Oral Exposure to Sodium Chloride without Subsequent Consumption Does Not Alter Salt Taste Function in Adults: A Cross-Over Intervention Study

Isabella Hartley, Nanna Riis, Djin Gie Liem, Russell Keast*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Background
Reduction in dietary sodium increases salt taste sensitivity; however, non-oral sodium supplementation does not, suggesting that oral exposure is more important for modulating taste perception than consumption without tasting.

Objective
Using psychophysical methods, we assessed the effect of a two-week intervention involving oral exposure to a tastant without consumption on modulating taste function.

Methods

In a cross-over intervention study, n = 42 adults (age, mean ± SD: 29.7 ± 8.0 years) completed 4 intervention treatments requiring participants to rinse their mouths with 30 mL of a tastant, 3 times daily for 2 weeks. Treatments included oral exposure to 400 mM sodium chloride (NaCl), monosodium glutamate (MSG), monopotassium glutamate, and sucrose. Participants’ taste function for salty, umami, and sweet [detection threshold (DT), recognition threshold (RT), and suprathreshold (ST)], and the glutamate-sodium discrimination status was evaluated before and after the tastant treatments. Effects of the interventions on taste function were assessed by using linear mixed models including treatment, time, and treatment x time interactions as fixed effects; significance was set at P > 0.05.

Results

There was no treatment × time interaction on DT and RT for all tastes assessed (P > 0.05). The only change in ST was following the NaCl intervention, participants’ salt ST decreased at the highest concentration (400 mM) compared with the pre-NaCl treatment taste assessment (mean difference (MD): −0.052 [95% CI: −0.093, −0.010] labeled magnitude scale, P = 0.016). Compared with the pre-MSG treatment taste assessment, participants improved their ability to perform the glutamate-sodium discrimination task after the MSG intervention (MD:1.64 [95% CI: 0.395, 2.878] correct discrimination tasks, P = 0.010).

Conclusion

Saltiness of an adult's free-living diet is unlikely to influence salt taste function, as oral exposure without consumption to a salt concentration greater than normally found in food, only attenuated taste responses to highly salty stimuli. This provides preliminary evidence that regulating salt taste function may require a coordinated response between oral activation and consumption of sodium.
Original languageEnglish
JournalJournal of Nutrition
Volume153
Issue number2
Pages (from-to)543-551
Number of pages9
ISSN0022-3166
DOIs
Publication statusPublished - 2023

Keywords

  • Taste intervention
  • Salt taste
  • Sodium chloride
  • Umami
  • Oral exposure
  • Taste
  • Psychophysics

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