[Sodium glucose cotransporter-2 inhibitors (SGLT2i) and risk of ketoacidosis]

SGLT2i can induce euglycemic diabetic ketoacidosis (eDKA) in conditions with relative insulin deficiency, such as infections, surgery, or fasting state. In comparison with classical DKA, eDKA typically presents with lower blood glucose levels and more diffuse symptoms like tiredness, tachypnea, nausea and abdominal pain. The diagnosis is commonly delayed, and signs are often attributed to other factors. Early diagnosis and prevention are critical due to the risk of lethal outcome or prolonged hospital stay. Generous screening for ketonemia in risk situations allows identification of eDKA. To minimize the risk, we propose that SGLT2i should be discontinued 3-4 days before surgery (1-2 weeks prior to bariatric surgery) and during infections, acute disease, or poor oral intake. Postoperative slow infusion of low-dose insulin may prevent eDKA if SGLT2i could not be stopped in time or in prolonged fasting state. In this overview, the pathogenesis behind eDKA is discussed.

Healthy Nordic diet and associations with plasma concentrations of metabolites in the choline oxidation pathway: a cross-sectional study from Northern Sweden

BACKGROUND

The choline oxidation pathway and metabolites involved have been linked to diseases including cardiovascular disease, type 2 diabetes and cancer. A healthy Nordic diet is a recently defined dietary pattern associated with decreased risk for these diseases. Our aim was to explore associations between adherence to a healthy Nordic diet and plasma concentrations of metabolites of the choline oxidation pathway.

METHODS

The Healthy Nordic Food Index (HNFI) and Baltic Sea Diet Score (BSDS) were applied to cross-sectional data (n = 969) from the Västerbotten Intervention Programme in Northern Sweden to score adherence to a healthy Nordic diet. Data included responses to a dietary questionnaire and blood sample analyses (1991-2008). Associations of diet scores with plasma concentrations of metabolites of the choline oxidation pathway and total homocysteine (tHcy), seven metabolites in total, were evaluated with linear regression, adjusting for age, BMI, education and physical activity.

RESULTS

HNFI scores showed linear relationships with plasma choline (β = 0.11), betaine (β = 0.46), serine (β = 0.98) and tHcy (β =  - 0.38), and BSDS scores with betaine (β = 0.13) and tHcy (β =  - 0.13); unstandardized beta coefficients, all significant at P < 0.05. The regression models predicted changes in plasma metabolite concentrations (± 1 SD changes in diet score) in the range of 1-5% for choline, betaine, serine and tHcy. No other statistically significant associations were observed.

CONCLUSIONS

A healthy Nordic diet was associated with plasma concentrations of several metabolites of the choline oxidation pathway. Although relationships were statistically significant, effect sizes were moderate. Further research is warranted to explore the underlying mechanisms and associations with health outcomes.

Elevated plasma cotinine is associated with an increased risk of developing IBD, especially among users of combusted tobacco

OBJECTIVE

Smoking has previously been associated with inflammatory bowel disease (IBD), but no study has reported on cotinine, an objective, biochemical measure of tobacco use. We aimed at testing the hypothesis that cotinine levels among healthy subjects are associated with an increased risk of developing IBD in later life.

DESIGN

We analysed plasma cotinine and evaluated corresponding lifestyle questionnaires that included tobacco habits in subjects (n = 96) who later developed late-onset IBD (70 ulcerative colitis (UC) and 26 Crohn's disease (CD)) and in sex and age-matched controls (n = 191).

RESULTS

Patients who later developed IBD had significantly higher plasma cotinine levels compared to controls. In multivariable analysis, higher log-cotinine was associated with a higher risk of developing IBD (OR 1.34 (95% CI 1.01-1.63)). After stratifying for time to diagnosis, the association was only significant in subjects with shorter time (< 5.1 years) to diagnosis (OR 1.45 (1.09-1.92)). The findings were similar for UC- and CD-cases, but did not reach statistical significance in CD-cases. Although plasma cotinine concentrations were higher in snuff users compared to combusted tobacco users, no increase in the risk of IBD and lower risk of developing IBD among subjects with shorter time (< 5.1 years) to diagnosis was seen among snuff users.

CONCLUSIONS

Cotinine, a biomarker of tobacco use, is associated with increased risk of developing late-onset IBD in general, and UC in particular. No increased risk among snuff users indicates that other components in combusted tobacco than nicotine may be involved in the pathogenesis of IBD among smokers.

Maternal blood folate status during early pregnancy and occurrence of autism spectrum disorder in offspring: a study of 62 serum biomarkers

BACKGROUND

Autism spectrum disorder (ASD) evolves from an interplay between genetic and environmental factors during prenatal development. Since identifying maternal biomarkers associated with ASD risk in offspring during early pregnancy might result in new strategies for intervention, we investigated maternal metabolic biomarkers in relation to occurrence of ASD in offspring using both univariate logistic regression and multivariate network analysis.

METHODS

Serum samples from 100 women with an offspring diagnosed with ASD and 100 matched control women with typically developing offspring were collected at week 14 of pregnancy. Concentrations of 62 metabolic biomarkers were determined, including amino acids, vitamins (A, B, D, E, and K), and biomarkers related to folate (vitamin B₉) metabolism, lifestyle factors, as well as C-reactive protein (CRP), the kynurenine-tryptophan ratio (KTR), and neopterin as markers of inflammation and immune activation.

RESULTS

We found weak evidence for a positive association between higher maternal serum concentrations of folate and increased occurrence of ASD (OR per 1 SD increase: 1.70, 95% CI 1.22-2.37, FDR adjusted P = 0.07). Multivariate network analysis confirmed expected internal biochemical relations between the biomarkers. Neither inflammation markers nor vitamin D₃ levels, all hypothesized to be involved in ASD etiology, displayed associations with ASD occurrence in the offspring.

CONCLUSIONS

Our findings suggest that high maternal serum folate status during early pregnancy may be associated with the occurrence of ASD in offspring. No inference about physiological mechanisms behind this observation can be made at the present time because blood folate levels may have complex relations with nutritional intake, the cellular folate status and status of other B-vitamins. Therefore, further investigations, which may clarify the potential role and mechanisms of maternal blood folate status in ASD risk and the interplay with other potential risk factors, in larger materials are warranted.

Dietary folate intake and pancreatic cancer risk: Results from the European prospective investigation into cancer and nutrition

Pancreatic cancer (PC) has an exceptionally low survival rate and primary prevention strategies are limited. Folate plays an important role in one-carbon metabolism and has been associated with the risk of several cancers, but not consistently with PC risk. We aimed to investigate the association between dietary folate intake and PC risk, using the standardised folate database across 10 European countries. A total of 477,206 participants were followed up for 11 years, during which 865 incident primary PC cases were recorded. Folate intake was energy-adjusted using the residual method. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. In multivariable analyses stratified by age, sex, study centre and adjusted for energy intake, smoking status, BMI, educational level, diabetes status, supplement use and dietary fibre intake, we found no significant association between folate intake and PC risk: the HR of PC risk for those in the highest quartile of folate intake (≥353 μg/day) compared to the lowest (<241 μg/day) was 0.81 (95% CI: 0.51, 1.31; ptrend = 0.38). In current smokers, a positive trend was observed in PC risk across folate quartiles [HR = 4.42 (95% CI: 1.05, 18.62) for ≥353 μg/day vs. <241 μg/day, ptrend = 0.01]. Nonetheless, there was no significant interaction between smoking and dietary folate intake (pinteraction = 0.99). We found no association between dietary folate intake and PC risk in this large European study.

