Folic acid: a public-health challenge

Lancet

Volumn 367, Issue 9519, 2006, Pages 1352-1361

  Eichholzer, Monika ^a   Tönz, Otmar ^b   Zimmermann, Roland ^c  

^a UNIVERSITY OF ZURICH   (Switzerland)

^b CHILDREN S HOSPITAL   (Switzerland)

^c UNIVERSITY HOSPITAL ZURICH   (Switzerland)

Author keywords

[No Author keywords available]

Indexed keywords

CARBAMAZEPINE; CYANOCOBALAMIN; FOLIC ACID; HOMOCYSTEINE; PHENYTOIN; PYRIDOXINE; VALPROIC ACID;

ANENCEPHALUS; BIRTH DEFECT; CANCER PREVENTION; CARCINOGENESIS; CARDIOVASCULAR DISEASE; CEREAL; CYANOCOBALAMIN DEFICIENCY; DIET SUPPLEMENTATION; DIETARY INTAKE; DRUG BLOOD LEVEL; DRUG HYPERSENSITIVITY; FOLIC ACID BLOOD LEVEL; FOLIC ACID DEFICIENCY; FOOD AND DRUG ADMINISTRATION; HEALTH EDUCATION; HUMAN; NEURAL TUBE DEFECT; NEUROBLASTOMA; NEUROPATHY; NONHUMAN; PREGNANCY; PREVALENCE; PRIORITY JOURNAL; PUBLIC HEALTH; REVIEW; RISK ASSESSMENT; RISK FACTOR; SEIZURE; SPINA BIFIDA; STROKE; TRISOMY 21; UTERINE CERVIX CANCER; VITAMIN SUPPLEMENTATION; WHEAT;

EID: 33646050916     PISSN: 01406736     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0140-6736(06)68582-6     Document Type: Review

References (137)

