Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FOLIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources
PubMed2000

Neural tube defects among Mexican Americans living on the US-Mexico border: effects of folic acid and dietary folate.

Populations of Mexican descent have high occurrences of neural tube defects (NTDs). A recent study suggested that folic acid supplements may not protect these populations from NTDs. In a case-control study, the authors investigated the role of folic acid and dietary folate intake in NTD risk among Mexican Americans living along the Texas-Mexico border. From January 1995 to February 1999, 148 Mexican-American women with NTD-affected pregnancies and 158 women with normal live births were interviewed in person about use of vitamin supplements and dietary intakes during a 6-month periconceptional period (from 3 months before conception to 3 months after conception). Daily preconceptional consumption of vitamin supplements containing folic acid was 2.5% in control women and 2.0% in case women (odds ratio = 0.77; 95% confidence interval (CI): 0.19, 3.22). With adjustment for maternal age, education, obesity, and previous stillbirth or miscarriage, the risk estimate was essentially null (odds ratio = 1.12; 95% CI: 0.22, 5.78). Combined folic acid intake from diet and supplements showed only a modest risk reduction for intakes of > or = 1.0 mg per day (adjusted odds ratio = 0.73; 95% CI: 0.31, 1.72). The fact that the primary folic acid exposure was in the form of dietary polyglutamates rather than the more easily absorbed supplemental monoglutamates may explain an apparent decreased effect in this population.

Adult↗
PubMed2005

Folic acid supplementation can reduce the endothelial damage in rat brain microvasculature due to hyperhomocysteinemia.

To evaluate the effects of dietary folic acid supplementation on the cerebral vascular damage induced by hyperhomocysteinemia, rats were fed a diet containing 3.0 g/kg homocystine for 2 wk and then either 3.0 g/kg homocystine or 3.0 g/kg homocystine plus 0.008 g/kg folic acid for 8 wk. Control rats consumed the AIN-93 Maintenance diet throughout the experiment. The cerebral expression of glucose transporter-1 was measured by Western blot analysis and cerebrovascular structural alterations were evaluated by electron microscopy. The homocystine diet significantly increased the plasma levels of homocysteine and TBARS and decreased the cerebral expression of glucose transporter-1 (GLUT-1) with a concomitant increase in the percentage of damaged cerebral vessels. The inclusion of dietary folic acid for 8 wk caused plasma homocysteine levels to be the same as in control rats and it significantly upregulated the cerebral expression of GLUT-1 that was significantly reduced by hyperhomocysteinemia. Folic acid supplementation also significantly decreased the incidence of damaged vessels due to hyperhomocysteinemia. These results and the electron microscopy findings suggested that folic acid supplementation might reduce the detrimental effects on the endothelium caused by experimentally induced hyperhomocysteinemia.

Animals↗
PubMed1984

A multidisciplinary study of folic acid neurotoxicity: interactions with kainate binding sites and relevance to the aetiology of epilepsy.

Folic acid has been injected unilaterally into the amygdaloid complex of awake chronically implanted rats, or in rats under anaesthesia. Clinical, electrographic, and metabolic changes (estimated by means of the 2-deoxyglucose method) have been studied in relation to subsequently demonstrated neuropathology using Fink-Heimer and Nissl stains. The observations are compared to the corresponding effects of intra-amygdaloid application of kainic acid. Major differences were noted between the folate and the kainate induced seizure/brain damage syndrome. Thus: folate produced essentially stereotypies, alternating with myoclonic unilateral jerks of head and limbs. In contrast, limbic motor seizures which are characteristically produced by kainic acid, were extremely rare. Folate did not produce the preferential and sequential electrographic activation of limbic structures as observed after kainate. 2-Deoxyglucose autoradiography revealed an enhanced metabolic activity in the injected amygdala and in the overlying piriform and entorhinal cortices. The most conspicuous rise in labelling, however, occurred in the entire fronto-parietal cortex (ipsilaterally) up to the cingulate region, as well as in the ventral thalamic complex and the globus pallidus, i.e. in structures which are not labelled after kainate treatment. Some extent of local damage was observed 1-8 days after the injection; distant from the injection site, we found massive anoxic-ischemic type of damage in the superficial layers of the fronto-parietal cortex, a complete necrosis of the piriform lobe, and neuronal cell loss in the ventral thalamus and several extrapyramidal structures. The full range of limbic damage associated with kainate was never produced by folate. The CA3 region of the hippocampus, most susceptible to kainate, was only mildly affected by folate. These differences between kainate and folate prompted us to re-evaluate the recently reported high affinity of folates for kainic acid membrane binding sites. We found that folic acid competed only very weakly with [3H]kainic acid for binding sites on striatal, cortical, hippocampal, amygdaloid, and cerebellar membranes. It is thus concluded, that folate is not a good candidate for an endogenous kainate-like substance. We propose intracerebral injections of folic acid as a useful tool to study the vulnerability of brain structures to anoxic-ischemic conditions.

