Investigation of associations of nutritional status and the olfactory function and perception of salty taste in the population of elderly nursing home residents

Abstract

Background & aims

The ageing process contributes to the declining function of the smell and taste senses, which consequently modifies the eating behaviour of the elderly and adversely impacts their nutritional status and health. The aim of this research was to determine the decline or loss of olfactory perception and salty taste sensitivity, as well as the nutritional status, body composition, and appetite of elderly people, and to find out if associations between impaired sense of smell and salty taste impact the nutritional status of elderly people in nursing homes.

Methods

The study included 123 elderly nursing home residents, mean age of 80.7 ± 5.8 y, 76.4% females, and 70 adults with a mean age of 42.8 ± 8.6 y, 90% females. Olfactory function was determined by The European Test of Olfactory Capabilities, parameters measured were detection and identification and based on the results proportion of subjects with hyposmia was calculated. Gustatory function was expressed by salty taste detection and recognition thresholds and measured by the rapid detection threshold method adapted for the elderly. Based on the recognition threshold, three groups of sensitivity to salty taste were developed. Sensory decline was established in comparison to the young adult group of participants. Nutritional status was determined by several methods: anthropometric measures of body mass index and body composition, the Mini Nutritional Assessment, and the Simplified Nutritional Appetite Questionnaire.

Results

The study determined a significant decline in the olfactory function of elderly subjects, with 65% of participants having hyposmia and declining salty taste perception (22.1 ± 14.9 mM) (P < 0.0001). The results showed increased body mass with a trend towards obesity, with a mean body mass index of 29.6 ± 5.2 kg/m², of which 8.1% of subjects were undernourished and 41.5% were overweight or obese. A mini-nutritional assessment showed that most respondents (75.6%) have a normal nutritional status (13.3 ± 0.9), about a fifth of respondents (22.8%) were at risk of malnutrition (9.8 ± 1.0), and 1.6% of respondents were malnourished (5.5 ± 2.1). Nutritional appetite analysis determined that 32.5% of elderly people were at a significant risk of at least 5% weight loss within six months. A significant impact of chemosensory function on measured parameters of nutritional status was only found in olfactory perception between individuals with normal status and those with malnutrition.

Conclusions

Elderly people, residents of nursing homes, have a declining chemosensory function, but there is also a high percentage of overweight and obese individuals. A potential weak effect of olfactory function was found on nutritional status; however, nutritional status seems to be independent of a decline in salty taste perception. Although this research did not show a significant impact of chemosensory function on nutritional status, further research is needed to clarify the causal effect for this group of elderly people.