The impact of folate and vitamin B12 intake and biomarker status on cognitive performance in older adults on the island of Ireland

Abstract

Background: Some studies have reported that suboptimal B vitamin status has been negatively associated with cognition in older adults, though, not all studies have observed this. This is hampered by the lack of new and recent population data on B vitamin and cognitive status within the population. Objective: To determine the folate and vitamin B12 dietary intake and biomarker status of older adults in Ireland and the association of these micronutrients with cognitive performance. Design: Participants were recruited for the Trinity, Ulster, Department of Agriculture (TUDA) ageing cohort and an additional follow up study of the cohort. Participants were asked to report their medication use, medical history, lifestyle and dietary intake including use of folic acid (FA) fortified foods and dietary supplements. They also completed three cognitive test batteries and gave a blood sample from which biomarker status of red blood cell folate (RCF), methylmalonic acid (MMA), serum total B12 and homocysteine concentration was measured. Results: Biomarker status of RCF decreased since baseline (p <0.001) and 49% of those who did not consume fortified foods were below the recommended nutrient intake (RNI) for folate. There was an increased prevalence of elevated homocysteine concentrations (p <0.001) and 15.8% participants were B12 deficient as indicated by their serum total B12 concentrations, despite good dietary intake across the cohort. There was a positive association between the use of FA fortified foods and RCF and serum B12 status as well as dietary intake of total folate and B12. There was an inverse relationship between FA fortified food use and MMA and homocysteine. Total folate intakes >206.1 µg but <357.3 µg per day were associated with higher scores (p<0.05) in the mini mental state examination (MMSE). RCF concentrations above 568nmol/L were associated with better (p<0.05) total repeatable battery for the assessment of neuropsychological status (RBANS) scores. The lowest MMA concentration (0 to 0.19µmol/L) had significantly higher (p<0.05) total RBANS scores than those with MMA concentrations >0.26µmol/L. Conclusion: This study supports the need to implement mandatory fortification policy as a method to improve dietary intake of FA and B12 to biomarker status in older Irish people to promote better health in ageing particularly a reduction in the rate of cognitive decline.