Amygdala↗
PubMed2005

[Does folic acid have effects on other health problems than neural tube defects?].

BACKGROUND: While it is widely accepted that periconceptional supplement of 400 microg (microgram) folic acid reduces the risk of neural tube defects in pregnancy, it remains to be established whether folic acid has other beneficial effects on larger population groups. Evidence concerning effect of increased intake on cardiovascular disease, cancer and other diseases has recently been evaluated in a report to the Directorate of Health and Social Welfare in Norway. MATERIAL AND METHODS: Research reports published mainly from 1998 to 2003 on folic acid intake and disease have been evaluated. RESULTS: Sufficient evidence that increased folic acid intake may prevent cancer or cardiovascular diseases is not yet available, hence at present there is no indication for recommending augmented intake for other groups than fertile women. However, several intervention studies with folic acid supplementation are in progress to establish its effect on cardiovascular mortality and morbidity. INTERPRETATION: If the ongoing intervention studies show a beneficial clinical effect on cardiovascular disease, it would be a further argument for fortification of foods, in addition to reducing the risk of neural tube defects in pregnancy.

Cardiovascular Diseases↗
PubMed2003

Low vitamin B-12 concentrations in patients without anemia: the effect of folic acid fortification of grain.

BACKGROUND: In some patients with vitamin B-12 deficiency mistakenly treated with folic acid, anemia resolved but neurologic complications became worse (masking). Fortification of enriched cereal grains with folic acid has raised concerns that people who consume large quantities of cereal grains, particularly the elderly, may be at increased risk of masking. It is unclear, however, what proportion of people with low vitamin B-12 concentrations do not have anemia and whether the proportion is increasing. OBJECTIVE: We investigated whether fortification has increased the proportion of patients with low vitamin B-12 but without anemia. DESIGN: We reviewed the laboratory results of every patient for whom a vitamin B-12 concentration was measured at the Veterans Affairs Medical Center in Washington, DC, between 1992 and 2000. Those with a low vitamin B-12 concentration (< 258 pmol/L) had their hematocrits and mean cell volumes checked. The proportion without anemia was examined by year before, during, and after folic acid fortification began. RESULTS: There were 1573 subjects with a low vitamin B-12 concentration. The proportion without anemia did not increase significantly from the prefortification period (39.2%) to the period of optional fortification (45.5%) and the postfortification period (37.6%). These findings did not change when the analysis was limited to patients aged > 60 y or when a more conservative definition of low vitamin B-12 (< 150 pmol/L) was used. CONCLUSIONS: Despite evidence that folic acid exposure has increased dramatically since food fortification began, this population showed no evidence of an increase in low vitamin B-12 concentrations without anemia. If confirmed, these results would indicate that food fortification has not caused a major increase in masking of vitamin B-12 deficiency.

Aged↗
PubMed2006

Effects of folic acid before and after vitamin B12 on plasma homocysteine concentrations in hemodialysis patients with known MTHFR genotypes.

