Riboflavin Is an Important Determinant of Vitamin B-6 Status in Healthy Adults (original) (raw)
Related papers
The American Journal of Clinical Nutrition
Background The generation of the active form of vitamin B-6, pyridoxal 5′-phosphate (PLP), in tissues is dependent upon riboflavin as flavin mononucleotide, but whether this interaction is important for maintaining vitamin B-6 status is unclear. Objective To investigate vitamin B-6 and riboflavin status, their metabolic interaction, and relationship with methylenetetrahydrofolate reductase (MTHFR) genotype in adulthood. Methods Data from 5612 adults aged 18–102 y were drawn from the Irish National Adult Nutrition Survey (NANS; population-based sample) and the Trinity-Ulster Department of Agriculture (TUDA) and Genovit cohorts (volunteer samples). Plasma PLP and erythrocyte glutathione reductase activation coefficient (EGRac), as a functional indicator of riboflavin, were determined. Results Older (≥65 y) compared with younger (<65 y) adults had significantly lower PLP concentrations (P < 0.001). A stepwise decrease in plasma PLP was observed across riboflavin categories, from ...
The American journal of clinical nutrition, 1998
Free-living elderly people aged > or = 65 y were recruited to assess riboflavin and vitamin B-6 intakes and status and the effect of riboflavin supplementation on biochemical indicators of these 2 vitamins. The status of riboflavin (erythrocyte glutathione reductase activation coefficient; EGRAC) and vitamin B-6 (plasma pyridoxal-5'-phosphate; PLP) were determined in a total sample of 92 subjects, from whom dietary intake data were obtained by using the diet history method (n = 83). Although dietary intakes of both vitamins were considered to be adequate according to current reference values, abnormal EGRAC and plasma PLP values were identified in 49% and 38% of subjects, respectively, with 21% having suboptimal status for both nutrients. A subgroup of subjects from the initial sample (n = 45) was assigned in a double-blind manner to receive either 1.6 or 25 mg riboflavin or placebo daily for 12 wk. In those subjects with a baseline EGRAC or plasma PLP value falling outside t...
Studies of biomarker responses to intervention with riboflavin: a systematic review
American Journal of Clinical Nutrition, 2009
Background: Mild vitamin B-12 deficiency is common among older adults, but evidence for setting dietary recommendations is limited because most studies have administered vitamin B-12 via nonoral routes or at doses several hundred times higher than current recommendations. Furthermore, different biomarkers of vitamin B-12 status have not been systematically reviewed. Objective: The aim was to assess the effectiveness of biomarkers of vitamin B-12 status through a systematic review of published randomized controlled trials of oral vitamin B-12 supplementation. Design: Methods included a structured search strategy on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases; formal inclusion and exclusion criteria; data extraction; validity assessment; and meta-analysis. Results: Eight randomized controlled trials were included, and all studies measured serum and plasma total vitamin B-12, 3 studies measured methylmalonic acid, and 6 studies measured total homocysteine response. All 3 biomarkers were found to be effective measures of altered vitamin B-12 intake in populations with low and borderline baseline vitamin B-12 status (P , 0.00001); however, in the case of total vitamin B-12, substantial heterogeneity that could not be fully explained by subgroup analysis was observed. Insufficient data were available to determine the effectiveness of plasma holotranscobalamin, which was measured in only one randomized controlled trial. Conclusions: The available evidence suggests that plasma and serum concentrations of total vitamin B-12, methylmalonic acid, and total homocysteine are all effective biomarkers of a change in vitamin B-12 intake; however, because the available data were limited, it was not possible to examine fully the factors that could explain the substantial heterogeneity in total vitamin B-12. Future trials should include low-dose vitamin B-12 in adults across the entire age spectrum and measure the holotranscobalamin response to supplementation.
BMC Public Health, 2009
Background: The functional significance of moderate riboflavin deficiency as it is currently assessed is not well understood. Animal and human studies have suggested a role for riboflavin in the absorption and mobilisation of iron and as such may be important in maintaining haematological status. Recent National Diet and Nutrition Surveys in the United Kingdom have shown that young women in particular are at risk of moderate riboflavin deficiency and low iron status. Methods/Design: A randomised placebo controlled intervention trial was conducted to investigate the effect of riboflavin supplementation on various measures of haematological status in a group of moderately riboflavin deficient young women aged 19 to 25 years. Women who were low milk consumers were initially screened for riboflavin status as assessed by the erythrocyte glutathione reductase activation coefficient assay (EGRAC). One hundred and twenty three women with EGRAC values >1.40 were randomised to receive 2 mg, 4 mg riboflavin or placebo for 8 weeks. In addition 36 of these women were randomly allocated to an iron bioavailability study to investigate the effect of the intervention on the absorption or utilisation of iron using an established red cell incorporation technique. Discussion: One hundred and nineteen women completed the intervention study, of whom 36 completed the bioavailability arm. Compliance was 96 ± 6% (mean ± SD). The most effective recruitment strategy for this gender and age group was e-communication (e-mail and website). The results of this study will clarify the functional significance of the current biochemical deficiency threshold for riboflavin status and will inform a re-evaluation of this biochemical threshold.
