Hypertension is one of the leading causes of morbidity and mortality in Brazil. Diet may play an important role in reducing blood pressure (BP), as has been shown for diets high in fruits, vegetables and low-fat dairy products and low in salt (Dietary Approaches to Stop Hypertension (DASH)-Na). A low-glycaemic index Brazilian diet combined with the principles of the DASH-Na diet was evaluated in a randomised study of 206 individuals who were followed for 6 months. In the control group (CG), counselling was based on standard care and mainly focused on salt intake reduction. An intention-to-treat analysis showed that, after 6 months, systolic BP was reduced by 14·4 mmHg and diastolic BP by 9·7 mmHg in the experimental group (EG), compared with 6·7 and 4·6 mmHg, respectively, in the CG. After adjusting for body weight, BP at baseline and age, these changes were 12·1 and 7·9 mmHg, respectively. Urinary Na excretion was also reduced by 43·4 mEq/24 h in the EG. Food intake was modified accordingly during the intervention with an increase in the consumption of vegetables (2·97–5·85 frequency of consumption measured in three non-consecutive days), fruits (4·09–7·18), beans (1·94–3·13) and fish (1·80–2·74) by the EG. The present study showed the feasibility of a Brazilian dietary approach to treating hypertension by reducing urinary Na excretion and BP, changes that may have a great impact on public health and promote the benefits of controlling hypertension.