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PubMed2006

The influence of a 3-month weight reduction therapy with Orlistat on serum vitamin B12 and folic acid concentration in obese women.

OBJECTIVE: Serum folic acid, but not the vitamin B(12) concentration, was found to be significantly lower in obese subjects than in the control ones. DESIGN: The aim of this study was to examine the levels of serum vitamin B(12) and folic acid in obese women before and after weight reduction therapy with Orlistat in comparison to healthy controls with normal body weight. SUBJECTS: Twenty obese women participated in a 3-month weight reduction therapy. The control group consisted of 20 healthy women. MEASUREMENTS: Body weight and height were measured and BMI was calculated. Body composition was analyzed with the impedance method using a Bodystat analyzer. In all patients before and after 3-month weight reduction therapy, serum concentrations of folic acid and vitamin B(12) were assessed. RESULTS: In obese women, serum concentrations of folic acid and vitamin B(12) did not change significantly after 3-month weight reduction therapy with Orlistat.

Adult↗
PubMed2006

Folic acid reverses endothelial dysfunction induced by inhibition of tetrahydrobiopterin biosynthesis.

While folic acid has been shown to reverse endothelial dysfunction, the exact underlying mechanism remains elusive. Here, folic acid reversed both the endothelial dysfunction and increased production of superoxide following depletion of rabbit aortic ring tetrahydrobiopterin (BH4) levels with 2,4-diamino-6-hydroxy-pyrimidine (DAHP) and N-acetyl-5-hydroxy-tryptamine (NAS). Incubation with l-nitroarginine methyl ester also attenuated the production of superoxide. DAHP and NAS reduced BH4 concentrations in both aorta and cultured porcine aortic endothelial cells. Folic acid had no effect on BH4 concentrations in either preparation. The superoxide anion scavenger Tiron but not folic acid reversed the endothelial dysfunction produced in aortic rings by inhibition of copper-zinc superoxide dismutase with diethyldithiocarbamic acid. Neither folic acid nor its metabolite 5-methyltetrahydrofolate prevented the in vitro oxidation of BH4. This study demonstrates that folic acid reverses the endothelial dysfunction induced by BH4 depletion independently of either the regeneration or stabilization of BH4 or an antioxidant effect.

Animals↗
PubMed1978

Folic acid transport by mammalian small intestine.

The unidirectional influx of folic acid across the mucosal border of hamster duodenum and rat jejunum was determined. Influx follows saturation kinetics, is sodium-dependent, and is inhibited by methotrexate and is sodium-dependent, and is inhbited by methotrexate and folinic acid in the mucosal bathing solution. In hamster duodenum, the maximal influx is 1.2 nmol/(cm2.h), and the folic acid concentration required to give a half maximal influx (Km) is 7.2 micron.. At mucosal folic acid concentration of 1.5 micron, influx is reduced at least 65% by removal of sodium from the bathing solution. The influx process is significantly inhibited by cyanide and 2,4-dinitrophenol. The possibility was evaluated that the acidic microclimate at the brush border regulates the rate of folic acid transport and that inhibition of transmural transport by sodium-free media, ouabain, and methotrexate is brought about indirectly by an increase in pH of the microclimate. The data favor the alternative concept of a sodium-dependent carrier mechanism for entry of folic acid into the cells. The information presented is consistent with active transport of folic acid by a sodium-gradient mechanism, but additional information will be necessary to substantiate such a model.

Animals↗
PubMed2005

Evidence of unmetabolised folic acid in cord blood of newborn and serum of 4-day-old infants.

Oral folic acid above certain threshold doses results in unmetabolised folic acid in serum. This raises a number of public health safety issues, principally the potential to mask pernicious anaemia; more recently the theoretical potential for high-dose folic acid to promote cancer has been highlighted. In this paper we set out to examine the appearance of unmetabolised folic acid both in cord blood from newborn full-term and premature infants and serum from 4-d-old infants post-formula feeding. Blood was collected from the umbilical cord of eleven infants in the delivery room immediately after birth. A follow-up serum sample (n 9) was collected 4 d later from infants post-formula feeding. We detected unmetabolised folic acid in cord blood from all infants at birth. In addition, unmetabolised folic acid was present in serum of seven infants post-formula feeding, six of which had increased from birth. Our results imply that infants in Ireland, which does not yet have mandatory fortification, could potentially have circulatory unmetabolised folic acid at the time of birth. We do not know if the presence of folic acid in cord blood will have any adverse consequences. However, if theoretical safety concerns are borne out by future research, the likelihood is that the longer the exposure the more likely the potential for harm. This would also be the case in infants exposed to unmetabolised folic acid as a result of formula feeding.

