Short-term administration of dark chocolate is followed by a significant increase in insulin sensitivity and a decrease in blood pressure in healthy persons.
BACKGROUND
Numerous studies indicate that flavanols may exert significant vascular protection because of their antioxidant properties and increased nitric oxide bioavailability. In turn, nitric oxide bioavailability deeply influences insulin-stimulated glucose uptake and vascular tone. Thus, flavanols may also exert positive metabolic and pressor effects.


OBJECTIVE
The objective was to compare the effects of either dark or white chocolate bars on blood pressure and glucose and insulin responses to an oral-glucose-tolerance test in healthy subjects.


METHODS
After a 7-d cocoa-free run-in phase, 15 healthy subjects were randomly assigned to receive for 15 d either 100 g dark chocolate bars, which contained approximately 500 mg polyphenols, or 90 g white chocolate bars, which presumably contained no polyphenols. Successively, subjects entered a further cocoa-free washout phase of 7 d and then were crossed over to the other condition. Oral-glucose-tolerance tests were performed at the end of each period to calculate the homeostasis model assessment of insulin resistance (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI); blood pressure was measured daily.


RESULTS
HOMA-IR was significantly lower after dark than after white chocolate ingestion (0.94 +/- 0.42 compared with 1.72 +/- 0.62; P < 0.001), and QUICKI was significantly higher after dark than after white chocolate ingestion (0.398 +/- 0.039 compared with 0356 +/- 0.023; P = 0.001). Although within normal values, systolic blood pressure was lower after dark than after white chocolate ingestion (107.5 +/- 8.6 compared with 113.9 +/- 8.4 mm Hg; P < 0.05).


CONCLUSIONS
Dark, but not white, chocolate decreases blood pressure and improves insulin sensitivity in healthy persons.
Grassi
Davide
D
Department of Internal Medicine and Public Health, University of L'Aquila, L'Aquila, Italy.
Lippi
Cristina
C
Necozione
Stefano
S
Desideri
Giovambattista
G
Ferri
Claudio
C
D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects*; D002099:Cacao / Q000737:chemistry*; D002182:Candy; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D005419:Flavonoids / Q000008:administration & dosage* / Q000494:pharmacology; D044948:Flavonols / Q000008:administration & dosage / Q000494:pharmacology; D005951:Glucose Tolerance Test; D006706:Homeostasis; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D008297:Male; D010636:Phenols / Q000008:administration & dosage* / Q000494:pharmacology; D059808:Polyphenols
D001786:Blood Glucose; D005419:Flavonoids; D044948:Flavonols; D007328:Insulin; D010636:Phenols; D059808:Polyphenols