B Vitamin Plasma Levels and the Risk of Ischemic Stroke and Transient Ischemic Attack in a German Cohort

Detrimental impact of solar and geomagnetic activity on plasma B-complex vitamins in the VA normative aging study cohort

It has been hypothesized that ultraviolet (UV) radiation can lead to depletion of plasma folate and B12 vitamin, but few studies have investigated effects of other parameters of solar and geomagnetic activity (SGA). We investigated the association between four SGA parameters-interplanetary magnetic field (IMF), sunspot number (SSN), Kp index, and ground shortwave solar radiation (SWR)-and three plasma B-complex vitamins-folate, B6, and B12-in 910 participants from the Normative Aging Study (NAS) between 1998 and 2017. Mixed-effects regression models were used for 1- to 28-moving day averages of SGA exposure, adjusted for covariates. We compared the impact of SGA in individuals under higher and lower B-complex supplementation (> or < 50th quartile). Our findings show that increases in solar activity variables IMF and SSN were found to be significantly associated with decreases in B12 vitamin. IMF and SSN were associated with decrease in folate levels, especially in individuals under higher levels of B-complex supplementation. No associations were found for SWR and Kp index. To our knowledge, this is the first study that demonstrated the detrimental impact of solar activity on plasma B12 and folate in a large cohort. These findings have clinical implications during periods of high solar activity.

Low concentration of serum vitamin B12 may be a strong predictor of large-artery atherosclerosis stroke: A case-control study

INTRODUCTION

Identifying controllable risk factors for large-artery atherosclerosis (LAA) stroke is crucial due to its significant role as a leading cause of ischemic stroke. We aimed to validate the correlation of serum vitamin B12 with LAA stroke.

METHODS

Inpatients with LAA stroke and healthy controls were retrospectively collected for a case-control study from January 2020 to May 2022. Serum vitamin B12 concentration and other blood indicators, demographic, lifestyle factors and comorbidities were investigated. Logistic regression analysis was used to identify the correlation of serum vitamin B12 concentrations with LAA stroke, meanwhile adjusted for confounding factors.

RESULTS

Patients with LAA stroke had significantly lower serum vitamin B12 concentrations in comparison to those of controls. In the fully adjusted model, vitamin B12 (per 1 interquartile range increase, odds ratio [OR] = 0.84, 95 % confidence interval [CI]: 0.77-0.91), vitamin B12 < 200 pg/mL (OR=7.70, 95 %CI: 2.19-27.03) and vitamin B12 < 300 pg/mL (OR=4.19, 95 %CI: 1.82-9.66) were independently factors for LAA stroke. Furthermore, the optimal cut-off values for vitamin B12 to predict LAA stroke were 305.25 pg/mL (area under the curve [AUC] = 0.71) when unadjusted and 308.25 pg/mL when adjusted for age and sex (AUC=0.68). Lower vitamin B12 concentrations were significantly associated with male sex, smoking, older age, higher neutrophil count, higher creatinine, lower folate and higher total homocysteine.

CONCLUSION

Results indicate that low concentration of serum vitamin B12 may be a strong predictor for the risk of LAA stroke.

Circulating B vitamins metabolites in depressive disorders - connections with the microbiota-gut-brain axis

PURPOSE

In this review, we aim to summarize recent information about the association of B vitamins with immune-metabolic aspects of depression and their connection with the gut-brain axis.

VIEWS

B vitamins may alter depressive symptoms by many various mechanisms such as reducing oxidative stress, inflammation, gut permeability, controlling epigenetics, modifying the microbiome, and stimulating it to produce many beneficial substances such as short-chain fatty acids or neurotransmitters: norepinephrine, dopamine, serotonin, gamma-aminobutyric acid, and acetylcholine.

CONCLUSIONS

Specifically, vitamins B1 (thiamine), B6 (pyridoxine), B9 (folate), and B12 (cyanocobalamin), B2 (riboflavin) have been observed to affect depression. Given probiotic's capability to produce vitamins from the B group, and modify intestinal function, inflammation, or metabolic dysfunction, their supplementation might be a possible treatment method for the immunometabolic form of depression. Thus, the intake of certain probiotic bacterial strains simultaneously with controlling the required daily intake of B vitamins may positively affect the course of depression. Circulating B vitamins metabolite levels, especially B9, B12, and B6 may also be biomarkers of depression. Further investigation is needed to find stronger evidence on this topic.

Serum levels of vitamin B12 combined with folate and plasma total homocysteine predict ischemic stroke disease: a retrospective case-control study

PURPOSE

This study aimed to identify and quantify the association and investigate whether serum vitamin B12 alone or vitamin B12 combined with folate and plasma total homocysteine (tHcy) levels could be used to predict the risk of acute ischemic stroke.

MATERIALS AND METHODS

This retrospective case-control study was conducted in the Department of Neurology, First Affiliated Hospital of Chongqing Medical University. It included 259 inpatients experiencing their first-ever acute ischemic stroke and 259 age-matched, sex-matched healthy controls. Patients were categorized into groups based on the etiology of their stroke: large-artery atherosclerosis (LAAS, n = 126), cardio embolism (CEI, n = 35), small vessel disease (SVD, n = 89), stroke of other determined etiology (ODE, n = 5), and stroke of undetermined etiology (UDE, n = 4). The associations of serum vitamin B12, folate, and plasma tHcy levels with the risk of ischemic stroke were evaluated using multivariable logistic regression analysis. Receiver operator characteristic (ROC) curves were used to assess the diagnostic power of vitamin B12, folate, and tHcy levels for ischemic stroke.

RESULTS

Serum vitamin B12 and folate levels were significantly lower in ischemic stroke patients compared to controls, while plasma tHcy levels were significantly higher. The first quartile of serum vitamin B12 levels was significantly associated with an increased risk of LAAS (aOR = 2.289, 95% CI = 1.098-4.770), SVD (aOR = 4.471, 95% CI = 1.110-4.945) and overall ischemic stroke (aOR = 3.216, 95% CI = 1.733-5.966). Similarly, the first quartile of serum folate levels was associated with an increased risk of LAAS (aOR = 3.480, 95% CI = 1.954-6.449), CEI (aOR = 2.809, 95% CI = 1.073-4.991), SVD (aOR = 5.376, 95% CI = 1.708-6.924), and overall ischemic stroke (aOR = 3.381, 95% CI = 1.535-7.449). The fourth quartile of tHcy levels was also significantly associated with an increased risk of LAAS (aOR = 2.946, 95% CI = 1.008-5.148), CEI (aOR = 2.212, 95% CI = 1.247-5.946), SVD (aOR = 2.957, 95% CI = 1.324-6.054), and overall ischemic stroke (aOR = 2.233, 95% CI = 1.586-4.592). For predicting different types of ischemic stroke, vitamin B12 alone demonstrated the best diagnostic value for SVD, evidenced by a sensitivity of 71.0% and negative predictive value of 90.3%, along with the highest positive likelihood ratio (+ LR) for SVD. Vitamin B12 + tHcy + folate are valuable in predicting different types of ischemic stroke, with the most significant effect observed in SVD, followed by LAAS, and the weakest predictive effect in CEI. Additionally, vitamin B12 alone in combination with other indicators, such as folate alone, tHcy alone, and folate + tHcy could reduce negative likelihood ratio (-LR) and improve + LR.

