Vanessa da Silva

Interests

Research

public health nutrition: diabetes prevention, nutritional influences on arsenic toxicity, dietary assessment, health disparities

Teaching

I am interested in mentoring undergraduate and graduate students in research related to public health nutrition. My role with Cooperative Extension allows for opportunities to engage with local communities in the implementation of health promotion programs.

Courses

Scholarly Contributions

Chapters

• da Silva, V. R. (2013). Folate. In Handbook of Vitamins. Taylor and Francis.

Journals/Publications

• Wong, S. S., Topham, G. L., Silva, V. D., Richards, R., Reicks, M., Monroe-lord, L., Lora, K., Jones, B. L., Hongu, N. K., Gunther, C., Banna, J., & Anderson, A. K. (2020). Development of Parent and Adolescent Questionnaires to Assess Food Parenting Practices That Address Adolescent Consumption During Independent Eating Occasions.. Journal of nutrition education and behavior, 52(3), 307-313. doi:10.1016/j.jneb.2019.10.018
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  To develop and test parent and early adolescent questionnaires to assess food parenting practices that influence early adolescent food consumption during independent eating occasions (iEOs)..Cross-sectional online questionnaires were completed by 206 and 62 low-income parent/early adolescent (11-14 years) dyads at Time 1 and 2, respectively, recruited via a Qualtrics (Provo, UT) US national panel database. Principal component analyses, internal consistency, and test-retest reliability checks were performed..Six parallel components were identified for parents and early adolescents with acceptable internal consistency and test-retest reliability. Scales included autonomy support, monitoring, availability, indulgence, expectations, and modeling. All except indulgence were positively correlated with importance of helping early adolescents make healthy choices during iEOs..Additional research is needed to test the questionnaires' validity regarding relationships between parenting practices and early adolescent consumption during iEOs. Findings could inform development of interventions to improve consumption during these occasions.
• da Silva, V. R., Gachupin, F. C., Bryant, H., & Brown, C. (2017). Usual Dietary Intake and Adherence to Dietary Recommendations among Southwest American Indian Youth at Risk for Type 2 Diabetes. Maternal and Child Health.
• Gachupin, F. C., Johnson, C. B., Torabzadeh, E., Bryant, H., & da Silva, V. R. (2019). Usual Dietary Intake and Adherence to Dietary Recommendations among Southwest American-Indian Youths at Risk of Type 2 Diabetes. Current developments in nutrition, 3(11), nzz111.
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  American Indians are disproportionately affected by obesity and diabetes, and American-Indian youths have the highest prevalence of obesity and diabetes among all ethnic groups in the USA.
• Gunther, C., Reicks, M., Banna, J., Suzuki, A., Topham, G., Richards, R., Jones, B., Lora, K., Anderson, A. K., da Silva, V., Penicka, C., Hopkins, L. C., Cluskey, M., Hongu, N., Monroe-Lord, L., & Wong, S. S. (2019). Food Parenting Practices That Influence Early Adolescents' Food Choices During Independent Eating Occasions. Journal of nutrition education and behavior, 51(8), 993-1002.
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  To identify practices that parents use to influence early adolescents' food choices during independent eating occasions (iEOs) from parent and child perspectives.
• Reicks, M., Banna, J., Anderson, A. K., Da Silva, V., Gunther, C., Hongu, N. K., Jones, B., Lora, K., Monroe-Lord, L., Richards, R., Topham, G., & Wong, S. S. (2019). Development of Parent and Adolescent Questionnaires to Assess Food Parenting Practices That Address Adolescent Consumption During Independent Eating Occasions. Journal of nutrition education and behavior.
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  To develop and test parent and early adolescent questionnaires to assess food parenting practices that influence early adolescent food consumption during independent eating occasions (iEOs).
• Kurzius-Spencer, M., da Silva, V., Thomson, C. A., Hartz, V., Hsu, C. H., Burgess, J. L., O'Rourke, M. K., & Harris, R. B. (2017). Nutrients in one-carbon metabolism and urinary arsenic methylation in the National Health and Nutrition Examination Survey (NHANES) 2003-2004. The Science of the total environment, 607-608, 381-390.
