A comparison of complementary measures of vitamin B6 status, function, and metabolism in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Maternal B-vitamin and vitamin D status before, during, and after pregnancy and the influence of supplementation preconception and during pregnancy: Prespecified secondary analysis of the NiPPeR double-blind randomized controlled trial

BACKGROUND

Maternal vitamin status preconception and during pregnancy has important consequences for pregnancy outcome and offspring development. Changes in vitamin status from preconception through early and late pregnancy and postpartum have been inferred from cross-sectional data, but longitudinal data on vitamin status from preconception throughout pregnancy and postdelivery are sparse. As such, the influence of vitamin supplementation on vitamin status during pregnancy remains uncertain. This study presents one prespecified outcome from the randomized controlled NiPPeR trial, aiming to identify longitudinal patterns of maternal vitamin status from preconception, through early and late pregnancy, to 6 months postdelivery, and determine the influence of vitamin supplementation.

METHODS AND FINDINGS

In the NiPPeR trial, 1,729 women (from the United Kingdom, Singapore, and New Zealand) aged 18 to 38 years and planning conception were randomized to receive a standard vitamin supplement (control; n = 859) or an enhanced vitamin supplement (intervention; n = 870) starting in preconception and continued throughout pregnancy, with blinding of participants and research staff. Supplement components common to both treatment groups included folic acid, β-carotene, iron, calcium, and iodine; components additionally included in the intervention group were riboflavin, vitamins B6, B12, and D (in amounts available in over-the-counter supplements), myo-inositol, probiotics, and zinc. The primary outcome of the study was glucose tolerance at 28 weeks' gestation, measured by oral glucose tolerance test. The secondary outcome reported in this study was the reduction in maternal micronutrient insufficiency in riboflavin, vitamin B6, vitamin B12, and vitamin D, before and during pregnancy. We measured maternal plasma concentrations of B-vitamins, vitamin D, and markers of insufficiency/deficiency (homocysteine, hydroxykynurenine-ratio, methylmalonic acid) at recruitment, 1 month after commencing intervention preconception, in early pregnancy (7 to 11 weeks' gestation) and late pregnancy (around 28 weeks' gestation), and postdelivery (6 months after supplement discontinuation). We derived standard deviation scores (SDS) to characterize longitudinal changes among participants in the control group and measured differences between the 2 groups. At recruitment, the proportion of patients with marginal or low plasma status was 29.2% for folate (<13.6 nmol/L), 7.5% and 82.0% for riboflavin (<5 nmol/L and ≤26.5 nmol/L, respectively), 9.1% for vitamin B12 (<221 pmol/L), and 48.7% for vitamin D (<50 nmol/L); these proportions were balanced between the groups. Over 90% of all participants had low or marginal status for one or more of these vitamins at recruitment. Among participants in the control group, plasma concentrations of riboflavin declined through early and late pregnancy, whereas concentrations of 25-hydroxyvitamin D were unchanged in early pregnancy, and concentrations of vitamin B6 and B12 declined throughout pregnancy, becoming >1 SDS lower than baseline by 28 weeks gestation. In the control group, 54.2% of participants developed low late-pregnancy vitamin B6 concentrations (pyridoxal 5-phosphate <20 nmol/L). After 1 month of supplementation, plasma concentrations of supplement components were substantially higher among participants in the intervention group than those in the control group: riboflavin by 0.77 SDS (95% CI 0.68 to 0.87, p < 0.0001), vitamin B6 by 1.07 SDS (0.99 to 1.14, p < 0.0001), vitamin B12 by 0.55 SDS (0.46 to 0.64, p < 0.0001), and vitamin D by 0.51 SDS (0.43 to 0.60, p < 0.0001), with higher levels in the intervention group maintained during pregnancy. Markers of vitamin insufficiency/deficiency were reduced in the intervention group, and the proportion of participants with vitamin D insufficiency (<50 nmol/L) during late pregnancy was lower in the intervention group (35.1% versus 8.5%; p < 0.0001). Plasma vitamin B12 remained higher in the intervention group than in the control group 6 months postdelivery (by 0.30 SDS (0.14, 0.46), p = 0.0003). The main limitation is that generalizability to the global population is limited by the high-resource settings and the lack of African and Amerindian women in particular.

