Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC12
The effect of vitamin B12 status and supplementation on autonomic nervous activity in a healthy elderly population
S. Sambashivaiah1, T. Thomas2, B. Samuel2, M. Vaz1,2
1. Department of Physiology, St John's Medical College, Bangalore, India. 2. St John's Research Institute, St John's National Academy of Health Sciences, Bangalore, India.
Vitamin B12 deficiency is a worldwide problem. There is no population data on vitamin B12 status in elderly Indians but the extent of the problem is likely to be at least as high, if not higher, than the prevalence reported in western countries for a variety of reasons. Present study objective was to assess cardiac sympathetic and parasympathetic activity using heart rate variability (HRV) in elderly individuals of low and high vitamin B12 status and to study the effect of vitamin B12 supplementation in those with low vitamin B12 status. 140 healthy elderly subjects aged >60 years were screened and 48 subjects fitted the criteria. They underwent blood sampling, HRV, nerve conduction and cognition assessment (Montreal Cognitive scoring). Nerve conduction assessment was performed on the median nerve and included both motor and sensory assessment (RMS EMG EP machine, Recorders and Medicare systems, Chandigarh, India). For motor nerve conduction studies, surface electrodes were used. For orthodromic sensory nerve conduction studies, surface ring electrodes were used. Evaluated variables included the latencies, conduction velocities and amplitude. Subjects were classified based on their age (<65 years and ≥65 years) and based on median plasma vitamin B12 level (118 pmol/L) into lower vitamin B12 and higher vitamin B12 groups. Low frequency (LF) HRV presented in absolute units was significantly higher in the high vitamin B12 group when represented as a complete group. When stratified by age, among < 65 years age group, high vitamin B12 group demonstrated a significantly greater response. About 9% of the variability in LF was explained by vitamin B12 status. Post supplementation LF and HF (high frequency) HRV in absolute units and total power were significantly raised as compared to pre-supplementation values when analyzed as a complete group and in < 65 years age group. In conclusion evaluation of vitamin B12 deficiency and its supplementation is best done in “younger” elderly individuals in order to achieve enhanced effects on the autonomic nervous system.
Where applicable, experiments conform with Society ethical requirements