Fetal Blood↗
PubMed1979

Serum vitamin B12 and folic acid levels in hyperthyroidism.

Serum vitamin B12 and folic acid levels were measured in 48 hyperthyroid patients and in a group of euthyroid controls. The levels of vitamin B12 ranged from 120-900 pg/ml with a mean of 429.3 +/- 30.9 pg/ml (SE). The mean serum vitamin B12 level was lower in hyperthyroid patients than in normal controls, the difference being statistically significant (t = 2.584, p less than 0.025). Serum vitamin B12 levels showed a statistically significant negative correlation with the clinical index of Grooks et al. (r = 0.344, p less than 0.05). The findings, although not excluding the involvement of auto-immune gastritis in patients with low serum vitamin B12 levels, suggest a direct action of increased thyroid hormone concentrations. Serum folic acid levels ranged from 0.5-13.8 ng/ml with a mean of 6.8 +/- 0.46 ng/ml (SE). The mean serum folic acid levels were higher in the hyperthyroid patients than in normal controls but the difference was not statistically significant (t = 1.2, p greater than 0.2). The serum folic acid levels did not show any statistically significant correlation with the clinical index of Grooks et al. The fact that no statistically significant difference was found between the mean value in hyperthyroid patients and the mean value in normal controls is probably due to the high folic acid intake in Greece.

Adult↗
PubMed2004

Changes of homocysteine levels and arterial endothelial function in patients with high risk of coronary artery disease after 6-month folic acid supplementation.

OBJECTIVES: This study aimed to assess whether folic acid supplementation could produce longer-term (6-month) improvements in homocysteine levels and arterial endothelial function in patients with a high risk (3 or more traditional risk factors) of coronary artery disease (CAD) and hyperhomocysteinaemia. METHODS: Thirty-one adults with 3 or more traditional risk factors of CAD and hyperhomocysteinaemia were selected, without CAD (the criterion of CAD is that more than one main vessel has an obstruction > or = 50%) by coronary angiography. All subjects were given folic acid (5 mg/day) for 6 months. Fasting plasma homocysteine levels were measured by high-performance liquid chromatography. Plasma folic acid and vitamin B12 levels were measured with immunoassay. Arterial endothelial function was measured as flow-mediated dilation of the brachial artery using high-resolution B-mode ultrasound. RESULTS: Folic acid supplementation for 6 months was associated with a significant increase in mean (+/- SD) plasma levels of folic acid (4.6 +/- 1.4 microg/l to 9.1 +/- 2.5 microg/l; P < 0.01) and a significant decline in homocysteine levels (18.3 +/- 3.9 micromol/l to 11.5 +/- 2.8 micromol/l; P < 0.01). Flow-mediated dilation also improved significantly, from 6.8% +/- 2.1% to 8.9% +/- 1.7% (P < 0.01). CONCLUSION: These results demonstrate that long-term (6-month) folic acid administration significantly declines homocysteine levels and improves arterial endothelial function and has potential implications for the prevention of atherosclerosis in adults with 3 or more traditional risk factors of CAD and hyperhomocysteinaemia.

Aged↗
PubMed1998

Drug and environmental factors associated with adverse pregnancy outcomes. Part II: Improvement with folic acid.

OBJECTIVE: To provide a comprehensive review of periconceptional folic acid supplementation and factors affecting folate supplementation trials. DATA SOURCES: A MEDLINE search was conducted through December 1997. Additional sources were obtained from Current Contents and citations from the references obtained. Search terms included folate, folic acid, neural tube defect, spina bifida, and anencephaly. STUDY SELECTION: Relevant animal and human studies examining the effects of folate were reviewed. DATA EXTRACTION: Data collected included: type of study, folate dosing, dietary folate intake, serum and red blood cell folate concentrations, type of defect(s) studied, vitamin usage, parental risk factors, factors affecting trial results. DATA SYNTHESIS: Nine key factors have been identified that affect outcomes of folic acid supplementation trials. Daily doses of 0.8 mg decreased the occurrence and doses of 4 mg decreased the recurrence of neural tube defects in randomized clinical trials. Since lower folic acid doses were effective in nonrandomized trials, research is needed to determine the lowest effective dosage. Other benefits involving pregnancy outcome are suggested. CONCLUSIONS: Women of childbearing age should take a daily folic acid supplement to reduce the risk of pregnancies resulting in infants with a neural tube defect and other potential adverse pregnancy outcomes. Further health benefits from folic acid supplementation are reviewed in Part III of this series.