One-carbon metabolite ratios as functional B-vitamin markers and in relation to colorectal cancer risk

One‐carbon metabolism biomarkers are easily measured in plasma, but analyzing them one at a time in relation to disease does not take into account the interdependence of the many factors involved. The relative dynamics of major one‐carbon metabolism branches can be assessed by relating the functional B‐vitamin marker total homocysteine (tHcy) to transsulfuration (total cysteine) and methylation (creatinine) outputs. We validated the ratios of tHcy to total cysteine (Hcy:Cys), tHcy to creatinine (Hcy:Cre) and tHcy to cysteine to creatinine (Hcy:Cys:Cre) as functional markers of B‐vitamin status. We also calculated the associations of these ratios to colorectal cancer (CRC) risk. Furthermore, the relative contribution of potential confounders to the variance of the ratio‐based B‐vitamin markers was calculated by linear regression in a nested case–control study of 613 CRC cases and 1,190 matched controls. Total B‐vitamin status was represented by a summary score comprising Z‐standardized plasma concentrations of folate, cobalamin, betaine, pyridoxal 5′‐phosphate and riboflavin. Associations with CRC risk were estimated using conditional logistic regression. We found that the ratio‐based B‐vitamin markers all outperformed tHcy as markers of total B‐vitamin status, in both CRC cases and controls. In addition, associations with CRC risk were similar for the ratio‐based B‐vitamin markers and total B‐vitamin status (approximately 25% lower risk for high vs. low B‐vitamin status). In conclusion, ratio‐based B‐vitamin markers were good predictors of total B‐vitamin status and displayed similar associations as total B‐vitamin status with CRC risk. Since tHcy and creatinine are routinely clinically analyzed, Hcy:Cre could be easily implemented in clinical practice.

What's new?

While total homocysteine (tHcy) levels are an important biomarker of B‐vitamin status and may be predictive for colorectal cancer (CRC) risk, they are influenced by a variety of factors, such as age, sex, and lifestyle. Here, tHcy was compared to ratio‐based biomarkers of total B‐vitamin status to assess functionality and relation to CRC risk. In CRC patients and controls, the ratio‐based markers outperformed tHcy as indicators of total B‐vitamin status. Their association with CRC risk was similar to that of total B‐vitamin status. Ratio‐based biomarkers could fill a valuable role in assessments of functional B‐vitamin levels and disease risk.

Long-Term Effectiveness of Sigmoidoscopy Screening on Colorectal Cancer Incidence and Mortality in Women and Men: A Randomized Trial

BACKGROUND

The long-term effects of sigmoidoscopy screening on colorectal cancer (CRC) incidence and mortality in women and men are unclear.

OBJECTIVE

To determine the effectiveness of flexible sigmoidoscopy screening after 15 years of follow-up in women and men.

DESIGN

Randomized controlled trial. (ClinicalTrials.gov: NCT00119912).

SETTING

Oslo and Telemark County, Norway.

PARTICIPANTS

Adults aged 50 to 64 years at baseline without prior CRC.

INTERVENTION

Screening (between 1999 and 2001) with flexible sigmoidoscopy with and without additional fecal blood testing versus no screening. Participants with positive screening results were offered colonoscopy.

MEASUREMENTS

Age-adjusted CRC incidence and mortality stratified by sex.

RESULTS

Of 98 678 persons, 20 552 were randomly assigned to screening and 78 126 to no screening. Adherence rates were 64.7% in women and 61.4% in men. Median follow-up was 14.8 years. The absolute risks for CRC in women were 1.86% in the screening group and 2.05% in the control group (risk difference, -0.19 percentage point [95% CI, -0.49 to 0.11 percentage point]; HR, 0.92 [CI, 0.79 to 1.07]). In men, the corresponding risks were 1.72% and 2.50%, respectively (risk difference, -0.78 percentage point [CI, -1.08 to -0.48 percentage points]; hazard ratio [HR], 0.66 [CI, 0.57 to 0.78]) (P for heterogeneity = 0.004). The absolute risks for death from CRC in women were 0.60% in the screening group and 0.59% in the control group (risk difference, 0.01 percentage point [CI, -0.16 to 0.18 percentage point]; HR, 1.01 [CI, 0.77 to 1.33]). The corresponding risks for death from CRC in men were 0.49% and 0.81%, respectively (risk difference, -0.33 percentage point [CI, -0.49 to -0.16 percentage point]; HR, 0.63 [CI, 0.47 to 0.83]) (P for heterogeneity = 0.014).

LIMITATION

Follow-up through national registries.

CONCLUSION

Offering sigmoidoscopy screening in Norway reduced CRC incidence and mortality in men but had little or no effect in women.

PRIMARY FUNDING SOURCE

Norwegian government and Norwegian Cancer Society.

Impact of clinical pharmacist engagement in ward teams on the number of drug-related readmissions among older patients with dementia or cognitive impairment: An economic evaluation

BACKGROUND

Clinical pharmacists play an increasing role in the pharmacological treatment of hospital-admitted older patients with dementia or cognitive impairment. In an earlier randomised controlled trial, clinical pharmacist involvement in the ward team could significantly reduce drug-related readmissions in patient subgroups. However, the economic impact of the intervention has not been addressed so far.

OBJECTIVES

To evaluate the economic impact of clinical pharmacist engagement in hospital ward teams for medication therapy management in older patients with dementia or cognitive impairments.

METHODS

Economic evaluation of a randomised controlled trial conducted in two hospitals in Northern Sweden between January 2012 and December 2014. Participants included 460 hospital-admitted older patients with dementia or cognitive impairments. Patients were randomly assigned to usual care, or usual care with pharmacist intervention; the intervention consisted of medication reconciliation, medication review, and participation in ward rounds. The outcomes were measured as drug-related readmissions to hospital as assessed by a group of external experts, 180 and 30 days after discharge. Costs included pharmacists' direct labour costs for the interventions, average costs for drug-related readmissions, and from this the total cost per person was calculated.

RESULTS

The effect of the intervention on drug-related readmissions within 180 days was significant in patients without heart failure (subgroup analysis), and the intervention resulted in cost savings of €950 per person in this subgroup. Drug-related readmissions within 30 days were reduced in the total sample (post-hoc analysis), and the cost-savings in this intervention group were €460 per person.

CONCLUSIONS

Post-hoc and subgroup analyses indicate that engagement of pharmacists in hospital ward teams reduced the number of drug-related readmissions, and that the cost per person was lower in the intervention group compared to the control group. Including clinical pharmacists created savings in the subgroups of older patients with dementia or cognitive impairments.

One-carbon metabolism biomarkers and genetic variants in relation to colorectal cancer risk by KRAS and BRAF mutation status

Disturbances in one-carbon metabolism, intracellular reactions involved in nucleotide synthesis and methylation, likely increase the risk of colorectal cancer (CRC). However, results have been inconsistent. To explore whether this inconsistency could be explained by intertumoral heterogeneity, we evaluated a comprehensive panel of one-carbon metabolism biomarkers and some single nucleotide polymorphisms (SNPs) in relation to the risk of molecular subtypes of CRC defined by mutations in the KRAS and BRAF oncogenes. This nested case-control study included 488 CRC cases and 947 matched controls from two population-based cohorts in the Northern Sweden Health and Disease Study. We analyzed 14 biomarkers and 17 SNPs in prediagnostic blood and determined KRAS and BRAF mutation status in tumor tissue. In a multivariate network analysis, no variable displayed a strong association with the risk of specific CRC subtypes. A non-synonymous SNP in the CTH gene, rs1021737, had a stronger association compared with other variables. In subsequent univariate analyses, participants with variant rs1021737 genotype had a decreased risk of KRAS-mutated CRC (OR per allele = 0.72, 95% CI = 0.50, 1.05), and an increased risk of BRAF-mutated CRC (OR per allele = 1.56, 95% CI = 1.07, 2.30), with weak evidence for heterogeneity (P_{heterogeneity} = 0.01). This subtype-specific SNP association was not replicated in a case-case analysis of 533 CRC cases from The Cancer Genome Atlas (P = 0.85). In conclusion, we found no support for clear subtype-specific roles of one-carbon metabolism biomarkers and SNPs in CRC development, making differences in CRC molecular subtype distributions an unlikely explanation for the varying results on the role of one-carbon metabolism in CRC development across previous studies. Further investigation of the CTH gene in colorectal carcinogenesis with regards to KRAS and BRAF mutations or other molecular characteristics of the tumor may be warranted.

Components of One-carbon Metabolism Other than Folate and Colorectal Cancer Risk

BACKGROUND

Despite extensive study, the role of folate in colorectal cancer remains unclear. Research has therefore begun to address the role of other elements of the folate-methionine metabolic cycles. This study investigated factors other than folate involved in one-carbon metabolism, i.e., choline, betaine, dimethylglycine, sarcosine, and methionine and relevant polymorphisms, in relation to the risk of colorectal cancer in a population with low intakes and circulating levels of folate.

