Folate bioavailability

Folate in Health and Disease, Second Edition

Volumn , Issue , 2009, Pages 25-47

  McNulty, Helene ^a   Pentieva, Kristina ^a  

^a UNIVERSITY OF ULSTER   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 85057911969     PISSN: None     EISSN: None     Source Type: Book    
DOI: None     Document Type: Chapter

References (122)

1. Murphy M, Keating M, Boyle P, Weir DG, Scott JM. The elucidation of the mechanism of folate catabolism in the rat. Biochem Biophys Res Commun 1976; 71:1017-24.
2. Colman N, Green R, Metz J. Prevention of folate deficiency by food fortification. II. Absorption of folic acid from fortified staple foods. Am J Clin Nutr 1975; 28:459-64.
3. Sauberlich HE, Kretsh MJ, Skala JH, Johnson HL, Taylor PC. Folate required and metabolism in nonpregnant women. Am J Clin Nutr 1987; 46:1016-28.
4. Brouwer IA, van Dusseldorp M, West CE, Meyboom S, Thomas CM, Duran M, van het Hof KH, Eskes TK, Hautvast JG, Steegers-Theunissen RP. Dietary folate from vegetables and citrus fruit decreases plasma homocysteine concentrations in humans in a dietary controlled trial. J Nutr 1999; 129:1135-39.
5. Hannon-Fletcher MP, Armstrong NC, Scott JM, Pentieva K, Bradbury I, Ward M, Strain JJ, et al. Determining bioavailability of food folates in a controlled intervention study. Am J Clin Nutr 2004; 80:911-18.
6. Yang TL, Hung J, Caudill MA, Urrutia TF, Alamilla A, Perry CA, Li R, Hata H, Cogger EA. A long-term controlled feeding study in young women supports the validity of the 1.7 multiplier in the dietary folate equivalency equation. J Nutr 2005; 135:1139-45.
7. Winkels RM, Brouwer IA, Siebelink E, Katan MB, Verhoef P. Bioavailability of food folates is 80% of that of folic acid. Am J Clin Nutr 2007; 85:465-73.
8. Gregory JF. Case study: Folate bioavailability. J Nutr 2001; 131:1376S-1382S.
9. Institute of Medicine, Panel on Folate, Other B Vitamins, and Choline. Dietary Reference Intake: Thiamine, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academy Press, 1998.
10. Melse-Boonstra A, de Bree A, Verhoef P, Bjorke-Monsen AL, Verschuren WMM. Dietary monoglutamate and polyglutamate folate are both associated with plasma folate concentrations in Dutch men and women aged 20-65 y. J Nutr 2002; 132:1307-12.
11. Stockstad ELR, Shin YS, Tamura T. Distribution of folate forms in food and folate availability. In: Food and Nutrition Board, National Research Council. Folic Acid: Biochemistry and Physiology in Relation to the Human Nutrition Requirement. Washington, DC: National Academy of Sciences, 1977:56-68.
12. Chandler CJ, Wang TT, Halsted CH. Pteroylpolyglutamate hydrolase from human jejunal brush borders. Purification and characterization. J Biol Chem 1986; 261:928-33.
13. Gregory JF, Ink SL, Cerda JJ. Comparison of pteroylpolyglutamate hydrolase (folate conjugase) from porcine and human brush border membrane. Comp Biochem Physiol1987; 88B:1135-41.
14. Tamura T, Shin YS, Buehring KU, Stokstad ELR. The availability of folate in man: Effect of orange juice supplement on intestinal conjugase. Br J Haematol 1976; 32:123-33.
15. Bailey LB, Cerda JJ, Bloch BS, Busby MJ, Vargas L, Chandler CJ, Halsted CH. Effect of age on poly- and monoglutamyl folacin absorption in human subjects. J Nutr 1984; 114: 1770-76.
16. Wei MM, Bailey LB, Toth JP, Gregory JF. Bioavailability for humans of deuteriumlabeled monoglutamyl and polyglutamyl folates is affected by selected foods. J Nutr1996; 126:3100-08.