CONCLUSIONS

Vitamin B12 was an independent risk factor for acute ischemic stroke. The risk calculation model constructed with vitamin B12 + tHcy + folate had the greatest diagnostic value for SVD.

From A to E: Uniting vitamins against stroke risk-A systematic review and network meta-analysis

BACKGROUND AND AIM

Stroke represents a significant public health challenge, necessitating the exploration of preventive measures. This network meta-analysis aimed to assess the efficacy of different vitamin treatments compared to a placebo in preventing stroke.

METHODS

A systematic electronic search in databases including PubMed, EmBASE, Web of Science, clinicaltrials.gov, and Google Scholar until 31 May 2023 was conducted, to identify published studies investigating the association between vitamin intake and the risk of stroke. Pooled risk ratio (RR) with 95% confidence intervals (CIs) was calculated using a frequentist network meta-analysis. Furthermore, we ranked vitamins based on p-scores, facilitating a comparative assessment of their effectiveness in preventing stroke.

RESULTS

A total of 56 studies, including 17 randomized controlled trials (RCTs) and 39 cohort studies were analyzed. Direct estimates obtained from network meta-analysis, we found that vitamin A (RR: .81 [.72-.91]), vitamin B-complex (RR: .85 [.74-.97]), vitamin B6 (RR: 79 [.68-.92]), folate (RR: .86 [.75-.97]), vitamin C (RR: .77 [.70-.85]) and vitamin D (RR: .73 [.64-.83]) were significantly associated with a decreased stroke risk. However, no significant association was observed for vitamin B2, vitamin B12, and vitamin E. Subsequent to network meta-analysis, vitamins were ranked in decreasing order of their efficacy in stroke prevention based on p-score, with vitamin D (p-score = .91), vitamin C (p-score = .79), vitamin B6 (p-score = .70), vitamin A (p-score = .65), vitamin B-complex (p-score = .53), folate (p-score = .49), vitamin B2 (p-score = .39), vitamin E (p-score = .28), vitamin B12 (.13) and placebo (.10).

CONCLUSION

Our study has established noteworthy connections between vitamin A, vitamin B-complex, vitamin B6, folate, vitamin C, and vitamin D in the realm of stroke prevention. These findings add substantial weight to the accumulating evidence supporting the potential advantages of vitamin interventions in mitigating the risk of stroke. However, to solidify and validate these observations, additional research is imperative. Well-designed clinical trials or cohort studies are needed to further explore these associations and formulate clear guidelines for incorporating vitamin supplementation into effective stroke prevention strategies.

Low vitamin B12 levels may predict the risk of ischemic stroke: A cross-sectional study

BACKGROUND

To examine serum vitamin B12 concentrations in relation to the risk of ischemic stroke among hospitalized patients in the Department of Neurology.

METHODS

We performed a cross-sectional study involving 2,212 inpatients discharged from the Department of Neurology of the First Affiliated Hospital of Chongqing Medical University, from January 2020 to January 2022. The results of laboratory assays such as serum vitamin B12, homocysteine, and folate levels were measured. Logistic regression analysis was used to investigate the association between serum vitamin B12 concentrations and ischemic stroke, with adjustment for a number of relevant demographic and lifestyle factors and comorbidities.

RESULTS

A total of 961 (43.4%) patients had an ischemic stroke. In the fully adjusted model, logistic regression analysis suggested a positive association between serum vitamin B12 levels<150 pg/mL (aOR: 1.42; 95% CI 1.02-1.97; p = 0.035), serum vitamin B12 150-300 pg/mL (aOR: 1.37; 95% CI 1.11-1.68; p = 0.003) and the prevalence of ischemic stroke. Furthermore, an inverse association was observed between serum vitamin B12 levels ≥ 900 pg/mL (aOR: 0.38; 95% CI: 0.19-0.77; p =0.007) and the prevalence of ischemic stroke. Moreover, the cut-off value of vitamin B12 concentration was 316.4 pg/mL and the discrimination power of the score evaluated by AUC-ROC was 0.71 (95%CI 0.68-0.73, p<0.001) in the vitamin B12 and ischemic stroke.

CONCLUSION

Findings suggest that low vitamin B12 levels may predict the risk of ischemic stroke, early and timely supplementation of vitamin B12 can improve the short-term prognosis of ischemic stroke patients.

Effects of vitamin B12 deficiency on risk and outcome of ischemic stroke

Ischemic stroke is the most prevalent form of stroke and has a high incidence in older adults, characterized by high morbidity, mortality, disability, and recurrence rate. Vitamin B₁₂ deficiency is prevalent in the elderly and has been reported to be associated with ischemic stroke. The mechanisms maybe include the disorder of methylation metabolism, accumulation of toxic metabolites, immune dysfunction, affecting gut microbial composition and gut-brain immune homeostasis, and toxic stress responses to the brain. Vitamin B₁₂ deficiency may lead to cerebral artery atherosclerosis, change myelination, influence the metabolism and transmission between nerve tissue, and ultimately causes the occurrence and development of ischemic stroke. This paper reviews the correlation between vitamin B₁₂ deficiency and ischemic stroke, looking forward to improving clinicians' understanding and providing new therapeutic directions for ischemic stroke.

Homocysteine is associated with higher risks of ischemic stroke: A systematic review and meta-analysis

BACKGROUND

High levels of homocysteine (Hct) have been associated with great risks of ischemic stroke. However, some controversy still exists. We performed a systematic review and meta-analysis to compare the levels of Hct between patients with ischemic stroke and controls.

METHODS

We performed a systematic literature search for articles reporting Hct levels of patients with occurrence of ischemic stroke. We employed a random-effects inverse-variance weighted meta-analytical approach in order to pool standardized mean differences, with estimation of τ2 through the DerSimonian-Laird method.

RESULTS

The initial search yielded 1361 studies. After careful analysis of abstracts and full texts, the meta-analysis included data from 38 studies, which involved almost 16 000 stroke events. However, only 13 studies reported means and standard deviations for cases and controls, and therefore were used in the meta-analysis. Those studies presented data from 5002 patients with stroke and 4945 controls. Standardized mean difference was 1.67 (95% CI 1.00-2.25, P < 0.01), indicating that Hct levels were significantly larger in patients with ischemic stroke compared to controls. Between-study heterogeneity was very large (I2 = 99%), particularly because three studies showed significantly large mean differences.