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  Exposure to inorganic arsenic (inAs), a potent toxicant, occurs primarily through ingestion of food and water. The efficiency with which it is methylated to mono and dimethyl arsenicals (MMA and DMA) affects toxicity. Folate, vitamins B12 and B6 are required for 1C metabolism, and studies have found that higher levels of these nutrients increase methylation capacity and are associated with protection against adverse health effects from inAs, especially in undernourished populations. Our aim was to determine whether 1C-related nutrients are associated with greater inAs methylation capacity in a general population sample with overall adequate nutrition and low levels of As exposure. Univariate and multivariable regression models were used to evaluate the relationship of dietary and blood nutrients to urinary As methylation in the National Health and Nutrition Examination Survey (NHANES) 2003-2004. Outcome variables were the percent of the sum of inAs and methylated As species (inAs+MMA+DMA) excreted as inAs, MMA, and DMA, and the ratio of MMA:DMA. In univariate models, dietary folate, vitamin B6 and protein intake were associated with lower urinary inAs% and greater DMA% in adults (≥18years), with similar trends in children (6-18). In adjusted models, vitamin B6 intake (p=0.011) and RBC folate (p=0.036) were associated with lower inAs%, while dietary vitamin B12 was associated with higher inAs% (p=0.002) and lower DMA% (p=0.030). Total plasma homocysteine was associated with higher MMA% (p=0.004) and lower DMA% (p=0.003), but not with inAs%; other blood nutrients showed no association with urinary As. Although effect size is small, these findings suggest that 1C nutrients can influence inAs methylation and potentially play an indirect role in reducing toxicity in a general population sample.
• da Silva, V. R. (2016). Social media use in the Expanded Food and Nutrition Education Program – the perspective of educators and program participants.. Journal of Extension.
• da Silva, V. R., Ralat, M. A., Quinlivan, E. P., DeRatt, B. N., Garrett, T. J., Chi, Y., Frederik Nijhout, H., Reed, M. C., & Gregory, J. F. (2014). Targeted metabolomics and mathematical modeling demonstrate that vitamin B-6 restriction alters one-carbon metabolism in cultured HepG2 cells. American journal of physiology. Endocrinology and metabolism, 307(1), E93-101.
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  Low vitamin B-6 nutritional status is associated with increased risk for cardiovascular disease and certain cancers. Pyridoxal 5'-phosphate (PLP) serves as a coenzyme in many cellular processes, including several reactions in one-carbon (1C) metabolism and the transsulfuration pathway of homocysteine catabolism. To assess the effect of vitamin B-6 deficiency on these processes and associated pathways, we conducted quantitative analysis of 1C metabolites including tetrahydrofolate species in HepG2 cells cultured in various concentrations of pyridoxal. These results were compared with predictions of a mathematical model of 1C metabolism simulating effects of vitamin B-6 deficiency. In cells cultured in vitamin B-6-deficient medium (25 or 35 nmol/l pyridoxal), we observed >200% higher concentrations of betaine (P < 0.05) and creatinine (P < 0.05) and >60% lower concentrations of creatine (P < 0.05) and 5,10-methenyltetrahydrofolate (P < 0.05) compared with cells cultured in medium containing intermediate (65 nmol/l) or the supraphysiological 2,015 nmol/l pyridoxal. Cystathionine, cysteine, glutathione, and cysteinylglycine, which are components of the transsulfuration pathway and subsequent reactions, exhibited greater concentrations at the two lower vitamin B-6 concentrations. Partial least squares discriminant analysis showed differences in overall profiles between cells cultured in 25 and 35 nmol/l pyridoxal vs. those in 65 and 2,015 nmol/l pyridoxal. Mathematical model predictions aligned with analytically derived results. These data reveal pronounced effects of vitamin B-6 deficiency on 1C-related metabolites, including previously unexpected secondary effects on creatine. These results complement metabolomic studies in humans demonstrating extended metabolic effects of vitamin B-6 insufficiency.
