Subclinical Vitamin B12 Deficiency and Heart Rate Variability Across Life Cycle

The present study aimed to evaluate association between plasma vitamin B12 and heart rate variability in clusters of population of various ages across life cycle.

47 healthy children from an ongoing pregnancy and birth cohort, 32 young adults and 47 healthy elderly subjects were recruited following inclusion and exclusion criteria. All subjects underwent plasma vitamin B12, anthropometry and heart rate variability (HRV).

The prevalence of vitamin B12 deficiency (<148 pmol/l) across age groups were 51.1 % for children, 56.2 % for young adults and 61.7 % for the elderly group respectively. There was large variability in vitamin B12 status across the age groups. Frequency distribution of low frequency (LF) absolute units HRV in the elderly was skewed, whereas in children and young adult group there was wide distribution of LF HRV. Association between Log LF absolute units HRV and plasma vitamin B12 across groups were tested using curve fit models. In children a linear curve estimation best fitted and explained 9.3 % of the association (n=47, .=0.003, P=0.03, R2=0.09). There was no association between log LF absolute units HRV and plasma vitamin B12 in the young adult group. In the elderly group a power curve fit model best fitted and explained 8.9 % of the association. Inspection of the power curve fit model demonstrated a curvilinear pattern; there was a linear association in the elderly with vitamin B12 levels less than 200 pmol/l. However, elderly with vitamin B12 values >200 pmol/l demonstrated saturation (plateauing) of log LF HRV.

The study demonstrated varied pattern of responses between vitamin B12 status and LF power of HRV across age groups. Thus, it is important to consider these associations before planning supplementation of vitamin B12.