Animals↗
PubMed2002

Use of an oral/intravenous dual-label stable-isotope protocol to determine folic acid bioavailability from fortified cereal grain foods in women.

Folic acid fortification, mandatory in the United States, is currently being considered by the UK. The hypothesis that the matrix of some cereal-product vehicles may result in low fortificant bioavailability was tested using a dual oral/intravenous (i.v.) isotopic-label approach, which was evaluated concurrently. Fifteen women received 225 microg oral folate (capsules, fortified white bread and fortified branflakes), mainly as folic acid labeled with (13)C on 6 carbons of the benzoyl ring ((13)C(6)-PteGlu), followed by i.v. injection of 100 microg folic acid labeled with (2)H on 4 hydrogens of the glutamic acid group ((2)H(4)-PteGlu). The urinary excretion ratio (UER) in intact folate of the percentage of labeled oral dose excreted divided by the percentage of i.v. dose excreted was used as the primary index of absorption. The geometric mean (95% confidence interval) UER for folic acid capsules was 3.68 (1.90, 7.14) at 24 h and 2.18 (1.24, 3.83) at 48 h. Because these were significantly in excess of 1.0, indicative of 100% absorption of the oral dose, it was concluded that oral and i.v. labeled folic acid are handled differently by the body and that "absolute" absorption cannot be calculated. Compared with the 48-h UER for folic acid capsules, the "relative" 48-h UER for white bread and branflakes was 0.71 and 0.37, respectively, indicating that some cereal-based vehicles may inhibit absorption of fortificant. However, even the validity of this "relative" approach is questioned.

Absorption↗
PubMed2000

[Folic acid use by pregnant women in Israel for preventing neural tube defects].

Spina bifida and anencephaly are the most common, serious malformations in neural tube defects (NTD). Randomized trials in the last 2 decades have demonstrated that folic acid, 0.4 mg/d, reduces the incidence of NTD by more than 50%. We investigated the use of folic acid and multivitamins containing folic acid in childbearing women. Of 221 women interviewed, 67 (30%) regularly took pills containing 0.4 mg folic acid. Women with higher educational levels were more likely to take multivitamins with folic acid than were the less educated (p = 0.05). Of the women who took folic acid, only 5 (7.5%) used separate folic acid tablets, before and during their pregnancy. The rest used multivitamins containing folic acid. The 5 women who took folic acid separately were college-educated and nonreligious, and they took multivitamins in addition (p > 0.05). Of the women interviewed, 58 (26.2%) were Bedouin of the Negev. 24 (41.4%) of them took pills containing folic acid on a regular basis. This percentage is higher than that in the Jewish women in the study who took folic acid for prevention of NTD (17%; p = 0.038). Most of the women took folic acid after the first trimester. Only a minority took daily periconceptional folic acid. Multivitamins containing 0.4 mg of folic acid were more popular than folic acid tablets alone. This study emphasizes the need for continuing efforts to increase consumption of folic acid and awareness of its benefits among women of childbearing age.

Adult↗
PubMed2005

Synergistic effect of folic acid and vitamin B12 in ameliorating arsenic-induced oxidative damage in pancreatic tissue of rat.

The efficacies of two nutritional factors, folic acid and vitamin B12, were assessed in this study against arsenic-induced islet cellular toxicity. Rats were divided into four groups consisting of five rats in each group: Group A, control; Group B, arsenic-treated; Group C, arsenic+folic acid; and Group D, arsenic+folic acid+vitamin B12. The dose of arsenic, folic acid and vitamin B12, respectively, was 3 mg, 36 microg and 0.63 microg kg(-1) body weight day(-1) for 30 days. Results showed that, compared to control group, there was a significant increase in the levels of nitric oxide (NO), malondialdehyde (MDA) and hydroxyl radical (OH-) formation in the pancreatic tissue of arsenic-treated rats, while the activity of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), and cellular content of antioxidant glutathione (GSH) were low in these animals. The serum level of tumor necrosis factor-alpha (TNF-alpha) and IL-6 was significantly high in these animals. Light microscopic examination showed a marked fall in the number of islet cells. Concomitant administration of either folic acid or folic acid and vitamin B12 with arsenic significantly restored all these parameters. Although folic acid alone could not restore the normal level of TNF-alpha and IL-6, combined folic acid and vitamin B12 could restore it. Folic acid and vitamin B12 combined also could recover islet cell count. These results suggest that folic acid+vitamin B12 are capable of reducing arsenic-induced cellular oxidative and inflammatory toxic changes. Thus, supplement with vitamin B12+folic acid may be predicted as a possible nutritional management strategy against arsenic-induced toxicity.

