Purpose The purpose of the present study is to evaluate chocolate consumption effects with a non invasive metodology. There is evidence that the consumption of dark chocolate and cocoa with high flavonoid content could have positive effects on blood pressure (BP) and weight management (WM); however, there are complications at the moment of obtaining blood samples to evaluate on children at a primary school level. Design/methodology/approach A total of 54 healthy scholars were included; consumption of 70 per cent cacao dark chocolate was integrated into the daily snack during a 30-day period. Blood pressure, body fat, total content of polyphenols in urine and total antioxidant capacity of saliva were measured. The results obtained were divided in relation of two groups of students, A and B, with lesser or higher difficulties to WM in a self-assessment test; variables were then statistically evaluated. Findings Consumption of chocolate produced changes in the total content of polyphenols (from 5.6 to 6.8 µg/mL, p < 0.016) and salivary antioxidant capacity [(14.76 ± 5.4 and 16.14 ± 3.9) TEU nmol versus. t = 0; p < 0.029 and p < 0.001 at 15 and 30 days, respectively]. Group B, which presented higher difficulties concerning WM, presented a body fat reduction of about 0.63 per cent after chocolate consumption (p = 0.045) and a diastolic blood pressure reduction of −2.8 mm Hg in average (p < 0.025). A significant weight gain (p < 0.023) was observed only in Group A. Research limitations/implications Despite the reduced sensitivity of the non-invasive methodology, differences in urine and salivary content of polyphenols and antioxidant capacity suggest that the design used could be feasible, although extended studies are needed to corroborate it. Originality/value A non-invasive study for screening the potential health benefits of dark chocolate was assayed. The results suggest that dark chocolate consumption in children as part of the daily snack could be a complementary element in weight management and in prevention of future risk factors to chronic diseases.