Vitamin B12 supplementation improves heart rate variability in healthy elderly Indian subjects

Association between vitamin B12 status and heart rate variability in patients with ischemic stroke

Autonomic dysfunction is common in patients with ischemic stroke. An ischemic stroke may induce abnormalities in autonomic tone, resulting in poor heart rate regulation and an increased risk of severe cardiac arrest and sudden death. Heart rate variability (HRV) is a reliable index for evaluating autonomic dysfunction. Vitamin B12 deficiency is frequent among older adults and is a known risk factor for ischemic stroke. As vitamin B12 deficiency affects the peripheral nerves and the central nervous system, it can lead to autonomic dysfunction. However, no study has been published on the correlation between HRV and vitamin B12 status in patients with ischemic stroke. This study aimed to investigate the relationship between HRV and vitamin B12 status and to determine whether the serum vitamin B12 level can be a predictor of HRV parameters. This retrospective study enrolled patients with ischemic stroke between January 2015 and December 2022. The patients underwent serum vitamin B12 level measurements and 24-h Holter monitoring. Pearson correlation analysis was used to investigate the correlation between serum vitamin B12 levels and HRV parameters. The impact of serum vitamin B12 status on HRV parameters was determined using multiple linear regression analysis. A total of 87 patients with ischemic stroke were included in this study. HRV parameters were significantly correlated with serum vitamin B12 status in the frequency domain. In multiple linear regression analysis, the serum vitamin B12 status was a significant predictor of HRV parameters. HRV parameters may be correlated with serum vitamin B12 status in patients with ischemic stroke. Therefore, the serum vitamin B12 status may be a significant predictor of autonomic dysfunction. Our results may provide objective evidence for the impact of serum vitamin B12 status on autonomic dysfunction in patients with ischemic stroke.

Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial

AIM

To investigate the effect of normalizing vitamin B12 (B12) levels with oral B12 (methylcobalamin) 1000 μg/day for one year in patients with diabetic neuropathy (DN).

PATIENTS AND METHODS

In this prospective, double-blind, placebo-controlled trial, 90 patients with type 2 diabetes on metformin for at least four years and both peripheral and autonomic DN were randomized to an active treatment group (n = 44) receiving B12 and a control group (n = 46) receiving a placebo. All patients had B12 levels less than 400 pmol/L. Subjects underwent measurements of sural nerve conduction velocity (SNCV), sural nerve action potential (amplitude) (SNAP), and vibration perception threshold (VPT), and they performed cardiovascular autonomic reflex tests (CARTs: mean circular resultant (MCR), Valsalva test, postural index, and orthostatic hypotension). Sudomotor function was assessed with the SUDOSCAN that measures electrochemical skin conductance in hands and feet (ESCH and ESCF, respectively). We also used the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE, respectively) and questionnaires to evaluate quality of life (QoL) and level of pain (pain score).

RESULTS

B12 levels increased from 232.0 ± 71.8 at baseline to 776.7 ± 242.3 pmol/L at follow-up, p < 0.0001, in the active group but not in the control group. VPT, MNSIQ, QoL, pain score, SNCV, SNAP, and ESCF significantly improved in the active group (p < 0.001, p = 0.002, p < 0.0001, p < 0.000, p < 0.0001, p < 0.0001, and p = 0.014, respectively), whereas CARTS and MNSIE improved but not significantly. MCR, MNSIQ, SNCV, SNAP, and pain score significantly deteriorated in the control group (p = 0.025, p = 0.017, p = 0.045, p < 0.0001, and p < 0.0001, respectively).

CONCLUSIONS

The treatment of patients with DN with 1 mg of oral methylcobalamin for twelve months increased plasma B12 levels and improved all neurophysiological parameters, sudomotor function, pain score, and QoL, but it did not improve CARTS and MNSIE.

Association between Micronutrients and Heart Rate Variability: A Review of Human Studies

Heart rate variability (HRV) is a measure of the variation between consecutive heartbeats. It provides a marker of the interplay between the parasympathetic and sympathetic nervous systems, and there is an increasing body of evidence confirming an increased HRV is associated with better mental and physical health. HRV may be a useful marker of stress as it represents the ability of the heart to respond to a variety of physiological and environmental stimuli. HRV tends to decrease as we age and is positively associated with physical activity, fitness, and healthier lifestyles. The relation between HRV and micronutrients (vitamins and minerals) has also received some attention in the research literature. In this review, cross-sectional and interventional studies on human populations examining the relation between HRV and micronutrients are appraised. Micronutrients identified and examined in this review include vitamins D, B-12, C, and E; the minerals magnesium, iron, zinc, and coenzyme Q10; and a multivitamin-mineral formula. Due to the paucity of research and significant heterogeneity in studies, definitive conclusions about the effects of these micronutrients on HRV cannot be made at this time. However, there is accumulating evidence suggesting deficiencies in vitamins D and B-12 are associated with reduced HRV, and zinc supplementation during pregnancy can have positive effects on HRV in offspring up until the age of 5 y. To further elucidate the relation between micronutrients and HRV, additional robustly designed and adequately powered studies are required.

