The impact of pistachio intake alone or in combination with high-carbohydrate foods on post-prandial glycemia

Background/Objectives: Dietary strategies that reduce post-prandial glycemia are important in the prevention and treatment of diabetes and coronary heart disease (CHD). This may be achieved by addition of high-quality protein and fat contained in pistachio nuts, to carbohydrate-containing foods or meals. Subjects/Methods: A total of 10 healthy volunteers (3 males, 7 females); aged 48.3 +/- 6.4 years; Body mass index (BMI) 28.0 +/- 4.8 kg/m(2) participated in two studies. Study 1 assessed the dose-response effect of 28, 56 and 84 g pistachios consumed alone or co-ingested with white bread (50 g available carbohydrate); Study 2 assessed the effective dose (56 g) of pistachios on post-prandial glycemia consumed with different commonly consumed carbohydrate foods (50 g available carbohydrate). Relative glycemic responses (RGRs) of study meals compared with white bread, were assessed over the 2 h post-prandial period. Results: The RGRs of pistachios consumed alone expressed as a percentage of white bread (100%) were: 28 g (5.7 +/- 1.8%); 56 g (3.8 +/- 1.8%); 84 g (9.3 +/- 3.2%), P<0.001. Adding pistachios to white bread resulted in a dose-dependent reduction in the RGR of the composite meal; 28 g (89.1 +/- 6.0, P = 0.100); 56 g (67.3 +/- 9.8, P = 0.009); 84 g (51.5 +/- 7.5, P<0.001). Addition of 56 g pistachios to carbohydrate foods significantly reduced the RGR: parboiled rice (72.5 +/- 6.0) versus rice and pistachios (58.7 +/- 5.1) (P = 0.031); pasta (94.8 +/- 11.4) versus pasta and pistachios (56.4 +/- 5.0) (P = 0.025); whereas for mashed potatoes (109.0 +/- 6.6) versus potatoes and pistachios, (87.4 +/- 8.0) (P = 0.063) the results approached significance. Conclusions: Pistachios consumed alone had a minimal effect on post-prandial glycemia and when taken with a carbohydrate meal attenuated the RGR. The beneficial effects of pistachios on post-prandial glycemia could, therefore, be part of the mechanism by which nuts reduce the risk of diabetes and CHD. European Journal of Clinical Nutrition (2011) 65, 696-702; doi:10.1038/ejcn.2011.12; published online 2 March 2011