1. Dietary reference intakes for thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline: a report of the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its panel on folate, other B vitamins, and choline and subcommittee on upper reference levels of nutrients (1998), National Academy Press, Washington, DC
2. Relton C., Pearce M., and Parker L. The influence of erythrocyte folate and serum vitamin B12 status on birth weight. Br J Nutr 93 (2005) 593-599
3. Taylor M., Carney S., Goodwin G., and Geddes J. Folate for depressive disorders: systematic review and meta-analysis of randomized controlled trials. J Psychopharmacol 18 (2004) 251-256
4. Garcia A., and Zanibbi K. Homocysteine and cognitive function in elderly people. CMAJ 171 (2004) 897-904
5. McLean R., Jacques P., Selhub J., et al. Homocysteine as a predictive factor for hip fracture in older persons. N Engl J Med 350 (2004) 2042-2049
6. van Meurs J., Dhonukshe-Rutten R., Pluijm S., et al. Homocysteine levels and the risk of osteoporotic fracture. N Engl J Med 350 (2004) 2033-2041
7. Oakley Jr. G., Weber M., Bell K., and Colditz P. Scientific evidence supporting folic acid fortification of flour in Australia and New Zealand. Birth Defects Res A Clin Mol Teratol 70 (2004) 838-841
8. Mitchell L., Adzick N., Melchionne J., Pasquariello P., Sutton L., and Whitehead A. Spina bifida. Lancet 364 (2004) 1885-1895
9. Ray J., Wyatt P., Vermeulen M., Meier C., and Cole D. Greater maternal weight and the ongoing risk of neural tube defects after folic acid flour fortification. Obstet Gynecol 105 (2005) 261-265
10. Medical Research Council. Vitamin prevention of neural tube defects: results of the Medical Research Council Vitamin Study. MRC Vitamin Study Research Group. Lancet 338 (1991) 131-137
11. Czeizel A., and Dudas I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med 327 (1992) 1832-1835
12. Lumley J., Watson L., Watson M., and Bower C. Periconceptional supplementation with folate and/or multivitamins for preventing neural tube defects. Cochrane Database Syst Rev 3 (2001) CD001056
13. Botto L., Olney R., and Erickson J. Vitamin supplements and the risk for congenital anomalies other than neural tube defects. Am J Med Genet C Semin Med Genet 125 (2004) 12-21
14. Tönz O. Purpose and goal of a general folic acid prophylaxis. Forum Med Suisse 13 (2002) 303-310 [in German]
15. Bailey L., and Berry R. Folic acid supplementation and the occurrence of congenital heart defects, orofacial clefts, multiple births, and miscarriage. Am J Clin Nutr 81 (2005) 1213S-1217S
16. Czeizel A. Periconceptional folic acid containing multivitamin supplementation. Eur J Obstet Gynecol Reprod Biol 78 (1998) 151-161
17. Myers M., Li S., Correa-Villasenor A., et al. China-US Collaborative Project for Neural Tube Defect Prevention. Folic acid supplementation and risk for imperforate anus in China. Am J Epidemiol 154 (2001) 1051-1056
18. Czeizel A., and Puho E. Maternal use of nutritional supplements during the first month of pregnancy and decreased risk of Down's syndrome: case-control study. Nutrition 21 (2005) 698-704
19. Barkai G., Arbuzova S., Berkenstadt M., Heifetz S., and Cuckle H. Frequency of Down's syndrome and neural-tube defects in the same family. Lancet 361 (2003) 1331-1335
20. Homocysteine Studies Collaboration. Homocysteine and risk of ischemic heart disease and stroke: a meta-analysis. JAMA 288 (2002) 2015-2022
21. Voutilainen S., Virtanen J., Rissanen T., et al. Serum folate and homocysteine and the incidence of acute coronary events: the Kuopio Ischaemic Heart Disease Risk Factor Study. Am J Clin Nutr 80 (2004) 317-323
22. Virtanen J., Voutilainen S., Happonen P., et al. Serum homocysteine, folate and risk of stroke: Kuopio Ischaemic Heart Disease Risk Factor (KIHD) Study. Eur J Cardiovasc Prev Rehabil 12 (2005) 369-375