METHODS

This was a prospective case-control study of 613 case subjects and 1,190 matched control subjects nested within the population-based Northern Sweden Health and Disease Study. We estimated odds ratios (OR) by conditional logistic regression, and marginal risk differences with weighted maximum likelihood estimation using incidence data from the study cohort.

RESULTS

Higher plasma concentrations of methionine and betaine were associated with modest colorectal cancer risk reductions (OR [95% confidence interval {CI}] for highest versus lowest tertile: 0.76 [0.57, 0.99] and 0.72 [0.55, 0.94], respectively). Estimated marginal risk differences corresponded to approximately 200 fewer colorectal cancer cases per 100,000 individuals on average. We observed no clear associations between choline, dimethylglycine, or sarcosine and colorectal cancer risk. The inverse association of methionine was modified by plasma folate concentrations (OR [95% CI] for highest/lowest versus lowest/lowest tertile of plasma methionine/folate concentrations 0.39 [0.24, 0.64], Pinteraction = 0.06).

CONCLUSIONS

In this population-based, nested case-control study with a long follow-up time from baseline to diagnosis (median: 8.2 years), higher plasma concentrations of methionine and betaine were associated with lower colorectal cancer risk.See Video Abstract at http://links.lww.com/EDE/B83.

Effects of Pharmacists' Interventions on Inappropriate Drug Use and Drug-Related Readmissions in People with Dementia-A Secondary Analysis of a Randomized Controlled Trial

Age-associated physiological changes and extensive drug treatment including use of potentially inappropriate medications (PIMs) pose a significant risk of drug-drug interactions and adverse drug events among elderly people with dementia. This study aimed at analysing the effects of clinical pharmacists' interventions on use of PIMs, risk of emergency department visits, and time to institutionalization. Furthermore, a descriptive analysis was conducted of circumstances associated with drug-related readmissions. This is a secondary analysis of data from a randomized controlled intervention study conducted in two hospitals in Northern Sweden. The study included patients (n = 460) 65 years or older with dementia or cognitive impairment. The intervention consisted of comprehensive medication reviews conducted by clinical pharmacists as part of a healthcare team. There was a larger decrease in PIMs in the intervention group compared with the control group (p = 0.011). No significant difference was found in time to first all-cause emergency department visits (HR = 0.994, 95% CI = 0.755-1.307 p = 0.963, simple Cox regression) or time to institutionalization (HR = 0.761, 95% CI = 0.409-1.416 p = 0.389, simple Cox regression) within 180 days. Common reasons for drug-related readmissions were negative effects of sedatives, opioids, antidepressants, and anticholinergic agents, resulting in confusion, falling, and sedation. Drug-related readmissions were associated with living at home, heart failure, and diabetes. Pharmacist-provided interventions were able to reduce PIMs among elderly people with dementia and cognitive impairment.

Plasma L-arginine levels distinguish pulmonary arterial hypertension from left ventricular systolic dysfunction

Pulmonary arterial hypertension (PAH) is a life-threatening condition, characterized by an imbalance of vasoactive substances and remodeling of pulmonary vasculature. Nitric oxide, formed from L-arginine, is essential for homeostasis and smooth muscle cell relaxation in PAH. Our aim was to compare plasma concentrations of L-arginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) in PAH compared to left ventricular systolic dysfunction (LVSD) and healthy subjects. This was an observational, multicenter study comparing 21 patients with PAH to 14 patients with LVSD and 27 healthy subjects. Physical examinations were obtained and blood samples were collected. Plasma levels of ADMA, SDMA, L-arginine, L-ornithine, and L-citrulline were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Plasma levels of ADMA and SDMA were higher, whereas L-arginine and L-arginine/ADMA ratio were lower in PAH patients compared to healthy subjects (p < 0.001). Patients with PAH also had lower levels of L-arginine than patients with LVSD (p < 0.05). L-Arginine correlated to 6 min walking distance (6MWD) (r _s = 0.58, p = 0.006) and L-arginine/ADMA correlated to WHO functional class (r _s = -0.46, p = 0.043) in PAH. In conclusion, L-arginine levels were significantly lower in treatment naïve PAH patients compared to patients with LVSD. Furthermore, L-arginine correlated with 6MWD in PAH. L-arginine may provide useful information in differentiating PAH from LVSD.

Pharmacist participation in hospital ward teams and hospital readmission rates among people with dementia: a randomized controlled trial

Purpose

To assess whether comprehensive medication reviews conducted by clinical pharmacists as part of a healthcare team reduce drug-related hospital readmission rates among people with dementia or cognitive impairment.

Methods

This randomized controlled trial was carried out between January 9, 2012, and December 2, 2014. Patients aged ≥65 years with dementia or cognitive impairment admitted to three wards at two hospitals located in Northern Sweden were included.

Results

Of the 473 deemed eligible for participation, 230 were randomized to intervention and 230 to control group by block randomization. The primary outcome, risk of drug-related hospital readmissions, was assessed at 180 days of follow-up by intention-to-treat analysis.

During the 180 days of follow-up, 18.9% (40/212) of patients in the intervention group and 23.0% (50/217) of those in the control group were readmitted for drug-related reasons (HR = 0.80, 95% CI = 0.53–1.21, p = 0.28, univariable Cox regression). Heart failure was significantly more common in the intervention group. After adjustment for heart failure as a potential confounder and an interaction term, multiple Cox regression analysis indicated that pharmacist participation significantly reduced the risk of drug-related readmissions (HR = 0.49, 95% CI = 0.27–0.90, p = 0.02). A post-hoc analysis showed a significantly reduced risk of 30-day readmissions due to drug-related problems in the total sample (without adjustment for heart failure).

Conclusion

Participation of clinical pharmacists in healthcare team conducting comprehensive medication reviews did not significantly reduce the risk of drug-related readmissions in patients with dementia or cognitive impairment; however, post-hoc and subgroup analyses indicated significant effects favoring the intervention. More research is needed. Trial registration: Clinical trials NCT01504672.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-017-2249-8) contains supplementary material, which is available to authorized users.

Vitamin B-6 and colorectal cancer risk: a prospective population-based study using 3 distinct plasma markers of vitamin B-6 status

Background: Higher plasma concentrations of the vitamin B-6 marker pyridoxal 5'-phosphate (PLP) have been associated with reduced colorectal cancer (CRC) risk. Inflammatory processes, including vitamin B-6 catabolism, could explain such findings.Objective: We investigated 3 biomarkers of vitamin B-6 status in relation to CRC risk.Design: This was a prospective case-control study of 613 CRC cases and 1190 matched controls nested within the Northern Sweden Health and Disease Study (n = 114,679). Participants were followed from 1985 to 2009, and the median follow-up from baseline to CRC diagnosis was 8.2 y. PLP, pyridoxal, pyridoxic acid (PA), 3-hydroxykynurenine, and xanthurenic acids (XAs) were measured in plasma with the use of liquid chromatography-tandem mass spectrometry. We calculated relative and absolute risks of CRC for PLP and the ratios 3-hydroxykynurenine:XA (HK:XA), an inverse marker of functional vitamin B-6 status, and PA:(PLP + pyridoxal) (PAr), a marker of inflammation and oxidative stress and an inverse marker of vitamin B-6 status.Results: Plasma PLP concentrations were associated with a reduced CRC risk for the third compared with the first quartile and for PLP sufficiency compared with deficiency [OR: 0.60 (95% CI: 0.44, 0.81) and OR: 0.55 (95% CI: 0.37, 0.81), respectively]. HK:XA and PAr were both associated with increased CRC risk [OR: 1.48 (95% CI: 1.08, 2.02) and OR: 1.50 (95% CI: 1.10, 2.04), respectively] for the fourth compared with the first quartile. For HK:XA and PAr, the findings were mainly observed in study participants with <10.5 y of follow-up between sampling and diagnosis.Conclusions: Vitamin B-6 deficiency as measured by plasma PLP is associated with a clear increase in CRC risk. Furthermore, our analyses of novel markers of functional vitamin B-6 status and vitamin B-6-associated oxidative stress and inflammation suggest a role in tumor progression rather than initiation.

