Incidence of Taste Disorder and Umami Taste Disorder among the Japanese Elderly and Youth

Abstract

The incidence of taste disorder has increased among both the elderly and the young in Japan. The loss of taste sensation not only affects the quality of life, but can also cause weight loss and health problems, particularly among the elderly. Taste disorder among the elderly has been attributed to side effects of medication, malnutrition (including zinc deficiency), systemic diseases, and oral diseases. We found that salivation was significantly decreased in elderly patients with taste disorder, but was normal in all elderly subjects with normal taste perception thresholds. This suggests that hyposalivation is closely related to taste disorder among the elderly. However, the cause of taste disorder among the young is unclear. In addition, we found that some elderly patients complained of loss of only umami taste sensation, whereas the other four basic taste sensations (sweet, salty, sour, bitter) were normal. Patients with loss of umami taste sensation were all over 65 years old, and they all complained of appetite and weight loss, resulting in poor general health. In this article, we surveyed the prevalence of taste disorder in Japan and discussed the causes of taste disorder.