23. Toole J., Malinow M., Chambless L., et al. Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial. JAMA 291 (2004) 565-575
24. Schnyder G., Roffi M., Pin R., et al. Decreased rate of coronary restenosis after lowering of plasma homocysteine levels. N Engl J Med 345 (2001) 1593-1600
25. Lange H., Suryapranata H., De Luca G., et al. Folate therapy and instent restenosis after coronary stenting. N Engl J Med 350 (2004) 2673-2681
26. Spence J., Bang H., Chambless L., and Stampfer M. Vitamin Intervention For Stroke Prevention trial: an efficacy analysis. Stroke 36 (2005) 2404-2409
27. Clarke R. Homocysteine-lowering trials for prevention of heart disease and stroke. Semin Vasc Med 5 (2005) 215-222
28. Bailey L., Rampersaud G., and Kauwell G. Folic acid supplements and fortification affect the risk for neural tube defects, vascular disease and cancer: evolving science. J Nutr 133 (2003) 1961S-19668
29. Bostom A., Selhub J., Jacques P., and Rosenberg I. Power shortage: clinical trials testing the homocysteine hypothesis against a background of folic acid-fortified cereal grain flour. Ann Intern Med 135 (2001) 133-137
30. Eichholzer M., Luthy J., Moser U., and Fowler B. Folate and the risk of colorectal, breast and cervix cancer: the epidemiological evidence. Swiss Med Wkly 131 (2001) 539-549
31. Butterworth Jr. C., Hatch K., Soong S., et al. Oral folic acid supplementation for cervical dysplasia: a clinical intervention trial. Am J Obstet Gynecol 166 (1992) 803-809
32. Childers J., Chu J., Voigt L., et al. Chemoprevention of cervical cancer with folic acid: a phase III Southwest Oncology Group Intergroup Study. Cancer Epidemiol Biomarkers Prev 4 (1995) 155-159
33. French A., Grant R., Weitzman S., et al. Folic acid food fortification is associated with a decline in neuroblastoma. Clin Pharmacol Ther 74 (2003) 288-294
34. Thompson J., Gerald P., Willoughby M., and Armstrong B. Maternal folate supplementation in pregnancy and protection against acute lymphoblastic leukaemia in childhood: a case-control study. Lancet 358 (2001) 1935-1940
35. Cornel M., Smit D., and de Jong-van den Berg L. Folic acid-the scientific debate as a base for public health policy. Reprod Toxicol 20 (2005) 411-415
36. Kim Y. Will mandatory folic acid fortification prevent or promote cancer?. Am J Clin Nutr 80 (2004) 1123-1128
37. Kim Y. Role of folate in colon cancer development and progression. J Nutr 133 suppl 1 (2003) 3731S-3739S
38. Charles D., Ness A., Campbell D., Davey Smith G., and Hall M. Taking folate in pregnancy and risk of maternal breast cancer. BMJ 329 (2004) 1375-1376
39. Kotsopoulos J., Medline A., Renlund R., et al. Effects of dietary folate on the development and progression of mammary tumors in rats. Carcinogenesis 9 (2005) 1603-1612
40. Busby A., Armstrong B., and Dolk H. Preventing neural tube defects in Europe: a missed opportunity. Reprod Toxicol 20 (2005) 393-402
41. National Health and Medical Research Council. Revised statement on the relationship between dietary folic acid and neural tube defects such as spina bifida (1993), NHMRC, Canberra
42. Daly S., Mills J., Molloy A., et al. Minimum effective dose of folic acid for food fortification to prevent neural-tube defects. Lancet 350 (1997) 1666-1669
43. Berry R., Li Z., Erickson J., et al. Prevention of neural-tube defects with folic acid in China. N Engl J Med 341 (1999) 1485-1490
44. Czeizel A. The primary prevention of birth defects: multivitamins or folic acid?. Int J Med Sci 1 (2004) 50-61
45. DACH. German Nutrition Society (DGE), Austrian Nutrition Society (ÖGE), Swiss Society for Nutrition Research (SGE), Swiss Nutrition Association (SVE): reference values for nutrient intake (2000), Umschau/Braus-Verlag, Frankfurt [in German]
46. Tönz O. Preventive potential of folic acid. Fifth Nutrition Report (2005), Federal Office of Public Health, Bern Eichholzer M, Camenzind-Frey E, Matzke A et al. (publishers) [in German]