• Zhao, M., Ralat, M. A., da Silva, V., Garrett, T. J., Melnyk, S., James, S. J., & Gregory, J. F. (2013). Vitamin B-6 restriction impairs fatty acid synthesis in cultured human hepatoma (HepG2) cells. American journal of physiology. Endocrinology and metabolism, 304(4), E342-51.
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  Vitamin B-6 deficiency has been reported to alter n-6 and n-3 fatty acid profiles in plasma and tissue lipids; however, the mechanisms underlying such metabolic changes remain unclear. The objective of this study was to determine the effects of vitamin B-6 restriction on fatty acid profiles and fatty acid synthesis in HepG2 cells. Cells were cultured for 6 wk in media with four different vitamin B-6 concentrations (10, 20, 50, and 2,000 nM added pyridoxal, representing deficient, marginal, adequate, and supraphysiological conditions) that induced a range of steady-state cellular concentrations of pyridoxal phosphate. Total cellular lipid content was greatest in the deficient (10 nM pyridoxal) medium. The percentage of arachidonic acid and the ratio of arachidonic acid to linoleic acid in the total lipid fraction were ~15% lower in vitamin B-6-restricted cells, which suggests that vitamin B-6 restriction affects n-6 fatty acid interconversions. Metabolic flux studies indicated significantly lower fractional synthesis rate of oleic acid and arachidonic acid at 10, 20, and 50 nM pyridoxal, whereas that of eicosapentaenoic acid was lower in the cells cultured in 10 nM pyridoxal. Additionally, relative mRNA expressions of Δ5 and Δ6 desaturases were 40-50% lower in vitamin B-6-restricted cells. Overall, these findings suggest that vitamin B-6 restriction alters unsaturated fatty acid synthesis, particularly n-6 and n-3 polyunsaturated fatty acid synthesis. These results and observations of changes in human plasma fatty acid profiles caused by vitamin B-6 restriction suggest a mechanism by which vitamin B-6 inadequacy influences the cardiovascular risk.
• da Silva, V. R., Hausman, D. B., Kauwell, G. P., Sokolow, A., Tackett, R. L., Rathbun, S. L., & Bailey, L. B. (2013). Obesity affects short-term folate pharmacokinetics in women of childbearing age. International journal of obesity (2005), 37(12), 1608-10.
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  Maternal folate status and body mass index (BMI) are independent risk factors for neural tube defects (NTD). Population-based studies have identified an inverse association between serum folate and BMI, after adjusting for intake. The objective of this intervention study was to compare the relationship between BMI and the short-term pharmacokinetic response to an oral dose of folic acid. Healthy obese (BMI 30.0 kg m(-2); n=16) and normal-weight (BMI 18.5-24.9 kg m(-2); n=16) women of childbearing age (18-35 years) were administered a single oral dose of folic acid (400 μg). Blood samples were collected over a 10-h period to evaluate the serum folate response. Fasting baseline serum folate was lower in the obese group (P=0.005); in contrast, red blood cell folate was higher (P=0.05). Area-under-the-curve for the absorption phase (0-3 h) and peak serum folate concentrations were lower in obese versus normal-weight women (P
• da Silva, V. R., Rios-Avila, L., Lamers, Y., Ralat, M. A., Midttun, Ø., Quinlivan, E. P., Garrett, T. J., Coats, B., Shankar, M. N., Percival, S. S., Chi, Y., Muller, K. E., Ueland, P. M., Stacpoole, P. W., & Gregory, J. F. (2013). Metabolite profile analysis reveals functional effects of 28-day vitamin B-6 restriction on one-carbon metabolism and tryptophan catabolic pathways in healthy men and women. The Journal of nutrition, 143(11), 1719-27.
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  Suboptimal vitamin B-6 status, as reflected by low plasma pyridoxal 5'-phosphate (PLP) concentration, is associated with increased risk of vascular disease. PLP plays many roles, including in one-carbon metabolism for the acquisition and transfer of carbon units and in the transsulfuration pathway. PLP also serves as a coenzyme in the catabolism of tryptophan. We hypothesize that the pattern of these metabolites can provide information reflecting the functional impact of marginal vitamin B-6 deficiency. We report here the concentration of major constituents of one-carbon metabolic processes and the tryptophan catabolic pathway in plasma from 23 healthy men and women before and after a 28-d controlled dietary vitamin B-6 restriction (
