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PubMed1975

Folic acid dosage for chronic hemodialysis patients.

The doses of folic acid, necessary to avoid folic acid deficiency in patients being maintained on hemodialysis, have been estimated to be between 1 and 5 mg daily. To more precisely define an adequate dose of folic acid, 6 anephric patients were studied. The patients were maintained on hemodialysis and received, in a crossover fashion, 1 mg and 5 mg of folic acid for 3 wk. In a second crossover study, 3 anephric patients were first maintained on 0 and then on 1 mg of folic acid after each dialysis for 3 wk periods. Pre- and postdialysis folic acid blood levels were measured and dialyzer clearances of folic acid were determined. The results of this study support the conclusion of the Food and Drug Administration report suggesting that daily doses of 1 mg of folic acid are adequate to sustain therapeutic folate levels. The data further indicate that the administration of 1 mg of folic acid after each dialysis, rather than 1 mg of folic acid daily, can provide adequate folate.

Administration, Oral↗
PubMed2005

Transient absorption spectra and kinetics of folic acid (vitamin B11) and some kinetic data of folinic acid and methotrexate.

Folic acid (FA; vitamin B11) exhibits antitumor properties. Its transients, resulting from reaction with OH radicals, are of special interest and were studied by pulse radiolysis. The complex composition of FA offers the formation of numerous transients having different electronic structure stability (lifetime). Investigating their kinetic profiles of decay at various wavelengths, it was established that transients with very unstable electron structure (very short-lived radicals) tend to convert into more stable electronic structures (longer lived) by intramolecular electron transfer process. The biological importance of a FA radical depends on its concentration and on its specific reaction rate constant (k value) for a given process. The rate constant for the OH attack is k(OH + FA) = 1.1 x 10(10) L mol(-1) s(-1). Superimposed absorption spectra of FA radicals as well as formation and decay rate constants of total processes are presented. The primary spectrum is characterized by lambda = 425 nm, epsilon = 1.64 x 10(4) L mol(-1) s(-1). The chemical structure of FA is similar to that of folinic acid (FNA) and of methotrexate (MTX), but their biological properties are different. Therefore, their rate constants for the reactions with e-aq and OH were also determined for comparison: k(FNA + e-aq) = 3.1 x 10(10) L mol(-1) s(-1), k(FNA + OH) = 0.8 x 10(10) L mol(-1) s(-1), k(MTX + e-aq) = 1 x 10(10) L mol(-1) s(-1); k(MTX + OH) = 2.3 x 10(10) L mol(-1) s(-1), and k(FA + e-aq) = 1.9 x 10(10) L mol(-1) s(-1).

Folic Acid↗
PubMed2003

Influence of educational level on determinants of folic acid use.

In The Netherlands, periconceptional folic acid use to prevent neural tube defects was promoted through a national 'Folic Acid Campaign'. In two regions, a local campaign supplemented the national campaign to increase the chances of reaching women with low socio-economic status (SES). A framework of outcome criteria, defined as awareness knowledge, perceived safety, attitudes and subjective norms, was developed to evaluate the effectiveness of the two local campaigns. Data were gathered by means of two cross-sectional studies conducted just before and 1 year after the campaigns took place. Before the campaigns were conducted, there were already differences in all effect criteria and folic acid use between women of different educational levels, mostly in favour of women with a high level of education. Although both educational campaigns appeared to have a positive impact on all outcome criteria, they failed to reduce the existing differences in these outcome criteria between women of different educational levels. Folic acid use can be promoted effectively by mass media campaigns, certainly in a large group of women with no prior knowledge of the health benefits associated with periconceptional folic acid use. However, in order to achieve more equal health outcomes among women of low and high SES, it seems that more tailored interventions for women of low SES are needed.

Attitude to Health↗
PubMed1987

Hydroperoxide-dependent folic acid degradation by cytochrome c.

Folic acid is degraded by cytochrome c in the presence of hydrogen peroxide/tert-butyl hydroperoxide at the C9-N10 bond. The degradation is increased with increasing temperature. When guanidine HCl or benzoate are included in the reaction medium, the amount of folic acid degradation is enhanced. Catalase, formate, and thiourea inhibited hydrogen peroxide-dependent folic acid degradation only, and not tert-butyl hydroperoxide dependent degradation. Cyanide and azide markedly inhibited both the hydroperoxide-dependent degradations. Superoxide dismutase, EDTA, ethanol, mannitol, and dimethyl sulfoxide did not inhibit the degradation. The mechanism of cytochrome c-catalyzed folic acid degradation is discussed.

Cytochrome c Group↗
PubMed1982

Diminished serum folic acid levels in renal transplant recipients.

