Epidemiology

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][4][5][6]

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 pre-school 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 living independently (15% in the UK).[3] One large review of global folate status in women of reproductive age reported folate deficiency <5% in higher-income countries and >20% in many low-income countries.[5] 

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.[7][8]

Countries with mandatory folic acid fortification have higher population plasma folate levels than countries with voluntary or no fortification policies.[6]

Folate deficiency may be under-reported in resource-limited countries.[9] Vitamin B12 deficiency or states of haemolysis (e.g., haemoglobinopathy, malaria) raise serum folate into the normal range, leading to underestimation of tissue folate.[10]

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