• Benight, N. M., Stoll, B., Chacko, S., da Silva, V. R., Marini, J. C., Gregory, J. F., Stabler, S. P., & Burrin, D. G. (2011). B-vitamin deficiency is protective against DSS-induced colitis in mice. American journal of physiology. Gastrointestinal and liver physiology, 301(2), G249-59.
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  Vitamin deficiencies are common in patients with inflammatory bowel disease (IBD). Homocysteine (Hcys) is a thrombogenic amino acid produced from methionine (Met), and its increase in patients with IBD indicates a disruption of Met metabolism; however, the role of Hcys and Met metabolism in IBD is not well understood. We hypothesized that disrupted Met metabolism from a B-vitamin-deficient diet would exacerbate experimental colitis. Mice were fed a B(6)-B(12)-deficient or control diet for 2 wk and then treated with dextran sodium sulfate (DSS) to induce colitis. We monitored disease activity during DSS treatment and collected plasma and tissue for analysis of inflammatory tissue injury and Met metabolites. We also quantified Met cycle activity by measurements of in vivo Met kinetics using [1-(13)C-methyl-(2)H(3)]methionine infusion in similarly treated mice. Unexpectedly, we found that mice given the B-vitamin-deficient diet had improved clinical outcomes, including increased survival, weight maintenance, and reduced disease scores. We also found lower histological disease activity and proinflammatory gene expression (TNF-α and inducible nitric oxide synthase) in the colon in deficient-diet mice. Metabolomic analysis showed evidence that these effects were associated with deficient B(6), as markers of B(12) function were only mildly altered. In vivo methionine kinetics corroborated these results, showing that the deficient diet suppressed transsulfuration but increased remethylation. Our findings suggest that disrupted Met metabolism attributable to B(6) deficiency reduces the inflammatory response and disease activity in DSS-challenged mice. These results warrant further human clinical studies to determine whether B(6) deficiency and elevated Hcys in patients with IBD contribute to disease pathobiology.
• Waller, J. C., Alvarez, S., Naponelli, V., Lara-Nuñez, A., Blaby, I. K., Da Silva, V., Ziemak, M. J., Vickers, T. J., Beverley, S. M., Edison, A. S., Rocca, J. R., Gregory, J. F., de Crécy-Lagard, V., & Hanson, A. D. (2010). A role for tetrahydrofolates in the metabolism of iron-sulfur clusters in all domains of life. Proceedings of the National Academy of Sciences of the United States of America, 107(23), 10412-7.
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  Iron-sulfur (Fe/S) cluster enzymes are crucial to life. Their assembly requires a suite of proteins, some of which are specific for particular subsets of Fe/S enzymes. One such protein is yeast Iba57p, which aconitase and certain radical S-adenosylmethionine enzymes require for activity. Iba57p homologs occur in all domains of life; they belong to the COG0354 protein family and are structurally similar to various folate-dependent enzymes. We therefore investigated the possible relationship between folates and Fe/S cluster enzymes using the Escherichia coli Iba57p homolog, YgfZ. NMR analysis confirmed that purified YgfZ showed stereoselective folate binding. Inactivating ygfZ reduced the activities of the Fe/S tRNA modification enzyme MiaB and certain other Fe/S enzymes, although not aconitase. When successive steps in folate biosynthesis were ablated, folE (lacking pterins and folates) and folP (lacking folates) mutants mimicked the ygfZ mutant in having low MiaB activities, whereas folE thyA mutants supplemented with 5-formyltetrahydrofolate (lacking pterins and depleted in dihydrofolate) and gcvP glyA mutants (lacking one-carbon tetrahydrofolates) had intermediate MiaB activities. These data indicate that YgfZ requires a folate, most probably tetrahydrofolate. Importantly, the ygfZ mutant was hypersensitive to oxidative stress and grew poorly on minimal media. COG0354 genes of bacterial, archaeal, fungal, protistan, animal, or plant origin complemented one or both of these growth phenotypes as well as the MiaB activity phenotype. Comparative genomic analysis indicated widespread functional associations between COG0354 proteins and Fe/S cluster metabolism. Thus COG0354 proteins have an ancient, conserved, folate-dependent function in the activity of certain Fe/S cluster enzymes.