17. Wei MM, Gregory JF. Organic acids in selected foods inhibit intestinal brush border pte-roylpolyglutamate hydrolase in vitro: Potential mechanism affecting the bioavailability of dietary polyglutamyl folate. JAgr Food Chem 1998; 46:211-19.
18. Rosenberg IH, Godwin HA. Inhibition of intestinal y-glutamyl carboxypeptidase by yeast nucleic acid: An explanation of variability in utilisation of dietary polyglutamyl folate. J Clin Invest 1971; 50:78a.
19. Butterworth CE, Newman AJ, Krumdieck CL. Tropical sprue: A consideration of possible etiologic mechanisms with emphasis on pteroylpolyglutamate metabolism. Transam Clin Climatol Assoc 1974; 86:11-22.
20. Keagy PM, Shane B, Oace SM. Folate bioavailability in humans: Effect of wheat bran and beans. Am J Clin Nutr 1988; 47:80-88.
21. Reisenauer AM, Halsted CH. Human brush border folate conjugase: Characteristics and inhibition by salicylazosulfapyridine. Biochem Biophys Acta 1981; 659:62-69.
22. Halsted CH, Villanueva JA, Devlin AM, Carol J, Chandler CJ. Metabolic interactions of alcohol and folate. J Nutr 2002; 132:2367S-72S.
23. Halsted CH. Intestinal absorption of dietary folates. In: Picciano MF, Stockstad ELR, Gregory JF, eds. Folic Acid Metabolism in Health and Disease. New York: Wiley-Liss, 1990:23-45.
24. Devlin AM, Ling E, Peerson JM, Fernando S, Clarke R, Smith AD, Halsted CH. Glutamate carboxypeptidase II: A polymorphism associated with lower levels of serum folate and hyperhomocysteinemia. Hum Mol Gen 2000; 9:2837-44.
25. 12 levels and its relationship to cardiovascular disease risk. Atherosclerosis 2002; 164:269-73.
26. Vargas-Martinez C, Ordovas JM, Wilson PW, Selhub J. The glutamate carboxypeptidase gene II (C>T) polymorphism does not affect folate status in the Framingham offspring cohort. J Nutr 2002; 132:1176-79.
27. Afman LA, Frans JM, Trijbels, Blom HJ. The H475Y polymorphism in the glutamate carboxypeptidase II gene increases plasma folate without affecting the risk for neural tube defects in humans. J Nutr 2003; 133:75-77.
28. Fodinger M, Dierkes J, Skoupy S, Rohrer C, Hagen W, Puttinger H, Hauser AC, Vychytil A, Sunder-Plassmann G. Effect of glutamate carboxypeptidase II and reduced folate carrier polymorphisms on folate and total homocysteine concentrations in dialysis patients. JAm Soc Nephrol 2003; 14:1314-19.
29. Halsted CH, Wong DH, Peerson JM, Warden CH, Refsum H, Smith DA, Nygard OK, Ueland PM, Vollset SE, Tell GS. Relations of glutamate carboxypeptidase II (GCPII) polymorphisms to folate and homocysteine concentrations and to scores of cognition, anxiety, and depression in a homogeneous Norwegian population: The Hordaland homocysteine study. Am J Clin Nutr 2007; 86:514-21.
30. Wang TT, Reisenauer AM, Halsted CH. Comparison of folate conjugase activities in human, pig, rat and monkey intestine. J Nutr 1985; 115:814-19.
31. Kesavan V, Noronha JM. Folate malabsorption in aged rats related to low levels of pancreatic folyl conjugase. Am J Clin Nutr 1983; 37:262-67.
32. Shafizadeh TB, Halsted CH. y-Glutamyl hydrolase, not glutamate carboxypeptidase II, hydrolyzes dietary folate in the small intestine. J Nutr 2007; 137:1149-53.
33. Elsenhans B, Ahmad O, Rosenberg IH. Isolation and characterisation of pteroylpolyglu-tamate hydrolase from rat intestinal mucosa. J Biol Chem 1984; 259:6364-68.
34. Wang TT, Chandler CJ, Halsted CH. Intracellular pteroylpolyglutamate hydrolase from human jejunal mucosa. Isolation and characterization. J Biol Chem 1986; 261:13551-55.