Untangling the role of one-carbon metabolism in colorectal cancer risk: a comprehensive Bayesian network analysis

The role of one-carbon metabolism (1CM), particularly folate, in colorectal cancer (CRC) development has been extensively studied, but with inconclusive results. Given the complexity of 1CM, the conventional approach, investigating components individually, may be insufficient. We used a machine learning-based Bayesian network approach to study, simultaneously, 14 circulating one-carbon metabolites, 17 related single nucleotide polymorphisms (SNPs), and several environmental factors in relation to CRC risk in 613 cases and 1190 controls from the prospective Northern Sweden Health and Disease Study. The estimated networks corresponded largely to known biochemical relationships. Plasma concentrations of folate (direct), vitamin B6 (pyridoxal 5-phosphate) (inverse), and vitamin B2 (riboflavin) (inverse) had the strongest independent associations with CRC risk. Our study demonstrates the importance of incorporating B-vitamins in future studies of 1CM and CRC development, and the usefulness of Bayesian network learning for investigating complex biological systems in relation to disease.

Abstract 4291: Vitamin B6 biomarkers and colorectal cancer: Modifications by time

Background: Pyridoxal 5’-phospate (PLP) is the most commonly used marker of circulating vitamin B6 status. In prospective case-control studies, individuals with higher plasma concentrations of PLP had a 30-50% decreased risk of colorectal cancer (CRC). This may partly be explained by decreased PLP due to inflammatory activity in persons at an increased risk of CRC. We aimed to investigate different markers of vitamin B6 in relation to CRC risk in a population with a very long follow-up time between screening and diagnosis.

Methods: This was a prospective case-control study of 613 incident CRC cases and 1190 matched controls nested within the population-based Northern Sweden Health and Disease Study. PLP, pyridoxal (PL), pyridoxic acid (PA), 3-hydoxykynurenine (HK) and xanthurenic acid (XA) were measured in plasma by LC-MS/MS. Besides PLP, we investigated the recently introduced metabolite ratios PAr (PA/(PLP+PL)) and HK:XA as markers of vitamin B6 status in relation to CRC risk.

Results: PAr, a marker of vitamin B6 catabolism during inflammation, was linearly associated with CRC risk, with a 50% higher risk in the highest vs. lowest quartile. In the group with a follow up time between screening and diagnosis over 10.5 years no association was observed, while in the groups with a follow up time between 5.8-10.5 years and below 5.8 years risk was approximately twofold in most quartiles vs the lowest quartile. A 50% risk decrease was observed in the in the third vs the lowest quartile of plasma PLP and a similar risk increase was observed in the highest vs the lowest quartile of the functional vitamin B6 marker HK:XA.

Conclusions: PAr may influence later stages of tumor development, but possibly not early tumorigenesis. Poor functional vitamin B6 status and inflammatory activity might influence both the risk of CRC and plasma concentrations of PLP. Our results underscore the need to use several biomarkers for vitamin B6 status together with the already well established plasma PLP. This may be generalizable not only to CRC but also other diseases with an inflammatory aspect.

Citation Format: Björn Gylling, Robin Myte, Jörn Schneede, Göran Hallmans, Jenny Häggström, Ingegerd Johansson, Arve Ulvik, Øivind Midttun, Per Magne Ueland, Bethany van Guelpen, Richard Palmqvist. Vitamin B6 biomarkers and colorectal cancer: Modifications by time. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4291.

Abstract 4294: One-carbon metabolism and colorectal cancer risk according to molecular subtypes: a Bayesian network learning approach

Background: Colorectal cancer (CRC) is a heterogeneous disease caused by a number of distinct pathways defined by genetic and epigenetic events. These molecular subtypes differ in prognosis and treatment options, and recent studies also imply differences in etiology. One-carbon metabolism has been extensively studied in relation to incident CRC risk because of its involvement in nucleotide synthesis and methylation reactions, yet only a few studies have evaluated if associations differ over CRC subtypes. In this study, we investigated a targeted panel of circulating metabolites and a set of single nucleotide polymorphisms involved in one-carbon metabolism in relation to the risk of overall CRC and CRC subtypes approximated by mutations in the BRAF and KRAS oncogenes, microsatellite instability (MSI), or CpG island methylator phenotype (CIMP).

Methods: This was a prospective population-based nested case control study of 613 CRC cases and 1190 matched controls. The data included plasma concentrations of 14 one-carbon metabolites, 17 related single nucleotide polymorphisms, and other lifestyle-related information for all subjects, and clinical and molecular information for the tumors. In order to account for interactions and dependencies between variables, we applied multivariate Bayesian network learning in combination with more traditional univariate multinomial logistic regression to investigate independent relations to subtype specific CRC risk.

Results: Preliminary findings show that vitamin B6 (Pyridoxal 5-phosphate, PLP) and vitamin B2 (riboflavin) had the strongest independent relations to overall CRC risk in the multivariate analyses. Folate, glycine, vitamin B6, and the RFC1 80G&gt;A polymorphism displayed signs of independent relations to CRC subtypes. In univariate multinomial logistic regression models, plasma folate expressed the strongest etiologic heterogeneity, and was more clearly related to the risk of CIMP low/high tumors, tumors with MSI, or tumors without KRAS mutation, respectively.

Conclusions: This study investigated a large set of prediagnostic circulating metabolites and single nucleotide polymorphisms related to one-carbon metabolism using multivariate statistical learning. We found that some components showed signs of subtype specific relations, of which the association for folate was clearest. Our results suggest that the role of one-carbon metabolism in colorectal carcinogenesis may differ between specific molecular pathways.

Citation Format: Robin Myte, Björn Gylling, Jenny Häggström, Jörn Schneede, Per Magne Ueland, Göran Hallmans, Ingegerd Johansson, Richard Palmqvist, Bethany Van Guelpen. One-carbon metabolism and colorectal cancer risk according to molecular subtypes: a Bayesian network learning approach. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4294.

Acute vasodilator response to vardenafil and clinical outcome in patients with pulmonary hypertension

PURPOSE

Acute vasodilator testing is recommended in patients with pulmonary arterial hypertension to identify individuals who may benefit from long-term treatment with oral calcium channel blockers. The aim of this study was to investigate the use of vardenafil in acute vasoreactivity testing compared to adenosine.

METHODS

A total of 20 patients eligible for right heart catheterisation were enrolled. Acute vasoreactivity testing was carried out with intravenous (iv) adenosine (n = 18) followed by oral vardenafil (n = 20). Haemodynamic responses were recorded at baseline and after 60 min (vardenafil). Responders were defined according to consensus guideline criteria.

RESULTS

Both vardenafil and adenosine significantly decreased mean pulmonary arterial pressure (mPAP, p < 0.001 and p = 0.026, respectively) and pulmonary vascular resistance (p < 0.001 and p > 0.001, respectively), and significantly increased cardiac output (p = 0.001 and p = 0.005, respectively). Vardenafil reduced mPAP more than adenosine (p = 0.044), while adenosine resulted in higher responses of cardiac index (p = 0.009) and pulmonary arterial oxygen saturation (p = 0.042). Acute adverse reactions were common with adenosine, while no side effects were observed after a single oral dose vardenafil. Vardenafil identified five responders (out of 20), while adenosine identified three responders (out of 18). During a 7-year follow-up, vardenafil responders had significantly lower NT-proBNP levels compared to non-responders.

CONCLUSIONS

Vardenafil may be safely used for acute vasoreactivity testing in patients with PH. A single oral dose of vardenafil is better tolerated than iv adenosine and may identify additional responders who could benefit from long-term vasodilator treatment.

Dietary folate intake and breast cancer risk: European prospective investigation into cancer and nutrition

BACKGROUND

There is limited evidence on the association between dietary folate intake and the risk of breast cancer (BC) by hormone receptor expression in the tumors. We investigated the relationship between dietary folate and BC risk using data from the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

A total of 367993 women age 35 to 70 years were recruited in 10 European countries. During a median follow-up of 11.5 years, 11575 women with BC were identified. Dietary folate intake was estimated from country-specific dietary questionnaires. Cox proportional hazards regression models were used to quantify the association between dietary variables and BC risk. BC tumors were classified by receptor status. Subgroup analyses were performed by menopausal status and alcohol intake. Intake of other B vitamins was considered. All statistical tests were two-sided.