CONCLUSIONS

Over 90% of the trial participants had marginal or low concentrations of one or more of folate, riboflavin, vitamin B12, or vitamin D during preconception, and many developed markers of vitamin B6 deficiency in late pregnancy. Preconception/pregnancy supplementation in amounts available in over-the-counter supplements substantially reduces the prevalence of vitamin deficiency and depletion markers before and during pregnancy, with higher maternal plasma vitamin B12 maintained during the recommended lactational period.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02509988; U1111-1171-8056.

Associations of vitamin B6 turnover rate with the risk of cardiovascular and all-cause mortality in hypertensive adults

BACKGROUND AND AIM

This study was to assess the association between vitamin B6 turnover rate and mortality in hypertensive adults.

METHODS AND RESULTS

Vitamin B6 status including serum pyridoxal-5'-phosphate (PLP) levels, serum 4-pyridoxal acid (4-PA) levels, and vitamin B6 turnover rate (4-PA/PLP) were obtained from the 2005-2010 National Health and Nutrition Examination Survey (NHANES) dataset of hypertensive adults with follow-up through December 30, 2019. Using Cox proportional risk regression models, Hazard ratios (HRs) and 95% confidence intervals (CIs) were analyzed for PLP, 4-PA and 4-PA/PLP quartiles in relation to cardiovascular and all-cause mortality. A total of 5434 participants were included in this study (mean age, 58.48 years; 50.4% men), and the median 4-PA/PLP was 0.75. The median follow-up time was 11.0 years, with 375 and 1387 cardiovascular and all-cause deaths, respectively. In multivariate COX regression models, PLP was negatively associated with cardiovascular mortality (HR [95% CI] quartile 4 vs. 1: 0.66 [0.47-0.94], P_trend = 0.03) and 4-PA/PLP was positively associated with cardiovascular mortality (HR [95% CI] quartile 4 vs.1: 1.80 [1.21-2.67], P_trend = 0.01). Similarly, the higher the quartile of PLP, the lower the risk of all-cause mortality (HR [95% CI] quartile 4 vs. 1: 0.67 [0.56-0.80], P_trend < 0.01). The higher the quartile of 4-PA and 4-PA/PLP, the higher the risk of all-cause mortality (HR [95% CI] quartile 4 vs. 1: 1.22 [1.01-1.48], P_trend < 0.01; and 2.09 [1.71-2.55], P_trend < 0.01).

CONCLUSION

The findings suggested that higher vitamin B6 turnover rate was associated with an increased risk of cardiovascular and all-cause mortality in hypertensive adults.

Associations of Serum Vitamin B6 Status and Catabolism With All-Cause Mortality in Patients With T2DM

CONTEXT

There is little evidence regarding the association between serum vitamin B6 status and catabolism and all-cause mortality in patients with type-2 diabetes mellitus (T2DM).

OBJECTIVE

We aimed to ascertain if the serum level of vitamin B6 and catabolism, including pyridoxal 5'-phosphate (PLP) and 4-pyridoxic acid (4-PA), were associated with risk of all-cause mortality in T2DM patients.

METHODS

This prospective cohort study involved 2574 patients with T2DM who participated in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2010. The serum concentrations of PLP and 4-PA were used to assess the serum level of vitamin B6. Mortality status was determined by routine follow-up using the National Death Index through December 31, 2015.

RESULTS

Over a median follow-up of 85 months, there were 588 deaths. The fully adjusted Cox model indicated that the highest serum PLP concentrations (> 63.6 nmol/L) were associated with a decrease in all-cause mortality (hazard ratio [HR], 0.74; 95% CI, 0.55-0.99, P trend = .035). The risk for all-cause mortality was 59% higher for participants with the highest quartile of 4-PA level compared with the lowest quartile (HR, 1.62; 95% CI, 1.12-2.35; P trend = .003). The sensitivity and specificity of the combination of PLP and 4-PA levels for the prediction of all-cause mortality were 59.5% and 60.9%, respectively (area under the receiver operating characteristic curve = 0.632). The Kaplan-Meier method was used to estimate overall survival for patients based on different combinations of PLP level and 4-PA level. Patients with PLP less than 24.3 nmol/L and 4-PA greater than or equal to 25.4 nmol/L had the worst outcomes (log-rank P < .001).