35. Halsted CH, Ling E, Carter RL, Vilanueva JA, Gardner JM, Coyle JT. Folylpoly-y-glutamate carboxypeptidase from pig jejunum molecular characterisation and relation to glutamate carboxypeptidase II. J Biol Chem 1998; 273:20417-24.
36. Gregory JF III, Quinlivan EP, Davis SR. Integrating the issue of folate bioavailability, intake and metabolism in the era of fortification. Trends Food Sci Technol 2005; 16:229-40.
37. 3H]pteroylheptaglutamate in man. Gastroenterology 1975; 69:364-73.
38. Gregory JF, Bhandari SD, Bailey LB, Toth JP, Baumgartner TG, Cerda JJ. Relative bioavailability of deuterium-labeled monoglutamyl and hexaglutamyl folates in human subjects. Am J Clin Nutr 1991; 53:736-40.
39. Melse-Boonstra A, West CE, Katan MB, Kok FJ, Verhoef P. Bioavailability of hepta-glutamyl relative to monoglutamyl folic acid in healthy adults. Am J Clin Nutr 2004; 79:424-29.
40. Melse-Boonstra A, Verhoef P, West CE, van Rhijn JA, van Breemen RB, Lasaroms JJP, Garbis SD, Katan MB, Kok FJ. A dual-isotope-labeling method of studying the bioavailability of hexaglutamyl folic acid relative to that of monoglutamyl folic acid in humans by using multiple orally administered low doses. Am J Clin Nutr 2006; 84:1128-33.
41. Tamura T, Stokstad ELR. The availability of food folate in man. Br J Haematol 1973; 25:513-32.
42. Bailey LB, Barton LE, Hillier SE, Cerda JJ. Bioavailability of mono and polyglutamyl folate in human subjects. Nutr Rep Intern 1988; 38:509-18.
43. Boodie AM, Dedlow ER, Nackashi JA, Opalko FJ, Kauwel GP, Gregory JF 3rd, Bailey LB. Folate absorption in women with a history of neural tube defect-affected pregnancy. Am J Clin Nutr 2000; 72:154-58.
44. Konings EJM, Troost FJ, Castenmiller JJM, Roomans HHS, van den Brandt PA, Saris WHM. Intestinal absorption of different types of folate in healthy subjects with an ileostomy. Br J Nutr 2002; 88:235-42.
45. McKillop DJ, McNulty H, Scott JM, McPartlin JM, Strain JJ, Bradbury I, Girvan J, et al. The rate of intestinal absorption of natural food folates is not related to the extent of folate conjugation. Am J Clin Nutr 2006; 84:167-73.
46. Hannon-Fletcher MPA, Armstrong NC, Scott JM, Ward M, Strain JJ, Pentieva K, Dunn AA, Molloy AM, Scullion M, McNulty H. A controlled intervention study to determine the bioavailability of food folates. J Inher Metab Dis 2003; 26(Suppl 1):11.
47. Reisenauer AM, Halsted CH. Issues and opinions in nutrition: Human folate requirements. J Nutr 1987; 117:600-02.
48. Rosenberg IH, Zimmerman J, Selhub J. Folate transport. Chemioterapia 1985; 4: 354-58.
49. Smith ME, Matty AJ, Blair JA. The transport of pteroylglutamic acid across the small intestine of the rat. Biochem Biophys Acta 1970; 219:124-29.
50. Bhandari SD, Gregory JF. Folic acid, 5-methyltetrahydrofolate and 5-formyltetrahydro-folate exhibit equivalent intestinal absorption, metabolism and in vivo kinetics in rats. J Nutr 1992; 122:1847-54.
51. Qui A, Jansen M, Sakaris A, Min SH, Chattopadhyay S, Tsai E, Sandoval C, Zhao R, Akabas MH, Goldman ID. Identification of an intestinal folate transporter and the molecular basis for hereditary folate malabsorption. Cell 2006; 127:917-28.
52. Subramanian VS, Marchant JS, Said HM. Apical membrane targeting and trafficking of the human proton-coupled transporter in polarized epithelia. Am J Physiol Cell Physiol2008; 294:C233-40.
