Objective To explore if there is an increased cancer risk associated with folic acid supplements given orally. Design Systematic review and meta-analysis of controlled studies of folic acid supplementation in humans reporting cancer incidence and/or cancer mortality. Studies on folic acid fortification of foods were not included. Data sources Cochrane Library, Medline, Embase and Centre of Reviews and Dissemination, clinical trial registries and hand-searching of key journals. Results From 4104 potential references, 19 studies contributed data to our meta-analyses, including 12 randomised controlled trials (RCTs). Meta-analysis of the 10 RCTs reporting overall cancer incidence (N=38 233) gave an RR of developing cancer in patients randomised to folic acid supplements of 1.07 (95% CI 1.00 to 1.14) compared to controls. Overall cancer incidence was not reported in the seven observational studies. Meta-analyses of six RCTs reporting prostate cancer incidence showed an RR of prostate cancer of 1.24 (95% CI 1.03 to 1.49) for the men receiving folic acid compared to controls. No significant difference in cancer incidence was shown between groups receiving folic acid and placebo/control group, for any other cancer type. Total cancer mortality was reported in six RCTs, and a meta-analysis of these did not show any significant difference in cancer mortality in folic acid supplemented groups compared to controls (RR 1.09, 95% CI 0.90 to 1.30). None of the observational studies addressed mortality. Conclusions A meta-analysis of 10 RCTs showed a borderline significant increase in frequency of overall cancer in the folic acid group compared to controls. Overall cancer incidence was not reported in the seven observational studies. Prostate cancer was the only cancer type found to be increased after folic acid supplementation (meta-analyses of six RCTs). Prospective studies of cancer development in populations where food is fortified with folic acid could indicate whether fortification similar to supplementation moderately increases prostate cancer risk.

DNA methylation has been suggested as a regulatory mechanism behind some inflammatory processes. The physiological actions of methyl donors, such as folic acid, choline, and vitamin B12 on inflammation-related disease have been associated with the synthesis of the universal methyl donor S-adenosyl methionine (SAM). The aim of this study was to evaluate the effects of folic acid, choline, vitamin B12, and a combination of all on preventing the lipopolysaccharide- (LPS-) induced inflammatory response in human THP-1 monocyte/macrophage cells. Folic acid and the mixture of methyl donors reduced interleukin 1 beta (IL1B) and tumour necrosis factor (TNF) expression as well as protein secretion by these cells. Folic acid and choline decreased C-C motif chemokine ligand 2 (CCL2) mRNA levels. In addition to this, the methyl donor mixture reduced Cluster of differentiation 40 (CD40) expression, but increased serpin family E member 1 (SERPINE1) expression. All methyl donors increased methylation levels in CpGs located in IL1B, SERPINE1, and interleukin 18 (IL18) genes. However, TNF methylation was not modified. After treatment with folic acid and the methyl donor mixture, ChIP analysis showed no change in the binding affinity of nuclear factor-κB (NF-κB) to IL1B and TNF promoter regions after the treatment with folic acid and the methyl donor mixture. The findings of this study suggest that folic acid might contribute to the control of chronic inflammation in inflammatory-related disease.

Clinical data suggests an association between systolic hypertension, renal function and hyperhomocysteinemia (HHcy). HHcy is a state of elevated plasma homocysteine (Hcy) levels and is known to cause vascular complications. In this study, we tested the hypothesis whether Ang II-induced hypertension increases plasma Hcy levels and contributes to renovascular remodeling. We also tested whether folic acid (FA) treatment reduces plasma Hcy levels by enhancing Hcy remethylation and thus mitigating renal remodeling. Hypertension was induced in WT mice by infusing Ang II using Alzet mini osmotic pumps. Blood pressure, Hcy level, renal vascular density, oxidative stress, inflammation and fibrosis markers, and angiogenic- and anti-angiogenic factors were measured. Ang II hypertension increased plasma Hcy levels and reduced renal cortical blood flow and microvascular density. Elevated Hcy in Ang II hypertension was associated with decreased 4, 5-Diaminofluorescein (DAF-2DA) staining suggesting impaired endothelial function. Increased expression of Nox-2, -4 and dihydroethidium stain revealed oxidative stress. Excess collagen IV deposition in the peri-glomerular area and increased MMP-2, and -9 expression and activity indicated renal remodeling. The mRNA and protein expression of asymmetric dimethylarginine (ADMA) was increased and eNOS protein was decreased suggesting the involvement of this pathway in Hcy mediated hypertension. Decreased expressions of VEGF and increased anti-angiogenic factors, angiostatin and endostatin indicated impaired vasculogenesis. FA treatment partially reduced hypertension by mitigating HHcy in Ang II-treated animals and alleviated pro-inflammatory, pro-fibrotic and anti-angiogenic factors. These results suggest that renovascular remodeling in Ang II-induced hypertension is, in part, due to HHcy.

