Presence of circulating folic acid in plasma and its relation with dietary intake, vitamin B complex concentrations and genetic variants
- 223 Downloads
The aim of this study was to investigate circulating folic acid (FA) and predict circulating FA concentrations in the population related to dietary intake, vitamin concentrations, and interaction with the genetic variants involved in folate metabolism.
Data were from the ‘Health Survey of São Paulo’ a cross-sectional population-based survey, conducted in São Paulo City, Brazil. The participants (n = 750) provided fasting blood samples and food intake data. Folate, homocysteine, and B6 and B12 vitamins were assayed. DNA was isolated, and the genotypes for polymorphisms involved in folate metabolism were determined. A generalized linear model was performed to predict circulating FA concentration.
The circulating FA was detected in 80.0% of the population, with a median concentration of 1.6 nmol/L (IQR 0.5–2.9). The increase of circulating FA concentrations was directly associated with total folate concentration (β coeff. 1.03; 95% CI 1.02–1.04), age (β coeff. 1.01; 95% CI 1.01–1.02), current smoker (β coeff. 1.51; 95% CI 1.16–1.97), self-reported skin color (β coeff. 1.83; 95% CI 1.51–2.20), as well as interaction between folate concentration and 19-bp deletion polymorphism in DHFR (β coeff. 1.02; 95% CI 1.01–1.03), and inversely associated with vitamin B6 (β coeff. 0.99; 95% CI 0.98–0.99).
In the current study, the presence of detectable circulating folic acid is high, and its concentration is elevated compared with other populations. Age, smoking, lower concentration of vitamin B6 and genetic variant are associated with increased levels of circulating FA. Further researches are needed to acknowledge and guarantee the safety of exposure to folic acid, especially in countries which have mandatory fortification.
KeywordsFolic acid Circulating folic acid Mandatory fortification Fortified foods
We thank the participants of the study and researchers of the GEIAS (“Grupo de Estudos Epidemiológicos e Inovação em Alimentação e Saúde”) and GAC (“Grupo de Pesquisa de Avaliação do ConsumoAlimentar”) and the members (staff, technicians, students and scientists) of the Vitamin Metabolism Laboratory in the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University for helping during the biochemical analysis.
Financial Support from Municipal Health Secretariat of São Paulo; National Counsel of Technological-CNPq; and Scientific Development and São Paulo Research Foundation—FAPESP (Grant numbers: #2010/19899-5, #2011/19788-1, #2012/05505-0 and #2015/12196-2).
Compliance with ethical standards
Conflict of interest
J. Steluti, J. Selhub, L. Paul, C. Reginaldo, R. M. Fisberg, D. M. Marchioni have no conflict of interest.
- 2.Caudill MA (2010) Folate bioavailability: implications for establishing dietary recommendations and optimizing status. Am J Clin Nutr 91(Suppl 5):S1455–S1460Google Scholar
- 3.FAO/WHO—Food and Agriculture Organization/World Health Organization (2001) Folate and Folic Acid. In: FAO/WHO expert consultation on human vitamin and mineral requirements. FAO, RomeGoogle Scholar
- 16.Brazil/Ministério da Saúde (2002) Resolução nº. 344, de 13 de dezembro de 2002. Aprova o regulamento técnico para a fortificação das farinhas de trigo e das farinhas de milho com ferro ácido fólico. Diário Oficial da República Federativa do Brasil. http://portal.anvisa.gov.br/documents/10181/2718376/RDC_344_2002_COMP.pdf/b4d87885-dcb9-4fe3-870d-db57921cf73f. Acessed 2 Feb 2018
- 19.Raper N, Perloff B, Ingwersen L et al (2004) An overview of USDA’s dietary intake data system. J Food Compost Anal 7:545–555Google Scholar
- 21.Kalmbach R, Paul L, Selhub J (2011) Determination of unmetabolized folic acid in human plasma using affinity HPLC. Am J Clin Nutr 94:S343–S347Google Scholar
- 23.Beckman Coulter, Inc. (2009) Vitamin B12—Access Immunoassay Systems®. California (Technical Lab Manual)Google Scholar
- 24.Abbott Diagnostics Division (2011) Homocysteine—Abbott Architect i2000. United Kingdom. (Technical Lab Manual)Google Scholar
- 41.Boen TR, Soeiro BT, Pereira-Filho ER et al (2008) Folic acid and iron evaluation in Brazilian enriched corn and wheat flours. J Braz Chem Soc 19:53–59Google Scholar
- 42.Soeiro BT, Boen TR, Pereira-Filho ER et al (2010) Investigação da qualidade de farinhas enriquecidas utilizando Análise por Componentes Principais (PCA). Ciênc Tecnol Aliment 30:618–624Google Scholar
- 44.Choi SW, Mason JB (2000) Folate and carcinogenesis: an integrated scheme. J Nutr 30:129–132Google Scholar
- 45.Giovannucci E (2002) Epidemiologic studies of folate and colorectal neoplasia: a review. J Nutr 132(Suppl 8):S2350–S2355Google Scholar
- 52.Brunacio KH, Verly-Jr E, Cesar CL et al (2015) Use of dietary supplements among inhabitants of the city of São Paulo, Brazil. Cad Saude Publica 29:1467–1472Google Scholar