistant starch supplementation, although systemic NEFA concentrations were not significantly altered. Short-chain fatty acid concentrations (acetate and propionate) were higher during the MTT (P = 0.05 and 0.01, respectively), as was acetate uptake by adipose tissue (P = 0.03). Fasting plasma ghrelin concentrations were higher with resistant starch supplementation (2769 compared with 2062 pg/mL; P = 0.03), although postprandial suppression (40-44%) did not differ significantly. Measurements of gene expression in adipose tissue and muscle were uninformative, which suggests effects at a metabolic level. The resistant starch supplement was well tolerated.


CONCLUSIONS
These results suggest that dietary supplementation with resistant starch has the potential to improve insulin sensitivity. Further studies in insulin-resistant persons are needed.
Robertson
M Denise
MD
Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom.
Bickerton
Alex S
AS
Dennis
A Louise
AL
Vidal
Hubert
H
Frayn
Keith N
KN
D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D005232:Fatty Acids, Volatile / Q000032:analysis; D005260:Female; D015870:Gene Expression; D054439:Ghrelin; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D036361:Peptide Hormones / Q000097:blood; D019518:Postprandial Period; D016037:Single-Blind Method; D013213:Starch / Q000008:administration & dosage / Q000494:pharmacology*
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D005232:Fatty Acids, Volatile; D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D013213:Starch