Radiological therapy/examination is the primary source of artificial radiation exposure in humans. While its application has contributed to major advances in disease diagnosis and treatment, ionizing radiation exposure is associated with ovarian damage. The use of natural products, either alone or as an adjunct, has become increasingly common for reducing the side effects of radiological therapy during disease treatment. Herein, we explored the protective effect of folic acid (FA), a widely used B vitamin, against radiation-induced ovarian injury and its mechanism of action. Female mice with normal ovarian function were randomly divided into control, FA, radiation, and radiation + FA groups. The intervention strategy included daily intragastric administration of FA (5 mg/kg) for 3 weeks prior to radiation exposure. Mice in the radiation and radiation + FA groups received a single dose of 5 Gy X-ray irradiation. Changes in the estrous cycle were then recorded, and ovarian tissues were collected. Pathophysiological changes as well as reproductive and endocrine-related indexes were determined via H&E staining, immunohistochemistry, Western blot, and ELISA. The reproductive performance and emotional symptoms of animals were also monitored. Our results indicated that FA intervention effectively alleviated ovarian damage, leading to more regular estrous cycles, lesser impairment of follicular morphology and endocrine status, as well as greater germ cell preservation. Reduced levels of oxidative stress, inflammation, and enhanced DNA repair were associated these changes. FA pre-administration improved the reproductive performance, leading to higher pregnancy rates and greater litter sizes. Further, the anxiety levels of animals were significantly reduced. Our results indicate that FA pre-administration significantly alleviates radiation-induced ovarian damage in rodents, highlighting its potential as a protective strategy against radiation exposure in the female population.

The glucose analog, 2-deoxyglucose (2-DG), specifically inhibits glycolysis of cancer cells and interferes with the growth of cancer cells. However, the excellent water solubility of 2-DG makes it difficult to be concentrated in tumor cells. In this study, a targeted nano-pharmacosome was developed with folic acid-modified 2-DG (FA-2-DG) by using amino ethanol as a cleavable linker. FA-2-DG was able to self-assemble, forming nano-particles with diameters of 10⁻30 nm. The biological effects were evaluated with cell viability assays and flow cytometry analysis. Compared with a physical mixture of folic acid and 2-DG, FA-2-DG clearly reduced cell viability and resulted in cell cycle arrest. A computational study involving docking simulation suggested that FA-2-DG can dock into the same receptor as folic acid, thus confirming that the structural modification did not affect the targeting performance. The results indicated that the nano-pharmacosome consisting of FA-2-DG can be used for targeting in a nano-drug delivery system.

The folate receptor (FR) is a promising cell membrane-associated target for molecular imaging and radionuclide therapy of cancer (FR-α) and potentially also inflammatory diseases (FR-β) through use of folic acid-based radioconjugate. FR is often overexpressed by cells of epithelial tumors, including tumors of ovary, cervix, endometrium, lungs, kidneys, etc. In healthy tissues, FR can be found in small numbers by the epithelial cells, mainly in the kidneys. Extremely high undesired accumulation of the folate radioconjugates in the renal tissue is a main drawback of FR-targeting concept. In the course of this work, we aimed to reduce the undesirable accumulation of folate radioconjugates in the kidneys by introducing a histidine/glutamic acid tag into their structure. Two folic acid based compounds were synthesized: NODAGA-1,4-butanediamine-folic acid (FA-I, as control) and NODAGA-[Lys-(HE)2]-folic acid (FA-II) which contains a (His-Glu)2 fragment. In vitro studies with FR (+) cells (KB and others) showed that both compounds have specificity for FR. Introduction of (HE)2-tag does not affect FR binding ability of the conjugates. In vivo biodistribution studies with normal laboratory animals, as well as with KB tumor bearing animals, were carried out. The results showed that introduction of the (HE)2 tag into the structure of folate radioconjugates can significantly reduce the accumulation of these compounds in non-target tissues and important organs (the accumulation in the kidneys is reduced 2-4 times), leaving the accumulation in tumor at least at the same level, and even increasing it.

The B-vitamin folate is among the most studied bioactive food compound, and a dietary intake meeting the daily requirements has been found to reduce the risk of cancer and cardiovascular diseases as well as preventing neural tube defects during fetal development. Several countries have therefore introduced dietary fortification with folic acid. However, clinical and animal studies suggest that folic acid has a dual role in cancer development.

