The effectiveness of nutritional interventions to prevent and maintain cognitive functioning in older adults has been gaining interest due to global population ageing. A systematic literature review was conducted to obtain and appraise relevant studies on the effects of dietary protein or thiamine on cognitive function in healthy older adults. Studies that reported on the use of nutritional supplementations and/or populations with significant cognitive impairment were excluded. Seventeen eligible studies were included. Evidence supporting an association between higher protein and/or thiamine intakes and better cognitive function is weak. There was no evidence to support the role of specific protein food sources, such as types of meat, on cognitive function. Some cross-sectional and case-control studies reported better cognition in those with higher dietary thiamine intakes, but the data remains inconclusive. Adequate protein and thiamine intake is more likely associated with achieving a good overall nutritional status which affects cognitive function rather than single nutrients. A lack of experimental studies in this area prevents the translation of these dietary messages for optimal cognitive functioning and delaying the decline in cognition with advancing age.

A pilot quasi-experimental study investigated whether provision of pork, a rich source of thiamin, as the main protein source in meals four times/week for 12 weeks resulted in improved muscle mass, body strength, and cognitive function in community-living older adults compared to similar meals containing chicken. Retirement villages were randomized to receive pre-prepared frozen meals containing either pork or chicken. Dietary intake was assessed by three-day food records and cognitive domains assessed using validated tests. Hand grip strength was measured and lower extremity performance assessed by the sit-to-stand test, get-up-and-go test and six-minute walk test. Forty-eight volunteers participated (78.2 ± 6.2 y). In linear mixed models, controlling for baseline physical activity and dietary protein and energy intake, no differences were found between pork (n = 19) and chicken (n = 12) groups. The chicken group had improved Rey Auditory Verbal Learning test scores (verbal learning and memory) at six weeks (p < 0.001). Provision of four pork meals a week did not result in improvements in cognitive function, nor measures of strength or physical function, compared to those receiving chicken meals in healthy older adults. This suggests that merely changing the type of dietary protein provided by meat does not impact physical or cognitive function.

Aim: Some studies have suggested that thiamin (vitamin B1) may have a protective effect on the maintenance of cognitive function in older people. The aim of this exploratory study was to investigate the association between dietary intakes, specifically protein and thiamin with cognitive function. Methods: A cross-sectional analysis was conducted on community-living older adults aged ≥60 years in the Illawarra region of New South Wales. Dietary intakes were collected using a three-day food record and various domains of cognition were tested. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS). Correlations and regressions were conducted to investigate the association between dietary intakes and areas of cognitive function. Results: Forty-eight volunteers participated (mean age: 78.2 ± 6.1 years; BMI: 28.8 ± 5.4 kg/m 2 ; MNA Score: 26.8 ± 2.4; 35% men). Men had higher intakes of energy (kJ), carbohydrate, saturated fat and sodium than women. No significant association was found between protein or thiamin and the tested domains of cognition. Associations were found between vitamin D intake and the Letter Fluency Test (r = −0.302, P < 0.05) and Rey Auditory Verbal Learning Test (r = −0.400, P < 0.001), and between both carbohydrate (r = 0.383, P = < 0.05) and iron intake (r = 0.333, P < 0.05) and the GDS. Conclusions: In a sample of generally healthy, well-nourished older adults, no associations were found between protein or thiamin intakes and the tested components of cognition. Further investigation is required to determine if an increase in these nutrients through the provision of food sources has benefits to improve cognitive function.

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