RESULTS

A borderline inverse association was observed between dietary folate and BC risk (hazard ratio comparing top vs bottom quintile [HRQ5-Q1] = 0.92, 95% CI = 0.83 to 1.01, P trend = .037). In premenopausal women, we observed a statistically significant trend towards lower risk in estrogen receptor-negative BC (HRQ5-Q1 = 0.66, 95% CI = 0.45 to 0.96, P trend = .042) and progesterone receptor-negative BC (HRQ5-Q1 = 0.70, 95% CI = 0.51 to 0.97, P trend = .021). No associations were found in postmenopausal women. A 14% reduction in BC risk was observed when comparing the highest with the lowest dietary folate tertiles in women having a high (>12 alcoholic drinks/week) alcohol intake (HRT3-T1 = 0.86, 95% CI = 0.75 to 0.98, P interaction = .035).

CONCLUSIONS

Higher dietary folate intake may be associated with a lower risk of sex hormone receptor-negative BC in premenopausal women.

Low folate levels are associated with reduced risk of colorectal cancer in a population with low folate status

BACKGROUND

A diet rich in folate is associated with a reduced colorectal cancer risk, whereas the role of circulating levels is less clear. The aim of this study was to relate prediagnostic plasma folate, vitamin B12, and homocysteine concentrations to the risk of colorectal cancer.

METHODS

This was a prospective case-control study of 331 cases and 662 matched controls nested within the population-based Northern Sweden Health and Disease Study. Median follow-up time from recruitment to diagnosis was 10.8 years.

RESULTS

Plasma folate concentrations were positively related to colorectal cancer risk; multivariate odds ratios were 1.62 [95% confidence intervals (CI), 1.08-2.42] and 1.42 (95% CI, 0.94-2.21) for the middle and highest versus lowest tertile, respectively. In subjects with follow-up <10.8 years, a statistically significant doubled risk was observed for the middle and highest versus lowest tertile, whereas findings for longer follow-up times were null. A positive risk relationship was also observed for tumor stage III-IV but not I-II. Plasma vitamin B12 concentrations were inversely associated with rectal cancer risk. Homocysteine was not significantly related to colorectal cancer risk.

CONCLUSIONS

In this population-based, nested case-control study, low plasma folate concentrations were associated with a reduced colorectal cancer risk. This protective role was mainly observed in subjects with higher tumor stage or shorter follow-up time between recruitment and diagnosis. Low circulating folate status may protect against colorectal cancer or suppress progression of preneoplastic or neoplastic lesions.

IMPACT

These findings may have relevance for the ongoing debate about mandatory folic acid fortification of flour.

High inter-individual variability of vardenafil pharmacokinetics in patients with pulmonary hypertension

PURPOSE

To evaluate the pharmacokinetic parameters of a single oral dose of vardenafil in patients with pulmonary hypertension (PH).

METHODS

Sixteen patients with PH received vardenafil in single oral doses (20, 10 or 5 mg), and repeated blood sampling for up to 9 h was performed. Vardenafil plasma concentration was determined using liquid chromatography tandem mass spectrometry. Pharmacokinetic parameters were calculated using model-independent analysis.

RESULTS

The plasma vardenafil concentration increased rapidly and exhibited a median time to maximum plasma concentration (t(max)) of 1 h and a mean elimination half-life (t(1/2)) of 3.4 h. The geometric mean and standard deviation of (1) the peak plasma concentration (C(max)) was 21.4 ± 1.7 μg/L, (2) the normalized C(max) (C(max, norm)) 79.1 ± 1.6 g/L, (3) the area under the time-concentration curve (AUC) 71.5 ± 1.6 μg · h/L and (4) the normalized AUC (AUC(norm)) 261.6 ± 1.7 g · h/L. Patients co-medicated with bosentan reached t(max) later and had a 90% reduction of C(max), C(max, norm), AUC and AUC(norm).

CONCLUSION

The pharmacokinetic profile of vardenafil overall revealed considerable inter-individual variability in patients with PH. Co-medication with bosentan resulted in a pharmacokinetic drug interaction, leading to significantly decreased plasma concentrations of vardenafil. Therapeutic drug monitoring for individual dose optimization may be warranted.

Blood Concentrations of Homocysteine and Methylmalonic Acid among Demented and Non-Demented Swedish Elderly with and without Home Care Services and Vitamin B(12) Prescriptions

BACKGROUND AND AIMS

Total plasma homocysteine (tHcy) has been suggested as a risk factor of dementia. Our aim was to investigate potential differences in tHcy status in relation to the prescription of vitamin B(12) and dementia diagnosis. We examined whether vitamin B(12) prescriptions, a family history of dementia, or the need for home care service might be associated with tHcy values.

METHODS

A cross-sectional monocenter study comprising 926 consecutive subjects attending our Memory Care Unit was conducted.

RESULTS

Demented subjects being prescribed vitamin B(12) had higher serum vitamin B(12) (p = 0.025) but also higher tHcy (p < 0.001) and serum methylmalonate (p = 0.032), and lower serum folate (p < 0.001) than those who did not receive vitamin B(12) prescriptions. tHcy levels were significantly higher in non-demented subjects receiving home care service (p = 0.007). This group also had lower serum albumin (dementia: p < 0.001; non-dementia: p = 0.004). There was no difference in renal function (estimated glomerular filtration rate) in demented or non-demented subjects with or without vitamin B(12) prescriptions (dementia with/without vitamin B(12) prescription: p = 0.561; non-dementia with/without vitamin B(12) prescription: p = 0.710).

CONCLUSION

Despite vitamin B(12) prescriptions, demented subjects had higher tHcy and methylmalonate values. The elevated metabolite values could not be explained by differences in renal function. Thus, elderly subjects on vitamin B(12) prescription appear to have unmet nutritional needs.

Biomarkers related to one-carbon metabolism as potential risk factors for distal colorectal adenomas

BACKGROUND

Efficient one-carbon metabolism, which requires adequate supply of methyl group donors and B-vitamins, may protect against colorectal carcinogenesis. However, plasma folate and vitamins B2 and B12 have inconsistently been associated with colorectal cancer risk, and there have been no previous studies relating plasma concentrations of methionine, choline, and betaine to this outcome.

METHODS

This study comprised 10,601 individuals, 50 to 64 years of age, participating in the Norwegian Colorectal Cancer Prevention (NORCCAP) screening study. Using logistic regression analyses, we crosssectionally investigated associations between distal colorectal adenoma occurrence-potential precursor lesions of colorectal carcinomas-and plasma concentrations of methyl group donors and B-vitamins, and polymorphisms of genes related to one-carbon metabolism.

RESULTS

Screening revealed 1,809 subjects (17.1%) with at least one adenoma. The occurrence of high-risk adenomas (observed in 421 subjects) was inversely associated with plasma concentrations of methionine (highest versus lowest quartile: odds ratio (OR) = 0.61; 95% confidence interval (CI) = 0.45-0.83), betaine: OR = 0.74; 95% CI = 0.54-1.02, the vitamin B2 form flavin-mononucleotide (FMN): OR = 0.65; 95% CI = 0.49-0.88, and the vitamin B6 form pyridoxal 5'-phosphate (PLP): OR = 0.69; 95% CI = 0.51-0.95, but not with folate, choline, vitamin B12 concentrations, or with the studied polymorphisms. High methionine concentration in combination with high vitamin B2 or B6 concentrations was associated with lower occurrence of high-risk adenomas compared with these factors individually.

CONCLUSIONS

High plasma concentrations of methionine and betaine, and vitamins B2 and B6 may reduce risk of developing colorectal adenomas.

IMPACT

In addition to B-vitamins, methyl group donors such as methionine and betaine may play a role in colorectal carcinogenesis.

Routine determination of serum methylmalonic acid and plasma total homocysteine in Norway

OBJECTIVE

To study the total number of combined analyses of methylmalonic acid (MMA) and total plasma homocysteine (tHcy) carried out during February 1998 at the Central Laboratory of Haukeland University Hospital.

