Influence of olfactory dysfunction on the perception of food

Eating-related problems are among the most frequent issues in olfactory impairment, causing a noticeable loss of quality of life for some of the affected persons. To what extent olfactory dysfunction impacts on the sensory perception of food is less explored. The aim of the present study was to examine the impact of olfactory dysfunction on the perception of food aromas, as well as the perception of the "basic tastes" salty, sour, sweet, and bitter.

Eighty-nine participants were recruited for the prospective study. Group 1 consisted of thoroughly examined patients with olfactory dysfunction (n = 48, mean age = 60.0 years), group 2 consisted of people with normal olfactory function (n = 41, mean age = 50.4 years). First, olfactory and gustatory functions were assessed for all participants with the help of the "Sniffin'Sticks" battery and the "taste strips" test. Second, food odors were rated for their pleasantness, intensity, familiarity and desirability. Last, real food items were tasted orally and the intensity for basic taste qualities (sweet, bitter, salty, and sour) and pleasantness was rated. In addition, salivation was measured following exposure to the food odors.

In comparison to controls, patients rated orthonasal food odors as less pleasant, intense, familiar, and less appetizing. "Taste strip" scores were significantly lower in patients (M = 9.56, SD = 2.76) as compared to controls (M = 10.88, SD = 1.89). In addition, ratings of food liking for chocolate and peanut were lower in patients compared to controls (chocolate: patients-M = 6.85, SD = 2.09, controls-M = 7.90, SD = 1.53; peanut: patients-M = 4.88, SD = 2.20, controls-M = 6.80, SD = 2.33). No significant differences were found regarding the comparison of the salivary flow rate in controls (M = 0.52 g/min, SD = 0.19) and patients (M = 0.50 SD = 0.17).

Changes in the perception of odors may change the perception of food with specific effects on food liking. Olfactory dysfunction affects gustatory function, indicating the central-nervous interaction between taste and smell. Still, olfactory dysfunction did not appear to affect patients' salivary flow.