47. WHOTechnical Report: Diet, nutrition and the prevention of chronic diseases (2003), WHO, Geneva
48. Botto L., Lisi A., Robert-Gnansia E., et al. International retrospective cohort study of neural tube defects in relation to folic acid recommendations: are the recommendations working?. BMJ 330 (2005) 571-573
49. Ward M., Hutton J., McDonnell R., et al. Folic acid supplements to prevent neural tube defects: trends in East of Ireland 1996-2002. Ir Med J 97 (2004) 274-276
50. de Jong-Van den Berg L., Hernandez-Diaz S., Werler M., Louik C., and Mitchell A. Trends and predictors of folic acid awareness and periconceptional use in pregnant women. Am J Obstet Gynecol 192 (2005) 121-128
51. Coll O., Pisa S., Palacio M., Quinto L., and Cararach V. Awareness of the use of folic acid to prevent neural tube defects in a Mediterranean area. Eur J Obstet Gynecol Reprod Biol 115 (2004) 173-177
52. Sillender M., and Pring D. How effective was the Health Education Authority's folic acid campaign?. J Obstet Gynaecol 20 (2000) 271-276
53. Chacko M., Anding R., Kozinetz C., Grover J., and Smith P. Neural tube defects: knowledge and preconceptional prevention practices in minority young women. Pediatrics 112 (2003) 536-542
54. de Walle H., van der Pal K., de Jong-van den Berg L., et al. Effect of mass media campaign to reduce socioeconomic differences in women's awareness and behaviour concerning use of folic acid: cross sectional study. BMJ 319 (1999) 291-292
55. Braekke K., and Staff A. Periconceptional use of folic acid supplements in Oslo. Acta Obstet Gynecol Scand 82 (2003) 620-627
56. Relton C., Hammal D., Rankin J., and Parker L. Folic acid supplementation and social deprivation. Public Health Nutr 8 (2005) 338-340
57. Ray J., Singh G., and Burrows R. Evidence for suboptimal use of periconceptional folic acid supplements globally. BJOG 111 (2004) 399-408
58. van der Pal-de Bruin K., de Walle H., Jeeninga W., et al. The Dutch Folic Acid Campaign-have the goals been achieved?. Paediatr Perinat Epidemiol 14 (2000) 111-117
59. Chan A., Pickering J., Haan E., et al. Folate before pregnancy: the impact on women and health professionals of a population-based health promotion campaign in South Australia. Med J Aust 174 (2001) 631-636
60. de Walle H., Cornel M., and de Jong-van den Berg L. Three years after the Dutch folic acid campaign: growing socioeconomic differences. Prev Med 35 (2002) 65-69
61. de Walle H., and de Jong-van den Berg L. Insufficient folic acid intake in the Netherlands: what about the future?. Teratology 66 (2002) 40-43
62. Stevenson R., Allen W., Pai G., et al. Decline in prevalence of neural tube defects in a high-risk region of the United States. Pediatrics 106 (2000) 677-683
63. Knudsen V., Orozova-Bekkevold I., Rasmussen L., Mikkelsen T., Michaelsen K., and Olsen S. Low compliance with recommendations on folic acid use in relation to pregnancy: is there a need for fortification?. Public Health Nutr 7 (2004) 843-850
64. Baerlocher K., Eichholzer M., Lüthy J., Moser U., and Tönz O. Measures to prevent neural tube defects and improve folic acid consumption in Switzerland. AG Folic Acid Prophylaxis of the Swiss Federal Nutrition Board (2002) [in German]
65. Beitz R., Mensink G., Fischer B., and Thamm M. Vitamins-dietary intake and intake from dietary supplements in Germany. Eur J Clin Nutr 56 (2002) 539-545
66. Nydhal M., Andersson J., Sidenvall B., Gustafsson K., and Fjellstrom C. Food and nutrient intake in a group of self-managing elderly Swedish women. J Nutr Health Aging 7 (2003) 67-74
67. Planells E., Sanchez C., Montellano M., Mataix J., and Llopis J. Vitamins B6 and B12 and folate status in an adult Mediterranean population. Eur J Clin Nutr 57 (2003) 777-785
68. Fletcher R., Bell I., and Lambert J. Public health aspects of food fortification: a question of balance. Proc Nutr Soc 63 (2004) 605-614