BACKGROUND: Treatment with folic acid and vitamin B12 appears to be effective in lowering total plasma homocysteine (tHcy) concentrations, but whether vitamin B12 alone lowers tHcy in patients with normal vitamin B12 status is unknown. The aims of the present study were to explore the effect of individual supplementation with folic acid or vitamin B12 on tHcy concentrations in hemodialysis (HD) patients and to compare changes in tHcy concentrations with MTHFR genotype. METHODS: We recruited 200 HD patients (119 men) from the "Umberto I" Hospital (Frosinone, Italy) and the Dialysis Unit of University Hospital "Tor Vergata". These patients were randomized blindly into 2 groups of 100 each. Unfortunately, during the study, 36 patients in the first group and 16 in the second group died. The first group was treated initially with vitamin B12 for 2 months and with folic acid for a following 2 months. The second group was treated initially with folic acid and then with vitamin B12. Samples were drawn before administration of either, after the first and second periods, and again 2 months after treatment. RESULTS: The concentrations of tHcy decreased in both groups after the consecutive vitamin therapies, and the decrease was genotype-dependent. The decrease was greater for the T/T genotype (P <0.05) and was more significant when the treatment was started with folic acid (P <0.01). CONCLUSION: The alternating vitamin treatment demonstrated for the first time the importance of folate therapy and the secondary contribution of vitamin B12 in lowering tHcy in HD patients.

Aged↗
PubMed2000

Influence of folic acid on postprandial endothelial dysfunction.

Triglyceride-rich lipoproteins that circulate postprandially are increasingly being recognized as potentially atherogenic. These particles also have been shown to cause endothelial dysfunction. We recently demonstrated that acute parenteral administration of folic acid restores endothelial function in vivo in patients with increased LDL cholesterol levels. In vitro data suggested that this effect could be mediated by a reduction of radical stress. In the present study, therefore, we evaluated the effect of an acute oral fat load on both endothelial function and oxygen radical production. Next, we studied whether 2 weeks of pretreatment with 10 mg folic acid PO could prevent these fat-induced changes. We conducted a prospective, randomized, placebo-controlled study to evaluate the effect of oral folic acid administration (10 mg/d for 2 weeks) on basal endothelial function as well as endothelial function on an acute fat load in 20 healthy volunteers 18 to 33 years old. Endothelial function was assessed as flow-mediated dilatation (FMD). Endothelium-independent dilatation was measured after sublingual nitroglycerin spray. Oxygen radical stress was assessed by measurement of the urinary excretion of the stable radical-damage end product malondialdehyde. During administration of placebo, FMD decreased significantly after an acute oral fat load, with a median from 10.6% (8.3% to 12.2%) to 5.8% (3.0% to 10.2%), P<0.05. During folic acid administration, FMD was unaffected by a fat load, with a median from 9.6% (7.1% to 12.8%) to 9.9% (7.5% to 14.1%), P=NS. The increase in malondialdehyde excretion in the urine after fat loading was also prevented during folic acid administration (absolute increase after an acute fat load during placebo, 0.11+/-0.1 micromol/L versus folic acid, 0.02+/-0.1 micromol/L, P<0.05). The response to the endothelium-independent vasodilator nitroglycerin remained unaltered throughout the study. Pretreatment with oral folic acid prevents the lipid-induced decrease in FMD as well as the lipid-induced increase in urinary radical-damage end products. Because these observations were made in healthy volunteers with normal folate and homocysteine levels, it is suggested that a higher folate intake in the general population may have vasculoprotective effects.

Adolescent↗
PubMed2001

Difference in the homocysteine-lowering effect of folic acid in haemodialysis patients with and without occlusive vascular disease.