Vitamin B12 deficiency is associated with cardiovascular autonomic neuropathy in patients with type 2 diabetes

AIMS

Vitamin B12 deficiency could be associated with cardiovascular autonomic neuropathy (CAN) in diabetes patients. We aim to investigate the association between serum levels of vitamin B12 and CAN in type 2 diabetes patients.

METHODS

469 ambulatory type 2 diabetes patients (mean diabetes duration 10.0years (IQR 5.0;17.0), mean age 59.0years (SD 11.6), 63% men, mean B12 289.0pmol/l (IQR 217;390)) were screened for CAN using three cardiovascular reflex tests, five minute resting heart rate (5min RHR) and heart rate variability indices.

RESULTS

Serum levels of vitamin B12 were significantly lower in patients treated with metformin and/or proton pump inhibitors (PPIs) compared with patients not treated (p<0.001). A 25pmol/l higher level of vitamin B12 was associated with an odds ratio of the CAN diagnosis of 0.94 (95% CI 0.88; 1.00, p=0.034), an increase in E/I-ratio of 0.21% (95% CI 0.01; 0.43, p=0.038), and a decrease in 5min RHR of 0.25 beats per minute (95% CI -0.47; -0.03, p=0.025).

CONCLUSION

Vitamin B12 may be inversely associated with CAN in patients with type 2 diabetes. Confirmatory studies investigating a causal role of vitamin B12 for the development of diabetic CAN are warranted.

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

BACKGROUND

Aging is associated with a progressive decline in vitamin B-12 status. Overt vitamin B-12 deficiency causes neurologic disturbances in peripheral and central motor and sensory systems, but the public health impact for neurologic disease of moderately low vitamin B-12 status in older people is unclear. Evidence from observational studies is limited by heterogeneity in the definition of vitamin B-12 status and imprecise measures of nerve function.

OBJECTIVE

We aimed to determine whether vitamin B-12 status is associated with electrophysiologic indexes of peripheral or central neurologic function in asymptomatic older people with moderately low vitamin B-12 status.

DESIGN

We used a cross-sectional analysis of baseline data from the Older People and Enhanced Neurological Function study conducted in Southeast England. This trial investigated the effectiveness of vitamin B-12 supplementation on electrophysiologic indexes of neurologic function in asymptomatic older people (mean age: 80 y) with moderately low vitamin B-12 status (serum vitamin B-12 concentrations ≥107 and <210 pmol/L without anemia, n = 201). Vitamin B-12 status was assessed with the use of total vitamin B-12, holotranscobalamin, and a composite indicator of vitamin B-12 status (cB-12). Electrophysiologic measures of sensory and motor components of peripheral and central nerve function were assessed in all participants by a single observer.

RESULTS

In multivariate models, there was no evidence of an association of vitamin B-12, holotranscobalamin, or cB-12 with any nerve conduction outcome. There was also no evidence of an association of vitamin B-12 status with clinical markers of neurologic function.

CONCLUSION

This secondary analysis of high-quality trial data did not show any association of any measure of vitamin B-12 status with either peripheral or central neurologic function or any clinical markers of neurologic function in older people with moderately low vitamin B-12 status. The results of this study are unlikely to be generalizable to a less healthy older population with more severe vitamin B-12 deficiency. This trial was registered at www.controlled-trials.com as ISRCTN54195799.

A combined supplementation of vitamin B12and omega-3 fatty acids across two generations improves cardiometabolic variables in rats

Our earlier studies indicate that micronutrients (vitamin B₁₂, folic acid) and omega-3 fatty acids especially docosahexaenoic acid (DHA) are interlinked in one carbon cycle.

Effects of vitamin B-12 supplementation on neurologic and cognitive function in older people: a randomized controlled trial

BACKGROUND

Moderate vitamin B-12 deficiency is relatively common in older people. However, there is little robust evidence on the effect of vitamin B-12 supplementation on neurologic and cognitive outcomes in later life.

OBJECTIVE

We investigated whether vitamin B-12 supplementation benefits neurologic and cognitive function in moderately vitamin B-12-deficient older people.