CONCLUSION

This meta-analysis shows that patients with ischemic stroke have higher levels of Hct compared to controls. Whether this is a modifiable risk factor remains to be assessed through larger prospective cohorts.

Probing the functional consequence and clinical relevance of CD320 p.E88del, a variant in the transcobalamin receptor gene

The biological and clinical significance of the p.E88del variant in the transcobalamin receptor, CD320, is unknown. This allele is annotated in ClinVar as likely benign, pathogenic, and of uncertain significance. To determine functional consequence and clinical relevance of this allele, we employed cell culture and genetic association studies. Fibroblasts from 16 CD320 p.E88del homozygotes exhibited reduced binding and uptake of cobalamin. Complete ascertainment of newborns with transiently elevated C3 (propionylcarnitine) in New York State demonstrated that homozygosity for CD320 p.E88del was over-represented (7/348, p < 6 × 10^-5 ). Using population data, we estimate that ~85% of the p.E88del homozygotes born in the same period did not have elevated C3, suggesting that cobalamin metabolism in the majority of these infants with this genotype is unaffected. Clinical follow-up of 4/9 homozygous individuals uncovered neuropsychological findings, mostly in speech and language development. None of these nine individuals exhibited perturbation of cobalamin metabolism beyond the newborn stage even during periods of acute illness. Newborns homozygous for this allele in the absence of other factors are at low risk of requiring clinical intervention, although more studies are required to clarify the natural history of various CD320 variants across patient populations.

Risk of Incident Stroke among Vegetarians Compared to Nonvegetarians: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

Vegetarian dietary patterns provide health benefits for cardiovascular health; however, the studies examining the association of vegetarian diets with stroke incidence showed inconsistent findings. We systematically evaluated the risk of incident stroke among vegetarians (diets excluding meat, poultry, fish, and seafood) compared among nonvegetarians. A systematic search of PubMed, EMBASE, Cochrane Library, and Web of Science was performed until 20 May 2021. Prospective cohort studies comparing the risk estimates for incident stroke between vegetarians and nonvegetarians were included. Of 398 articles identified in the database search, data from seven cohort studies (408 total stroke cases in 29,705 vegetarians and 13,026 total stroke cases in 627,728 nonvegetarians) were included. The meta-analysis revealed no significant association between adhering to the vegetarian dietary patterns and the risk of incident stroke (HR = 0.86; 95% CI = 0.67-1.11; I² = 68%, n = 7). Subgroup analyses suggested that studies conducted in Asia and those with a mean baseline age of participants 50-65 years showed a lower risk of stroke in vegetarians. Moreover, no significant association between vegetarian diets and the risk of ischemic stroke (HR = 0.56; 95% CI = 0.22-1.42; I² = 82%, n = 3) or hemorrhagic stroke (HR = 0.77; 95% CI = 0.19-3.09; I² = 85%, n = 2) was found. To be conclusive, no strong relationship between vegetarian diets and the incidence of stroke was observed. Given the limited certainty of evidence from NutriGrade, future well-designed studies are warranted to provide solid evidence on this topic.

Emerging role of white matter lesions in cerebrovascular disease

White matter lesions have been implicated in the setting of stroke, dementia, intracerebral haemorrhage, several other cerebrovascular conditions, migraine, various neuroimmunological diseases like multiple sclerosis, disorders of metabolism, mitochondrial diseases and others. While much is understood vis a vis neuroimmunological conditions, our knowledge of the pathophysiology of these lesions, and their role in, and implications to, management of cerebrovascular diseases or stroke, especially in the elderly, are limited. Several clinical assessment tools are available for delineating white matter lesions in clinical practice. However, their incorporation into clinical decision-making and specifically prognosis and management of patients is suboptimal for use in standards of care. This article sought to provide an overview of the current knowledge and recent advances on pathophysiology, as well as clinical and radiological assessment, of white matter lesions with a focus on its development, progression and clinical implications in cerebrovascular diseases. Key indications for clinical practice and recommendations on future areas of research are also discussed. Finally, a conceptual proposal on putative mechanisms underlying pathogenesis of white matter lesions in cerebrovascular disease has been presented. Understanding of pathophysiology of white matter lesions and how they mediate outcomes is important to develop therapeutic strategies.

Profiling immuno-metabolic mediators of vitamin B12 deficiency among metformin-treated type 2 diabetic patients in Ghana

BACKGROUND

The association between prolong metformin usage and B12 deficiency has been documented. However, the prevalence estimates of metformin-induced vitamin B12 deficiency showed substantial disparity among studies due to varied study definitions of vitamin B12 deficiency. Metformin blocks the calcium dependent absorption of the vitamin B12-Intrinsic Factor complex at the terminal ileum. Lack of intrinsic factor due to the presence of auto-antibodies to parietal cells (IFA) could lead to vitamin B12 deficiency and subsequently cause peripheral neuropathy. We investigated the prevalence of vitamin B12 deficiency using more sensitive, combined markers of vitamin B12 status (4cB12) and the immuno-biochemical mediators of vitamin B12 deficiency.

METHODS

In this observational study, 200 consecutive consenting metformin-treated T2DM patients, aged 35 and above, attending the diabetic clinic at KATH were recruited. Vitamin B12 deficiency was classified based on the Fedosov age-normalized wellness quotient. Anthropometric measurement was taken as well as blood samples for immunological and biochemical mediators. Peripheral neuropathy was assessed using the Michigan Neuropathy Screening Instrument (MNSI). Statistical analysis was performed using the R Language for Statistical Computing.

RESULTS

Using the combined indicator (4cB12), the prevalence of metformin induced vitamin B12 deficiency was 40.5% whilst the prevalence of MNSI-Q and MNSI-PE diabetic neuropathy was 32.5% and 6.5% respectively. Participants with vitamin B12 deficiency had significantly higher levels of IFA, GPA, TNF-α, TC, LDL and albumin compared to those with normal vitamin B12 levels (p < 0.05). Correlation analysis revealed a statistically significant negative association between 4cB12 and the immunological markers [IFA (rs = -0.301, p<0.0001), GPA (rs = -0.244, p = 0.001), TNF-α (rs = -0.242, p = 0.001) and IL-6 (rs = -0.145, p = 0.041)]. Likewise, 4cB12 was negatively associated with TC (rs = -0.203, p = 0.004) and LDL (rs = -0.222, p = 0.002) but positively correlated with HDL (rs = 0.196, p = 0.005).