METHODS

Laboratory data and requester comments of 2917 subjects in whom MMA was requested during February 1998, were retrieved from the laboratory information system (LIS). In 2520 cases, the results from the combined analyses of MMA and tHcy were available. Requester comments were registered in the LIS in 1084 cases. Results from additional laboratory analyses were accessible in about 10%, of cases.

RESULTS

General practitioners requested MMA and tHcy on three main indications, i.e. low cobalamin, "control" and neurological symptoms. Metabolites were requested in twice as many women than men. Furthermore, MMA was requested in younger age groups of women compared with men. Plasma tHcy and MMA showed positive correlations with age and serum creatinine, and tHcy was generally 1-2 micromol/L higher in men than in premenopausal women. In cobalamin- (serum cobalamin > 300 pmol/L) and/or folate- (serum folate > 10 nmol/L) replete subjects, the average difference in MMA or tHcy according to the highest and lowest creatinine quartiles was 0.08 and 5-6 micromol/L, respectively. Different combinations of MMA and tHcy were evaluated by using a 5 x 5 matrix of predefined concentration intervals. Based on this matrix, cobalamin and folate deficiency could be excluded or the likely diagnoses proposed in 76% of cases. Cobalamin deficiency or folate deficiency was likely in about 7% and 12% of the subjects investigated, respectively.

CONCLUSIONS

A combined analysis of MMA and tHcy provides complementary diagnostic information. When interpreting MMA and tHcy values, age, gender and renal function in particular must be taken into account. Typical combinations of MMA and tHcy concentration intervals could be proposed, which could either exclude deficiency or indicate likely diagnoses and/or influence of confounders.

Prerequisites for establishing general recommendations for diagnosis and treatment of vitamin B12deficiency and cost‐utility evaluation of these guidelines

There is currently no consensus on how to define, diagnose and treat vitamin B12 deficiency. This is partly due to insufficient and non-uniform study design. It is essential to come to a harmonization of rational study designs. In order to evaluate new tests for the diagnosis of vitamin B12 deficiency, it is important that independent and unequivocal criteria for a clear-cut definition of the disease are used. Furthermore, it is crucial to have a mutual understanding on the progression of the disease, how fast the different symptoms may develop and on the expected time frame of treatment and evaluation of response. The kind and intensity of treatment must also be agreed upon. The present article overviews the potential strategies of how to define and diagnose vitamin B12 deficiency and on follow-up of treatment response. Finally, based on these considerations, the prerequisites of a cost-utility analysis of guidelines for diagnosing vitamin B12 deficiency are discussed.

Quantification of methylmalonic acid in human plasma with hydrophilic interaction liquid chromatography separation and mass spectrometric detection

BACKGROUND

Measurement of methylmalonic acid (MMA) in serum or plasma is useful for diagnosing cobalamin deficiency. We developed a method for quantifying MMA in plasma based on hydrophilic interaction liquid chromatography (HILIC) and single-stage negative electrospray ionization (ESI) mass spectrometry.

METHODS

We deproteinized plasma samples (200 microL) with 800 microL acidified acetonitrile containing 0.17 micromol/L deuterated MMA (D(3)-MMA) internal standard, centrifuged the samples, and injected 4 microL of the supernatant into the LC-MS instrument. Separation was achieved within 3 min on a Merck SeQuant ZIC-HILIC column with a mobile phase consisting of 4 volumes acetonitrile plus 1 volume 100 mmol/L ammonium acetate buffer, pH 4.5, at a flow rate of 400 microL/min. Subsequent column washing and reconditioning contributed to a total run time of 10 min. MMA and D(3)-MMA were quantified by single-ion monitoring (m/z 117.2 and 120.2, respectively) in negative ESI mode at a drying-gas flow rate of 10 L/min, 300 degrees C, and a capillary voltage of 3.0 kV.

RESULTS

The estimated limits of MMA quantification and detection were 0.09 micromol/L and 0.03 micromol/L, respectively, in plasma. The assay was linear to 200 micromol/L. Interassay and intraassay CVs were < or = 5% at all tested concentrations. Recoveries were 90%-93%.

CONCLUSIONS

This robust assay allows analysis of MMA in human plasma without derivatization. Sample preparation is simple and suitable for automation.

[Measurement of methylmalonic acid, homocysteine and methionine in cobalamin and folate deficiencies and homocysteinuria]

BACKGROUND

Deficiencies of cobalamin (vitamin B12) or folate are common conditions that predispose for anemia and chronic diseases. An elevated concentration of methylmalonic acid in plasma/serum is an indicator of cobalamin deficiency, whereas an increased concentration of total homocysteine in plasma occurs with deficiency of both cobalamin and folate. The biomarkers methylmalonic acid and homocysteine are therefore complementary, and the combination is often requested when conventional tests fail to provide an unambiguous diagnosis.

MATERIAL AND METHODS

This article summarizes publications, retrieved through Medline, describing novel strategies for laboratory diagnostics of cobalamin and folate deficiencies.

RESULTS AND INTERPRETATION

Adverse health effects of food fortification and uncritical supplementation with folic acid are explanations for a renewed interest in individual diagnosis of B-vitamin deficiency. Interpretation of methylmalonic acid and homocysteine test results requires knowledge of kidney function, as renal failure causes an increase in the concentrations of both metabolites. Homocystinuria is a condition that also causes increased levels of plasma homocysteine. This condition is an inborn error with a higher prevalence (1 : 6400) than previously recognized; which usually responds favourably to homocysteine-lowering therapy. Patients with homocysteinuria have high levels of methionine in plasma and knowledge of plasma methionine concentration may therefore distinguish these patients from those with conditions like B-vitamin deficiencies or renal failure, which are accompanied by normal or low to normal methionine concentrations. Complementarity, logistics, small sample volumes and costs therefore favour a combined analysis of methylmalonic acid, homocysteine and methionine in a single sample. Such an approach also allows assessment of cobalamin status in small volume capillary blood samples drawn from newborns and infants.

Cobalamin and folate status in infants and young children in a low-to-middle income community in India

BACKGROUND

Population-based data on the prevalence of cobalamin and folate deficiency in India are lacking.

OBJECTIVE

The objective was to measure the prevalence of cobalamin and folate deficiency among children aged 6-30 mo residing in a low-to-middle income community in North India.

DESIGN

Children aged 6-30 mo (n = 2482) were identified through a community survey in a low-to-middle socioeconomic area in New Delhi, India. Non-fasting venous blood samples were collected before enrollment in another trial.

RESULTS

The median (interquartile range; IQR) cobalamin concentration in 6-11-mo-old children was substantially lower in breastfed (183; 120-263 pmol/L) than in nonbreastfed (334; 235-463 pmol/L) children. Cobalamin concentrations decreased progressively with increasing age in the nonbreastfed children. Median (IQR) plasma folate concentrations in the 6-11-mo-old group were higher in breastfed (20.3; 11.7-34.4 nmol/L) than in nonbreastfed (5.3; 3.4-7.7 nmol/L) children (P < 0.001). Folate concentrations decreased with increasing age in the breastfed children. In the nonbreastfed children, folate concentrations increased with increasing age. Low concentrations of plasma cobalamin (<150 pmol/L) were detected in 36% of breastfed and 9% of nonbreastfed children (P < 0.001). The proportions of children with plasma folate concentrations <5 nmol/L in these 2 subgroups were 6% and 33%, respectively (P < 0.001).

CONCLUSIONS

In north Indian preschool children, cobalamin and folate concentrations were commonly low and were associated with elevated total homocysteine and methylmalonic acid concentrations. Because low cobalamin and folate concentrations have functional consequences, population-based measures for improving cobalamin and folate concentrations need to be seriously considered.