Serum folic acid levels were determined by radioimmunoassay in 26 chronic hemodialysis patients, in 52 renal transplant recipients and in 20 healthy controls. In the dialyzed patients, the mean serum folic acid level was 3.37 +/- 1.25 ng/ml and was significantly lower than that of the controls (6.1 +/- 1.38 ng/ml, P less than 0.001). In renal transplant recipients the mean folic acid concentration was 4.09 +/- 1.58 ng/ml and was also significantly decreased (P less than 0.001). 15 (29 per cent) out of 52 renal transplant patients showed serum folic acid concentrations lower than 3.0 ng/ml. Diminished serum folic acid levels were found not only in patients shortly after surgery but also in cases with excellent graft function up to 6 years after transplantation. The highest serum folic acid level was observed in one transplant patient who had taken no azathioprine for 24 months. Macrocytosis was found in 52 per cent of our renal transplant patients. There was no significant difference between the serum folic acid levels of renal transplant recipients with (n = 27) and without (n = 25) macrocytosis; however, serum creatinine levels were significantly lower in cases revealing macrocytosis. Relative folic acid deficiency does not seem to be responsible for macrocytosis after renal transplantation. Macrocytosis was observed only in patients with good graft function treated with azathioprine. Serum vitamin B12 levels were within the normal range in both dialyzed and renal transplant patients.

Adolescent↗
PubMed1981

Effects of diets with or without folic acid, with or without methionine, on fetus development, folate stores and folic acid-dependent enzyme activities in the rat.

Wistar female rats fed, since mating, with diets lacking either methionine, replaced in this case by homocystine (HF), or folic acid (MO), or both (HO). With diets lacking either one of the two factors, fetal weights remained in the range of the controls. When both factors were absent from the diet (HO), underweight fetuses were observed on day 20. In the offspring of folic acid-deficient mothers (MO), only folyloligoglutamates were lowered; total ones remained near control level. Switching HO females to a folic acid-supplemented diet from day 16 to 20 of pregnancy restored fetal weight and folates to the control level. The activity of folico-dependent enzymes of the whole fetal body or liver varied in parallel to fetal weight. We conclude from these data that: (1) methionine has a protective effect on folates in MO groups; (2) when folic acid is present in a diet containing homocystine but no methionine (MF), endogenous methionine synthesis is sufficient to cover maternal and fetal needs; (3) when the vitamin is also withdrawn (HO), methionine synthesis is no more adequate and fetal underdevelopment appears.

Animals↗
PubMed2006

Folic acid and cognition in older persons.

Folic acid supplementation has drawn much attention in recent years for the prevention of Alzheimer's disease and cognitive decline. In this review, the authors describe how current evidence does not support the use of folic acid supplements to protect against cognitive decline. Although a few studies suggest that folic acid supplementation may provide neuroprotection among persons who are folate deficient, there is also data to indicate that supplementation in persons without folate deficiency may pose a risk to neurological function. Vitamin B12 deficiency is common in old age and may not be easy to recognise. Folic acid supplementation may mask the anaemia associated with vitamin B12 deficiency and, therefore, may delay treatment while allowing progression of neurological symptoms. Whether or not folic acid supplementation exacerbates neurological symptoms of vitamin B12 deficiency is not clear. Further studies are needed to determine the possible risks and benefits of folic acid supplementation in older persons.

Aged↗
PubMed1992

Responses of serum folates of preruminant and ruminant calves to a dietary supplement of folic acid.

The effect of dietary supplemental folic acid on serum folates of preruminant and ruminant calves was studied. In Trial 1, doses of 0, .07, .14, .28, and .56 mg of folic acid per kilogram of BW were added to the milk of preruminant calves. In Trial 2, doses of 0, .5, 1, 2, and 4 mg of folic acid per kilogram of BW were incorporated into the concentrates of ruminant heifers. In the first part of each trial, serum folates were determined in blood samples taken 0, 1, 2, 4, 8, 16 (both trials), and 32 h (Trial 2) after a single meal supplemented with folic acid. In the second part of the two trials, the supplement of folic acid was given in feed during seven consecutive days. Blood samples were taken the day before the trial and subsequently every day during 7 d. In preruminant and ruminant calves, the area under the curve and the peak of concentration of serum folates after a meal increased with the dose ingested (P less than or equal to .05, linear and quadratic effect of doses, respectively) but the amount of folic acid needed to obtain a similar response was lower for preruminant than for ruminant calves. In preruminants, the time to reach the maximal concentration was 3 to 4 h after the meal, whatever the dose ingested (P less than or equal to .05), whereas in ruminants this time decreased with the dose ingested (quadratic effect of treatment, P less than or equal to .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1980

Reversible binding of the chemoattractant folic acid to cells of Dictyostelium discoideum.

The chemoattractant folic acid binds reversibly to receptors at the surface of Dictyostelium cells. In undifferentiated cells (t0.5) 6 X 10(4) binding sites per cell with a K0.5 value of 1.5 X 10(-7) M were determined. The number of folic acid receptors per cell decreases slightly during cell development. In differentiated cells (t10) 3.3 X 10(4) binding sites per cell were estimated. The folic acid binding sites appear to be specific for folic acid and its derivatives. 2-Deamino-2-hydroxyfolic acid, 4-amino-folic acid (aminopterin), and 4-amino-10-methylfolic acid (amethopterin) compete for the folic-acid-binding sites. Nor do adenosine 3',5'-phosphate and guanosine 3',5'-phosphate affect binding of folic acid. The folic acid receptors appear to be distinct from the catalytic sites of the membrane-bound folic acid deaminase.

