Evaluation of taste acuity by the filter-paper disc in Japanese young women: the relationship with micronutrients status.

The aim of the present study is to investigate the taste acuity in Japanese young women in relation to their micronutrient status. Thirty-eight healthy young women (mean age; 21.3, range; 19-27 years) were enrolled. Gustatory thresholds were estimated for four basic tastes: sweet (sucrose), salty (sodium chloride), sour (tartaric acid), and bitter (quinine hydrochloride) by a filter-paper disk method. Various concentrations at each taste were serially scored from disc number 1 (lowest) to number 5 (highest). The lowest concentration at which the quality of the taste was correctly identified was defined as the recognition threshold. The mean of three measurements for each test on three different days was calculated. We divided our participants into normal taste and hypogeusia groups based on the mean threshold disc numbers, <=3.5 and >3.5, respectively, according to previous literature using the same method. We also measured serum concentrations and dietary intakes of micronutrients including zinc, iron, copper, and selenium. The numbers of participants belonging to the hypogeusia group were 24 (63.2%) for sweet, 19 (50.0%) for sour, 17 (44.7%) for bitter, and 16 (42.1%) for salty taste. Although the hypogeusia group exhibited significantly lower serum iron concentrations, except for the salty taste, the other three micronutrients concentrations did not show any association with the four taste acuities. Dietary micronutrient intake did not show any association with the four taste acuities. This study indicates that in addition to zinc status, iron status should be considered in the study of taste acuity.

Effects of zinc supplementation on serum zinc concentration and ratio of apo/holo-activities of angiotensin converting enzyme in patients with taste impairment.

OBJECTIVE: The aim of the present study was to evaluate the effects of zinc supplementation on hypogeusia, serum zinc concentration and the ratio of apo/holo-activities of angiotensin converting enzyme (ACE ratio) in patients with taste impairment. ACE ratio was used as an index of zinc nutritional status. METHODS: Forty patients complaining of taste impairment were divided into two groups: zinc deficiency taste impairment (n=12) and idiopathic taste impairment (n=28). Patients with zincemia values of less than 63 microg/dl with no history of other disorder or medication known to cause dysgeusia were diagnosed as zinc deficiency group, while those with the same condition and values more than 64 microg/dl were considered to belong to the idiopathic group. Patients orally received 150 mg of polaprezinc containing 33 mg of zinc every day. Subjective symptom was scored according to visual analogue scale (VAS). RESULTS: Zinc supplementation improved hypogeusia in both idiopathic and zinc deficiency groups. The mean improvements of VAS were 3.02+/-3.03 in the idiopathic group and 3.13+/-2.53 in the zinc deficiency group. Thus, there were no significant differences in idiopathic and zinc deficiency groups. Significant correlations were found between the improvement of VAS score and the ACE ratio after zinc supplementation in both idiopathic and zinc deficiency groups. On the contrary, significant correlations were not found between the improvement of VAS score and the zinc concentration in the serum after zinc supplementation in both groups. CONCLUSION: The results of the present study indicated that zinc deficiency is a predominant factor underlying taste impairment and ACE ratio may be a predictor of the prognosis for taste impairment after zinc supplementation, in addition to a more sensitive indicator of zinc nutrition than zinc concentration in the serum.

Clinical and physiological investigations in patients with taste abnormality.

The cause of taste abnormality was investigated in 25 patients with decreased taste sensation (hypogeusia group) and 14 patients with abnormal taste sensation (dysgeusia group) by examining taste threshold, salivary flow rate, Candida cell culture, and laboratory examination of peripheral blood. The cause of hypogeusia was identified as iron deficiency in 7 patients, oral candidiasis in 6, hyposalivation (xerostomia) in 6, and psychiatric distress in 3, and could not be determined in 3 (idiopathic). Dysgeusia was associated with psychiatric distress in 8 patients, oral candidiasis in 3, drug medication in 2, and hyposalivation in 1. In the hypogeusia group, the decreased taste sensation generally corresponded with elevated taste thresholds, which decreased along with improvement of the decreased taste sensation in all except the 3 patients with psychiatric etiology and 2 of the 3 patients with idiopathic etiology. In contrast, no elevation or depression of taste thresholds were observed in the dysgeusia group, and the abnormal taste sensation did not disappear in most cases; however, drug-induced dysgeusia improved completely within 2 months after cessation of the drug administration. The serum copper and zinc levels were not decreased in any patient, but a decreased serum iron level was observed in 7 patients. Based on these results, it is concluded that abnormal taste sensation may be induced by many oral and systemic disturbances and that hypogeusia, which may be induced by deficiency of iron but not of zinc or copper, is usually accompanied by elevation of taste thresholds, while dysgeusia is not.