BACKGROUND: Hyperhomocysteinaemia has been identified as an independent cardiovascular risk factor and is found in more than 85% of patients on maintenance haemodialysis. Previous studies have shown that folic acid can lower circulating homocysteine in dialysis patients. We evaluated prospectively the effect of increasing the folic acid dosage from 1 to 6 mg per dialysis on plasma total homocysteine levels of haemodialysis patients with and without a history of occlusive vascular artery disease (OVD). METHODS: Thirty-nine stable patients on high-flux dialysis were studied. Their mean age was 63 +/-11 years and 17 (43%) had a history of OVD, either coronary and/or cerebral and/or peripheral occlusive disease. For several years prior to the study, the patients had received an oral post-dialysis multivitamin supplement including 1 mg of folic acid per dialysis. After baseline determinations, the folic acid dose was increased from 1 to 6 mg/dialysis for 3 months. RESULTS: After 3 months, plasma homocysteine had decreased significantly by approximately 23% from 31.1 +/- 12.7 to 24.5 +/- 9 micromol/l (P = 0.0005), while folic acid concentrations had increased from 6.5 +/- 2.5 to 14.4+/-2.5 microg/l (P < 0.0001). However, the decrease of homocysteine was quite different in patients with and in those without OVD. In patients with OVD, homocysteine decreased only marginally by approximately 2.5% (from 29.0 +/- 10.3 to 28.3 +/- 8.4 micromol/l, P = 0.74), whereas in patients without OVD there was a significant reduction of approximately 34% (from 32.7+/-14.4 to 21.6+/-8.6 micromol/l, P = 0.0008). Plasma homocysteine levels were reduced by > 15% in three patients (18%) in the group with OVD compared with 19 (86%) in the group without OVD (P = 0.001), and by > 30% in none of the patients (0%) in the former group compared with 13 (59%) in the latter (P = 0.001). CONCLUSIONS: These results indicate that the homocysteine-lowering effect of folic acid administration appears to be less effective in haemodialysis patients having occlusive vascular disease than in those without evidence of such disease.

Aged↗
PubMed1995

Gestation and lactation of dairy cows: a role for folic acid?

Twenty-four multiparous and 16 primiparous dairy cows were assigned by parity, BW, and milk production to 20 blocks of 2 cows each. Within each block, the cows were injected weekly with either 0 or 160 mg of folic acid from 45 d after mating to 6 wk after parturition. Supplementary folic acid augmented the placental and colostral transfer of folates to the calf but had no effect on blood hemoglobin, birth weight, or growth and feed intake of the calf during the first 10 wk of life. The supplemental folic acid increased serum folates but had no marked effect on blood hemoglobin and BW of cows. Supplementary folic acid tended to increase milk folates, milk production, and the percentage of milk protein during the last half of the lactation curve but had no effect on milk folates and milk production during the first 6 wk after parturition when the injections of folic acid increased the percentage of milk protein in multiparous cows but had no effect on primiparous cows. The supply of folates by the diet and the synthesis by ruminal microflora is sufficient to prevent folic acid deficiency in dairy cows and to maintain normal gestation and lactation, but not to achieve maximal production of milk and protein in multiparous dairy cows during gestation and lactation.

Animals↗
PubMed1999

Serum levels of folic acid and vitamin B12 in Korean patients with vitiligo.

The association of vitiligo and pernicious anemia has been previously documented. The low levels of folic acid and vitamin B12 were thought to be related to vitiligo. To date, there have been very few reports about the serum levels of folic acid and vitamin B12 in patients with vitiligo. Using radioimmunoassay, we measured the serum levels of folic acid and vitamin B12 in 100 Korean patients with vitiligo. The mean serum levels of folic acid and vitamin B12 were 6.31 +/- 2.82 ng/ml and 630.25 +/- 230.94 pg/ml, respectively, in patients with vitiligo. These levels showed no significant difference compared to the normal control group, suggesting that folic acid and vitamin B12 do not appear to play a role in the pathogenesis of vitiligo.

Adolescent↗
PubMed1998

Folic acid supplementation prevents deficient blood folate levels and hyperhomocysteinemia during longterm, low dose methotrexate therapy for rheumatoid arthritis: implications for cardiovascular disease prevention.

OBJECTIVE: To determine the effect of longterm methotrexate (MTX) therapy and folic acid supplementation on folate nutriture and homocysteine levels in patients with rheumatoid arthritis. METHODS: A double blind, placebo controlled trial lasting one year was conducted at one academic medical center. A total of 79 patients taking low dose MTX were followed up to one year. The patients were randomized to receive placebo or 5 or 27.5 mg folic acid supplementation per week. RESULTS: Plasma and erythrocyte folate levels and plasma homocysteine levels were determined. The folate nutriture of patients taking low dose MTX declined without folic acid supplementation. Plasma homocysteine levels increased significantly over a one year period in the placebo group. Low folate nutriture and hyperhomocysteinemia occurred with greater frequency in the placebo group than in the folic acid supplemented groups. CONCLUSION: For longterm, low dose MTX therapy, there are now at least 3 reasons to consider supplementation with folic acid (a low cost prescription): (1) to prevent MTX toxicity, (2) to prevent or treat folate deficiency, and (3) to prevent hyperhomocysteinemia, considered by many investigators to be a risk factor for cardiovascular disease.