Longitudinal study of the effect of pregnancy on maternal and fetal cobalamin status in healthy women and their offspring

Compromised cobalamin status during pregnancy may put both mother and child at risk of deficiency during lactation and subsequent development. We investigated whether changes in cobalamin status during pregnancy are associated with impaired status in the mother and the cord. Plasma cobalamin, methylmalonic acid (MMA), and holotranscobalamin (holoTC) concentrations were determined in 92 women at preconception, 8, 20, and 32 wk of pregnancy, at labor, and in the cord. All variables [geometric mean percentiles 10, 90 (P(10), P(90))] were significantly reduced from preconception [cobalamin: 293 (155, 535) pmol/L; holoTC: 63 (38,98) pmol/L; MMA: 0.12 (0.09, 0.17) micromol/L] by 20 wk of pregnancy [cobalamin: 230 (123, 432) pmol/L; holoTC: 48 (34,78) pmol/L; MMA: 0.11 (0.08, 0.15) micromol/L P < 0.001]. Plasma cobalamin and holoTC remained lower throughout the remainder of pregnancy [32 wk: 198 (107, 339); labor: 224 (117, 444); P < 0.001] and [32 wk: 45 (26,82); labor: 40 (23,79); P < 0.05], respectively. By 32 wk, MMA was greater than preconception [0.14 (0.09, 0.20) micromol/L; P < 0.01]. Plasma holoTC at 32 wk and at labor was negatively correlated with cord MMA (r = -0.51, P < 0.001 and r = -0.40, P < 0.01, respectively). Women with lower holoTC at preconception had greater increases in MMA at 32 wk and at labor. Maternal MMA at 32 wk and at labor was significantly and independently associated with cord MMA only in women with lower holoTC at preconception (regression models: R(2) = 0.707, 0.682, respectively; P < 0.01). The moderate increases observed in the cobalamin biomarker, MMA, during pregnancy may indicate a functional depletion in intracellular cobalamin status.

Changes in markers of cobalamin status after cessation of oral B-vitamin supplements in elderly people with mild cobalamin deficiency

Mildly cobalamin-deficient elderly were supplemented with 1000 microg cobalamin (group C, n=34), 1000 microg cobalamin with 400 microg folic acid (group CF, n=31) or a placebo (n=30) for 6 months. Participants provided one single blood sample 3, 5 or 7 months after cessation of supplementation to monitor early changes in plasma concentrations of cobalamin, holotranscobalamin (holoTC) and methylmalonic acid (MMA). At the end of supplementation (groups C+CF), one participant met our criteria for mild cobalamin deficiency, as did 13, 14 and 43% of the participants assessed at respectively 3, 5 and 7 months post-supplementation. Cobalamin and holoTC declined on average with 47 and 56% relative to concentrations at the end of supplementation for the group assessed at 7 months post-supplementation. Essentially similar declines were observed for those participants assessed at 3 and 5 months post-supplementation. Mean MMA concentrations increased by 15% (P=0.07) in those participants assessed at 3 and 5 months post-supplementation, and increased by 50% (P=0.002) in those participants assessed at 7 months post-supplementation. Considering MMA as a sensitive tissue marker for cobalamin status, oral supplementation may afford adequate cobalamin status for a period of up to 5 months after cessation in the majority of participants.

Effect of oral vitamin B-12 with or without folic acid on cognitive function in older people with mild vitamin B-12 deficiency: a randomized, placebo-controlled trial

BACKGROUND

Vitamin B-12 deficiency is associated with cognitive impairment in older people. However, evidence from randomized trials of the effects of vitamin B-12 supplementation on cognitive function is limited and inconclusive.

OBJECTIVE

The objective was to investigate whether daily supplementation with high doses of oral vitamin B-12 alone or in combination with folic acid has any beneficial effects on cognitive function in persons aged >/=70 y with mild vitamin B-12 deficiency.

DESIGN

In a double-blind, placebo-controlled trial, 195 subjects were randomly assigned to receive 1000 microg vitamin B-12, 1000 microg vitamin B-12 + 400 microg folic acid, or placebo for 24 wk. Vitamin B-12 status was assessed on the basis of methylmalonic acid, total homocysteine (tHcy), and holotranscobalamin (holoTC) concentrations before and after 12 and 24 wk of treatment. Cognitive function was assessed before and after 24 wk of treatment with the use of an extensive neuropsychologic test battery that included the domains of attention, construction, sensomotor speed, memory, and executive function.

RESULTS

Vitamin B-12 status did not change significantly after treatment in the placebo group; however, oral vitamin B-12 supplementation corrected mild vitamin B-12 deficiency. Vitamin B-12 + folic acid supplementation increased red blood cell folate concentrations and decreased tHcy concentrations by 36%. Improvement in memory function was greater in the placebo group than in the group who received vitamin B-12 alone (P = 0.0036). Neither supplementation with vitamin B-12 alone nor that in combination with folic acid was accompanied by any improvement in other cognitive domains.

CONCLUSION

Oral supplementation with vitamin B-12 alone or in combination with folic acid for 24 wk does not improve cognitive function.

Oral cyanocobalamin supplementation in older people with vitamin B12 deficiency: a dose-finding trial

BACKGROUND

Supplementation with high doses of oral cobalamin is as effective as cobalamin administered by intramuscular injection to correct plasma markers of vitamin B(12) deficiency, but the effects of lower oral doses of cobalamin on such markers are uncertain.

METHODS

We conducted a randomized, parallel-group, double-blind, dose-finding trial to determine the lowest oral dose of cyanocobalamin required to normalize biochemical markers of vitamin B(12) deficiency in older people with mild vitamin B(12) deficiency, defined as a serum vitamin B(12) level of 100 to 300 pmol/L (135-406 pg/mL) and a methylmalonic acid level of 0.26 mumol/L or greater. We assessed the effects of daily oral doses of 2.5, 100, 250, 500, and 1000 mug of cyanocobalamin administered for 16 weeks on biochemical markers of vitamin B(12) deficiency in 120 people. The main outcome measure was the dose of oral cyanocobalamin that produced 80% to 90% of the estimated maximal reduction in the plasma methylmalonic acid concentration.

RESULTS

Supplementation with cyanocobalamin in daily oral doses of 2.5, 100, 250, 500, and 1000 mug was associated with mean reductions in plasma methylmalonic acid concentrations of 16%, 16%, 23%, 33%, and 33%, respectively. Daily doses of 647 to 1032 mug of cyanocobalamin were associated with 80% to 90% of the estimated maximum reduction in the plasma methylmalonic acid concentration.

CONCLUSION

The lowest dose of oral cyanocobalamin required to normalize mild vitamin B(12) deficiency is more than 200 times greater than the recommended dietary allowance, which is approximately 3 mug daily.

Novel and Established Markers of Cobalamin Deficiency: Complementary or Exclusive Diagnostic Strategies

New developments in diagnostic markers and a better understanding of the limitations of traditional diagnostic strategies have allowed diagnosis of earlier stages and atypical forms of cobalamin deficiency. Still, there are no generally accepted guidelines for the definition, diagnosis, treatment, and follow-up of cobalamin deficiency. The new trend toward defining cobalamin deficiency purely on the basis of biochemical test outcomes in the absence of overt clinical signs and symptoms could, however, be problematic and may result in overdiagnosis and overtreatment. Use of metabolic markers for the assessment of cobalamin deficiency allows the demonstration of tissue deficiency, but the establishment of the cause of deficiency should also be part of the diagnostic approach. Four groups of diagnostic tests are currently available and these include total cobalamin and cobalamin fractions (such as holo-transcobalamin), tests of gastrointestinal dysfunction, tests of metabolic function, and different gene tests. Among the available tests, only homocysteine, methylmalonic acid, holo-transcobalamin, and possibly methylcitric acid are considered to be useful in clinical practice to add to cobalamin. Gastrointestinal function tests may identify the cause of cobalamin deficiency, whereas the diagnostic usefulness of genetic testing needs to be evaluated. This article provides an overview of recent developments and a reappraisal of novel and established diagnostic markers for cobalamin deficiency.

Low bone mineral density and bone mineral content are associated with low cobalamin status in adolescents

BACKGROUND

Cobalamin deficiency is prevalent in vegetarians and has been associated with increased risk of osteoporosis.

AIM OF THE STUDY

To examine the association between cobalamin status and bone mineral density in adolescents formerly fed a macrobiotic diet and in their counterparts.

METHODS

In this cross-sectional study bone mineral density (BMD) and bone mineral content (BMC) were determined by DEXA in 73 adolescents (9-15 y) who were fed a macrobiotic diet up to the age of 6 years followed by a lacto-(-ovo-) vegetarian or omnivorous diet. Data from 94 adolescents having consumed an omnivorous diet throughout their lives were used as controls. Serum concentrations of cobalamin, methylmalonic acid (MMA) and homocysteine were measured and calcium intake was assessed by questionnaire. Analysis of covariance (MANCOVA) was performed to calculate adjusted means for vitamin B12 and MMA for low and normal BMC and BMD groups.