Astrocytes are the most widely distributed cells in the brain, and astrocyte apoptosis may play an important role in the pathogenesis of neurodegenerative diseases. Folate is required for the normal development of the nervous system, but its effect on astrocyte apoptosis is unclear. In this study, we hypothesized that folic acid (the therapeutic form of folate) decreases astrocyte apoptosis by preventing oxidative stress-induced telomere attrition. Primary cultures of astrocytes were incubated for 12 days with various concentrations of folic acid (0-40 μmol/L), then cell proliferation, apoptosis, intracellular folate concentration, intracellular homocysteine (Hcy) concentration, intracellular reactive oxygen species (ROS) levels, telomeric DNA oxidative damage, and telomere length were determined. The results showed that folic acid deficiency decreased intracellular folate, cell proliferation, and telomere length, whereas it increased Hcy concentration, ROS levels, telomeric DNA oxidative damage, and apoptosis. In contrast, folic acid dose-dependently increased intracellular folate, cell proliferation, and telomere length but it decreased Hcy concentration, ROS levels, telomeric DNA oxidative damage, and apoptosis. In conclusion, folic acid inhibited apoptosis in astrocytes. The underlying mechanism for this protective effect may be that folic acid decreased oxidative stress and thereby prevented telomeric DNA oxidative damage and telomere attrition.

The cardiotoxic effect of selective cyclo-oxygenase-2 inhibitors is well known. While rofecoxib and valdecoxib have been withdrawn, celecoxib remains on the market. Folic acid, a naturally occurring vitamin, has been shown to reduce myocardial ischemia and post-reperfusion injury in rats.

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer as well as non-cancer diseases, which involves the uptake of photosensitizers (PSs) by cancer cells followed by irradiation. The use of nanomaterials as carriers of PSs is a very promising approach to improve the development of PDT in clinical medicine. In this study, a novel folic acid-conjugated graphene oxide (GO) was strategically designed and prepared as targeting drug delivery system to achieve higher specificity. The second generation photosensitizer (PS) Chlorin e6 (Ce6) was effectively loaded into the system via hydrophobic interactions and π-π stacking. The nanocarriers can significantly increase the accumulation of Ce6 in tumor cells and lead to a remarkable photodynamic efficacy on MGC803 cells upon irradiation. These suggested that folic acid-conjugated GO loaded Ce6 had great potential as effective drug delivery system in targeting PDT.

Folic acid supplements are commonly used by infertile women which leads to a positive folate status. However, the effect of folic acid supplements on pregnancy outcome in women with unexplained infertility has not been well investigated. This study evaluated folic acid supplement use and folate status in women with unexplained infertility in relation to IVF pregnancy outcome. In addition, use of folic acid supplements and folate status were compared between women with unexplained infertility and fertile, nonpregnant control women. Women with unexplained infertility used significantly more folic acid supplements and had higher median total folic acid intake from supplements compared with fertile control women (both P < 0.001). Women with unexplained infertility also had significantly higher median plasma folate and lower median plasma homocysteine concentrations than fertile women (both P < 0.001), but folic acid supplementation or folate status were not related to pregnancy outcome in women with unexplained infertility. In conclusion, folic acid supplementation or good folate status did not have a positive effect on pregnancy outcome following infertility treatment in women with unexplained infertility. Folate is one of the B vitamins which has been suggested to be related to infertility. Folic acid is an artificial form of folate which is commonly used in dietary supplements. Folic acid supplementation has been shown to increase folate concentrations and decrease concentrations of the amino acid homocysteine in the blood. Folic acid supplementation is commonly used by infertile women, but the effect on pregnancy outcome in women with a diagnosis of unexplained infertility has not been thoroughly investigated. In the present study, folic acid supplement use and folate status (concentrations of folate and homocysteine) in women with unexplained infertility were evaluated in relation to pregnancy outcome. In addition, the use of folic acid supplements and folate status were compared between women with unexplained infertility and fertile control women. Our results showed that women with unexplained infertility used considerably more folic acid supplements and had higher total folic acid intake from supplements compared with fertile control women. Women with unexplained infertility had better blood folate and homocysteine concentrations than fertile women, but folic acid supplementation or folate status were not related to pregnancy outcome following the infertility treatment. In conclusion, high folic acid intake or good folate status did not increase the possibility of a birth of a healthy baby after infertility treatment in women with unexplained infertility.