Presentations

• Infante, V. R., Edwards, Z., Berg, A., Brown, J., & Rafie, C. (2022). An Extension Implementation Toolkit for Diabetes Prevention. National Health Outreach Conference.
• Infante, V. R. (2022). When is the best time to prevent diabetes? . UA Life & Work Connections webinar series.
• Infante, V. R. (2022). An Extension Implementation Toolkit for Diabetes Prevention. New Technologies for Ag Extension - Showcase of Projects.
• Infante, V. R. (2022). Extension as a Key Partner in Diabetes Prevention. Association of Southern Region Directors. Ft Worth, Texas.
• Infante, V. R. (2022). When is the best time to prevent diabetes?. Arizona State University - Employee Wellness webinar. Zoom.
• Infante, V. R., Berg, A., Rafie, C., & Jarvandi, S. (2022). An Extension Implementation Toolkit for Diabetes Prevention. NEAFCS Webinar Series.
• Armstrong Florian, T. L., Martinez, C. L., & Infante, V. R. (2021, Dec). Motivational Interviewing with Groups. UA Staff Training. via Zoom.
• Infante, V. R., Martinez, C. L., & Armstrong Florian, T. L. (2021, June). Motivational Interviewing with Groups. Arizona Health Zone - ADHS Training. via Zoom.
• Infante, V. R., Rafie, C., Shalcross, L., & Hermann, J. (2021). Develop a Quality, Sustainable Diabetes Prevention Program in Your State. National Health Outreach Conference.

Poster Presentations

• Yanez-Olivas, D., Wyatt, M. A., Wilson, H., Serratos, R., Shepp, N., Scobie, B., Rogers, J., Martinez, C. L., Jacobo, M., Gonzales, M., Castillo, E., Armstrong Florian, T. L., Aspengren, C., & da Silva, V. (2019, Aug). The University of Arizona Cooperative Extension National Diabetes Prevention Program. ALVSCE (CALS) Conference. Tucson: ALVSCE.

Others

• Wyatt, M., & da Silva, V. (2017, September). Eating for Two -- A Healthy Pregnancy Starts With a Healthy Diet. Extension Publication.
• da Silva, V. R., & Zilliox, P. (2017, May). Folate and Folic Acid: Healthy Moms Mean Healthy Babies. Extension Publication.
• Gregory, J. F., Park, Y., Lamers, Y., Bandyopadhyay, N., Chi, Y., Lee, K., Kim, S., da Silva, V., Hove, N., Ranka, S., Kahveci, T., Muller, K. E., Stevens, R. D., Newgard, C. B., Stacpoole, P. W., & Jones, D. P. (2013). Metabolomic analysis reveals extended metabolic consequences of marginal vitamin B-6 deficiency in healthy human subjects. PloS one.
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  Marginal deficiency of vitamin B-6 is common among segments of the population worldwide. Because pyridoxal 5'-phosphate (PLP) serves as a coenzyme in the metabolism of amino acids, carbohydrates, organic acids, and neurotransmitters, as well as in aspects of one-carbon metabolism, vitamin B-6 deficiency could have many effects. Healthy men and women (age: 20-40 y; n = 23) were fed a 2-day controlled, nutritionally adequate diet followed by a 28-day low-vitamin B-6 diet (