Folate is a water-soluble B vitamin that facilitates the transfer of carbon atoms in the synthesis of nucleic acids and amino acids. The word folate is derived from folium meaning leaf. The name is a reminder that green leafy plants like spinach and lettuce are a rich source of folate. Other sources include okra, asparagus, organ meat (liver, kidney) and tomato juice. These food sources account for 20% of our folate levels the rest being produced by intestinal microorganisms.
Folate is commonly used in the treatment for reduced amount red blood cells in a condition called megaloblastic anemia. Mixed results have been found when using folate in the treatment of depression, as a cognitive enhancer or as a way of lowering the risk for cancer (e.g., colonorectal, pancreatic).
Deficiencies of folate are seen primarily in people with poor diets, alcohol dependence, pregnancy, digestive problems, and individuals with kidney or liver disease. Low folate levels are manifested by soreness and shallow ulcerations in the tongue and oral mucosa, and changes in fingernail pigmentation. When testing folate levels the physician takes into account the age of the patient, whether the levels were taken from red blood cells (reflecting long-term folate intake) or plasma (reflecting short-term folate intake), and the possible intake of vitamin or dietary supplements.
Folate supplementation during pregnancy decreases the risk of acquiring major malformations of the nervous system (i.e., being born with a split open spinal cord or lacking most of the brain) by 50-70%. However, according to some authors, very high levels of folate in pregnant women may increase the risk for autism. High folate levels in pregnant women may be due to excessive supplementation. However, cells need vitamin B12 in order to metabolize folate. If vitamin B12 levels are low folate may accumulate and build up in the blood.
The results of studies linking autism to folate levels may be arguable and open to criticism depending on whether some confounds have been taken into account including prescription of vitamins, food intake and/or nutrient supplementation in children with autism, and how the folate levels were measured. When many of these confounds are taken into account the medical literature leads to inconsistent conclusions (Castro et al, 2014, DeVilbiss et al. 2015). Indeed, feeding behaviors in autistic individuals differ significantly from those of controls and may expose them to inadequate calcium, sodium, iron, vitamin C intake and folate (Castro et al, 2016). Some studies have even claimed that folate supplementation during pregnancy may actually decrease the risk for autism spectrum disorder in the offspring and possibly more so if the mother is taking anticonvulsants for seizures (Anderson, 2016).
References
Anderson P. Folic acid linked to less autism in kids of women with epilepsy. Medscape Medical News, June 9, 2016 (http://www.medscape.com/viewarticle/864563)
Castro K, Kelin LD, Baronio D, Gottfried C, Riesgo R, Perry IS. Folic acid and autism: What do we know? Nutr Neurosci [Epub ahead of time] PMID: 25087906
Castro K, Faccioli LS, Baronio D, Gottfried C, Perry IS, Riesgo R. Feeding behavior and dietary intake of male children and adolescents with Autism Spectrum Disorder: a case-control study. Int J Dev Neurosci [Epub ahead of print] PMID: 27432261
DeVibiss EA, Gardner RM, Newsschaffer CJ, Lee BK. Maternal folate as a risk factor for autism spectrum disorders: a review of existing literature. Br J Nutr 114(5):663-72, 2015.