Impact of salt reduction interventions on salt taste sensitivity and liking, a cluster randomized controlled trial

Background
Excessive intake of salt is associated with high blood pressure, a risk factor for cardiovascular disease. Moreover, a high salt consumption has been related to a reduced salt taste sensitivity, and an increased liking of high salt content foods. Whether a reduction in salt intake over a long period of time can increase salt taste sensitivity and liking of foods with lower salt content requires further research.

Objective
This study aims to investigate the effect of gradually lowering salt content in bread, either alone or in combination with dietary counselling, on salt taste sensitivity and liking of salt reduced bread.

Methods
A four-month, single blinded, cluster RCT with a parallel design was conducted among Danish families. Families were randomized to receive bread gradually reduced in salt content (Intervention A), bread gradually reduced in salt content in combination with dietary counselling (Intervention B) or bread with regular salt content (control). Salt taste detection thresholds (DT) and recognition thresholds (RT) were measured at baseline and follow-up. Moreover, overall liking of bread with very low (0.4 g/100 g), low (0.8 g/100 g) and normal (1.2 g/100 g) salt content was measured using a 7-point hedonic scale.
Results
Eighty-nine families (n = 215) participated in the study. No significant differences between groups were found for DT or RT, but a significant reduction in DT of 18% (−28, −7) and a trend towards a reduction in RT of −16% (−30, 2) was found in Intervention B from baseline to follow-up. The intervention resulted in significantly higher liking of bread with 0.4 g salt/100 g in intervention B compared to the control and borderline significantly higher liking in intervention A compared to the control (p-value = 0.055). No differences were seen between groups in liking of bread with 0.8 g and 1.2 g salt/100 g. From baseline to follow-up all three groups reduced their liking of bread with 1.2 g salt/100 g and in the control group liking of bread with 0.4 g salt/100 g was significantly reduced.

Conclusion
Reducing salt intake by lowering salt content in bread and receiving dietary counselling increased salt taste sensitivity (baseline to follow-up) and resulted in higher liking of bread with very low salt content (0.4 g salt/100 g) compared to control.