CONCLUSION

Vitamin B12 deficiency and diabetic neuropathy are very high among metformin-treated T2DM patients and it is associated with increased GPA, IFA, TNF-α and cardiometabolic risk factors (higher LDL and TC and lower HDL). Upon verification of these findings in a prospective case-control study, it may be beneficial to include periodic measurement of Vitamin B12 using the more sensitive combined indicators (4cB 12) in the management of patients with T2DM treated with metformin in Ghana.

Vitamin B6, Inflammation, and Cardiovascular Outcome in a Population-Based Cohort: The Prevention of Renal and Vascular End-Stage Disease (PREVEND) Study

Background: a large number of studies have linked vitamin B6 to inflammation and cardiovascular disease in the general population. However, it remains uncertain whether vitamin B6 is associated with cardiovascular outcome independent of inflammation. Methods: we measured plasma pyridoxal 5’-phosphate (PLP), as an indicator of vitamin B6 status, at baseline in a population-based prospective cohort of 6249 participants of the Prevention of Renal and Vascular End-stage Disease (PREVEND) study who were free of cardiovascular disease. As indicators of low-grade systemic inflammation, we measured high-sensitivity C-reactive protein and GlycA; Results: median plasma PLP was 37.2 (interquartile range, 25.1–57.0) nmol/L. During median follow-up for 8.3 (interquartile range, 7.8–8.9) years, 409 non-fatal and fatal cardiovascular events (composite outcome) occurred. In the overall cohort, log transformed plasma PLP was associated with the composite outcome, independent of adjustment for age, sex, smoking, alcohol consumption, body mass index (BMI), estimated glomerular filtration rate (eGFR), total cholesterol:high-density lipoprotein (HDL)-cholesterol ratio, and blood pressure (adjusted hazard ratio per increment of log plasma PLP, 0.66; 95% confidence interval (CI), 0.47–0.93). However, adjustment for high-sensitivity C-reactive protein and GlycA increased the hazard ratio by 9% and 12% respectively, to non-significant hazard ratios of 0.72 (95% confidence interval, 0.51–1.01) and 0.74 (95% confidence interval, 0.53–1.05). The association of plasma PLP with cardiovascular risk was modified by gender (adjusted P_interaction = 0.04). When stratified according to gender, in women the prospective association with cardiovascular outcome was independent of age, smoking, alcohol consumption, high-sensitivity C-reactive protein, and GlycA (adjusted hazard ratio, 0.50, 95% confidence interval, 0.27–0.94), while it was not in men (adjusted hazard, 0.99, 95% confidence interval, 0.65–1.51). Conclusions: in this population-based cohort, plasma PLP was associated with cardiovascular outcome, but this association was confounded by traditional risk factors and parameters of inflammation. Notably, the association of low plasma PLP with high risk of adverse cardiovascular outcome was modified by gender, with a stronger and independent association in women.

Nutritional and medical food therapies for diabetic retinopathy

Diabetic retinopathy (DR) is a form of microangiopathy. Reducing oxidative stress in the mitochondria and cell membranes decreases ischemic injury and end-organ damage to the retina. New approaches are needed, which reduce the risk and improve the outcomes of DR while complementing current therapeutic approaches. Homocysteine (Hcy) elevation and oxidative stress are potential therapeutic targets in DR. Common genetic polymorphisms such as those of methylenetetrahydrofolate reductase (MTHFR), increase Hcy and DR risk and severity. Patients with DR have high incidences of deficiencies of crucial vitamins, minerals, and related compounds, which also lead to elevation of Hcy and oxidative stress. Addressing the effects of the MTHFR polymorphism and addressing comorbid deficiencies and insufficiencies reduce the impact and severity of the disease. This approach provides safe and simple strategies that support conventional care and improve outcomes. Suboptimal vitamin co-factor availability also impairs the release of neurotrophic and neuroprotective growth factors. Collectively, this accounts for variability in presentation and response of DR to conventional therapy. Fortunately, there are straightforward recommendations for addressing these issues and supporting traditional treatment plans. We have reviewed the literature for nutritional interventions that support conventional therapies to reduce disease risk and severity. Optimal combinations of vitamins B1, B2, B6, L-methylfolate, methylcobalamin (B12), C, D, natural vitamin E complex, lutein, zeaxanthin, alpha-lipoic acid, and n-acetylcysteine are identified for protecting the retina and choroid. Certain medical foods have been successfully used as therapy for retinopathy. Recommendations based on this review and our clinical experience are developed for clinicians to use to support conventional therapy for DR. DR from both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) have similar retinal findings and responses to nutritional therapies.

Association between serum folate and cardiovascular deaths among adults with hypertension

BACKGROUND

A significant shift toward high folate concentrations has been taking place following the mandatory folate fortification. Yet the relationship between folate and health outcomes beyond neural tube defects remains understudied. We longitudinally examined relationships between serum folate and risk of cardiovascular death.

METHODS

We analyzed data of 3116 adults aged ≥19 who participated in the Third National Health and Nutrition Examination Survey, 1991-1994 and were diagnosed with hypertension. Vital status was followed through December 31, 2010. Cox regression was used to estimate hazard ratios (HRs) of cardiovascular deaths for individuals with serum folate in the first quartile and fourth quartile compared with the patients with interquartile folate.

RESULTS

After 33627 person years (p*ys) of follow-up, 1298 deaths were recorded with 638 cardiovascular disease (CVD) deaths (109 strokes and 529 heart diseases). A U-shaped association appeared after multivariable adjustment for heart disease, acute myocardial infarction, and overall CVD deaths. The mortality rate for heart disease in patients with low, moderate, and high folate were 12.18/1000 p*ys, 14.12/1000 p*ys, and 23.80/1000 p*ys, respectively, and the corresponding adjusted HRs were 1.79 (95% confidence interval, CI = 1.63-1.98), 1.00 (reference), and 1.31 (1.17-1.46). The HRs of acute myocardial infarction were 2.28 (1.80-2.88), 1.00 (reference), and 1.77 (1.42-2.20) for hypertensive patients with serum folate in low quartile, interquartile, and high quartile, respectively.

CONCLUSIONS

Among hypertensive adults, both low and high folate were associated with an elevated risk of dying from cardiovascular diseases compared with adults with moderate serum folate concentration.

Interaction of serum vitamin B12 and folate with MTHFR genotypes on risk of ischemic stroke

OBJECTIVE

We evaluated the interaction of serum folate and vitamin B₁₂ with methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on the risk of first ischemic stroke and on the efficacy of folic acid treatment in prevention of first ischemic stroke.

METHODS

A total of 20,702 hypertensive adults were randomized to a double-blind treatment of daily enalapril 10 mg and folic acid 0.8 mg or enalapril 10 mg alone. Participants were followed up every 3 months.