Adult↗
PubMed2003

Hyperhomocysteinemia and oxidative stress in hemodialysis: effects of supplementation with folic acid.

This study was undertaken to evaluate two different doses of folic acid and their effects on the control of hyperhomocysteinemia, and on pro-oxidant and antioxidant changes in a group of 32 hemodialysis (HD) patients. Blood samples were collected in a group of patients at three different times: before (basal; B), after the first (S1), and after the second (S2) three-month supplementation periods, and compared to samples from a group of healthy individuals. Analysis of vitamins (C, E, folate, and B12), oxidant parameters (lipid and protein oxidation), and homocysteine were performed. Hyperhomocysteinemia of different degrees was observed in all patients on HD (45.30 +/- 24.89 microM). Oxidative stress was also detected, with lipoperoxidation and protein oxidation being associated with lower concentrations of antioxidant substances (vitamins E and C). The first folate dose (2.5 mg after each dialysis session) reduced by half the initial concentrations of homocysteine (44.92 +/- 22.05 to 20.56 +/- 6.79 microM; p < 0.05) but did not normalize its values. The second dose (15 mg) did not show an additional effect, but it was at this time that lipoperoxidation was significantly reduced, although the protein oxidation showed no change. It was concluded that the first dose of folic acid was efficient in reducing homocysteine concentrations, without normalization of values. The participation of hyperhomocysteinemia in oxidative stress appeared to be partial, but in combination with dialysis treatment, may contribute to the induction of an oxidative environment in this group. The possible antioxidant action of folate must also be considered in this case, acting directly against lipoperoxidation or through hyperhomocysteinemia control. Routine supplementations of folic acid and other antioxidant vitamins should be considered in hemodialysis in order to reduce homocysteine levels to lower values, that although not normal, may be more beneficial in minimizing the cardiovascular risk in this group.

Ascorbic Acid↗
PubMed1995

Knowledge and use of folic acid by women of childbearing age--United States, 1995.

Each year in the United States approximately 2500 infants are born with spina bifida and anencephaly (1), and an estimated 1500 fetuses affected by these birth defects are aborted. Recent studies indicate that the B vitamin folic acid can reduce the risk for spina bifida and anencephaly by at least 50% when consumed daily before conception and during early pregnancy. In September 1992, the Public Health Service (PHS) recommended that all women of childbearing age who are capable of becoming pregnant consume 0.4 mg of folic acid daily (1). Folic acid can be obtained from multivitamins or other supplements containing folic acid and some breakfast cereals. This report summarizes the results of a survey conducted during January-February 1995 regarding knowledge and practices of women of childbearing age in the United States about consumption of folic acid from supplements and breakfast cereals.

Adult↗
PubMed1993

Supplemental folic acid: a requirement for optimizing swine reproduction.

The administration of supplemental folic acid to female reproducing swine (either via injection or dietary supplementation) is a fairly recent research phenomenon. The majority of publications have occurred during the past 5 yr; few publications on this topic appeared before 1983. Although folic acid supplementation is a young research area compared to that involving many other vitamins, the reported results are quite consistent. There seem to be no major benefits to lactational supplementation; although supplementation in lactation is effective in elevating sow serum folate, milk folate, and nursing pig serum folate, it has not produced changes in sow BW, litter size weaned, or pig gain. Supplementation during gestation has yielded a consistent benefit: a positive response in total pigs born in all studies. The response in gestation of increased litter size seems to be a result of improved embryo or fetal survival rather than increased ovulation, although the mechanism whereby survival rate is improved is yet to be understood. Clearly, supplemental folic acid is required to maximize sow prolificacy.

Animal Feed↗
PubMedDate not supplied

Knowledge on periconceptional use of folic acid in women of British Columbia.