RESULTS

Serum cobalamin concentrations were significantly lower (geometric mean (GM) 246 pmol/L vs. 469 pmol/L) and MMA concentrations were significantly higher (GM 0.27 micromol/L vs. 0.16 micromol/L) in the formerly macrobiotic-fed adolescents compared to their counterparts. In the total study population, after adjusting for height, weight, bone area, percent lean body mass, age, puberty and calcium intake, serum MMA was significantly higher in subjects with a low BMD (p = 0.0003) than in subjects with a normal BMD. Vitamin B12 was significantly lower in the group with low BMD (p = 0.0035) or BMC (p = 0.0038) than in the group with normal BMD or BMC. When analyses were restricted to the group of formerly macrobiotic-fed adolescents, MMA concentration remained higher in the low BMD group compared to the normal BMD group.

CONCLUSIONS

In adolescents, signs of an impaired cobalamin status, as judged by elevated concentrations of methylmalonic acid, were associated with low BMD. This was especially true in adolescents fed a macrobiotic diet during the first years of life, where cobalamin deficiency was more prominent.

Vitamin B12 and folate deficiency in later life

OBJECTIVES

to examine the prevalence of vitamin B12 deficiency and folate deficiency in later life in representative samples of the elderly population in the United Kingdom.

DESIGN

a population-based cross-sectional analysis of 3,511 people aged 65 years or older from three studies was used to estimate the age-specific prevalence of vitamin B12 deficiency and of folate deficiency. Vitamin B12 deficiency is conventionally diagnosed if serum vitamin B12 < 150 pmol/l ('low vitamin B12'). We defined 'metabolically significant vitamin B12 deficiency' as vitamin B12 < 200 pmol/l and blood total homocysteine >20 micro mol/l. Folate deficiency, which usually refers to serum folate <5 nmol/l, was defined as 'metabolically significant' if serum folate was <7 nmol/l and homocysteine >20 micro mol/l.

RESULTS

the prevalence of vitamin B12 deficiency, whether defined as low vitamin B12 or metabolically significant vitamin B12 deficiency increased with age in all three studies, from about 1 in 20 among people aged 65-74 years to 1 in 10 or even greater among people aged 75 years or greater. The prevalence of folate deficiency also increased with age, and was similar to that for vitamin B12 deficiencies, but only about 10% of people with low vitamin B12 levels also had low folate levels.

CONCLUSION

the high prevalence of vitamin B12 and folate deficiency observed in older people indicates a particular need for vigilance for deficiency of these vitamins. Reliable detection and treatment of vitamin deficiency could reduce the risk of deficiency-related disability in old age.

Homocysteine and its relation to B-vitamins in Graves' disease before and after treatment: effect modification by smoking

OBJECTIVES

To investigate plasma total homocysteine levels and its relation to B-vitamins and smoking in Graves' disease before and after antithyroid therapy.

DESIGN

A longitudinal study taking place at four hospitals in Norway.

METHODS AND SUBJECTS

Plasma total homocysteine, serum folate, serum cobalamin and riboflavin, flavin mononucleotide and flavin adenine dinucleotide in plasma were investigated in 182 patients with hyperthyroidism before treatment. The same parameters were reinvestigated in 112 of these patients after attaining euthyroid state.

RESULTS

In hyperthyroidism, plasma total homocysteine was low, and inversely related to folate, cobalamin and riboflavin, and positively related to serum creatinine and age. Following antithyroid therapy, total homocysteine increased and the concentration of folate, cobalamin, riboflavin, flavin mononucleotide and flavin adenine dinucleotide decreased significantly. The most pronounced reduction (35%) was observed for flavin mononucleotide. In the hyperthyroid state, smokers had lower levels of folate and flavin mononucleotide than non-smokers. After restoration of euthyroidism, both folate and riboflavin were significantly lower in smokers than non-smokers. Plasma total homocysteine increased according to decreasing quartiles of B-vitamins. For riboflavin, this relation was confined to smokers.

CONCLUSION

Plasma total homocysteine changes according to thyroid status. These changes may be partly attributable to altered folate, cobalamin but also riboflavin status, particularly in smokers.

Relationship between methylmalonic acid, homocysteine, vitamin B12 intake and status and socio-economic indices, in a subset of participants in the British National Diet and Nutrition Survey of people aged 65 y and over

OBJECTIVE

Assessment of functional vitamin B(12) status in a subset of the respondents in the British National Diet and Nutrition Survey of people aged 65 y and over.

SETTING

National Diet and Nutrition Survey: a British nationwide cross-sectional sample of people aged 65 y and over, living either in the community or in institutions such as nursing homes, during one calendar year spanning 1994-1995.

METHODS

Methylmalonic acid (MMA) concentrations were measured in plasma samples from 313 subjects (ca 14% of those originally enrolled in the survey). The results were compared with those for serum vitamin B(12), vitamin B(12) intakes and other status and intake estimates and with socio-demographic indices.

RESULTS

Of the NDNS participants overall, 20% had serum vitamin B(12) concentrations<150 pmol/l. In the subset studied here, 24% of free-living and 46% of institution-living participants had MMA>0.5 micromol/l. Geometric mean MMA increased with age, from 0.25 micro mol/l in people aged 65-74 y to 0.38 micro mol/l in people aged 85+y. There was little evidence for any gender difference in MMA. It was inversely correlated with serum vitamin B(12) and with red blood cell folate; it was positively correlated directly with total homocysteine, but not significantly with serum folate or with vitamin B(12) intake. Among respondents with high MMA, a subgroup had normal serum vitamin B(12) but higher-than-average plasma urea and creatinine. Socio-demographic co-variates of MMA included receipt of State income benefits, social class of head of household, and educational attainment. These indices were not correlated with serum vitamin B(12).

CONCLUSIONS

The progressive increase in MMA with age is metabolic evidence for increasing risk of functional vitamin B(12) deficiency with increasing age in older people. There is evidence that renal function is linked to high MMA in some older people. Age and renal function are thus both important when establishing upper reference limits for MMA. The socio-demographic observations suggest a link between poverty and poor functional vitamin B(12) status in older British people.

Homocysteine and methylmalonic acid levels in pregnant Nepali women. Should cobalamin supplementation be considered?

OBJECTIVE

The aim of this study was to investigate homocysteine and methylmalonic acid levels as markers of functional cobalamin and folate status in pregnant Nepali women.

DESIGN

Cross-sectional study.

SETTING

Patan Hospital, Kathmandu, Nepal.

SUBJECTS

A sub-sample (n=382) of all pregnant women (n=2856) coming for their first antenatal visit in a 12 month period, 1994-1995. The selection of the sub-sample was based on maternal haematocrit values, categorised into three groups: severely, moderately and non-anaemic women. As serum levels of total homocysteine (s-tHcy) and methylmalonic acid (s-MMA) were similar in the three groups, pooled data are presented. Women who had already received micronutrient supplementation (n=54) were excluded. The remaining women (n=328) were included in the statistical analysis.

RESULTS

Overall mean values (+/-s.d.) of s-tHcy and s-MMA were 9.5 (+/-4.2) micromol/l and 0.39 (+/-0.32) micromol/l, respectively. Elevated s-tHcy (>7.5 micromol/l) was found in 68% of the women, while 61% had elevated s-MMA (>0.26 micromol/l). Low s-cobalamin values (<150 pmol/l) were observed in 49% of the women, while only 7% had low s-folate values (< or =4.5 nmol/l). s-tHcy was significantly correlated with s-MMA (r=0.28, P<0.001), s-cobalamin (r=-0.30, P<0.001) and s-folate (r=-0.24, P<0.001). s-MMA was significantly associated with s-cobalamin (r=-0.40, P<0.001), but not with s-folate.

CONCLUSIONS

Functional cobalamin deficiency was very common in the study population, while functional folate deficiency was rather uncommon. We suggest considering cobalamin supplementation to pregnant Nepali women.

SPONSORSHIP

The Norwegian Research Council and the Norwegian Universities Committee for Development, Research and Education.