The gut-liver axis (GLA) plays an important role in the development of alcohol-induced liver injury. Alcohol consumption is typically associated with folic acid deficiency. However, no clear evidence has confirmed the effect of folic acid supplementation on alcohol-induced liver injury via GLA homeostasis. In this study, male C57BL/6J mice were given 56% (v/v) ethanol and 5.0 mg/kg folic acid daily by gavage for 10 weeks to investigate potential protective mechanisms of folic acid in alcohol-induced liver injury via GLA homeostasis. Histopathological and biochemical analyses showed that folic acid improved lipid deposition and inflammation in the liver caused by alcohol consumption and decreased the level of ALT, AST, TG, and LPS in serum. Folic acid inhibited the expression of the TLR4 signaling pathway and its downstream inflammatory mediators in the liver and upregulated the expression of ZO-1, claudin 1, and occludin in the intestine. But compared with the CON group, folic acid did not completely eliminate alcohol-induced intestine and liver injury. Furthermore, folic acid regulated alcohol-induced alterations in gut microbiota. In alcohol-exposed mice, the relative abundance of Bacteroidota was significantly increased, and the relative abundance of unclassified_Lachnospiraceae was significantly decreased. Folic acid supplementation significantly increased the relative abundance of Verrucomicrobia, Lachnospiraceae_NK4A136_group and Akkermansia, and decreased the relative abundance of Proteobacteria. The results of Spearman's correlation analysis showed that serum parameters and hepatic inflammatory cytokines were significantly correlated with several bacteria, mainly including Bacteroidota, Firmicutes, and unclassified_Lachnospiraceae. In conclusion, folic acid could ameliorate alcohol-induced liver injury in mice via GLA homeostasis to some extent, providing a new idea and method for prevention of alcohol-induced liver injury.

Women in many countries are advised to use folic acid supplements before and early during pregnancy to reduce the risk of neural tube defects in their infants. This study aimed to update the prevalence and to identify possible determinants of preconception folic acid supplement use in Italian women.

Closure of the neural tube during embryogenesis is a crucial step in development of the central nervous system. Failure of this process results in neural tube defects, including spina bifida and anencephaly, which are among the most common birth defects worldwide. Maternal use of folic acid supplements reduces risk of neural tube defects but a proportion of cases are not preventable. Folic acid is thought to act through folate one-carbon metabolism, which transfers one-carbon units for methylation reactions and nucleotide biosynthesis. Hence suboptimal performance of the intervening reactions could limit the efficacy of folic acid. We hypothesized that direct supplementation with nucleotides, downstream of folate metabolism, has the potential to support neural tube closure. Therefore, in a mouse model that exhibits folic acid-resistant neural tube defects, we tested the effect of specific combinations of pyrimidine and purine nucleotide precursors and observed a significant protective effect. Labelling in whole embryo culture showed that nucleotides are taken up by the neurulating embryo and incorporated into genomic DNA. Furthermore, the mitotic index was elevated in neural folds and hindgut of treated embryos, consistent with a proposed mechanism of neural tube defect prevention through stimulation of cellular proliferation. These findings may provide an impetus for future investigations of supplemental nucleotides as a means to prevent a greater proportion of human neural tube defects than can be achieved by folic acid alone.

Folic acid has been identified to be integral in rapid tissue growth and cell division during fetal development. Different studies indicate folic acid's importance in improving childhood behavioral outcomes and underline its role as a modifiable risk factor for autism spectrum disorders. The aim of this systematic review is to both elucidate the potential role of folic acid in autism spectrum disorders and to investigate the mechanisms involved. Studies have pointed out a potential beneficial effect of prenatal folic acid maternal supplementation (600 µg) on the risk of autism spectrum disorder onset, but opposite results have been reported as well. Folic acid and/or folinic acid supplementation in autism spectrum disorder diagnosed children has led to improvements, both in some neurologic and behavioral symptoms and in the concentration of one-carbon metabolites. Several authors report an increased frequency of serum auto-antibodies against folate receptor alpha (FRAA) in autism spectrum disorder children. Furthermore, methylene tetrahydrofolate reductase (MTHFR) polymorphisms showed a significant influence on ASD risk. More clinical trials, with a clear study design, with larger sample sizes and longer observation periods are necessary to be carried out to better evaluate the potential protective role of folic acid in autism spectrum disorder risk.

The association between folic acid (FA) and erectile dysfunction (ED) was contradictory in the published original articles, and no meta-analysis was conducted to pool these data.