69. Czernichow S., Noisette N., Blacher J., et al. Case for folic acid and vitamin B12 fortification in Europe. Semin Vasc Med 5 (2005) 156-162
70. Regulation of the Swiss Federal Department of Home Affairs on the addition of vitamins to food and their labeling (1957), Swiss Federal Department of Home Affairs, Berne
71. Cuskelly G., McNulty H., and Scott J. Fortification with low amounts of folic acid makes a significant difference in folate status in young women: implications for the prevention of neural tube defects. Am J Clin Nutr 70 (1999) 234-239
72. Food and Drug Administration. Food standards: amendment of standards of identity for enriched grain products to require addition of folic acid. Fed Regist 61 (1996) 8781-8807
73. US Food and Drug Administration. how folate can help prevent birth defects. 1996, revised 1999. http://vm.cfsan.fda.gov/∼dms/%20fdafolic.html (accessed Mar 15, 2006)
74. Oakley Jr. G., and Johnston Jr. R. Balancing benefits and harms in public health prevention programmes mandated by governments. BMJ 329 (2004) 41-43
75. Bower C., Miller M., Payne J., Serna P., de Klerk N., and Stanley F. Folate promotion in western Australia and the prevention of neural tube defects. Aust N Z J Public Health 28 (2004) 458-464
76. Bower C., Eades S., Payne J., D'Antoine H., and Stanley F. Trends in neural tube defects in Western Australia in Indigenous and non-Indigenous populations. Paediatr Perinat Epidemiol 18 (2004) 277-280
77. Centers for Disease Control and Prevention. Folate status in women of childbearing age-United States, 1999. MMWR Morb Mortal Wkly Rep 49 (2000) 962-965
78. Williams L., Mai C., Edmonds L., et al. Prevalence of spina bifida and anencephaly during the transition to mandatory folic acid fortification in the United States. Teratology 66 (2002) 33-39
79. Liu S., West R., Randell E., et al. A comprehensive evaluation of food fortification with folic acid for the primary prevention of neural tube defects. BMC Pregnancy Childbirth 4 (2004) 20-29
80. Ray J., Meier C., Vermeulen M., Boss S., Wyatt P., and Cole D. Association of neural tube defects and folic acid food fortification in Canada. Lancet 360 (2002) 2047-2048
81. De Wals P., Rusen I., Lee N., Morin P., and Niyonsenga T. Trend in prevalence of neural tube defects in Quebec. Birth Defects Res A Clin Mol Teratol 67 (2003) 919-923
82. Persad V., Van den Hof M., Dube J., and Zimmer P. Incidence of open neural tube defects in Nova Scotia after folic acid fortification. CMAJ 167 (2002) 241-245
83. Lopez-Camelo J., Orioli I., da Graca Dutra M., et al. Reduction of birth prevalence rates of neural tube defects after folic acid fortification in Chile. Am J Med Genet A 135 (2005) 120-125
84. Shane B. Folate fortification: enough already?. Am J Clin Nutr 77 (2003) 8-9
85. Rosano A., Smithells D., Cacciani L., et al. Time trends in neural tube defects prevalence in relation to preventive strategies: an international study. J Epidemiol Community Health 53 (1999) 630-635
86. Rader J., Weaver C., and Angyal G. Total folate in enriched cereal-grain products in the United States following fortification. Food Chem 70 (2000) 275-289
87. Choumenkovitch S., Selhub J., Wilson P., Rader J., Rosenberg I., and Jacques P. Folic acid intake from fortification in United States exceeds predictions. J Nutr 132 (2002) 2792-2798
88. Quinlivan E., and Gregory J. Effect of food fortification on folic acid intake in the United States. Am J Clin Nutr 77 (2003) 221-225
89. Jacques P., Selhub J., Bostom A., Wilson P., and Rosenberg I. The effect of folic acid fortification on plasma folate and total homocysteine concentrations. N Engl J Med 340 (1999) 1449-1454
90. Choumenkovitch S., Jacques P., Nadeau M., Wilson P., Rosenberg I., and Selhub J. Folic acid fortification increases red blood cell folate concentrations in the Framingham study. J Nutr 131 (2001) 3277-3280
