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Background: Riboflavin is required to generate the active form of vitamin B-6 (pyridoxal 5'-phosphate; PLP) in tissues, but the relevance of this metabolic interaction for nutritional status of vitamin B-6 is unclear because riboflavin biomarkers are rarely measured in human studies., Objectives: The purpose of this study was to identify the determinants of biomarkers of vitamin B-6 and riboflavin status and to examine the relationship between these nutrients in healthy adults., Methods: Multiple linear regression was performed on observational data in 407 healthy adults aged 18-92 y who did not use B-vitamin supplements. Vitamin B-6 status was assessed by plasma PLP concentrations and erythrocyte glutathione reductase activation coefficient (EGRac) was used as a functional indicator of riboflavin status., Results: Dietary intakes of vitamin B-6 and riboflavin were below the average requirements in 10% and 29% of participants, respectively. Suboptimal status of vitamin B-6 (PLP ≤30.0 nmol/L) was more prevalent in adults aged ≥60 y than in younger participants (i.e., 14% compared with 5%), whereas a high proportion (i.e., overall 37%) of both age groups had deficient riboflavin status (EGRac ≥1.40). In multiple regression analysis, EGRac (P = 0.019) was a significant determinant of plasma PLP, along with dietary vitamin B-6 intake (P = 0.003), age (P < 0.001), BMI (kg/m2) (P = 0.031), and methylenetetrahydrofolate reductase gene (MTHFR) genotype (P < 0.001). Significant determinants of EGRac were dietary riboflavin intake (P < 0.001), age (P < 0.001) and MTHFR genotype (P = 0.020). Plasma PLP showed a stepwise decrease across riboflavin status categories from optimal (EGRac ≤1.26) to low (EGRac 1.27-1.39) to deficient status (P = 0.001), independent of dietary vitamin B-6 intake., Conclusions: The findings are consistent with the known metabolic dependency of vitamin B-6 on riboflavin status and indicate that riboflavin may be the limiting nutrient, particularly in older people, for maintaining adequate vitamin B-6 status., (Copyright © The Author(s) on behalf of the American Society for Nutrition 2020.)

Background: Urban populations have grown globally alongside emerging simultaneous burdens of undernutrition and obesity. Yet, how heterogeneous urban environments are associated with this nutritional double burden is poorly understood., Objective: We aimed to determine: 1) the prevalence of the nutritional double burden and its components in urban, peri-urban, and rural areas of Bolivia; and 2) the association of residence in these areas with the nutritional double burden and its components., Design: We surveyed 3946 randomly selected households from 2 metropolitan regions of Bolivia. Census data and remotely sensed imagery were used to define urban, peri-urban, and rural districts along a transect in each region. We defined 5 nutritional double burdens: concurrent overweight and anemia among women of reproductive age (15-49 y), and children (6-59 mo), respectively; concurrent overweight and stunting among children; and households with an overweight woman and, respectively, an anemic or stunted child. Capillary hemoglobin concentrations were measured to assess anemia (women: hemoglobin <120 g/L; children: hemoglobin <110 g/L), and overweight and stunting were calculated from height, weight, and age data., Results: In multiple logistic regression models, peri-urban, but not urban residence, was associated with higher odds of concurrent overweight and anemia among children (OR: 1.8; 95% CI; 1.0, 3.2) and of households with an overweight woman and stunted child (1.8; 1.2, 2.7). Examining the components of the double burden, peri-urban women and children, respectively, had higher odds of overweight than rural residents [women (1.5; 1.2, 1.8); children (1.5; 1.0, 2.4)], and children from peri-urban regions had higher odds of stunting (1.5; 1.1, 2.2)., Conclusions: Peri-urban, but not urban, residence in Bolivia is associated with a higher risk of the nutritional double burden than rural areas. Understanding how heterogeneous urban environments influence nutrition outcomes could inform integrated policies that simultaneously address both undernutrition and obesity.