RESULTS

Median values of folate and B₁₂ concentrations at baseline were 8.1 ng/mL and 280.2 pmol/L, respectively. Over a median of 4.5 years, among those not receiving folic acid, participants with baseline serum B₁₂ or serum folate above the median had a significantly lower risk of first ischemic stroke (hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.57-0.96), especially in those with MTHFR 677 CC genotype (wild-type) (HR, 0.49; 95% CI, 0.31-0.78). Folic acid treatment significantly reduced the risk of first ischemic stroke in participants with both folate and B₁₂ below the median (2.3% in enalapril-folic acid group vs 3.6% in enalapril-only group; HR, 0.62; 95% CI, 0.46-0.86), particularly in MTHFR 677 CC carriers (1.6% vs 4.9%; HR, 0.24; 95% CI, 0.11-0.55). However, TT homozygotes responded better with both folate and B₁₂ levels above the median (HR, 0.28; 95% CI, 0.10-0.75).

CONCLUSIONS

The risk of first ischemic stroke was significantly higher in hypertensive patients with low levels of both folate and B₁₂. Effect of folic acid treatment was greatest in patients with low folate and B₁₂ with the CC genotype, and with high folate and B₁₂ with the TT genotype.

Gradient Relationship between Increased Mean Corpuscular Volume and Mortality Associated with Cerebral Ischemic Stroke and Ischemic Heart Disease: A Longitudinal Study on 66,294 Taiwanese

The gradient relationship between mean corpuscular volume (MCV) and mortality due to ischemic vascular disease has not been researched using a large-scale population-based study. This study evaluated the association between MCV and death attributable to cerebrovascular disease (CVD) and cardiovascular disease (CAD) in a large population- and community-based Taiwanese cohort. A longitudinal study with a 9-year follow-up was conducted to evaluate individuals aged 20 years or older who had participated in the Keelung (the northernmost city in Taiwan) community-based integrated screening (abbreviated as KCIS) program since September 1999. The mortality rates associated with CVD and CAD were classified across a range of different MCV levels. Increased MCV levels were associated with an increased risk of CVD/CAD-related death (adjusted hazard ratio [aHR] = 1.42, trend test P = 0.0119). Marginally statistically significant associations were noted for specific deaths from ischemic heart disease (aHR = 1.44, trend test P = 0.0992) and cerebral ischemic stroke (aHR = 1.66, trend test P = 0.0667), respectively, but no significant gradient relationship was noted for death from cerebral hemorrhage stroke (aHR = 1.23, trend test, P = 0.6278). A gradient relationship between baseline MCV level and CVD/CAD-related death was noted, but whether such gradient relationships existed for two specific deaths and how these relationships may be confounded by extraneous factors that were not considered here should be investigated in the future.

Plasma Cystathionine and Risk of Incident Stroke in Patients With Suspected Stable Angina Pectoris

Background Cystathionine is an intermediate product in the transsulfuration pathway and formed during the B6-dependent conversion of methionine to cysteine. Elevated plasma cystathionine has been related to atherosclerosis, which is a major etiological factor for ischemic stroke. However, the role of cystathionine in stroke development is unknown. Therefore, we prospectively assessed the association of circulating levels of cystathionine with risk of total and ischemic stroke. Methods and Results Two-thousand thirty-six patients (64% men; median age, 62 years) undergoing coronary angiography for suspected stable angina pectoris were included. Stroke cases were identified by linkage to the CVDNOR (Cardiovascular Disease in Norway) project. Hazard ratios with confidence intervals (95% confidence interval) were estimated by using Cox-regression analyses. During 7.3 years of median follow-up, 124 (6.1%) incident strokes were ascertained, which comprised 100 cases of ischemic stroke. There was a positive association of plasma cystathionine with risk of total stroke and ischemic stroke. Comparing the fourth versus the first cystathionine quartiles, age- and sex-adjusted hazard ratios (95% confidence interval) were 2.11 (1.19-3.75) and 2.56 (1.31-4.99) for total and ischemic stroke, respectively. Additional adjustment for major stroke risk factors only slightly attenuated the associations, which tended to be stronger in patients without previous or existing atrial fibrillation at baseline (hazard ratio [95% confidence interval], 2.43 [1.27-4.65] and 2.88 [1.39-5.98] for total and ischemic stroke, respectively). Conclusions In patients with suspected stable angina pectoris, plasma cystathionine was independently related to increased risk of total stroke and, in particular, ischemic stroke. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 00354081.

Are serum concentrations of vitamin B-12 causally related to cardiometabolic risk factors and disease? A Mendelian randomization study

Background

Several observational studies have shown that low serum vitamin B-12 is associated with increased body mass index (BMI) and adverse cardiometabolic outcomes. However, it is unclear if these associations reflect a causal effect of vitamin B-12 on cardiometabolic risk factors and diseases, latent confounding, or reverse causality.

Objectives

The aims of this study were to investigate 1) the possible causal relation between vitamin B-12 and indicators of body fat, lipid, and glucose variables; type 2 diabetes (T2D); and cardiovascular disease by using a 2-sample Mendelian randomization (MR) method and 2) the possible pleiotropic role of fucosyltransferase 2 (FUT2).

Design

We selected 11 single nucleotide polymorphisms (SNPs) robustly associated with serum concentrations of vitamin B-12 in a previous genomewide association study (GWAS) in 45,576 individuals. We performed 2-sample MR analyses of the relation between vitamin B-12 and cardiometabolic risk factors and diseases with the use of publicly available GWAS summary statistics for 15 outcomes in ≤339,224 individuals. The robustness of results was tested with sensitivity analyses by using MR Egger regression and weighted-median estimation, and by performing additional analyses excluding a variant in the FUT2 gene, which may be pleiotropic.

Results

We found a suggestive causal relation between vitamin B-12 and fasting glucose and β cell function [homeostatic model assessment (HOMA) of β cell function (HOMA-B)]. However, we found no evidence that serum concentrations of vitamin B-12 were causally related to BMI, waist-to-hip ratio, plasma leptin, body fat, fasting insulin, insulin resistance (from HOMA of insulin resistance), glycated hemoglobin, triglycerides, T2D, coronary artery disease, or HDL, LDL, or total cholesterol.

Conclusions

We found no evidence that serum concentrations of vitamin B-12 are causally related to body weight or the majority of cardiometabolic outcomes investigated. However, vitamin B-12 may have a causal effect on fasting glucose and HOMA-B, although these results will require replication in large independent data sets. This trialwas registered at http://www.isrctn.com/ISRCTN47414943 as ISRCTN47414943.