Binding, Competitive↗
PubMed1995

Risks of orofacial clefts in children born to women using multivitamins containing folic acid periconceptionally.

Women are advised to take folic acid before they conceive as a precaution against neural-tube defects. However, the use of folic acid in preventing orofacial clefts is unknown. We investigated whether a woman's periconceptional use of multivitamins containing folic acid was associated with a reduced risk of orofacial clefts. We derived data from a population-based case-control study of fetuses and liveborn infants with orofacial anomalies among a 1987-89 cohort of births in California. We interviewed 731 (84.7%) of eligible mothers with orofacial cleft case infants and 734 (78.2%) mothers with non-malformed control infants. We found a reduced risk of orofacial clefts if the mother had used multivitamins containing folic acid during the period from one month before through two months after conception. The odds ratios ranged from 0.50-0.73 depending on cleft phenotype. Controlling for the potential influence of other variables did not substantially alter the results. Maternal daily consumption of cereal containing folic acid was also associated with a reduced risk of orofacial clefts. Women who used multivitamins containing folic acid periconceptionally had a 25-50% reduction in risk for offspring with orofacial clefts compared to women who did not use such vitamins. However, this association may not be attributable to folic acid specifically, but may be a consequence of other multivitamin supplement components, or behaviours, that are highly correlated with the use of multivitamins containing folic acid.

Adult↗
PubMed2000

The Dutch 'Folic Acid Campaign'--have the goals been achieved?

Periconceptional folic acid use considerably reduces the risk of neural tube defects. The aim of this study was to measure the effect of the national and the local 'Folic Acid Campaign' on periconceptional folic acid use. Before (1995 survey) and 1 year after the campaign (1996 survey), the awareness and use of folic acid was measured among pregnant women in four regions of the Netherlands. To this end, pregnant women who visited the midwife, general practitioner or obstetrician for the first or second prenatal visit were asked to complete a questionnaire. The results showed that use of folic acid for any period around conception increased from 25.1% in 1995 to 53.5% in 1996. Appropriate use (4 weeks before until 8 weeks after conception) increased from 4.8% in 1995 to 21.0% in 1996. No additional effect of the local Folic Acid Campaign was found (adjusted odds ratio= 1.0; 95% confidence interval = 0.7, 1.4). It was possible to conclude that folic acid use at the recommended time increased considerably as a result of the national and the local Folic Acid Campaign, but the target (use in 46% of women wishing to conceive) was not achieved. New health education programmes are needed to increase further its use at the appropriate times.

Adolescent↗
PubMed1986

Folic acid malabsorption in atrophic gastritis. Possible compensation by bacterial folate synthesis.

Folic acid absorption was studied in 12 elderly subjects with atrophic gastritis and 10 elderly normal controls using tritium-labeled pteroylmonoglutamic acid. Two folic acid absorption tests were carried out on each subject with 120 ml of either water or 0.1 N HCl. Folic acid absorption was significantly lower in subjects with atrophic gastritis than in normal controls (31% vs. 51%, respectively; p less than 0.01). In subjects with atrophic gastritis, folic acid absorption rose significantly to 54% (p less than 0.001) when administered with acid, but did not change in normal controls (50%). Serum folate levels were normal in all subjects. Proximal small intestinal pH was higher in atrophic gastritis subjects than in normal controls (7.1 vs. 6.7, respectively; p less than 0.05), as were bacterial counts of small intestinal fluid (p less than 0.01). Bacteria cultured from the aspirates of subjects with atrophic gastritis were able to synthesize folate in vitro when incubated in a folate-free medium. Atrophic gastritis results in folic acid malabsorption but not in folate deficiency, possibly due to increased bacterial synthesis of folate in the small intestine.

Aged↗
PubMed2003

Periconceptional use of folic acid supplements in Oslo.

BACKGROUND: Periconceptional supplementation with folic acid has been shown to decrease the occurrence of neural tube defects (NTD). A daily supplement of 400 micro g folic acid from the month before pregnancy and the first 2 to 3 months of pregnancy is recommended in Norway. We wanted to evaluate the use of folic acid supplements among pregnant women in Oslo, and to explore demographic factors that were associated with periconceptional intake. METHODS: All women attending antenatal ultrasound screening at the two main obstetric departments in Oslo during 3 months in 2001 were invited to answer questions regarding folic acid supplementation before and during their present pregnancy. RESULTS: A total of 1541 women (91, 5%) participated in the study, of which 26% were nonwestern immigrants. Only 17% of all women had started the folic acid supplementation preconceptionally (22% of the nonimmigrant vs. 2% of the immigrant population). Folic acid had been used by 58% at some time during the present pregnancy (73% of the nonimmigrant vs. 19% of the immigrant population). Regression analysis demonstrated that the difference in periconceptional use of folic acid between the two population groups could not be explained by registered demographic factors other than immigrant status. CONCLUSIONS: Most pregnant women in Oslo do not use folic acid as recommended and a dramatically low usage is seen among the immigrant population, indicating that more widespread information is necessary. Furthermore, fortification of cereals with folic acid should be considered to secure a sufficient intake of folic acid in all fertile women.

Adolescent↗