Animals↗
PubMed2003

Effect of food fortification on folic acid intake in the United States.

BACKGROUND: The addition of folic acid to all enriched cereal-grain foods, mandated by the Food and Drug Administration (FDA), was initiated in January 1998. Although this program was designed such that typical folate intakes would be increased by approximately 100 micro g/d and that the risk of intakes > 1000 micro g/d (the FDA's safe upper limit of daily intake) would be minimal, its actual effect on folate intake has yet to be determined. OBJECTIVE: The objective was to estimate the effect of folic acid fortification on the amount of folate consumed by persons in the United States. DESIGN: Linear regression analysis of data from published studies was used to determine the relation between a chronic folic acid dose and the resulting increase in steady state concentrations of folate in plasma or serum. Using this regression equation and reverse prediction, we quantified the increase in folic acid intake from fortification required to achieve the increase in plasma or serum folate observed in published studies. RESULTS: The increase in circulating folate concentration was linearly related to folic acid intake over the range of 100-1000 micro g/d (r = 0.984, P < 0.0001). Predicted increases in folic acid intake from fortified food ranged from 215 to 240 micro g/d. CONCLUSIONS: Typical intakes of folic acid from fortified foods are more than twice the level originally predicted. The effect of this much higher level of fortification must be carefully assessed, especially before calls for higher levels of fortification are considered.

Female↗
PubMed2004

Ineffectiveness of dietary folic acid supplementation on the incidence of lipomyelomeningocele: pathogenetic implications.

OBJECT: Periconceptual folic acid supplementation is effective in myelomeningocele prevention. The relationship between folic acid and lipomyelomeningocele (LMM) and the overall incidence of this occult form of spina bifida has never been studied. The objectives of this study were to determine the impact of dietary folic acid supplementation on the incidence of LMM and to measure its overall incidence. METHODS: In a retrospective population-based study the authors calculated the incidence of LMM in Nova Scotia between 1985 and 2001. Because of changes in public policy during this period, there are three intervals defined in relation to the treatment of the food supply with folic acid: 1) prior to folic acid fortification (1985-1994); 2) postsupplementation but prefortification (1995-1998); and 3) postfortification. The overall incidence of LMM in Nova Scotia between 1985 and 2001 was 16 per 100,000 live births or one case per 6121 live births. Its incidence between 1985 and 1994 was 15 per 100,000 live births, and between 1995 and 1998 it was 12 per 100.000 live births (relative risk [RR] 0.82, 95% confidence interval [CI] 0.31-2.22; p = 0.7). Between 1999 and 2001, the incidence of LMM was 29 per 100,000 live births, which was not significantly different from that between 1995 and 1998 (RR 2.41. 95% CI 0.79-7.36; p = 0.11) or between 1985 and 1994 (RR 1.98, 95% CI 0.86-4.56; p = 0.1). CONCLUSIONS: The overall incidence of LMM between 1985 and 2001 in Nova Scotia was 16 per 100,000 live births and has not been reduced by dietary folic acid supplementation. This finding provides epidemiological evidence that the embryogenesis of LMM is fundamentally different from that of myelomeningocele.

Cauda Equina↗
PubMed1976

[Folic acid absorption in tropical enteropathy (author's transl)].

Folic acid absoprtion was measured in 45 patients before and after folic acid treatment by means of a folate tolerance test in serum and red-blood-cell-folate. 10 healthy men recently returned from the tropics volunteered as controls. There is no significant difference in the folate-tolerance tests in serum. The difference is significant however in the red-blood-cell-folate, which is markedly lower with the patients before treatment and raises after folate-treatment to the normal value of the control group. As the transport of folic acid in the mucosa follows two steps it is taken that the disturbance is localized in the hydrolysis of polyglutamate to monoglutamate-folic acid.

Adult↗
PubMed2005

[Relations between serum homocysteine and folic acid levels with congenital heart disease].

