The sweet-salty combination dulls the sense of avoiding high salt concentrations and can lead to greater salt intake, a study by Kyoto Prefectural University of Medicine and House Foods Group has found.

The tendency is more pronounced among people with chronic kidney disease, or CKD, underscoring the need for salt reduction that takes the effect of sweetness into account.

The findings were published in British magazine Scientific Reports in July.

The research team studied how sweetness affects aversion to high salt concentrations, based on the fact that mammals tend to prefer low salt levels and avoid high ones.

A group of healthy individuals and a group of CKD patients participated in the research.

Participants from both groups were asked to hold two types of filter paper in their mouths for three seconds. One of the two contains only salted water, and the other salted water plus 80% sugared water.

With the salt concentration changed in the research, 32% of healthy participants showed aversion at 5% salinity, slightly higher than that of seawater, which is around 3%. When sugared water was added, the aversion rate dropped to 17%.

At 10% salinity, 45% of the participants showed aversion without sugared water, compared with 25% with sweetness.

Among the CKD patients, who experience a dulled sense of salty flavors, only 15% reacted to 10% salinity without sugar. The aversion rate dropped further to 3% when sweetness was added.

At 20% salinity, higher than that of soy sauce, which is around 15%, the aversion rate was 21% with only saltiness, and fell to 8% with the addition of sweetness.

"Sweet-and-salty foods may make people unknowingly consume excessive amounts of salt, so caution is needed," Tetsuro Kusaba, assistant professor at the university's nephrology department, said. "Reducing sweetness can improve sensitivity to salty taste and help cut salt intake."