Diet and primary prevention of stroke: Systematic review and dietary recommendations by the ad hoc Working Group of the Italian Society of Human Nutrition

BACKGROUND AND AIMS

To systematically review the latest evidence on established and emerging nutrition-related risk factors for incidence of and mortality from total, ischemic and haemorrhagic strokes. The present review was conducted in the framework of the work carried out through 2015 and 2016 for the preparation of the Italian Guidelines for the Prevention and Treatment of Stroke, 8th Edition, by ISO-SPREAD (Italian Stroke Organization and the Stroke Prevention and Educational Awareness Diffusion).

METHODS AND RESULTS

Systematic review of articles focused on primary prevention of stroke published between January 2013 to May 2016 through an extensive search of the literature using MEDLINE/PUBMED, EMBASE and the Cochrane Library. Articles were ranked according to the SIGN methodology while the GRADE system was used to establish the strength of recommendations. As a result of our literature search, we examined 87 meta-analyses overall (mainly of prospective studies), a few isolated more recent prospective studies not included in the meta-analyses, and a smaller number of available randomized controlled trials and case-control studies. Based on the analysis of the above articles, 36 Syntheses of the available evidence and 36 Recommendations were eventually prepared. The present document was developed by organizing the available evidence into three individual areas (nutrients, food groups and dietary patterns) to provide a systematic and user-friendly overview of the available evidence on the relationship between nutrition and primary prevention of stroke. Yet analysis of foods and food patterns allowed translating the information about nutrients in a tool more amenable to use in daily life also in the light of the argument that people eat foods rather than nutrients.

CONCLUSIONS

The present literature review and dietary recommendations provide healthcare professionals and all interested readers with a useful overview for the reduction of the risk of total, ischemic and haemorrhagic stroke through dietary modifications.

Vitamin B12

The biosynthesis of B₁₂, involving up to 30 different enzyme-mediated steps, only occurs in bacteria. Thus, most eukaryotes require an external source of B₁₂, and yet the vitamin appears to have only two functions in eukaryotes: as a cofactor for the enzymes methionine synthase and methylmalonylCoA mutase. These two functions are crucial for normal health in humans, and in particular, the formation of methionine is essential for providing methyl groups for over 100 methylation processes. Interference with the methionine synthase reaction not only depletes the body of methyl groups but also leads to the accumulation of homocysteine, a risk factor for many diseases. The syndrome pernicious anemia, characterized by lack of intrinsic factor, leads to a severe, sometimes fatal form of B₁₂ deficiency. However, there is no sharp cutoff for B₁₂ deficiency; rather, there is a continuous inverse relationship between serum B₁₂ and a variety of undesirable outcomes, including neural tube defects, stroke, and dementia. The brain is particularly vulnerable; in children, inadequate B₁₂ stunts brain and intellectual development. Suboptimal B₁₂ status (serum B₁₂<300pmol/L) is very common, occurring in 30%-60% of the population, in particular in pregnant women and in less-developed countries. Thus, many tens of millions of people in the world may suffer harm from having a poor B₁₂ status. Public health steps are urgently needed to correct this inadequacy.

Association between hyperhomocysteinemia and stroke with atherosclerosis and small artery occlusion depends on homocysteine metabolism-related vitamin levels in Chinese patients with normal renal function

This study was conducted to investigate the role of different homocysteine metabolism-related vitamin (HMRV) levels in the correlation between hyperhomocysteinemia (HHCY) and ischemic stroke (IS) subtypes. Three hundred and forty-eight IS patients manifesting different vascular subtypes were subclassified on the basis of HMRV deficiencies. Correlation between HHCY and IS subtypes was investigated in all the subgroups. In this study, HHCY was significantly correlated with the IS subtypes in large artery atherosclerosis (OR 1.126, 95%CI: 1.051 ~ 1.206, P = 0.001) and small artery occlusion (OR 1.105, 95%CI: 1.023 ~ 1.193, P = 0.012). Subgroup analysis revealed a correlation between HHCY and IS subgroup (OR 1.201, 1.178, 95%CI: 1.081 ~ 1.334, 1.058 ~ 1.313, P = 0.001, P = 0.003, respectively) in HMRV deficiency, but not significantly with the IS subgroup in normal HMRV levels. Serum vitamin B12 concentrations are inversely correlated with both IS subtypes in HMRV deficiency subgroups (OR 0.992, 0.995, 95%CI: 0.987 ~ 0.996, 0.991 ~ 0.999, P < 0.001, P = 0.007, respectively), which may contribute to HHCY incidence in these populations. The correlation between HHCY and IS subtypes is affected by HMRV levels in this case-control study. Our findings are helpful to understand the inconsistency in prior homocysteine studies. Serum vitamin B12 levels may play a critical role in HHCY incidence in this Chinese population.Cerebrovascular disease has emerged as the leading cause of disability and mortality in both urban and rural areas of China (Neurology branch of Chinese Medical Association 2015). Ischemic stroke (IS) constitutes 60% to 80% of all cerebrovascular disease (Neurology branch of Chinese Medical Association 2014). Among a variety of risk factors, hyperhomocysteinemia (HHCY) has been closely correlated with IS due to intracranial small-vessel disease and extracranial large-artery disease (Selhub et al. 1995; Eikelboom et al. 2000; Alvarez et al. 2012; Jeon et al. 2014). However, the failure to lower homocysteine (HCY) via homocysteine metabolism-related vitamin (HMRV, including folic acid and vitamin B12 but not vitamin B6 in this study) supplementation to reduce stroke morbidity questions the role of HCY as a risk factor for stroke (Lonn et al. 2006; Hankey et al. 2010). Theoretically, HMRV supplementation merely lowers the incidence of stroke induced by HHCY resulting from HMRV deficiency, whereas HHCY-induced stroke concomitant with normal HMRV levels may be refractory to treatment. The correlation between HCY varying with HMRV levels and IS subtypes is still unclear. In this study, we investigated the impact of variation in HMRV levels on the correlation between HHCY and IS subtypes in 348 acute IS patients with large and small vessel diseases. We sought to determine the factors underlying the conflicting results associated with lowering HCY by HMRV supplementation to reduce stroke incidence.

Vitamin B12 deficiency is associated with adverse lipid profile in Europeans and Indians with type 2 diabetes

Background

Metformin, a standard therapy in type 2 diabetes, reduces vitamin B12 levels. Studies linking low vitamin B12 levels and cardiovascular disease are equivocal and suggest improving B12 levels may help in primary prevention. The role of vitamin B12 deficiency on cardiovascular risk factors, especially in type 2 diabetes has not been explored. The aim of this study is to investigate whether vitamin B12 deficiency in type 2 diabetes patients is associated with cardiovascular risk factors in two different ethnic groups in UK and India.

Methods

Type 2 diabetes patients from two secondary care diabetic centres (Europeans - UK and Indians - India) were studied. Serum vitamin B12, folate and biochemical parameters were measured.