CONCLUSION

Overall, our data suggest that a low serum level of PLP and high serum level of 4-PA, which represent the serum level of vitamin B6, increases the risk of all-cause mortality significantly in patients with T2DM.

Association between Micronutrient Intake and Breast Cancer Risk According to Body Mass Index in South Korean Adult Women: A Cohort Study

This study investigated the association between micronutrient intake and breast cancer risk in South Korean adult women. This association was stratified according to body mass index (BMI) categories. Data from the Korean Genome and Epidemiology Study (KoGES) and the Health Examinee Study were analyzed. Altogether, 63,337 individuals (aged ≥40 years) completed the baseline and first follow-up surveys; 40,432 women without a history of cancer at baseline were included in this study. The association between micronutrient intake and breast cancer was determined by estimating the hazard ratio (HR) and 95% confidence interval (CI) using the Cox proportional hazard regression model. A stratified analysis by BMI (<25 kg/m2 and ≥25 kg/m2) was performed. The an analysis of 15 micronutrients and breast cancer risk revealed that none of the micronutrients were associated with breast cancer risk after adjusting for covariates. In obese women, the risk of breast cancer was significantly reduced in the group that consumed vitamin C more than the recommended level (HR = 0.54, 95% CI: 0.31−0.93) and vitamin B6 levels above the recommended level (HR = 0.48, 95% CI: 0.25−0.89). In obese women, exceeding the recommended daily intake levels of vitamin C and vitamin B6 was associated with a lower risk of breast cancer. However, other micronutrients were not associated with breast cancer risk in these women.

Association of Markers of Inflammation, the Kynurenine Pathway and B Vitamins with Age and Mortality, and a Signature of Inflammaging

BACKGROUND

Inflammation is a key feature of aging. We aimed to (i) investigate the association of 34 blood markers potentially involved in inflammatory processes with age and mortality and (ii) develop a signature of "inflammaging."

METHODS

Thirty-four blood markers relating to inflammation, B vitamin status, and the kynurenine pathway were measured in 976 participants in the Melbourne Collaborative Cohort Study at baseline (median age = 59 years) and follow-up (median age = 70 years). Associations with age and mortality were assessed using linear and Cox regression, respectively. A parsimonious signature of inflammaging was developed and its association with mortality was compared with 2 marker scores calculated across all markers associated with age and mortality, respectively.

RESULTS

The majority of markers (30/34) were associated with age, with stronger associations observed for neopterin, cystatin C, interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), several markers of the kynurenine pathway and derived indices KTR (kynurenine/tryptophan ratio), PAr index (ratio of 4-pyridoxic acid and the sum of pyridoxal 5'-phosphate and pyridoxal), and HK:XA (3-hydroxykynurenine/xanthurenic acid ratio). Many markers (17/34) showed an association with mortality, in particular IL-6, neopterin, C-reactive protein, quinolinic acid, PAr index, and KTR. The inflammaging signature included 10 markers and was strongly associated with mortality (hazard ratio [HR] per SD = 1.40, 95% CI: 1.24-1.57, p = 2 × 10-8), similar to scores based on all age-associated (HR = 1.38, 95% CI: 1.23-1.55, p = 4 × 10-8) and mortality-associated markers (HR = 1.43, 95% CI: 1.28-1.60, p = 1 × 10-10), respectively. Strong evidence of replication of the inflammaging signature association with mortality was found in the Hordaland Health Study.

CONCLUSION

Our study highlights the key role of the kynurenine pathway and vitamin B6 catabolism in aging, along with other well-established inflammation-related markers. A signature of inflammaging based on 10 markers was strongly associated with mortality.