DESIGN

We conducted a double-blind, randomized, placebo-controlled trial in 7 general practices in South East England, United Kingdom. Study participants were aged ≥75 y and had moderate vitamin B-12 deficiency (serum vitamin B-12 concentrations: 107-210 pmol/L) in the absence of anemia and received 1 mg crystalline vitamin B-12 or a matching placebo as a daily oral tablet for 12 mo. Peripheral motor and sensory nerve conduction, central motor conduction, a clinical neurologic examination, and cognitive function were assessed before and after treatment.

RESULTS

A total of 201 participants were enrolled in the trial, and 191 subjects provided outcome data. Compared with baseline, allocation to vitamin B-12 was associated with a 177% increase in serum concentration of vitamin B-12 (641 compared with 231 pmol/L), a 331% increase in serum holotranscobalamin (240 compared with 56 pmol/L), and 17% lower serum homocysteine (14.2 compared with 17.1 μmol/L). In intention-to-treat analysis of covariance models, with adjustment for baseline neurologic function, there was no evidence of an effect of supplementation on the primary outcome of the posterior tibial compound muscle action potential amplitude at 12 mo (mean difference: -0.2 mV; 95% CI: -0.8, 0.3 mV). There was also no evidence of an effect on any secondary peripheral nerve or central motor function outcome, or on cognitive function or clinical examination.

CONCLUSION

Results of the trial do not support the hypothesis that the correction of moderate vitamin B-12 deficiency, in the absence of anemia and of neurologic and cognitive signs or symptoms, has beneficial effects on neurologic or cognitive function in later life. This trial was registered at www.isrctn.com as ISRCTN54195799.

Heart rate variability is reduced in underweight and overweight healthy adult women

Heart rate variability (HRV) is altered in obese subjects, but whether this is true also in underweight (UW) subjects is still under debate. We investigated the HRV profile in a sample of healthy adult women and its association with adiposity. Five-minute resting state electrocardiographic activity was recorded in 69 subjects grouped according to their body mass index, [23 normal weight (NW), 23 overweight/obese (OW) and 23 UW). Body fat mass (FM) was measured by bio-impedance. Frequency- and time-domain analyses were performed. Compared to NW, UW and OW subjects showed a significant decrease in HRV indices, as revealed by spectral analysis. No differences were observed between UW and OW subjects. A second-order polynomial regression unveiled an inverted U-shaped relationship between FM extent and HRV indices. A decrease of HRV indices was associated with changes in FM extent, proving that in UW and OW subjects, the adaptive flexibility of autonomic cardiac function was reduced. These findings provide important clues to guide future studies addressed to determine how changes in adiposity and autonomic cardiac function may contribute to health risk.

Is there an association of vitamin B12 status with neurological function in older people? A systematic review

Low vitamin B12 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 B12 status with neurological function and clinically relevant neurological outcomes in adults aged 50+ 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 B12 status with some, but not all, neurological outcomes. Among groups with clinical and/or biochemical evidence of low vitamin B12 status, one longitudinal study reported an association of vitamin B12 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 B12 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 B12 status in older people.

Low maternal vitamin B12 status during pregnancy is associated with reduced heart rate variability indices in young children

Vitamin B12 plays a vital role in neuronal development, particularly in myelinogenesis. Demyelination of the autonomic nervous system occurs early in vitamin B12 deficiency. However, the impact of maternal vitamin B12 deficiency during pregnancy on neuronal function in the offspring is poorly documented. The objective of this study was to assess cardiac autonomic nervous activity in children born to mothers with low vitamin B12 status during pregnancy using heart rate variability (HRV) indices in the frequency domain. Seventy-nine healthy children between 3 and 8 years of age were evaluated from an ongoing birth cohort. The blood sample of the mother had been stored and was analysed for plasma vitamin B12 following enrolment of the child. Subjects were divided, based on the median maternal first trimester vitamin B12 status (114 pmol L(-1)), into lower (n = 40) and higher (n = 39) vitamin B12 status groups. A lead II electrocardiogram was recorded in the supine posture and subjected to HRV analysis. Low-frequency HRV in absolute units was reduced significantly in children of the lower vitamin B12 status group (P = 0.03) and was 53% that of the higher vitamin B12 status group. There was a significant association between low-frequency and total power HRV with cord blood vitamin B12 levels (ρ = 0.31 and 0.30, both P = 0.03). In summary, children born to mothers with a lower vitamin B12 status have a reduced cardiac sympathetic activity. The long-term implication of this needs to be evaluated by follow-up studies.