The prevalence and the magnitude of folate deficiency across the world are variable. The condition occurs commonly in countries without folic acid fortification of cereal-grain products, and rarely in countries with folic acid fortification.[3]McLean E, de Benoist B, Allen LH. Review of the magnitude of folate and vitamin B12 deficiencies worldwide. Food Nutr Bull. 2008 Jun;29(2 suppl):S38-51.
http://www.ncbi.nlm.nih.gov/pubmed/18709880?tool=bestpractice.com
[4]Metz J. Haematological implications of folate food fortification. S Afr Med J. 2013 Oct 11;103(12 Suppl 1):978-81.
http://www.ncbi.nlm.nih.gov/pubmed/24300642?tool=bestpractice.com
[5]Rogers LM, Cordero AM, Pfeiffer CM, et al. Global folate status in women of reproductive age: a systematic review with emphasis on methodological issues. Ann N Y Acad Sci. 2018 Nov;1431(1):35-57.
https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/nyas.13963
http://www.ncbi.nlm.nih.gov/pubmed/30239016?tool=bestpractice.com
Several national surveys have shown that folate deficiency can be a public health problem in the absence of fortification. The primary age groups affected include preschool children (33.8% of the folate-deficient population in Venezuela), pregnant women (48.8% in Costa Rica and 25.5% in Venezuela), and older people (15% in the UK).[3]McLean E, de Benoist B, Allen LH. Review of the magnitude of folate and vitamin B12 deficiencies worldwide. Food Nutr Bull. 2008 Jun;29(2 suppl):S38-51.
http://www.ncbi.nlm.nih.gov/pubmed/18709880?tool=bestpractice.com
One large review of global folate deficiency in women of reproductive age, who are at increased risk of neural tube defect-affected pregnancies when maternal folate levels are low, reported folate deficiency <5% in higher-income countries and >20% in many low-income countries.[5]Rogers LM, Cordero AM, Pfeiffer CM, et al. Global folate status in women of reproductive age: a systematic review with emphasis on methodological issues. Ann N Y Acad Sci. 2018 Nov;1431(1):35-57.
https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/nyas.13963
http://www.ncbi.nlm.nih.gov/pubmed/30239016?tool=bestpractice.com
Mandatory folic acid fortification of enriched cereal-grain products was initiated in the US in 1996 and Canada in 1998. Subsequently, surveys of regional and nationally representative populations have shown that serum and red blood cell folate concentrations have increased in the general population in these countries.[6]Pfeiffer CM, Sternberg MR, Zhang M, et al. Folate status in the US population 20 y after the introduction of folic acid fortification. Am J Clin Nutr. 2019 Nov 1;110(5):1088-97.
https://academic.oup.com/ajcn/article/110/5/1088/5555582
http://www.ncbi.nlm.nih.gov/pubmed/31504109?tool=bestpractice.com
[7]Colapinto CK, O'Connor DL, Tremblay MS. Folate status of the population in the Canadian Health Measures Survey. CMAJ. 2011 Feb 8;183(2):E100-6.
https://www.cmaj.ca/content/183/2/E100
http://www.ncbi.nlm.nih.gov/pubmed/21149516?tool=bestpractice.com