The combination of sweet and salty flavors can reduce the sensitivity of taste receptors to excess salt, which increases the risk of consuming too much sodium. This conclusion was reached by Japanese researchers after conducting an experiment involving both healthy individuals and patients with chronic kidney disease (CKD). For the latter, limiting salt intake is crucial to control blood pressure and prevent fluid retention in the body.

The Harm of Excess Salt

The dangers of excessive salt consumption—more specifically, sodium—are well known. Too much salt in the diet raises the risk of cardiovascular diseases, stroke, and dementia, and can also negatively affect bone health and kidney function. Some scientists even suggest placing warning labels on salt-containing products, similar to those found on cigarette packages.

Taste Perception in CKD Patients

Doctors from Kyoto Prefectural University, together with a Japanese spice manufacturer, previously discovered that patients with chronic kidney disease may have impaired perception of salty flavors. Many of them completely lack an aversion to high concentrations of salt.

New Experiment: The Effect of Sweet Taste

In a new study, scientists tested the hypothesis that combining sweet and salty flavors can dull the negative reaction to excess salt. The experiment involved 66 CKD patients and 100 healthy volunteers—students and university staff. The results were published in the journal Scientific Reports.

Participants were asked to place strips of filter paper soaked in NaCl solutions of varying concentrations, as well as combinations with sucrose solution, on their tongues. Similarly, the perception of sour and bitter tastes was tested using tartaric acid and quinine hydrochloride solutions. The aversion threshold was defined as the minimum intensity of taste that caused unpleasant sensations.

Study Results

As the concentration of substances increased, aversion to all tastes intensified. For sodium chloride solution, the aversion threshold was 5% (for comparison, seawater salinity is about 3.5%). However, 44% of healthy participants and nearly 80% of CKD patients did not experience aversion even to a 20% NaCl solution.

When sweetness was added to the salty strips, the proportion of people unable to tolerate the taste decreased. Among healthy volunteers, at NaCl concentrations of 5% and 10%, this figure dropped from 32% and 45% to 17% and 25%, respectively. For the 20% salt solution with sucrose, 52% of participants tolerated the taste, compared to 44% without sucrose.

In CKD patients, who often have reduced taste sensitivity, the effect was even more pronounced. At NaCl concentrations of 10% and 20%, the proportion of aversion after adding the sweet solution fell to 3% and 7.6%, down from 15.2% and 21.2%.

Sweetness slightly reduced aversion to sourness but did not affect tolerance to bitterness: adding sucrose did not improve the acceptability of the quinine solution in any group.

Conclusions and Recommendations

The study confirmed that sweetness can mask the unpleasantness of overly salty foods. When consuming products that combine sweet and salty flavors, people may unknowingly eat more salt. Therefore, those who need to limit their salt intake should not only reduce the amount of salt in their diet but also avoid overly sweet foods that can disguise the salty taste, doctors warn.