53. Zhao R, Min SH, Qiu A, Sakaris A, Goldberg GL, Sandoval C, Malatack JJ, Rosenblatt DS, Goldman ID. The spectrum of mutations in the PCFT gene, coding for an intestinal folate transporter, that are the basis for hereditary folate malabsorption. Blood 2007; 110:1147-52.
54. Said HM, Hollander D, Katz D. Absorption of 5-methyltetrahydrofolatein rat jejunum with intact blood and lymphatic vessels. Biochem Biophys Acta 1984; 775:402-08.
55. Russell RM, Kransinski SD, Samloff IM, Jacob RA, Hartz SC, Brovender SR. Folic acid malabsorption in atrophic gastritis. Possible compensation by bacterial folate synthesis. Gastroenterology 1986; 91:1476-82.
56. Russell RM, Golner BB, Kransinski SD, Sadowski JA, Suter PM, Braun CL. Effect of antacid and H2 receptor antagonists on the intestinal absorption of folic acid. J Lab Clin Med 1988; 112:458-63.
57. Russell RM, Dhar GJ, Dutta SK, Rosenberg IH. Influence of intraluminal pH on folate absorption: Studies in control subjects and in patients with pancreatic insufficiency. J Lab Clin Med 1979; 93:428-36.
58. de Meer K, Smulders YM, Dainty JR, Smith DEC, Kok RM, Stehouwer CDA, Finglas PM, Jakobs C. [6S]5-Methyltetrahyrofolate or folic acid supplementation and absorption and initial elimination of folate in young and middle-aged adults. Eur J Clin Nutr2005; 59:1409-16.
59. Said HM, Chatterjee N, Hag RU, Subramanian VS, Ortiz A, Matherly LH, Sirotnak FM, Halsted C, Rubin SA. Adaptive regulation of intestinal folate uptake: Effect of dietary folate deficiency. Am J Physiol Cell Physiol 2000; 279:C1889-95.
60. Subramanian VS, Chatterjee N, Said HM. Folate uptake in the human intestine: Promoter activity and effect of folate deficiency. J Cell Physiol 2003; 196:403-08.
61. Ashokkumar B, Mohammed ZM, Vaziri ND, Said HM. Effect of folate oversupplementation on folate uptake by human intestinal and renal epithelial cells. Am J Clin Nutr2007; 86:159-66.
62. Fleming RE. Advances in understanding the molecular basis for the regulation of dietary iron absorption. Curr Opin Gastroenterol 2005; 21:201-06.
63. Alemdaroglu NC, Dietz U, Wolffram S, Spahn-Langguth H, Langguth P. Influence of green and black tea on folic acid pharmacokinetics in healthy volunteers: Potential risk of diminished folic acid bioavailability. Biopharm Drug Dispos 2008; 29:335-48.
64. Alemdaroglu NC, Wolffram S, Boissel JP, Closs E, Spahn-Langguth H, Langguth P. Inhibition of folic acid uptake by catechins and tea extracts in Caco-2 cells. Planta Med2007; 73:27-32.
65. Mason JB, Rosenberg IH. Intestinal absorption of folate. In: Johnson LR, ed. Physiology of the Gastrointestinal Tract, 3d ed. New York: Raven Press, 1994:1979-96.
66. Rong N, Selhub J, Goldin BR, Rosenberg IH. Bacterially synthesized folate in rat large intestine is incorporated into host tissue folyl polyglutamates. J Nutr 1991; 121:1955-59.
67. Kim TH, Yang J, Darling PB, O’Connor DL. A large pool of available folate exists in the large intestine of human infants and piglets. J Nutr 2004; 134:1389-94.
68. Asrar FM, O’Connor DL. Bacterially synthesized folate and supplemental folic acid are absorbed across the large intestine in piglets. J Nutr Biochem 2005; 16:587-93.
69. Aufreiter S, Gregory JF, Pfeiffer CM, Fazili Z, Kim YI, Marcon N, Kamalaporn P, Pencharz PB, O’Connor DL. Folate is absorbed across the large intestine in adults: Evidence from cecal infusion of 13C-labeled [6S]-5-formyltetrahydrofolate. Am J Clin Nutr 2009; 90:116-23.
