Folemprim is a biologically active supplement which contains 400 mcg Folic acid.

Folate (vitamin B9) is an essential nutrient that is required for DNA replication and as a substrate for a range of enzymatic reactions involved in amino acid synthesis and vitamin metabolism. [1]
Folic acid intake is an important public health goal that can reduce the risk of neural tube defects (NTDs). This B-group vitamin occurs naturally in green leafy vegetables, citrus fruits and legumes, as well as in animal source foods, such as eggs and liver. The supply of naturally occurring folates through food is possible and, sometimes, sufficient, however, their absorption from food can be limited, as these compounds are very sensitive to many factors, including high temperature.  [2,3]
More than 150 folate compounds are known. Folates are characterized by a pteridine and a para-aminobenzoic acid ring, with up to 8 glutamate residues attached to the carboxyl terminus. Folates are therefore also referred to as pteroyl polyglutamates. Folic acid is a synthetic compound with a monoglutamate residue at the end of the carboxyl group; a pteroyl monoglutamate, it is the most stable form of folate. Folic acid is commonly used in pharmaceuticals and dietary supplements. All of these vitamin-active compounds, whether they are natural or synthetic, are referred to under the umbrella term “folate”. As the term “folic acid” is only used for the synthetic vitamin form, references such as “folic acid requirement” and “folic acid deficiency” are no longer strictly correct. Individual folate compounds demonstrate different absorption rates; folic acid is highly absorbed, whereas the availability of folates from food is limited and difficult to assess on an individual basis. The bio-availability of individual folates in food is primarily influenced by the ratio of mono- and polyglutamates 3, with a mean availability of around 50 % in a mixed diet. [4]
A synthetic form of naturally occurring folate is used in supplements and in fortified foods. Over several years, many studies have corroborated that preconception supplementation with folic acid reduces the risk of developing neural tube defects (e.g., anencephaly, spina bifida). [5]
Folic acid deficiency can arise from multiple causes, including inadequate dietary intake. Heating during cooking destroys folic acid. Folate is absorbed in the jejunum by active and passive transport mechanisms across the intestinal wall. Hence, diseases such as celiac disease, tropical sprue, short bowel syndrome, amyloidosis, gastric bypass, or mesenteric vascular insufficiency can inhibit folate absorption resulting in a deficiency. Elevated pH, as occurs in achlorhydria, can also lead to poor folate absorption. Drugs such as methotrexate, phenytoin, sulfasalazine, and trimethoprim can antagonize folate utilization, inhibit its absorption or conversation to its active form resulting in folate deficiency. Congenital deficiencies of enzymes required in folate metabolism can lead to folate deficiency.  Folic acid deficiency can occur subsequent to vitamin B-12 deficiency due to an impairment of methionine synthase resulting in the trapping of folate as methyltetrahydrofolate whereby methylene THFA accumulates in serum leading to folate trap phenomenon and increased urinary excretion of folate. Alcoholism is a significant cause of folate deficiency. Pregnancy, hemolytic anemia, and dialysis can also result in folate deficiency. [6]
All patients with folate deficiency should be offered supplemental folic acid for the correction of the deficiency. Typically, oral folic acid suffices to treat folate deficiency [1]. Intravenous, subcutaneous, or intramuscular formulations of folic acid can be used for patients unable to tolerate oral medications. The duration of therapy depends on whether the cause of the initial deficiency persists. Patients with malabsorption or short gut syndromes may typically require long-term treatment. In patients who have a concomitant vitamin B12 deficiency, it is imperative to replete vitamin B12 as well. Folate treatment alone does not improve neurological symptoms and signs due to B12 deficiency, which, if untreated, may likely progress and cause permanent neurological damage [7].
Periconceptional folic acid supplementation protects against fetal structural anomalies, including NTD and congenital heart defects. Recent data suggest that it may also protect against preterm birth. [8]
The current implementation of mandatory folic acid fortification has achieved its intended benefit of reducing the incidence of NTDs in newborns. Along with this, there have been a few unintended benefits that have improved the health status of some populations, including a reduction in tHcy concentrations, which is considered an independent risk factor for CVD. Other unintended benefits of folic acid fortification include virtually eliminating folic acid deficiency from the US, reducing the prevalence of anemia, and decreasing hemoglobin concentrations. However, the effect of folic acid fortification on cognitive health, stroke, and diabetes is not very clear. [9]

References
[1] Folic Acid Supplementation and Pregnancy: More Than Just Neural Tube Defect Prevention. James A Greenberg, MD,1 Stacey J Bell, DSc, RD,2 Yong Guan, MD,3 and Yan-hong Yu.
[2] Cieślik E., Cieślik I. Occurrence and Significance of Folic Acid. Pteridines. 2018;29:187–195. doi: 10.1515/pteridines-2018-0017. 
[3] McKeating A., Farren M., Cawley S., Daly N., McCartney D., Turner M.J. Maternal Folic Acid Supplementation Trends 2009–2013. Acta Obstet. Gynecol. Scand. 2015;94:727–733. doi: 10.1111/aogs.12656.
[4] Thaler CJ. Folate Metabolism and Human Reproduction. Geburtshilfe Frauenheilkd. 2014 Sep;74(9):845-851. doi: 10.1055/s-0034-1383058. PMID: 25278626; PMCID: PMC4175124.
[5] Wald N.J., Morris J.K., Blakemore C. Public Health Failure in the Prevention of Neural Tube Defects: Time to Abandon the Tolerable Upper Intake Level of Folate. Public Health Rev. 2018;39:1–11. doi: 10.1186/s40985-018-0079-6.
[6] Kashif M. Khan1; Ishwarlal Jialal2. Folic Acid Deficiency Last Update: June 26, 2023.
[7] Okada A, Koike H, Nakamura T, Watanabe H, Sobue G. Slowly progressive folate-deficiency myelopathy: report of a case. J Neurol Sci. 2014 Jan 15;336(1-2):273-5.
[8] Barua, S., Kuizon, S. & Junaid, M.A. Folic acid supplementation in pregnancy and implications in health and disease. J Biomed Sci 21, 77 (2014). https://doi.org/10.1186/s12929-014-0077-z
[9] Ismail, S.; Eljazzar, S.; Ganji, V. Intended and Unintended Benefits of Folic Acid Fortification—A Narrative Review. Foods 2023, 12, 1612. https://doi.org/10.3390/foods12081612