Almost every product in the lunchtime buffet served to those in the intervention group was replaced by an alternative containing 29 to 61% less sodium. The study showed that participants did not eat any more or any less, and that they enjoyed most of the products just as much. The intervention group consumed an average of 2.5 grams less salt than the control group, who continued to eat food with regular sodium levels. The participants were not informed about the reduction in salt during the study.
To check whether a reduced-sodium lunch actually reduces total daily salt intake, the amount of sodium excreted via the urine over 24 hours was measured in both groups. This gives an accurate indication of how much common salt someone has consumed. Sodium excretion dropped in line with the low salt levels in the lunch. “We can therefore conclude that the people who ate the reduced-sodium lunch did not compensate their lower salt intake at other eating times during the day by eating crisps or salty liquorice, for example,” says Dr Anke Janssen, Senior Scientist Consumer Science at Food & Biobased Research.
Realistic test environment
The research was conducted in the Restaurant of the Future, where the 74 participants were free to choose whatever they liked from a lunchtime buffet every day. This real-life test environment is unusual because it allows researchers to observe the participants’ choices unnoticed. Most other studies into the acceptance of reduced-sodium products are carried out in a laboratory setting, where test subjects assess the taste of reduced-sodium varieties in a more analytical way. Repeated exposure is not usually a part of this method. “The realistic setting leads us to conclude that consumers can cope with substantial reductions in salt without spoiling their enjoyment of food,” says Janssen.
The randomised controlled trial involving 74 healthy young adults between 18 and 35 years of age was part of the Reformulating Foods project. Various Dutch food producers developed reduced-sodium lunch products for the study in collaboration with TNO.