Diabetes can be caused by an insufficiency in β-cell mass. Here, we performed a genetic screen in a zebrafish model of β-cell loss to identify pathways promoting β-cell regeneration. We found that both folate receptor 1 (folr1) overexpression and treatment with folinic acid, stimulated β-cell differentiation in zebrafish. Treatment with folinic acid also stimulated β-cell differentiation in cultures of neonatal pig islets, showing that the effect could be translated to a mammalian system. In both zebrafish and neonatal pig islets, the increased β-cell differentiation originated from ductal cells. Mechanistically, comparative metabolomic analysis of zebrafish with/without β-cell ablation and with/without folinic acid treatment indicated β-cell regeneration could be attributed to changes in the pyrimidine, carnitine, and serine pathways. Overall, our results suggest evolutionarily conserved and previously unknown roles for folic acid and one-carbon metabolism in the generation of β-cells.

Nanomedicine is a very promising field and nanomedical drugs have recently been used as therapeutic agents against cancer. In a previous study, we showed that Nanoceria (NCe), nanoparticles of cerium oxide, significantly inhibited production of reactive oxygen species, cell migration and invasion of ovarian cancer cells in vitro, without affecting cell proliferation and significantly reduced tumor growth in an ovarian cancer xenograft nude model. Increased expression of folate receptor-α, an isoform of membrane-bound folate receptors, has been described in ovarian cancer. To enable NCe to specifically target ovarian cancer cells, we conjugated nanoceria to folic acid (NCe-FA). Our aim was to investigate the pre-clinical efficacy of NCe-FA alone and in combination with Cisplatin.

The use of doxorubicin (DOXO) as a chemotherapeutic drug has been hampered by cardiotoxicity leading to cardiomyopathy and heart failure. Folic acid (FA) is a modulator of endothelial nitric oxide (NO) synthase (eNOS), which in turn is an important player in diseases associated with NO insufficiency or NOS dysregulation, such as pressure overload and myocardial infarction. However, the role of FA in DOXO-induced cardiomyopathy is poorly understood. The aim of this study was to test the hypothesis that FA prevents DOXO-induced cardiomyopathy by modulating eNOS and mitochondrial structure and function. Male C57BL/6 mice were randomized to a single dose of DOXO (20 mg/kg intraperitoneal) or sham. FA supplementation (10 mg/day per oral) was started 7 days before DOXO injection and continued thereafter. DOXO resulted in 70% mortality after 10 days, with the surviving mice demonstrating a 30% reduction in stroke volume compared with sham groups. Pre-treatment with FA reduced mortality to 45% and improved stroke volume (both P < 0.05 versus DOXO). These effects of FA were underlain by blunting of DOXO-induced cardiomyocyte atrophy, apoptosis, interstitial fibrosis and impairment of mitochondrial function. Mechanistically, pre-treatment with FA prevented DOXO-induced increases in superoxide anion production by reducing the eNOS monomer:dimer ratio and eNOS S-glutathionylation, and attenuated DOXO-induced decreases in superoxide dismutase, eNOS phosphorylation and NO production. Enhancing eNOS function by restoring its coupling and subsequently reducing oxidative stress with FA may be a novel therapeutic approach to attenuate DOXO-induced cardiomyopathy.

Introduction: In this study, novel folic acid (FA)-modified curcumin (CUR) liposomes (LPs) were developed and evaluated for their antitumor activity in vitro and in vivo. Methods: Characterization of the LPs, including transmission electron microscopy, morphology, particle size, and zeta potential studies, was carried out. Drug entrapment efficiency, drug-loading capacity, and release properties in vitro were tested. The in vitro growth inhibition activity, cellular uptake efficiency, and cell apoptosis of FA-modified CUR LPs were also investigated by a cervical cancer HeLa cell model. Results: The optimized distearoyl-l-a-phosphatidylethanolamine (DSPE)-PEG2000-FA-LPs/CUR formed spherical vesicles of nanometer sizes and had particle sizes of 112.3±4.6 nm, polydispersity index of 0.19±0.03, and zeta potential of -15.3±1.4 mV. In addition, the EE% and DL% of (DSPE)-PEG2000-FA-LPs/CUR were 87.6% and 7.9%, respectively. Compared with the free drug, FA-modified CUR LPs had sustained-release properties in vitro. In vivo, a strong green fluorescence was observed in the cytoplasmic region after incubation of (DSPE)-PEG2000-FA-LPs/CUR for 2 hrs. Conclusion: (DSPE)-PEG2000-FA-LPs/CUR showed a superior antiproliferative effect on HeLa cells and had a better antitumor effect in vivo than the non-modified LPs. These results indicated that (DSPE)-PEG2000-FA-LPs/CUR was a promising candidate for antitumor drug delivery.