Results

The prevalence rates of vitamin B12 deficiency (<191 ng/L) were 27% and 12% in Europeans and Indians, respectively and higher in metformin treated type 2 diabetes patients. In linear regression analysis, after adjusting for all likely confounding factors, vitamin B12 independently associated with triglycerides in both the populations and cholesterol/HDL ratio in Indians. Logistic regression showed type 2 diabetes patients with vitamin B12 deficiency were at significantly higher odds of having coexisting coronary artery disease (CAD) in Europeans with similar but non-significant trend in Indians, after adjusting for all likely confounding factors.

Conclusions

The prevalence of vitamin B12 deficiency is common in type 2 diabetes patients and is associated with adverse lipid parameters. Type 2 diabetes management guidelines should include the recommendation for regular testing for B12 levels, especially for those on metformin.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-014-0129-4) contains supplementary material, which is available to authorized users.

Dietary folic acid intake differentially affects methionine metabolism markers and hippocampus morphology in aged rats

PURPOSE

Folic acid (FA) is an emerging nutritional factor in the pathogenesis of diverse neurodegenerative disorders by still unknown mechanisms. The hippocampus is altered during the loss of cognitive abilities in humans and selectively affected when homocysteine increases. The aim was to evaluate the potential protective role of folic acid in the maintenance of biochemical markers related to the methionine cycle, as well as the integrity of the hippocampus as part of the brain in aged rats.

METHODS

Male Sprague-Dawley rats (18 months old) were assigned to four different folic acid groups (0 mg FA/kg diet, deficient; 2 mg FA/kg diet, control; 8 mg FA/kg diet, moderate supplementation; 40 mg FA/kg diet, extra supplementation) for 30 days. We evaluated several parameters related to the methionine cycle. In addition, hippocampus areas were immunostained for specific neuronal markers and astrocytes.

RESULTS

Serum folate levels increased according to FA dietary level (p < 0.01). There was a significant increase in the serum homocysteine concentrations in the folic acid-deficient diet group (p < 0.01). However, brain S-adenosylmethionine and S-adenosylhomocysteine did not differ significantly between the folic acid groups. Consequently, the methylation ratio was also unchanged. The morphometric analysis did not show any differences in the number of neurons and astrocytes between groups, except when comparing the folic acid-deficient diet versus folic acid-supplemented diet in the striatum of the hippocampus.

CONCLUSIONS

Clearly, the dietary FA deficiency negatively affects the methionine metabolism biomarkers, while excessive supplementation seems to be unnecessary for optimal maintenance of the methylation cycle and hippocampus integrity.

Atherosclerotic and thrombophilic risk factors in patients with ischemic central retinal vein occlusion

PURPOSE

To investigate atherosclerotic and thrombophilic risk factors in patients affected by acute ischemic and nonischemic central retinal vein occlusions (CRVOs).

METHODS

One hundred and three patients with acute unilateral CRVO (41 ischemic and 62 nonischemic) were studied. The frequency of traditional cardiovascular risk factors was assessed, and the plasma levels of a variety of thrombophilic markers were measured. Univariate logistic regression was performed to determine risk factors for ischemic CRVO.

RESULTS

Arterial hypertension, hypercholesterolemia, postmethionine hyperhomocysteinemia (HHcy), elevated factor VIII, and reduced folic acid and B6 plasma levels were more frequent in patients with ischemic CRVO than in those with nonischemic CRVO (P = 0.030, P = 0.025, P = 0.011, P < 0.001, P < 0.001, and P = 0.044, respectively). Risk factors for ischemic CRVO were arterial hypertension (odds ratio [OR], 3.22; 95% confidence interval [CI], 1.13-9.21; P = 0.037), hypercholesterolemia (OR, 3.03; 95% CI, 1.06-8.65; P = 0.042), reduced folic acid levels (OR, 6.77; 95% CI, 1.59-28.79; P = 0.011), and elevated FVIII levels (OR, 6.17; 95% CI, 2.56-14.82; P < 0.001). Postmethionine HHcy was associated with low folic acid levels (r = -0.413; P = 0.007; OR, 9.33; 95% CI, 2.06-42.18; P = 0.005).

CONCLUSION

The results of the present study suggest that some atherosclerotic and thrombophilic risk factors may increase the risk of having an ischemic form of CRVO.

Is a low blood level of vitamin B12 a cardiovascular and diabetes risk factor? A systematic review of cohort studies

PURPOSE

To assess the prior hypothesis that low blood vitamin B12, partly through hyperhomocysteinemia and partly through direct effects, increases the risk of cardiovascular diseases and diabetes. As background, we also extracted all-cause mortality from the studies that met our criteria.

METHODS

A systematic review of prospective cohort studies identified through searching six electronic databases, screening of reference lists, and citation search. Included studies reported data on the association between vitamin B12 blood levels, or other appropriate surrogate biological markers e.g. holotranscobalamin or serum/urine methylmalonic acid, and fatal or non-fatal incident diabetes and cardiovascular events.

RESULTS

Seven studies were included. Studies differed regarding the population studied, length of follow-up, study outcomes, and data analysis--a narrative synthesis approach was performed to examine the results. Most studies met few of the quality assessment criteria which were adapted from the Scottish Intercollegiate Guidelines Network (SIGN). Only one high-quality study reported that low B12 increased the risk of incident cerebral ischaemia (RR = 1.76; 95% CI = 1.16-2.68). After controlling for homocysteine, the association persisted although weakened (RR = 1.57; 95% CI = 1.02-2.43), suggesting that the effects of low B12 were only partly mediated by homocysteine. In two studies, higher B12 levels were associated with a greater risk of total mortality (RR = 1.00; 95% CI = 1.00-1.00 and HR = 1.15; 95% CI = 1.08-1.22, respectively) and combined fatal and non-fatal coronary events (RR = 1.00; 95% CI = 1.00-1.00). No association between study outcomes and vitamin B12 levels was found in four other studies.

CONCLUSIONS

Surprisingly, there is only very limited evidence that vitamin B12 deficiency predisposes to the risk of mortality and morbidity from either cardiovascular diseases or diabetes in adults. Current data do not support vitamin B12 supplementation to reduce the risk of cardiovascular diseases or diabetes.

Homocysteine, vitamin B12 and folate levels in Iranian patients with ischemic stroke

OBJECTIVES

Homocysteine, folate, and some group B vitamins have been proposed as a cause of Cerebro-Vascular Accidents (CVA). We conducted a case-control study to compare the plasma levels of folate, vitamin B12 and homocysteine in Iranian subjects with and without cerebro-vascular accident.