70. Houghton LA, Green TJ, Donovan UM, Gibson RS, Stephen AM, O’Connor DL. Association between dietary fiber intake and the folate status of a group of female adolescents. Am J Clin Nutr 1997; 66:1414-21.
71. van het Hof KH, Tijburg LBM, Pietrzik K, Weststrate JA. Influence of feeding different vegetables on plasma levels of carotenoids, folate and vitamin C. Effect of disruption of the vegetable matrix. Br J Nutr 1999; 82:203-12.
72. Castenmiller JJM, van de Poll CJ, West CE, Brouwer IA, Thomas CMG, van Dusseldorp M. Bioavailability of folate from processed spinach in humans. Ann Nutr Metab 2000; 44:163-69.
73. Bhandari SD, Gregory JF. Inhibition by selected food components of human and porcine intestinal pteroylpolyglutamate hydrolase activity. Am J Clin Nutr 1990; 51:87-94.
74. Pfeiffer CM, Rogers LM, Bailey LB, Gregory JF. Absorption of folate from fortified cereal-grain products and of supplemental folate consumed with or without food determined by using a dual-label stable-isotope protocol. Am J Clin Nutr 1997; 66:1388-97.
75. Hurdle ADF, Barton D, Searles IH. A method for measuring folate in foods and its application to a hospital diet. Am J Clin Nutr 1968; 21:1202-07.
76. Leichter J, Switzer VP, Landymore AF. Effect of cooking on folate content of vegetables. Nutr Rep Intern 1978; 8:475-79.
77. De Souza SC, Eitenmiller RR. Effects of processing and storage on the folate content of spinach and broccoli. J Food Sci 1986; 51:626-28.
78. McKillop D, Pentieva K, Daly D, McPartlin JM, Hughes J, Strain JJ, Scott JM, McNulty H. The effect of different cooking methods on folate retention in various foods which are amongst the major contributors to folate intake in the UK diet. Br J Nutr 88:681-88.
79. Dang J, Arcot J, Shrestha A. Folate retention in selected processed legumes. Food Chem2000; 68:295-98.
80. Seyom E, Selhub J. Properties of food folates determined by stability and susceptibility to intestinal pteroylpolyglutamate hydrolase action. J Nutr 1998; 128:1956-60.
81. Andersson A, Oste R. Loss of ascorbic acid, folate and vitamin B12, and changes in oxygen content of UHT-milk. II. Results and discussion. Milchwissenschaft 1992; 47: 299-302.
82. Verwei M, Arkbage K, Mocking H, Havenaar R, Groten J. The FBP binding characteristics during gastric passage are different for folic acid and 5-methyltetrahydrofolate as studied in a dynamic in vitro gastrointestinal model. J Nutr 2004; 134:31-37.
83. Jones ML, Nixon PF. Tetrahydrofolates are greatly stabilized by binding to bovine milk folate-binding protein. J Nutr 2002; 132:2690-94.
84. Picciano MF, West SG, Ruch AL, Kris-Etherton PM, Zhao G, Johnston KE, Maddox DH, Fishell VK, Dirienzo DB, Tamura T. Effect of cow milk on food folate bioavailability in young women. Am J Clin Nutr 2004; 80:1565-69.
85. Winkels RM, Brouwer IA, Verhoef P, van Oort FVA, Durga J, Katan MB. Gender and body size affect the response of erythrocyte folate to folic acid treatment. J Nutr 2008; 138:1456-61.
86. Homocysteine Lowering Trialists’ Collaboration. Dose-dependent effects of folic acid on blood concentrations of homocysteine: A meta-analysis of the randomized trials. Am J Clin Nutr 2005; 82:806-12.
87. Perry CA, Renna SA, Khitun E, Ortiz M, Moriarty DJ, Caudill MA. Ethnicity and race influence the folate status response to controlled folate intakes in young women. J Nutr2004; 134:1786-92.
88. Wilcken B, Bamforth F, Li Z, Zhu H, Ritvanen A, Redlund M, Stoll C, et al. Geographical and ethnic variation of the 677C^T allele of 5, 10 methylenetetrahydrofolate reductase (MTHFR): Findings from over 7000 newborns from 16 areas world wide. J Med Genet2003; 40:619-25.
