Is there an association of vitamin B₁₂status with neurological function in older people? A systematic review

Abstract

Low vitamin B 12 status is common in older people; however, its public health significance in terms of neurological manifestations remains unclear. The present systematic review evaluated the association of vitamin B 12 status with neurological function and clinically relevant neurological outcomes in adults aged 50þ years. A systematic search of nine bibliographic databases (up to March 2013) identified twelve published articles describing two longitudinal and ten cross-sectional analyses. The included study populations ranged in size (n 28 -2287) and mean/median age (range 65-81 years). Studies reported various neurological outcomes: nerve function; clinically measured signs and symptoms of nerve function; self-reported neurological symptoms. Studies were assessed for risk of bias, and results were synthesised qualitatively. Among the general population groups of older people, one longitudinal study reported no association, and four of seven cross-sectional studies reported limited evidence of an association of vitamin B 12 status with some, but not all, neurological outcomes. Among groups with clinical and/or biochemical evidence of low vitamin B 12 status, one longitudinal study reported an association of vitamin B 12 status with some, but not all, neurological outcomes and three cross-sectional analyses reported no association. Overall, there is limited evidence from observational studies to suggest an association of vitamin B 12 status with neurological function in older people. The heterogeneity and quality of the evidence base preclude more definitive conclusions, and further high-quality research is needed to better inform understanding of public health significance in terms of neurological function of vitamin B 12 status in older people.Key words: Vitamin B 12 : Neurological function: Nerve conduction: Older people Ageing is associated with a decline in vitamin B 12 status (1,2) , and there is widespread evidence of low vitamin B 12 status in older people (1,3) . In the UK, 5 % of adults aged 65 -74 years and 10 % adults aged $75 years have low vitamin B 12 levels (defined as vitamin B 12 , 150 pmol/l) or metabolically significant vitamin B 12 deficiency (defined as vitamin B 12 , 200 pmol/l and homocysteine level . 20 mmol/l) (1) . However, intakes of vitamin B 12 in adults are mostly adequate and in the most recent National Diet and Nutrition Survey of the UK, only 1 % of adults aged 65 -74 years and $75 years had vitamin B 12 intakes below the lower reference nutrient intakes (4) . Several factors relating to vitamin B 12 absorption may contribute to poor status in older people, including a decrease in gastric acidity, the presence of atrophic gastritis, compromised functional and structural integrity of vitamin B 12 -binding proteins, and lack of liver vitamin B 12 stores (5) .Indeed, food-cobalamin malabsorption can account for up to 60 -70 % of confirmed cases of vitamin B 12 deficiency in older people (6) .The clinical manifestations of vitamin B 12 deficiency can be haematological, neur...

Biomarkers and Algorithms for the Diagnosis of Vitamin B12 Deficiency

“…Despite an apparent sufficient intake, vitamin B 12 deficiency is common among the elderly, and the prevalence is shown to increase with age (Allen, 2009 ; Miles et al, 2015 ). This is most likely not a physiological change due to aging per se , but a consequence of the elderly being more prone to gastric dysfunction, with variable degrees of gastric atrophy and achlorhydria interfering with the absorption of vitamin B 12 from foods (Carmel, 1997 ).…”

Nutrition and the gut microbiome in the elderly

“…75 The association of B-group vitamins with neurological disorders has been recently discussed. 76 The role of other nutrients at this age remains to be elucidated.…”

Vitamin B-12 status and neurologic function in older people: a cross-sectional analysis of baseline trial data from the Older People and Enhanced Neurological Function (OPEN) study,

“…Neurologic signs and symptoms associated with moderately low vitamin B-12 status can be nonspecific and are often undetected because they are attributed to "old age," yet they can have an important impact on physical function. A recent systematic review (8) evaluated the association of vitamin B-12 status with neurologic function and clinically relevant neurologic outcomes in older people. Evidence from observational studies was limited, and the heterogeneity and quality of the available studies precluded definitive conclusions.…”