Background Fucoidan is derived from seaweed widely used in Japanese cuisine, but little is known about its influence on glucose metabolism. To obtain information about the physiological effects of fucoidan on glucose metabolism, the digestive system, and the gustatory system controlling taste sensation in patients with type 2 diabetes, we conducted a randomized, double-blind, placebo-controlled study. Methods Thirty patients with type 2 diabetes on diet therapy were recruited from an outpatient clinic (22 men and 8 women aged 59.10 ± 13.24 years, body mass index: 25.18 ± 3.88, hemoglobin A1c: 7.04 ± 1.24%). They were divided into 2 groups and underwent 2 interventions with a 4-week interval. One group received fucoidan for 12 weeks (a daily 60 mL test beverage containing 1,620 mg of fucoidan) and then placebo (60 mL) for the subsequent 12-week period, while the order was reversed in the other group. Evaluation was performed just before and after each intervention. Taste sensitivity was measured for 5 basic tastes by the filter paper disk method and food intake was evaluated with a validated diet questionnaire. Results No adverse events occurred during the study period. Despite no change of the diet, stool frequency increased during fucoidan intake (from 7.78 ± 4.64/week in Week 1 to 9.15 ± 5.03/week in Week 5, P < 0.001), and it increased more in lean subjects. In 11 subjects whose stool frequency exceeded the mean value, the thresholds for sweet, salty, bitter and umami tastes were significantly reduced (enhancement of sensitivity) after fucoidan intake. In 14 subjects with normal HOMA-IR (homeostatic model assessment of insulin resistance, < 2.5), hemoglobin A1c decreased after fucoidan intake (from 6.73 ± 1.00 to 6.59 ± 1.00%, P < 0.05), as did the fasting plasma level of GLP-1 (glucagon-like peptide-1, from 6.42 ± 3.52 to 4.93 ± 1.88 pmol/L, P < 0.05). Conclusion Sustained fucoidan intake led to alterations of gastrointestinal function, including increased stool frequency and enhanced taste sensitivity, which could contribute to better control of diabetes.

Patients with Alzheimer's disease (AD) develop olfactory and gustatory disorders. However, the order of failure and relevance of the pathophysiology are unclear. We compared olfactory identification and whole mouth gustation in patients with AD to those with mild cognitive impairment (MCI) and to healthy controls (HC) and assessed correlations with pathophysiology. Patients with AD (n = 40), MCI (n = 34), and HC (n = 40) were recruited. We performed the Odor Stick Identification Test for Japanese (OSIT-J), gustatory test by the intraoral dropping method using taste solutions, Mini-Mental State Examination (MMSE), Alzheimer's Disease Assessment Scale-cognitive subscale Japanese version (ADAS-J cog), Touch Panel-type Dementia Assessment Scale (TDAS), and measurement of amyloid β (Aβ) 42 and phosphorylated tau (p-tau) 181 levels in cerebrospinal fluid (CSF). Patients with AD and MCI had lower OSIT-J scores than did the HC. The OSIT-J score was correlated with the MMSE, ADAS-J cog, TDAS, and Aβ42 results. There were no significant differences in the gustatory test scores among the three groups. The gustatory test score was only correlated with the MMSE, ADAS-J cog, and TDAS results. Olfactory function decreased in AD and MCI patients and was associated with CSF biomarker levels and cognitive disorders. The results suggest that olfactory function is impaired in early stage of AD. Gustatory function was not correlated with CSF biomarkers, which suggests that it may not be impaired in early stage of AD.

Objective We examined the benefits of a community‐based program combining physical exercise, cognitive training, and education on dementia and lifestyle habits. Methods This crossover open‐label trial included 141 community‐dwelling elderly people with suspected mild cognitive decline (MCD). Subjects were assigned to a 6‐month intervention‐first/6‐month observation‐second (INT‐OBS) group or an OBS‐INT group. The 6‐month intervention consisted of 2 h of physical exercise, cognitive training, and classroom study or rest once weekly. Primary outcome was change in Touch Panel‐type Dementia Assessment Scale (TDAS) score. Results TDAS score improved significantly during the intervention period compared with the observation period for all subjects (P < 0.05). Some physical functions also improved significantly during the intervention period compared with the observation period in the OBS‐INT group (P < 0.05). Interpretation This community‐based program improved both cognitive and physical function in elderly people with suspected MCD.

Background: Patients with Alzheimer's disease dementia (ADD) are thought to exhibit taste disorders; however, this has not been extensively studied. We investigated gustatory functions and factors affecting taste in patients with ADD or mild cognitive impairment (MCI) and in non-demented controls (NDCs) and evaluated associations between cognitive impairment and gustatory functions. Methods: We recruited 29 patients with ADD, 43 with MCI, and 14 with NDCs. We obtained medical and medication history, measured salivary secretion volumes, and performed cognitive function tests, blood tests, whole-mouth gustatory tests, and dietary and gustatory questionnaires. Results: Patients with ADD showed significantly higher recognition threshold values than NDCs (p < 0.05). Many individuals did not recognize umami at the maximum concentration, and this happened more frequently in patients with ADD or MCI than in NDCs. Evaluation items other than cognitive function tests did not show significant differences among the groups, but many individuals had decreased salivation, low serum zinc levels, and were on multiple medications. We found a significant correlation between recognition threshold and age (r = 0.229, p < 0.05) and cognitive function test score (r = 0.268, p < 0.05). Conclusions: Patients with ADD showed impairment of gustatory function. Gustatory impairment in patients with MCI could not be confirmed. However, many individuals with MCI did not recognize umami, either. Our results suggest that taste disorders in elderly people with cognitive decline occur independently of factors affecting taste such as salivation, zinc levels, or prescription drugs. Trial registration: The study was registered in the UMIN Clinical Trials Registry on February 10, 2017, with reference number UMIN000026087.

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