89. Frosst P, Blom HJ, Milos R, Goyette P, Sheppard CA, Matthews RG, Boers GJH, et al. A candidate genetic risk factor for vascular disease: A common mutation in methylene-tetrahydrofolate reductase. Nat Genet 1995; 10:111-13.
90. Molloy AM, Daly S, Mills JL, Kirke PN, Whitehead AS, Ramsbottom D, Conley MR, Weir DG, Scott JM. Thermolabile variant of 5,10-methylenetetrahydrofolate reductase associated with low red-cell folates: Implications for folate intake recommendations. Lancet 1997; 349:1591-93.
91. Perry J, Chanarin I. Intestinal absorption of reduced folate compounds in man. Br J Haematol 1970; 18:329-39.
92. Brown JP, Scott JM, Foster FG, Weir DG. Ingestion and absorption of naturally occurring pteroylmonoglutamates (folates) in man. Gastroenterology 1973; 64:223-32.
93. Pietrzik K, Remer T. Zur Bioverfugbarkeitsprufung von Mikronahrstoffen (Bioavailability study of micronutrients). Z Ernahrungswiss 1989; 28:130-41.
94. Pentieva K, McNulty H, Reichert R, Ward M, Strain JJ, McKillop D, McPartlin JM, Connolly E, Molloy A, Krämer K, Scott JM. The short-term bioavailabilities of [6S]-5-methyltetrahydrofolate and folic acid are equivalent in men. J Nutr 2004; 134: 580-85.
95. Fenech M, Noakes M, Clifton P, Topping D. Aleurone flour is a rich source of bioavailable folate in humans. J Nutr 1999; 129:1114-19.
96. Gregory JF. The bioavailability of folate. In: Bailey LB, ed. Folate in Health and Disease. New York: Marcel Dekker, 1995:195-235.
97. Pietrzik K, Hages M, Remer T. Methodological aspects in vitamin bioavailability testing. J Micronutr Anal 1990; 7:207-22.
98. Gregory JF. Improved synthesis of [3', 5'-2H2] folic acid: Extent and specificity of deuterium labelling. J Agr Food Chem 1990; 38:1073-76.
99. Maunder P, Finglas PM, Mallet AI, Mellon FA, Razzaque MA, Ridge B, Vahteristo L, Witthoft C. The synthesis of folic acid, multiply labelled with stable isotopes, for bioavailability studies in human nutrition. J Chem Soc Perkin Transact 1999; 1:1311-23.
100. Gregory JF, Toth JP. Stable-isotopic methods for in vivo investigation of folate absorption and metabolism. In: Picciano MF, Stokstad ELR, Gregory JF, eds. Folic Acid Metabolism in Health and Disease. New York: Wiley-Liss Inc, 1990:151-69.
101. Gregory JF, Quinlivan EP. In vivo kinetics of folate metabolism. Ann Rev Nutr 2002; 22:199-220.
102. Wright AJA, Finglas PM, Dainty JR, Hart DJ, Wolfe CA, Southon S, Gregory JF. Single oral doses of 13C forms of pteroylmonoglutamic acid and 5-formyltetrahydrofolic acid elicit differences in short-term kinetics of labelled and unlabelled folates in plasma: Potential problems in interpretation of folate bioavailability studies. Br J Nutr 2003; 90:363-71.
103. Wright AJ, Finglas PM, Dainty JR, Wolfe CA, Hart DJ, Wright DM, Gregory JF. Differential kinetic behaviour and distribution for pteroylglutamic acid and reduced folates: A revised hypothesis of the primary site of PteGlu metabolism in humans. J Nutr 2005; 135:619-23.
104. Dueker SR, Lame M, Lin Y, Clifford AJ, Buchholz BA, Vogel JS. Traditional and accelerator mass spectrometry for quantitation of human folate pools. Trends Food Sci Technol 2005; 16:267-70.
105. Sweeney MR, McPartlin J, Scott J. Folic acid fortification and public health: Report on threshold doses above which unmetabolized folic acid appear in serum. BMC Public Health 2007; 7:41-47.
