February 21, 2024

Study finds J-shaped association between dietary thiamine intake and worsening mental acuity

A study published in the open-access journal General Psychiatry suggests a notable relationship between dietary thiamine (vitamin B1) and cognitive function decline among older adults without cognitive impairment. The research indicates a J-shaped curve, revealing that while a moderate daily intake of approximately 0.68 mg of thiamine is optimal for cognitive health, higher or lower levels may lead to decline.

Thiamine is a crucial water-soluble B vitamin involved in energy metabolism and neurotransmitter activity in the brain. It is found in foods like whole grains, fortified cereals, legumes, liver, and salmon. While previous studies hinted at the benefits of high thiamine doses for individuals with mild cognitive impairment, the impact of typical dietary intake on cognitive decline remained unclear.

To investigate further, researchers analyzed data from the China Health and Nutrition Survey (CHNS), a long-term study tracking health-related trends since 1989. The study involved over 3,100 participants aged 55 and above, with cognitive assessments conducted repeatedly between 1997 and 2006.

Dietary information was collected through detailed surveys and 24-hour dietary recall interviews conducted over three consecutive days. Cognitive function was assessed using various tests, including verbal memory, attention, and numerical fluency.

The findings revealed a J-shaped association between thiamine intake and cognitive decline over a nearly 6-year period. Optimal cognitive function was observed at a daily intake of around 0.68 mg of thiamine. Below this threshold, there was little impact on cognitive health, but above it, higher intake was linked to significant decline.

Each additional daily unit increase in thiamine intake above the optimal level was associated with a notable decline in cognitive scores within five years. This association was stronger among certain subgroups, such as obese individuals and non-smokers.

Further analysis indicated that thiamine intake between 0.6 and less than 1 mg/day was associated with the lowest risk of cognitive decline. These findings held true even after accounting for other dietary factors and demographics.

While the study highlights the importance of maintaining optimal thiamine intake for cognitive health, it is observational and cannot establish causation. Additionally, the study's focus on older Chinese adults may limit its generalizability to other populations.

Nevertheless, the research underscores the potential role of thiamine in cognitive function and suggests the importance of further exploration in preventing cognitive decline through dietary interventions.