Replacing white rice bars with peanuts as snacks in the habitual diet improves metabolic syndrome risk among Chinese adults: a randomized controlled trial

Background: Observational studies have suggested that intake of nuts is associated with lower risk of cardiometabolic diseases, whereas refined grain consumption has been linked to higher risk. Little is known about whether substituting white rice, a refined grain, with nuts may confer benefit among adults at high risk of cardiometabolic diseases. Objectives: We aimed to evaluate isocaloric substitution of peanuts for white rice bars as snacks on changes in fasting glucose, lipid profile, body weight, as well as changes in metabolic syndrome (MetS) status among participants with MetS or at risk of MetS. Methods: This parallel-arm randomized controlled trial included 224 participants either with MetS (according to the International Diabetes Federation criteria for Chinese adults, n = 163) or at risk of MetS (central obesity plus 1 additional MetS risk factor, n = 61). Participants were randomly assigned to either the peanut arm (56 g/d as snacks, n = 113) or the control arm (isocaloric white rice bars, n= 111) for 12 wk. Results: A total of 209 participants (93.3%) completed the 12-wk intervention with a compliance rate > 85% among all participants. No between-group differences were found for improvements in fasting glucose, HDL cholesterol, waist circumference, and body weight. Participants in the peanut group had a significantly higher MetS reversion rate (no longer meeting MetS criteria after the 12-wk trial) than those in the control group (RR: 2.33; 95% CI: 1.10, 4.89; P = 0.026). Conclusions: Including peanuts as a snack in the habitual diet in place of a refined-grain snack did not significantly change glycemic or lipid parameters, but improved overall MetS risk without promoting weight gain among Chinese adults at high risk of cardiometabolic diseases. Further larger-scale trials are needed to confirm these findings and elucidate underlying biological mechanisms.