106. Buchholz BA, Arjomand A, Dueker SR, Schneider PD, Clifford AJ, Vogel JS. Intrinsic erythrocyte labelling and attomole pharmacokinetic tracing of 14C-labeled folic acid with accelerator mass spectrometry. Anal Biochem 1999; 269:348-52.
107. Lin Y, Dueker SR, Follett JR, Fadel JG, Arjomand A, Schneider PD, Miller JW, et al.Quantitation of in vivo human folate metabolism. Am J Clin Nutr 2004; 80:680-91.
108. Venn BJ, Green TJ, Moser R, McKenzie JE, Skeaff CM, Mann J. Increases in blood folate indices are similar in women of childbearing age supplemented with [6S]-5-meth-yltetrahydrofolate and folic acid. J Nutr 2002; 132:3353-55.
109. Venn BJ, Green TJ, Moser R, Mann JI. Comparison of the effect of low-dose supplementation with L-5-methyltetrahydrofolate or folic acid on plasma homocysteine: A randomized placebo-controlled study. Am J Clin Nutr 2003; 77:658-62.
110. Lamers Y, Prinz-Langenohl R, Moser R, Pietrzik K. Supplementation with [6S] -5-methyltetrahydrofolate or folic acid equally reduces plasma total homocysteine concentrations in healthy women. Am J Clin Nutr 2004; 79:473-78.
111. Houghton LA, Sherwood KL, Pawlosky R, Ito S, O’Connor DL. [6S]-5-Methyltetra-hydrofolate is at least as effective as folic acid in preventing a decline in food folate concentrations during lactation. Am J Clin Nutr 2006; 83: 842-50.
112. Cuskelly GJ, McNulty H, Scott JM. Effect of increasing dietary folate on red-cell folate: Implications for prevention of neural tube defects. Lancet 1996; 347:657-59.
113. Ashfield-Watt PAL, Whiting JM, Clark ZE, Moat SJ, Newcombe RG, Burr ML, McDowell IFW. A comparison of the effect of advice to eat either ‘5-a-day’ fruit and vegetables or folic acid-fortified foods on plasma folate and homocysteine. Eur J Clin Nutr 2003; 57:316-23.
114. Riddell LJ, Chisholm A, Williams S, Mann JI. Dietary strategies for lowering homocysteine concentrations. Am J Clin Nutr 2000; 71:1448-54.
115. Medical Research Council Vitamin Study Research Group. Prevention of neural tube defects: Results of the Medical Research Council Vitamin Study. Lancet 1991; 338:131-37.
116. Czeizel AE, Dudas I. Prevention of first occurrence of neural tube defects by pericon-ceptional vitamin supplementation. N Engl J Med 1992; 327:1832-35.
117. Wang X, Qin X, Demirtas H, Li J, Mao G, Huo Y, Sun N, Liu L, Xu X. Efficacy of folic acid supplementation in stroke prevention: A meta-analysis. Lancet 2007; 369:1876-82.
118. Ericson U, Sonestedt E, Gullberg B, Olsson H, Wirfalt E. High folate intake is associated with lower breast cancer incidence in postmenopausal women in the Malmo Diet and Cancer cohort. Am J Clin Nutr 2007; 86:434-43.
119. Sato Y, Honda Y, Iwamoto J, Kanoko T, Satoh K. Effect of folate and mecobalamin on hip fractures in patients with stroke: A randomized controlled trial. JAMA 2005; 293:1082-88.
120. Durga J, van Boxtel MPJ, Schouten EG, Kok FJ, Jolles J, Katan MB, Verhoef P. Effect of 3-year folic acid supplementation on cognitive function in older adults in the FACIT trial: A randomised, double blind, controlled trial. Lancet 2007; 369:208-16.
121. Hoey L, McNulty H, Askin N, Dunne A, Ward M, Pentieva K, Strain JJ, Molloy AM, Flynn CA, Scott JM. Impact of a voluntary food fortification policy on folate, related B-vitamin status and homocysteine in healthy adults. Am J Clin Nutr 2007; 86:1405-13.
122. Tamura T, Mizuno Y, Johnston KE, Jacob RA. Food folate assay with protease, a-amylase and folate conjugase treatments. JAgr Food Chem 1997; 45:135-39.