Recent research published in the open-access journal General Psychiatry indicates a notable relationship between dietary thiamine (vitamin B1) and cognitive function among cognitively healthy older adults. Based on data from the China Health and Nutrition Survey involving 3,106 participants aged 55 and above, the study reveals a distinctive J-shaped curve in thiamine intake and its impact on mental acuity.
The study’s key findings underscore a critical threshold of 0.68 mg of thiamine per day. Below this level, there is minimal impact on cognitive function, while exceeding it is significantly associated with cognitive decline. The optimal range for maintaining cognitive function was found to be between 0.6 and less than 1 mg of thiamine per day.
Thiamine, an essential water-soluble vitamin crucial for energy metabolism and brain neurotransmitter activity, is commonly found in whole grains, fortified cereals, legumes, liver, and salmon. The study utilised detailed dietary data collected over several survey rounds, supplemented by 24-hour dietary recalls, to analyse nutrient intake using Chinese food composition tables.
Participants underwent cognitive assessments over six years, including tests for verbal memory, attention, and numerical fluency. The results demonstrated that higher thiamine intake above the optimal range was associated with a notable decline in cognitive scores over five years. Specifically, a 1 mg/day increase in thiamine intake correlated with a significant decrease in global cognitive and composite scores.
Interestingly, subgroup analyses revealed that these associations were more pronounced among individuals who were obese or had high blood pressure. However, further analysis indicated that smoking and high blood pressure did not significantly modify the observed effects.
The study divided thiamine intake into several levels to explore the broader implications. The lowest risk for cognitive decline was associated with an intake range of 0.6 to less than 1 mg/day. These patterns persisted even after adjusting for the intake of other B vitamins and dietary factors.
Despite these compelling findings, the study authors caution that their research is observational, meaning it cannot establish causation. They also acknowledge limitations, such as the reliance on 24-hour dietary recalls, which may not capture long-term dietary habits accurately. Additionally, the study focused exclusively on older adults in China, potentially limiting its generalisability to other populations.
The researchers propose that thiamine deficiency could disrupt neuronal energy supply and acetylcholine signalling in the brain, contributing to cognitive impairment. They stress the importance of further research to validate these findings and emphasise the significance of maintaining optimal thiamine intake to support mental health in older populations. This call for further research is particularly important given the study’s limitations and the potential for future work in this area.
While the study provides valuable insights into the relationship between thiamine intake and cognitive function, it also underscores the need for more research. This research is crucial to establish definitive dietary guidelines that can help mitigate cognitive decline in ageing populations worldwide, a significant concern for healthcare professionals and researchers.
More information: Chengzhang Liu et al, J-shaped association between dietary thiamine intake and the risk of cognitive decline in cognitively healthy, older Chinese individuals, General Psychiatry. DOI: 10.1136/gpsych-2023-101311
Journal information: General Psychiatry Provided by BMJ Group
