Polyphenol-rich curry made with mixed spices and vegetables benefits glucose homeostasis in Chinese males (Polyspice Study): a dose-response randomized controlled crossover trial

PurposeTo investigate acute effects of two doses of a polyphenol-rich curry made with seven different spices and four base vegetables, eaten with white rice, on 24h glucose response, postprandial insulinemia, triglyceridemia and 24h urinary total polyphenol excretion (TPE).MethodsRandomized, controlled, dose-response crossover trial in healthy, Chinese men [n=20, meanstandard deviation (SD) age 23.72.30years, BMI 23.0 +/- 2.31kg/m(2)] who consumed test meals matched for calories, macronutrients and total vegetables content, consisting either Dose 0 Control (D0C) or Dose 1 Curry (D1C) or Dose 2 Curry (D2C) meal. 24h glucose concentration was measured using continuous glucose monitoring (CGM), together with postprandial plasma insulin and triglyceride for up to 7h. Total polyphenol content (TPC) of test meals and urinary TPE were measured using the Folin-Ciocalteu assay.ResultsTPC for D0C, D1C and D2C were 130 +/- 18, 556 +/- 19.7 and 1113 +/- 211.6mg gallic acid equivalent (GAE) per portion served, respectively (p<0.0001). Compared with D0C meal, we found significant linear dose-response reductions in the 3-h postprandial incremental AUC (iAUC) for CGM glucose of 19% and 32% during D1C and D2C meals respectively (p<0.05) and non-significant linear dose response reductions in iAUC of insulin (p=0.089). Notably, we found significant dose-dependent increases in postprandial triglyceride with increasing curry doses (p<0.01). Significant increases in TPE with increasing curry doses were also observed (p<0.01).ConclusionPolyphenol-rich curry intake can improve postprandial glucose homeostasis. The longer term effects remain to be established.