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Intakes and status of riboflavin in a representative sample of Irish adults aged 18–90 years screened for MTHFR C677T polymorphism
- Emma O'Sullivan, Laura Kehoe, Janette Walton, Helene McNulty, Mary Ward, Liadhan McAnena, Sinead M. Hopkins, Breige A. McNulty, Anne P. Nugent, Albert Flynn
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E71
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Meta-analyses of epidemiological data report that adults who carry a common polymorphism, the MTHFR 677C→T, in the gene encoding the folate-metabolising enzyme methylenetetrahydrofolate reductase (MTHFR) have a 40% increased risk of CVD and an 87% increased risk of hypertension. Riboflavin (vitamin B2), in its co-enzymatic form flavin adenine nucleotide (FAD), is required as a co-factor by MTHFR and previous trials in hypertensive patients have shown a blood pressure lowering response to riboflavin supplementation that is specific to individuals homozygous for this polymorphism (TT genotype). Low folate status is commonly reported in adults with the TT genotype however the effect of this genetic variant on riboflavin status has not previously been investigated. The aim of this study, therefore, was to investigate dietary intake and biomarker status of riboflavin by MTHFR genotype in Irish adults using data from the National Adult Nutrition Survey (2008–2010) (www.iuna.net).
A 4-day semi-weighed food record was used to collect food and beverage intake data from a representative sample of 1500 Irish adults (18–90 years). Dietary intake data were analysed using WISP© based on UK food composition tables (modified to include recipes of composite dishes, nutritional supplements, fortified foods and generic Irish foods that were commonly consumed). Usual intakes were calculated via the NCI-method using SAS© Enterprise Guide. Blood samples (n = 1126) were collected by venepuncture by a trained professional and were processed and analysed using standard operating procedures. Biomarker status of riboflavin was determined by erthyrocyte gluthathione reductase activation coefficient (EGRac), a functional assay that measures the activity of the enzyme glutathione reductase before and after in vitro activation with its prosthetic group FAD; a lower value indicates better status.
It was found that 12% of the population had the TT genotype. As expected, there was no significant difference in riboflavin intake across the genotype (CC, CT or TT) groups. Similarly, no significant genotype differences in riboflavin status (EGRac) were observed (1.36 vs 1.37 vs 1.38 respectively). Overall, 61% of the total population had EGRac values > 1.3, indicative of low/deficient status with no significant difference observed between the genotype groups (60%,61% and 61%, respectively).
These data suggest that riboflavin status is not influenced by the C677T polymorphism in MTHFR in this cohort of nationally representative Irish adults. Further research is needed to see the impact of riboflavin status on blood pressure across the genotype groups in this nationally representative cohort of Irish adults.
Plasma riboflavin concentration as novel indicator for vitamin-B2 status assessment: suggested cutoffs and its association with vitamin-B6 status in women
- Amy Tan, Mohammad Zubair, Chia-ling Ho, Liadhan McAnena, Helene McNulty, Mary Ward, Yvonne Lamers
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E658
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Riboflavin (vitamin B2), as the coenzymes flavin mononucleotide (FMN) and flavin dinucleotide (FAD), is essential for oxidation-reduction reactions and energy metabolism. Riboflavin also interacts with vitamin B12, B6 and folate in one-carbon metabolism, and is required for the conversion of dietary vitamin B6 forms to the coenzyme pyridoxal 5’-phosphate (PLP). Biochemical riboflavin status is rarely measured given the lack of convenient and accessible biomarkers. The current gold-standard marker is erythrocyte glutathione reductase activation coefficient (EGRac) that involves laborious sample processing. High prevalence of riboflavin deficiency (EGRac ≥ 1.4) and suboptimal status (EGRac of 1.3–1.39) have been reported in the UK and Ireland; yet the functional significance is unclear. Plasma riboflavin concentration may serve as an alternative indicator; its association with related metabolites has not yet been investigated. Secondary analysis was conducted to determine the change-point of plasma riboflavin with EGRac, to derive a reference interval for plasma riboflavin, and to determine the association of riboflavin status with plasma PLP, using data of 223 older adult women from a cross-sectional study. Fasting blood samples and sociodemographic, anthropometric and dietary data were available for a convenience sample of 223 older adult women. Plasma PLP and related metabolites were quantified using isotope-dilution liquid chromatography-tandem mass spectrometry. The change-point (95% CI) between EGRac and plasma riboflavin occurred at plasma riboflavin concentration of 26.5 (20.5; 32.5) nmol/L (with EGRac of 1.25). The median (IQR) plasma riboflavin concentration was 15.7 (11.2, 23.8); and the upper and lower limits (90%CI) of the central 95% reference interval were 6.70 (6.33, 7.79) and 64.2 (55.0, 74.6) nmol/L, respectively. Plasma PLP (geometric mean (95%CI)) was significantly lower in women with riboflavin deficiency, 54.0 (46.8, 62.2) nmol/L (n = 64), and suboptimal riboflavin status, 56.1 (48.9, 64.3) nmol/L (n = 48), compared to those with riboflavin adequacy, 135 (112, 161) nmol/L (n = 110). Plasma PLP was positively associated with plasma riboflavin concentration after adjustment for total B6 intake, age, ethnicity, BMI, education, household income and C-reactive protein concentration [β (95% CI) = 1.92 (.670, 3.17) nmol/L; p = 0.003]; a significant interaction between plasma riboflavin and total dietary B6 intake was observed (p = 0.024). In conclusion, we are presenting for the first time a reference range for plasma riboflavin concentration and its change-point with EGRac in healthy women. Vitamin B6 status is strongly associated with riboflavin status; more research is needed to elucidate this relationship in a larger sample and ideally intervention study.
