• 1
    Parkin DM, Kramarova E, Draper GJ, et al. International Incidence of Childhood Cancer. Lyon, France: IARC on Cancer Scientific Publications; 1998.
  • 2
    Stiller CA, Parkin DM. Geographic and ethnic variations in the incidence of childhood cancer. Br Med Bull. 1996; 52: 682-703.
  • 3
    Howe HL, Wu X, Ries LA, et al. Annual report to the nation on the status of cancer, 1975-2003, featuring cancer among US Hispanic/Latino populations. Cancer. 2006; 107: 1711-1742.
  • 4
    Bunin GR, Meadows AT, Emanuel BS, Buckley JD, Woods WG, Hammond GD. Pre- and postconception factors associated with sporadic heritable and nonheritable retinoblastoma. Cancer Res. 1989; 49: 5730-5735.
  • 5
    Rushlow D, Piovesan B, Zhang K, et al. Detection of mosaic RB1 mutations in families with retinoblastoma. Hum Mutat. 2009; 30: 842-851.
  • 6
    Ohtani-Fujita N, Dryja TP, Rapaport JM, et al. Hypermethylation in the retinoblastoma gene is associated with unilateral, sporadic retinoblastoma. Cancer Genet Cytogenet. 1997; 98: 43-49.
  • 7
    Kanber D, Berulava T, Ammerpohl O, et al. The human retinoblastoma gene is imprinted [serial online]. PLoS Genet. 2009; 5: e1000790.
  • 8
    Orjuela MA, Titievsky L, Liu X, et al. Fruit and vegetable intake during pregnancy and risk for development of sporadic retinoblastoma. Cancer Epidemiol Biomarkers Prev. 2005; 14: 1433-1440.
  • 9
    van-der-Put NM, Steegers-Theunissen RP, Frosst P, et al. Mutated methylenetetrahydrofolate reductase as a risk factor for spina bifida. Lancet. 1995; 346: 1070-1071.
  • 10
    Xu X, Gammon MD, Wetmur JG, et al. A functional 19bp deletion polymorphism of dihydrofolate reductase and risk of breast cancer in multivitamin users. Am J Clin Nutr. 2007; 85: 1098-1102.
  • 11
    Abuli A, Fernandez-Rozadilla C, Alonso-Espinaco V, et al. Case-control study for colorectal cancer genetic susceptibility in EPICOLON: previously identified variants and mucins [serial online]. BMC Cancer. 2011; 11: 339.
  • 12
    Johnson WG, Stenroos ES, Spychala JR, Chatkupt S, Ming SX, Buyske S. New 19bp deletion polymorphism in intron-1 of DHFR: a risk factor for spina bifida acting in mothers during pregnancy? Am J Med Genet A. 2004; 124A: 339-345.
  • 13
    Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, VitaminB6, Folate, VitaminB12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academies Press; 1998.
  • 14
    Kalmbach RD, Choumenkovitch SF, Troen AP, Jacques PF, D'Agostino R, Selhub J. A 19-base pair deletion polymorphism in dihydrofolate reductase is associated with increased unmetabolized folic acid in plasma and decreased red blood cell folate. J Nutr. 2008; 138: 2323-2327.
  • 15
    Mejia-Rodriguez F, Orjuela MA, Garcia-Guerra A, Quezada-Sanchez AD, Neufeld LM. Validation of a novel method for retrospectively estimating nutrient intake during pregnancy using a semi-quantitative food frequency questionnaire. Matern Child Health J. 2011 Epub Nov 25, 2011 DOI: 10.1007/s10995-011-0912-8.
  • 16
    Mejia-Rodriguez F, Sotres-Alvarez D, Neufeld LM, Garcia-Guerra A, Hotz C. Use of nutritional supplements among Mexican women and the estimated impact on dietary intakes below the EAR and above the UL. J Am Coll Nutr. 2007; 26: 16-23.
  • 17
    deBree A, Verschuren WM, Bjorke-Monsen AL, et al. Effect of the methylenetetrahydrofolate reductase 677C[RIGHTWARDS ARROW]T mutation on the relations among folate intake and plasma folate and homocysteine concentrations in a general population sample. Am J Clin Nutr. 2003; 77: 687-693.
  • 18
    Bailey SW, Ayling JE. The extremely slow and variable activity of dihydrofolate reductase in human liver and its implications for high folic acid intake. Proc Natl Acad Sci U S A. 2009; 106: 15424-15429.