British Journal of Nutrition, 2003
The aim of the present study was to assess the nutritional status for thiamin (vitamin B 1 ) and riboflavin (vitamin B 2 ) in an adult Mediterranean population, in order to identify patterns of intake, groups at risk for deficiency and factors that might influence this risk. A cross-sectional survey was carried out in Andalusia, a western Mediterranean region in southern Spain. Nutrient intakes were studied in a random sample of 3390 subjects (1746 men, 1644 women) who were between 25 and 60 years of age. Blood samples were obtained for biochemical assays in a random subsample of 372 subjects (181 men, 191 women). Food consumption was assessed by 48 h recall. Vitamin B 1 and B 2 were measured as erythrocyte transketolase and as erythrocyte glutathione reductase activation coefficients, respectively. Energy and vitamin intakes were significantly higher in men than in women. Intakes were below two-thirds of the recommended dietary allowance for vitamin B 1 in 7·80 % of the men and 4·50 % of the woman, and were below this level for vitamin B 2 in 18·00 % of the men and 11·70 % of the women. Age, educational level, alcohol use and smoking were also associated with differences in the intake of these nutrients. Biochemical analyses showed that vitamin B 1 and B 2 status was deficient in 6·40 and 5·30 % of the population, respectively. Although factors such as gender, age, level of education, drinking and smoking can have an effect on the risk of inadequate intake of these nutrients, these factors did not affect biochemical indices of nutritional status in the present study. Vitamin B 1 and B 2 status: Micronutrient status: Adults: Mediterranean region * Corresponding author: Dr Juan Llopis, fax þ 34 958 248959, email jllopis@ugr.es Abbreviations: EGR, erythrocyte glutathione reductase activity; ETK, erythrocyte transketolase activity; RDA, recommended dietary allowance.
Vitamin B6 Status among Vegetarians: Findings from a Population-Based Survey
Nutrients
Vitamin B6 from plant foods may have lower bioavailability than vitamin B6 from animal foods, but studies on objectively measured vitamin B6 status among vegetarians compared to non-vegetarians are lacking. Thus, the vitamin B6 status among vegetarians, but also pescatarians, and flexitarians, compared to meat-eaters was assessed in the population-based NHANES study (cycles 2007–2008 and 2009–2010). Data on serum pyridoxal-5′-phosphate (PLP) and 4-pyridoxic acid (4-PA) measured by high-performance liquid chromatography (HPLC) as well as dietary intakes from 24-h recalls were available for 8968 adults aged 20–80 years. Geometric mean (±standard error) PLP concentrations were 58.2 ± 6.0, 52.1 ± 3.7, 49.2 ± 4.6 and 51.0 ± 1.1 nmol/L among vegetarians, pescatarians, flexitarians, and meat-eaters. The 4-PA concentrations were 32.7 ± 4.0, 29.0 ± 2.5, 34.8 ± 5.6 and 33.0 ± 0.7, respectively. There were no statistically significant differences in PLP, 4-PA, and their ratio across the groups...
Direct and Functional Biomarkers of Vitamin B6 Status
Annual Review of Nutrition, 2014
Measures of B6 status are categorized as direct biomarkers and as functional biomarkers. Direct biomarkers measure B6 vitamers in plasma/serum, urine and erythrocytes, and among these plasma pyridoxal 5-phosphate (PLP) is most commonly used. Functional biomarkers include erythrocyte transaminase activities and, more recently, plasma levels of metabolites involved in PLP-dependent reactions, such as the kynurenine pathway, one-carbon metabolism, transsulfuration (cystathionine), and glycine decarboxylation (serine and glycine). Vitamin B6 status is best assessed by using a combination of biomarkers because of the influence of potential confounders, such as inflammation, alkaline phosphatase activity, low serum albumin, renal function, and inorganic phosphate. Ratios between substrate-products pairs have recently been investigated as a strategy to attenuate such influence. These efforts have provided promising new markers such as the PAr index, the 3hydroxykynurenine:xanthurenic acid ratio, and the oxoglutarate:glutamate ratio. Targeted metabolic profiling or untargeted metabolomics based on mass spectrometry allow the simultaneous quantification of a large number of metabolites, which are currently evaluated as functional biomarkers, using data reduction statistics.