91. Health Canada. Regulations amending the Food and Drug Regulations (1066). Can Gaz Part 1 131 (1997) 3702-3737
92. Liu S., Longerich L., Steel O'Connor K., et al. Evaluation of food fortification with folic acid for the primary prevention of neural tube defects. Executive summary 1997-2003. Public health agency of Canada. Available at: http://www.phac-aspc.gc.ca/about_apropos/index.html (accessed Mar 15, 2006)
93. Ray J., Vermeulen M., Boss S., and Cole D. Increased red cell folate concentrations in women of reproductive age after Canadian folic acid food fortification. Epidemiology 13 (2002) 238-240
94. Crane J., Sun C., Hutchens D., and Crowley M. The epidemiology of neural tube defects in Newfoundland and Labrador. J Soc Obstet Gynaecol Can 23 (2001) 510-514
95. Ray J., Vermeulen M., Boss S., and Cole D. Declining rate of folate insufficiency among adults following increased folic acid food fortification in Canada. Can J Public Health 93 (2002) 249-253
96. Ray J., Meier C., Vermeulen M., Wyatt P., and Cole D. Association between folic acid food fortification and congenital orofacial clefts. J Pediatr 143 (2003) 805-807
97. Ray J., Meier C., Vermeulen M., Cole D., and Wyatt P. Prevalence of trisomy 21 following folic acid food fortification. Am J Med Genet A 120 (2003) 309-313
98. Castilla E., Orioli I., Lopez-Camelo J., Dutra Mda G., Nazer-Herrera J., and Latin American Collaborative Study of Congenital Malformations (ECLAMC). Preliminary data on changes in neural tube defect prevalence rates after folic acid fortification in South America. Am J Med Genet A 123 (2003) 123-128
99. Hertrampf E., Cortes F., and Erickson J. Consumption of folic acid-fortified bread improves folate status in women of reproductive age in Chile. J Nutr 133 (2003) 3166-3169
100. Casas-Becerra L. Women prosecuted and imprisoned for abortion in Chile. Reproductive Health Matters 9 (1997) 29-30
101. Hirsch S., de la Maza P., Barrera G., Gattas V., Petermann M., and Bunout D. The Chilean flour folic acid fortification program reduces serum homocysteine levels and masks vitamin B-12 deficiency in elderly people. J Nutr 132 (2002) 289-291
102. Committee on Aspects of Food Policy. Folic acid and the prevention of disease. Report on Health and Social subjects (50) (2000), Stationery Office, London
103. Food Standards Agency. Board reaches conclusion on folic acid (2002). http://www.food.gov.uk/news/newsarchive/2002/may/62488 (last accessed Mar 15, 2006)
104. Postma M., Londeman J., Veenstra M., de Walle H., and de Jong-van den Berg L. Cost-effectiveness of periconceptional supplementation of folic acid. Pharm World Sci 24 (2002) 8-11
105. Koletzko B., and Pietrzik K. Public health significance of folic acid consumption. Dtsch Arztebl 101 (2004) A 1670-A 1681 [in German]
106. Bower C., and Stanley F. Case for mandatory fortification of food with folate in Australia, for the prevention of neural tube defects. Birth Defects Res A Clin Mol Teratol 70 (2004) 842-843
107. Food Standards Agency. Agency board discusses folate and health (April 6, 2006). http://www.foodstandards.gov.uk/news/newsarchive/2006/apr/folatehealth (accessed April 10, 2006)
108. Campbell N. How safe are folic acid supplements?. Arch Intern Med 156 (1996) 1638-1644
109. Eichholzer M., Luthy J., Moser U., Stahelin H., and Gutzwiller F. Safety aspects of folic acid for the general population. Schweiz Rundsch Med Prax 91 (2002) 7-16 [in German]
110. Sisk E., Lockner D., Wold R., Waters D., and Baumgartner R. The impact of folic acid fortification of enriched grains on an elderly population: the New Mexico Aging Process Study. J Nutr Health Aging 8 (2004) 140-143
111. Mills J., Von Kohorn I., Conley M., et al. Low vitamin B-12 concentrations in patients without anemia: the effect of folic acid fortification of grain. Am J Clin Nutr 77 (2003) 1474-1477