OBJECTIVE: Our purpose was to evaluate the knowledge of folic acid and its use preconceptionally in women of British Columbia. METHODS: The study was conducted at British Columbia Women's Hospital in Vancouver, Canada, between April 15 and June 15, 1999. Pregnant women and women in the postpartum period were asked to complete a survey on folic acid. RESULTS: In total, 1,004 women completed the questionnaire during the study period. Seventy-one percent of the women knew that vitamins could help prevent birth defects. Of those, 76.3% identified folic acid as the one vitamin specifically associated with reduction of birth defects. It was identified that 49.4% of all women took vitamins prior to pregnancy. CONCLUSIONS: Women in the population studied were relatively well informed about the benefits of folic acid, but less than 50% of them took vitamins prior to conception.

Adult↗
PubMed2005

Interaction between maternal periconceptional supplementation of folic acid and reduced folate carrier gene polymorphism of neural tube defects.

OBJECTIVE: To search the interaction between reduced folate carrier gene (RFC1 A80G) polymorphism of children with neural tube defects (NTDs) and maternal periconceptional no supplementation of folic acid. The purpose is to provide the epidemiological evidence for finding genetic marker of NTDs. METHODS: RFC1 (A80G) genotype was detected using PCR-restricted fragment length polymorphism for the blood DNA of 104 trios with NTDs-affected child, and 100 control families with non-malformed control children. The authors investigated the gene-environment interactions between the offspring RFC1 genotype and maternal periconceptional folic acid supplementation through a case-control study. RESULTS: It was observed that the offspring with the GG genotype were associated with a 2.56-fold increased risk of NTDs when compared to those with the AA genotype (OR = 2.56; 95% CI = 1.04-6.36) in this population under investigation. The risk of mothers who did not take folic acid for having an NTDs-affected infants was 7.69 (95% CI = 2.86-21.75). Among the mothers who did not utilize folic acid supplements, the NTDs risk was 3.30 (95% CI = 1.15-9.65) for offspring with the GG genotype, compared to the reference (AA) genotype. Children who had the GG genotype and whose mothers did not take folic acid had an elevated risk for NTDs (OR = 8.80, 95% CI = 2.86 - 29.82), compared to "offspring with AA or GA genotype" and "maternal folic acid use", the interactive coefficient being 1.45. CONCLUSION: The above findings indicate that the RFC1 genotype (GG) is a possible susceptible gene marker for an increased NTDs risk in Chinese population, and there is a potential gene-nutrient interaction between offspring RFC1 GG genotype and maternal periconceptional intake of folic acid on the risk of NTDs. However,the sample size of this study was limited, a larger sample of population-based study is required to pursue the initial observation.

Adult↗
PubMed1999

The role of folic acid in oral clefting.

The objective of this study is to describe the role of periconceptional folic acid supplementation and assess it's potential in the prevention of foetal abnormalities, and consists of a review of the literature undertaken using an electronic and hand search. This includes research trials and methodology associated with folic acid supplementation. It is recommended that all women planning to conceive should supplement their diet with folic acid in order to prevent abnormalities in neural tube development, particularly if there is a history of a previously affected pregnancy. There is increasing evidence that folic acid supplementation may, in addition, reduce the incidence of oral facial clefting. Further research with multi-disciplinary approaches in biochemistry, genetics, gene/environment interactions, and embryology are indicated.

Cleft Lip↗
PubMed2001

Do we need another randomized controlled trial of folic acid alone?

As a public health strategy to help prevent neural tube defect-affected pregnancies, enriched flour and pasta in the United States and Canada are being fortified with folic acid, and women are being advised to take supplementary folic acid around the time of pregnancy to ensure an adequate intake. But in spite of the recently published results of a public health campaign in China, the burden of proof that folic acid alone is responsible for a decreased risk of these birth defects rests on the results of a randomized controlled trial conducted by the Medical Research Council of the United Kingdom. Supporting evidence comes primarily from studies that have shown a protective effect of multivitamins containing folic acid as one of many nutrients. Based on a striking and potentially hazardous type of non-compliance observed in an earlier study in which a participant took multiple vitamin doses simultaneously and a suggestion of similar incidents in the Medical Research Council study, we conclude that a further randomized controlled trial of the protective effect of folic acid alone may be necessary.

Adult↗