Relationship of obesity with B vitamin status: analysis of NDNS data from UK women of reproductive age
- Maeve Kerr, Barbara Livingstone, Mary Ward, Liadhan McAnena, Lorna Cox, Ruth Price, Kristina Pentieva, Helene McNulty
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E600
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Pre-pregnancy obesity is associated with a 2-fold increased risk of Neural Tube Defects (NTD), an effect not explained by lower dietary folate intake, or non-use of folic acid supplements (as recommended globally to women before and in early pregnancy for NTD prevention). While the exact mechanism linking NTD and obesity is poorly understood, it is possible that a compromised status or metabolism of folate and/or of the closely related micronutrients (vitamin B12, B6 and riboflavin) may be involved. To date however, this hypothesis has not been adequately explored. This study therefore aimed to investigate the relationship of obesity with folate and related B vitamin biomarkers in a representative cohort of non-pregnant UK women of reproductive age. Data were accessed from the most recent UK National Diet and Nutrition Survey (NDNS; Years 7–8; 2015–16), a rolling cross-sectional survey designed to gather information from a representative sample of the UK population on nutrient intakes, food consumption and nutritional status. Data for women aged 16–45 years (non B vitamin supplement users; n 364), were extracted on: anthropometry (height, weight, body mass index [BMI] and waist circumference [WC]), dietary intakes of B vitamins and biomarkers for serum and red blood cell folate, vitamin B12 (total serum B12 and holotranscobalamin), vitamin B6 (plasma pyridoxal-5-phosphate [PLP]) and riboflavin (erythrocyte glutathione reductase activation coefficient EGRAac]). Prevalence of overweight and obesity (i.e. BMI: 25–30kg/m2 and > 30kg/m2) was 28% and 22% respectively, whilst abdominal obesity (i.e. WC > 88cm) was present in 31% of the women. Total serum B12 (r -0.215, P 0.012) and PLP (r -0.270, P 0.002) were negatively correlated with WC, with similar, albeit weaker, correlations found for BMI. Correspondingly, women with abdominal obesity compared to those without, had a lower status of total serum B12 (Median values of: 212 v 249 v pmol/L; P 0.049), B6 (31.5 v 40.5 nmol/L; P 0.002) and EGRac (1.43 v 1.36; P 0.031). No differences in B vitamin dietary intake were observed by categories of abdominal obesity. Abdominal obesity may be a risk factor for low status of both vitamins B12 and B6, independently of dietary intake. Further investigation to elucidate the potential underlying mechanism is warranted. These findings also highlight the importance of taking abdominal obesity into account, in addition to BMI, when examining possible adverse impacts of obesity on micronutrient status.
Zinc supplementation has no effect on circulating levels of peripheral blood leucocytes and lymphocyte subsets in healthy adult men
- Maxine Bonham, Jacqueline M. O'Connor, H. Denis Alexander, James Coulter, Paula M. Walsh, Liadhan B. McAnena, C. Stephen Downes, Bernadette M. Hannigan, J. J. Strain
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- Journal:
- British Journal of Nutrition / Volume 89 / Issue 5 / May 2003
- Published online by Cambridge University Press:
- 09 March 2007, pp. 695-703
- Print publication:
- May 2003
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As a result of evidence documenting harmful effects of Zn supplementation on immune function and Cu status, thirty-eight men were recruited onto a Zn supplementation trial. The aim was to examine the effects of chronic Zn supplementation on circulating levels of peripheral blood leucocytes and lymphocyte subsets. Subjects (n 19) took 30 mg Zn/d for 14 weeks followed by 3 mg Cu/d for 8 weeks to counteract adverse effects, if any, of Zn supplementation on immune status resulting from lowered Cu status. A control group (n 19) took placebo supplements for the duration of the trial. Dietary intakes of Zn approximated 10 mg/d. Blood samples, taken throughout the trial, were assessed for full blood profiles and flow cytometric analyses of lymphocyte subsets. Putative indices of Cu status were also examined. Results indicate that there was no effect of Zn supplementation on circulating levels of peripheral blood leucocytes or on lymphocyte subsets. Cu status was also unaltered. Independent of supplement, there appeared to be seasonal variations in selected lymphocyte subsets in both placebo and supplemented groups. Alterations in circulating levels of B cells (cluster of differentiation (CD) 19), memory T cells (CD45RO) and expression of the intracellular adhesion molecule-1 (CD54) on T cells were observed. Findings indicated no adverse effects of Zn supplementation on immune status or Cu status and support the US upper level of Zn tolerance of 40 mg/d. The seasonal variations observed in lymphocyte subsets in the group as a whole could have implications for seasonal variability in the incidence of infectious diseases.