112. Suter P. Nutrition checklist (2002), Thieme, Stuttgart, New York [in German]
113. Ray J., Langman L., Mamdani M., and Cole D. Absence of effect of folic acid flour fortification on anticonvulsant drug levels. Am J Med 118 (2005) 444-445
114. Benchalal M., Yahchouchy-Chouillard E., Fouere S., and Fingerhut A. Anaphylactic shock secondary to intravenous administration of folinic acid: a first report. Ann Oncol 13 (2002) 480-481
115. Czeizel A., Metneki J., and Dudas I. The higher rate of multiple births after periconceptional multivitamin supplementation: an analysis of causes. Acta Genet Med Gemellol (Roma) 43 (1994) 175-184
116. Ericson A., Källen B., and Åberg A. Use of multivitamins and folic acid in early pregnancy and multiple births in Sweden. Twin Res 4 (2001) 63-66
117. Werler M., Cragan J., Wasserman C., Shaw G., Erickson J., and Mitchell A. Multivitamin supplementation and multiple births. Am J Med Genet 71 (1997) 93-96
118. Martin J., and Park M. Trends in twin and triplet births: 1980-97. Natl Vital Stat Reps 47 (1999) 1-16
119. Signore C., Mills J., Cox C., and Trumble A. Effects of folic acid fortification on twin gestation rates. Obstet Gynecol 105 (2005) 757-762
120. Waller D., Tita A., and Annegers J. Rates of twinning before and after fortification of foods in the US with folic acid, Texas, 1996 to 1998. Paediatr Perinat Epidemiol 17 (2003) 378-383
121. Shaw G., Carmichael S., Nelson V., Selvin S., and Schaffer D. Food fortification with folic acid and twinning among California infants. Am J Med Genet 119A (2003) 137-140
122. Li Z., Gindler J., Wang H., et al. Folic acid supplements during early pregnancy and likelihood of multiple births: a population-based cohort study. Lancet 361 (2003) 380-384
123. Berry R., Kihlberg R., and Devine O. Impact of misclassification of in vitro fertilisation in studies of folic acid and twinning: modelling using population based Swedish vital records. BMJ 330 (2005) 815-818
124. Vollset S., Gjessing H., Tandberg A., et al. Folate supplementation and twin pregnancies. Epidemiology 16 (2005) 201-205
125. Katz J., West Jr. K., Khatry S., et al. Twinning rates and survival of twins in rural Nepal. Int J Epidemiol 30 (2001) 802-807
126. Kallen B. Reply to letter to the Editor. Early Hum Dev 81 (2005) 469-470
127. Munoz-Moran E., Dieguez-Lucena J., Fernandez-Arcas N., Peran-Mesa S., and Reyes-Engel A. Genetic selection and folate intake during pregnancy. Lancet 352 (1998) 1120-1121
128. Lucock M., and Yates Z. Folic acid-vitamin and panacea or genetic time bomb?. Nat Rev Genet 6 (2005) 235-240
129. Rosenberg I. Science-based micronutrient fortification: which nutrients, how much, and how to know?. Am J Clin Nutr 82 (2005) 279-280
130. Kadir R., and Economides D. Neural tube defects and periconceptional folic acid. CMAJ 167 (2002) 255-256
131. Salvi V., and Damania K. Neural tube defects in India-time for action. Lancet 366 (2005) 871-872
132. McDonald S., Ferguson S., Tam L., Lougheed J., and Walker M. The prevention of congenital anomalies with periconceptional folic acid supplementation. J Obstet Gynaecol Can 25 (2003) 115-121
133. Koren G. Periconception folic acid supplementation. Knowledge and practice of Canadian family physicians. Can Fam Physician 43 (1997) 851-852
134. Husler M., Krahenmann F., Streicher A., and Zimmermann R. State of the art prenatal care from the Swiss viewpoint. Ther Umsch 59 (2002) 641-649 (German)
135. Larson R., Woloshin S., Schwartz L., and Welch H. Celebrity endorsements of cancer screening. J Natl Cancer Inst 97 (2005) 693-695
136. Department of Health and Human Services, USA. Prevention report (2004). http://odphp.osophs.dhhs.gov/pubs/prevrpt/Volume19/Issue1Cover.htm (accessed Mar 15, 2006)
137. Quadagno D., Eberstein I., Foster K., Sittig J., Sly D., and Kistner J. Magic Johnson and children's conceptions of AIDS. AIDS Educ Prev 9 (1997) 359-372