OBJECTIVE: To investigate the relations between serum homocysteine (Hcy) and folic acid with congenital heart disease (CHD) in CHD nuclear families. METHODS: In Liaoning Province 151 CHD patients and their biological parents were selected as the case group, with another 98 normal subjects and their parents as control. For some filial individuals and their mothers the serum total Hcy (tHcy) levels were detected by fluorescence polarization immunoassay. And for all members the serum levels of folic acid and vitamin B12 (VB12) were determined by radio-immunoassay. RESULTS: There were not significantly differences in the serum tHcy and folic acid levels and theirs abnormality prevalence between CHD patients and the control, neither were their parents in the study. Compared with the control group the serum VB12 levels of CHD patients were apparently higher (315.36 pmol/L and 185.34 pmol/L, P < 0.05), and the VB12 deficiency prevalence of patients and their fathers were lower. Analysis of different CHD types showed that in ventricular septal defect patients the serum tHcy levels were lower than the control with VB12 levels higher, and in parents of patent ductus arteriosus patients the serum folic acid levels were increased (P < 0.05). The study also indicated that the folic acid and VB12 of parents were significantly positively associated with that of filial generation. In the case group the tHcy levels of mothers were positively correlated with filial generation, and in CHD patients the tHcy was negatively associated with folic acid. In filial individuals of the control group the tHcy was negatively related with VB12 (P < 0.05). CONCLUSION: Folic acid and VB12 were important influencing factors of serum Hcy and they were negatively correlated. In this study, the folic acid and Hcy were not significantly related with CHD, and it needs further investigations to confirm it. There were not significant differences in the serum tHcy and folic acid levels and theirs abnormality prevalence between CHD patients and the control, neither were their parents in the study. Compared with the control group the serum VB12 levels of CHD patients were apparently higher (315.36 pmol/L and 185.34 pmol/L, P < 0.05), and the VB12 deficiency prevalence of patients and their fathers were lower. Analysis of different CHD types showed that in ventricular septal defect patients the serum tHcy levels were lower than the control with VB12 levels higher, and in parents of patent ductus arteriosus patients the serum folic acid levels were increased (P < 0.05). The study also indicated that the folic acid and VB12 of parents were significantly positively associated with that of filial generation. In the case group the tHcy levels of mothers were positively correlated with filial generation, and in CHD patients the tHcy was negatively associated with folic acid. In filial individuals of the control group the tHcy was negatively related with VB12 (P < 0.05). CONCLUSION: Folic acid and VB12 were important influencing factors of serum Hcy and they were negatively correlated. In this study, the folic acid and Hcy were not significantly related with CHD, and it needsfurther investigations to confirm it.

Adolescent↗
PubMed1998

Reduction of plasma homocyst(e)ine levels by breakfast cereal fortified with folic acid in patients with coronary heart disease.

BACKGROUND: The Food and Drug Administration (FDA) has recommended that cereal-grain products be fortified with folic acid to prevent congenital neural-tube defects. Since folic acid supplementation reduces levels of plasma homocyst(e)ine, or plasma total homocysteine, which are frequently elevated in arterial occlusive disease, we hypothesized that folic acid fortification might reduce plasma homocyst(e)ine levels. METHODS: To test this hypothesis, we assessed the effects of breakfast cereals fortified with three levels of folic acid, and also containing the recommended dietary allowances of vitamins B6 and B12, in a randomized, double-blind, placebo-controlled, crossover trial in 75 men and women with coronary artery disease. RESULTS: Plasma folic acid increased and plasma homocyst(e)ine decreased proportionately with the folic acid content of the breakfast cereal. Cereal providing 127 microg of folic acid daily, approximating the increased daily intake that may result from the FDA's enrichment policy, increased plasma folic acid by 31 percent (P=0.045) but decreased plasma homocyst(e)ine by only 3.7 percent (P= 0.24). However, cereals providing 499 and 665 microg of folic acid daily increased plasma folic acid by 64.8 percent (P<0.001) and 105.7 percent (P=0.001), respectively, and decreased plasma homocyst(e)ine by 11.0 percent (P<0.001) and 14.0 percent (P=0.001), respectively. CONCLUSIONS: Cereal fortified with folic acid has the potential to increase plasma folic acid levels and reduce plasma homocyst(e)ine levels. Further clinical trials are required to determine whether folic acid fortification may prevent vascular disease. Until then, our results suggest that folic acid fortification at levels higher than that recommended by the FDA may be warranted.

Aged↗