The adverse effects of an excessive folic acid intake

Abstract

Folate is a vital component of a healthy diet, being essential for numerous bodily functions. Deficiency of folate is common, with studies suggesting prevalence of deficiencyas high as 85.5% as was shown in women between the ages of 16 and 49, living in the UK. Causes of folate deficiency range from diet and lifestyle, to pathological and pharmacological processes. Because of the well-known role of folate in prevention of neural tube defects, numerous countries have implemented strategies to increase folate intake, with programs such as mandatory grain fortification. As a result, the intake of folate in these countries is often higher than the recommended dietary allowance for many groups of people. Although folate is believed to be non-toxic, the potential adverse effects of excessive intake of folic acid (synthetic form of folate) have not been highlighted well by authorities to people taking supplements; despite this, many studies have addressed this issue. However, the results of these studies provide discrepant results, leading to confusion as to whether mandatory folic acid fortification should be introduced in other countries. The purpose of this review was to provide a summary of evidence related to high folic acid ingestion and to look at the unwanted effects it may have on the certain groups within the general population.

The effect of the systemic folic acid intake as an adjunct to scaling and root planing on clinical parameters and homocysteine and C‐reactive protein levels in gingival crevicular fluid of periodontitis patients: A randomized placebo‐controlled clinical trial

“…Although it is controversial, long‐term unintentional effects of FA including various malignancies (colorectal, prostate and mammary), impaired cognitive function in elderly and masking of pernicious anaemia (Patel & Sobczyńska‐Malefora, 2017) mostly occur with high FA doses (>200 µg), in which chronic exposure of the liver to FA induces its saturation in the vascular system (Patanwala et al, 2014). Besides serious effects, risk of allergic reaction and findings of flushing, loss of appetite, nausea, bloating, bitter or bad taste in the mouth, depression, sleep problems and feeling excited are the less frequently reported short‐term effects of FA.…”

Excess micronutrient intake: defining toxic effects and upper limits in vulnerable populations

“…Adverse outcomes of lifetime excess are still being investigated (see Ref. for proposed research priorities) and no clear consensus exists regarding the safety of high intakes of folic acid . Intake data from the United States and Mexico show that folic acid intake among young children approximates the UL (Table ).…”

“…2 Each nutrient is considered systematically, and any judgments or assumptions made are explicitly described in a discussion of the scientific uncertainties involved. 2,33 Risk assessment of nutrients follows four steps: 2 1,7,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] General value is divided by an uncertainty factor (UF), creating a buffer of safety to arrive at the UL (see discussion on NOAELs, LOAELs, CEs, and UFs below). Different ULs are set for different life-stage groups.…”

Gestational folic acid supplementation does not affects the maternal behavior and the early development of rats submitted to neonatal hypoxia‐ischemia but the high supplementation impairs the dam's memory and the Na+, K+ ‐ ATPase activity in the pup's hippocampus

“…Positive effect of FA supplementation on the offspring neurodevelopment has been identified; in a large case‐cohort study, including 45,300 children, Levine et al, (2018) demonstrated that maternal exposure to FA before or during pregnancy was significantly associated with a low likelihood of autism spectrum disorder in the offspring. Some findings have pointed that normonutride women might have an excess of FA by the supplements and diet itself (Bailey et al, 2010; Patel and Sobczyńska‐Malefora, 2017; Selhub and Rosenberg, 2016). After the FA fortification regime in the US, it was identified an increase in FA intake that was approximately twice as large as previously projected (Choumenkovitch et al, 2002).…”