METHODS

We recruited 82 patients with ischemic stroke as cases and 60 subjects as controls (using simple nonrandom sampling). Homocysteine was measured by fluorimetric high-performance liquid chromatography. Plasma folate and vitamin B12 levels were measured by an ion-capture method.

RESULTS

Mean plasma level of vitamin B12 in cases and controls were 358.4 ± 290.3 Pg/ml and 369.8 ± 110.4 Pg/ml, respectively which did not show any significant difference. Mean plasma level of folate in cases was significantly lower than the controls (6.8 ± 4.5 ng/ml vs. 12.2 ± 3.0 ng/ml, p = 0.001). It was also shown that mean plasma level of total homocysteine in cases was significantly higher than the controls (21.1 ± 9.8 μM/L vs. 13.5 ± 3.2 μM/L, P=0.001). Homocysteine and folate but not plasma B12 had linear relation with age. Male cases had significantly lower Folate and B12 in contrast to women. In addition, male cases had significantly higher Homocysteine level in contrast to women.

CONCLUSIONS

Our data shows that the level of homocysteine was higher and the level of folate was significantly lower in patients with ischemic stroke in contrast to controls. Effectiveness of supplementary folate and B 12 in such patients needs further well-structured prospective placebo controlled studies.

Periventricular White Matter Lucencies Relate to Low Vitamin B12 Levels in Patients With Small Vessel Stroke

Background and Purpose— Blood–brain barrier dysfunction may be an early phenomenon in the development of the small vessel disease, which underlies white matter lesions. Because vitamin B12 plays a role in maintaining the integrity of the blood–brain barrier, we studied serum vitamin B12 level in relation to such lesions.

Methods— In 124 patients with first lacunar stroke, we measured serum vitamin B12 level and rated the degree of white matter lesions on MRI.

Results— Mean vitamin B12 level was 202 pmol/L (SD, 68.9). Thirty-nine patients (31.5%) had a vitamin B12 level less than the lower reference value of 150 pmol/L. Lower vitamin B12 level was (statistically significant) associated with more severe periventricular white matter lesions (odds ratio/100 pmol/L decrease, 1.773; 95% CI, 1.001–3.003), but not with deep white matter lesions (odds ratio/100 pmol/L decrease, 1.441; 95% CI, 0.881–2.358; ordered multivariate regression analysis).

Conclusions— More severe periventricular white matter lesions in lacunar stroke patients relate to lower vitamin B12 levels. A possible causal relationship should now be studied prospectively.

Dietary sources of vitamin B-12 and their association with plasma vitamin B-12 concentrations in the general population: the Hordaland Homocysteine Study

BACKGROUND

Limited information is available on the association between vitamin B-12 status and intake from different dietary sources.

OBJECTIVE

We investigated the relation of dietary intake of different food items with plasma vitamin B-12 concentrations in the general population.

DESIGN

A cross-sectional, population-based study of 5937 subjects in 2 age groups (47-49 and 71-74 y) from the Hordaland Homocysteine Study in Norway was conducted by using a food-frequency questionnaire and measurements of plasma vitamin B-12 concentrations.

RESULTS

A significant difference in plasma vitamin B-12 concentrations was observed with increasing total vitamin B-12 intake. A plateau was reached at an intake of approximately 10 microg/d. Plasma vitamin B-12 was associated with intakes of increasing amounts of vitamin B-12 from dairy products or fish (P for trend <0.001 for both) but not with intakes of vitamin B-12 from meat or eggs. For the same content of vitamin B-12, intake from dairy products led to the greatest increase in plasma vitamin B-12. Total intake of vitamin B-12, particularly from milk and fish, decreased the risk of vitamin B-12 concentrations <200 pmol/L and impaired vitamin B-12 function (vitamin B-12 <200 pmol/L and methylmalonic acid >0.27 micromol/L) in the total group and in 71-74-y-old subjects.

CONCLUSIONS

Dietary intake of dairy products and fish are significant contributors to plasma vitamin B-12 and may improve plasma vitamin B-12 status. Vitamin B-12 appears to be more bioavailable from dairy products; guidelines for improving vitamin B-12 status should take this into consideration.

Urinary methylmalonic acid levels in patients with acute ischemic stroke

OBJECTIVES

Vitamin B-12 and folate deficiency are common, especially in people aged 55 or over, and accompanied by elevated methylmalonic acid (MMA) and homocysteine concentrations. The aims of the study were to investigate the relationship between serum vitamin B-12, homocysteine, folate, erythrocyte folate and urinary MMA in patients with ischemic stroke, and to develop a simple screening HPLC method for the measurement of urinary MMA.

DESIGN AND METHODS

Twenty-eight patients aged 55 years and over with ischemic stroke and 23 age- and sex- matched healthy controls were included in the study. Serum vitamin B-12 and folate were measured by immunoassay; serum total homocysteine and urinary MMA concentrations by HPLC.

RESULTS

There was no significant difference in vitamin B-12, folate and homocysteine concentrations between the patient and control groups. Urinary MMA concentrations and erythrocyte folate levels were significantly higher in patients than controls. There was a significantly negative correlation between vitamin B-12 and MMA.

CONCLUSIONS

Increased urinary MMA excretion is associated with ischemic stroke and it may more robustly reflect vitamin B-12 deficiency in patients with ischemic stroke. The method used in this study is eligible for routine urinary MMA measurements.

Is ischemic stroke risk related to folate status or other nutrients correlated with folate intake?

BACKGROUND AND PURPOSE

Folate status was inversely associated with plasma homocysteine concentration, a potential risk factor of cardiovascular disease. However, it is uncertain whether folate is causally associated with risk of ischemic stroke (IS). We aimed to examine the association between IS incidence and folate intake, biochemical folate status, and folate associated nutrients.

METHODS

Information on baseline characteristics and food frequency questionnaire was collected in 1990 to 1993 and included for analyses data from 1772 adults over 40 years, who were free of stroke and cancer at baseline from the CardioVascular Disease risk FACtor Two-township Study. Multivariate Cox proportional hazard model was used to relate baseline nutrient status with IS event.

RESULTS

Over an average of 10.6 years of follow-up, 132 incident IS events were documented. Low folate intake (1st and 2nd quartiles) was significantly and independently associated with increased IS risk (HR=1.61; 95% CI: 1.04 to 2.48 and HR=1.82; 95% CI: 1.20 to 2.76) compared with those in the 3rd and 4th quartile combined, whereas no association was observed for plasma folate concentration. On the other hand, several nutrients correlated with dietary folate: vitamin B2, potassium, iron, vitamin A of plant origin, calcium were also associated with IS risk in an inverse linear manner with HR ranging from 1.5 to 1.9 for the first quartile.

CONCLUSIONS

The protective association of dietary folate on IS risk may be in part through that of other correlated nutrients or other dietary components.