Background: UVB-induced skin synthesis is considered the key source of vitamin D, yet exposure to UVB is poorly accounted for in epidemiological studies. Objectives: The aim of this study was to examine the association of serum 25-hydroxyvitamin D [25(OH)D] concentration with accurately measured ambient UVB dose, sun enjoyment, supplements, and other factors. Methods: An all-Irish cohort of community-dwelling participants aged >60 y [median age: 73; 67% female; median 25(OH)D: 54.5 nmol/L] was used. Participants from this large, cross-sectional study completed a questionnaire to provide information on demographic factors and lifestyle (including supplement use and sun enjoyment). The Tropospheric Emission Monitoring Internet Service database was used to extract the daily ambient UVB dose at wavelengths that could induce vitamin D synthesis (D-UVB) over Ireland (latitude: 51°N-55°N). Blood sampling occurred throughout the year. Ambient exposure at the place of residence was calculated for each participant individually. Associations between determinants and serum 25(OH)D concentration were examined in a multivariate model. Random forest analysis was used to establish prediction models of vitamin D deficiency, and area under the curve (AUC) is shown. Results: In total, 5138 individuals were included. Median D-UVB was 63 mJ/cm 2 , which varied between seasons and latitudes, despite the small latitude differential. Vitamin D supplementation (β = 27.7; P < 10 × 10 -10 ), D-UVB (β = 1.58 per 1000 mJ/cm 2 ; P < 10 × 10 -10 ), and sun enjoyment (β = 6.6; P < 0.001) were strongly positively associated with serum 25(OH)D. Those who avoided sunshine were largely at risk of deficiency (<40 nmol/L), whereas those who enjoyed sunshine tended to be vitamin D sufficient (≥50 nmol/L). D-UVB and sun enjoyment improved prediction of deficiency in non-supplement-taking individuals; the overall AUC improved by 3.5%. Conclusion: D-UVB and sun enjoyment are important predictors of vitamin D status, even in this elderly population at northern latitudes. Accurate estimation of ambient UVB can help to further clarify the role of other determinants of vitamin D status and inform sunshine recommendation guidelines., Competing Interests: 2: Author disclosures: F O’Sullivan, E Laird, D Kelly, J van Geffen, M van Weele, H McNulty, L Hoey, M Healy, K McCarroll, C Cunningham, M Casey, M Ward, JJ Strain, AM Molloy, and L Zgaga, no conflicts of interest., (© 2017 American Society for Nutrition.)

Low folate status is a risk factor for colon carcinogenesis; mechanisms proposed to account for this relationship include uracil misincorporation into DNA and global DNA hypomethylation. We investigated whether such biomarkers are related to folate status in isolated colonocytes from colonoscopy patients. In cases with adenomatous polyps (n = 40) or hyperplastic polyps (n = 16), colonocytes were isolated from biopsies from the polyp, from a site adjacent to the polyp, and from normal mucosa 10-15 cm distal to the polyp. In polyp-free controls (n = 53), biopsies were taken from ascending, transverse, and descending areas of colon. Within adenoma cases, there was a trend (P-trend < 0.001) of decreasing colonocyte folate (pg/10⁵ cells, mean ± CI) from the site distal to the polyp (16.9 ± 2.4), to the site adjacent to the polyp (14.7 ± 2.3), to the polyp (12.8 ± 2.0). Correspondingly, there were increases in uracil misincorporation (P-trend < 0.001) and global DNA hypomethylation (P-trend = 0.012) across the 3 sites. Colonocyte folate concentrations were significantly correlated with RBC folate concentrations, but only in individuals with generally lower (≤484 μg/L) RBC folate status (r = 0.54; P = 0.006; n = 24), and were also significantly lower in normal mucosa of cases with adenomatous polyps than in controls matched for colonic segment. In conclusion, localized folate deficiency in specific areas of colon might create carcinogenic fields and affect the development of colorectal polyps through uracil misincorporation and DNA hypomethylation; alternatively, the polyp itself might deplete folate in the surrounding tissue. Folate supplementation trials aimed at colon cancer prevention should target individuals with suboptimal folate status.

As evidence from small-scale trials has accumulated concerning the efficacy of low-cost interventions to address undernutrition, the design, implementation, and strengthening of large-scale programs to deliver these interventions has become a high priority. This scaling up process involves a large number of technical, logistical, administrative, political, and social considerations and little research exists on how to address these in a systematic way. This paper introduces the Program Assessment Guide (PAG), a set of analysis and decision tools that seeks to fill this gap, and reports on its application in Kyrgyzstan and Bolivia. The PAG places a special focus on eliciting and systematizing contextual knowledge and experience through a structured, participatory workshop and is grounded in theory, principles, and experience from program planning, management, change management, and intervention planning. When applied in Kyrgyzstan and Bolivia, the PAG was successful in helping workshop participants identify key implementation bottlenecks, questionable assumptions in the program theory, and feasible ways to address some of the shortcomings. These experiences also identified the need for a number of modifications to the PAG related to the workshop design itself, the preparations prior to the workshop, and follow-up after the workshop. The PAG represents one approach for strengthening decisions related to the design and large-scale implementation of interventions. The development and full-scale testing of alternative methods such as these for strengthening program analysis and decision making is an important and intellectually challenging subject for further research.