  • 19
    Kelly P, McPartlin J, Goggins M, Weir DG, Scott JM. Unmetabolized folic acid in serum: acute studies in subjects consuming fortified food and supplements. Am J Clin Nutr. 1997; 65: 1790-1795.
  • 20
    Troen AM, Mitchell B, Sorensen B, et al. Unmetabolized folic acid in plasma is associated with reduced natural killer cell cytotoxicity among postmenopausal women. J Nutr. 2006; 136: 189-194.
  • 21
    Pickell L, Brown K, Li D, et al. High intake of folic acid disrupts embryonic development in mice. Birth Defects Res A Clin Mol Teratol. 2011; 91: 8-19.
  • 22
    Achon M, Reyes L, Alonso-Aperte E, Ubeda N, Varela-Moreiras G. High dietary folate supplementation affects gestational development and dietary protein utilization in rats. J Nutr. 1999; 129: 1204-1208.
  • 23
    Vacca P, Moretta L, Moretta A, Mingari MC. Origin, phenotype and function of human natural killer cells in pregnancy. Trends Immunol. 2011; 32: 517-523.
  • 24
    LeBouteiller P, Siewiera J, Casart Y, et al. The human decidual NK-cell response to virus infection: what can we learn from circulating NK lymphocytes? J Reprod Immunol. 2011; 88: 170-175.
  • 25
    Cole BF, Baron JA, Sandler RS, et al. Folic acid for the prevention of colorectal adenomas: a randomized clinical trial. JAMA. 2007; 297: 2351-2359.
  • 26
    Kim YI. Folate, colorectal carcinogenesis, and DNA methylation: lessons from animal studies. Environ Mol Mutagen. 2004; 44: 10-25.
  • 27
    Ibiebele TI, Hughes MC, Pandeya N, et al. High intake of folate from food sources is associated with reduced risk of esophageal cancer in an Australian population. J Nutr. 2011; 141: 274-283.
  • 28
    Hirsch S, Sanchez H, Albala C, et al. Colon cancer in Chile before and after the start of the flour fortification program with folic acid. Eur J Gastroenterol Hepatol. 2009; 21: 436-439.
  • 29
    Stolzenberg-Solomon RZ, Chang SC, Leitzmann MF, et al. Folate intake, alcohol use, and postmenopausal breast cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Am J Clin Nutr. 2006; 83: 895-904.
  • 30
    Figueiredo JC, Grau MV, Haile RW, et al. Folic acid and risk of prostate cancer: results from a randomized clinical trial. J Natl Cancer Inst. 2009; 101: 432-435.
  • 31
    Ebbing M, Bonaa KH, Nygard O, et al. Cancer incidence and mortality after treatment with folic acid and vitamin B12. JAMA. 2009; 302: 2119-2126.
  • 32
    Bentley TG, Weinstein MC, Willett WC, Kuntz KM. A cost-effectiveness analysis of folic acid fortification policy in the United States. Public Health Nutr. 2009; 12: 455-467.
  • 33
    Shakur YA, Rogenstein C, Hartman-Craven B, Tarasuk V, O'Connor DL. How much folate is in Canadian fortified products 10 years after mandated fortification? Can J Public Health. 2009; 100: 281-284.
  • 34
    Hoyo C, Murtha AP, Schildkraut JM, et al. Folic acid supplementation before and during pregnancy in the Newborn Epigenetics STudy (NEST) [serial online]. BMC Public Health. 2011; 11: 46.
  • 35
    Norma Oficial Mexicana (NOM). NOM-147-SSA1-1996. Cereales y sus Productos. Harinas de Cereales. Disposiciones Specificaciones Sanitarias Nutrimentales [August 5, 1997]. Mexico City, Mexico: Comision Federal Para la Proteccion Contra Riesgos Sanitarios; 1996.
  • 36
    Bourges H, Casanueva E, Rosado JL. Recomendaciones Ingestion Nutrimentos. Mexico DF, Mexico: Editorial Medica Panamericana; 2005.
  • 37
    Barquera S, Hernandez-Barrera L, Campos-Nonato I, et al. Energy and nutrient consumption in adults: analysis of the Mexican National Health and Nutrition Survey 2006. Salud Publica Mex. 2009; 51( suppl 4): S562-S573.
  • 38
    International Agency for Research of Cancer-World Health Organization [IARC-WHO]. International Incidence of Childhood Cancer. Volume 3. Lyon, France: IARC-WHO; 2012. Available from: [Accessed February 20, 2012.]