The Role of Vitamin B6 in Women's Health.

Vitamin B6, a cofactor in many biochemical reactions in the cells of living organisms, is an essential coenzyme for various catabolic and anabolic processes. Although vitamin B6 deficiency in young healthy women with a balanced diet is thought to be unusual, it can be seen with certain medications, health conditions, and dietary deficits, as well as aging. Vitamin B6 deficiency is associated with a variety of ill health effects, and correction of deficiency is considered beneficial. Women particularly are affected by unique health issues that are part of the array of disorders potentially alleviated through vitamin B6 supplementation.

Vitamin B6 blood concentrations in paediatric dialysis patients.

OBJECTIVES: We investigated vitamin B6 blood concentrations in children on long-term dialysis at our centre. METHODS: Retrospective cross-sectional review of vitamin B6 blood concentrations in children on maintenance dialysis [peritoneal dialysis (PD), intermittent haemodialysis (IHD)]. RESULTS: We reviewed 28 children (16 boys), 15 IHD and 13 PD with median (interquartile range, IQR) age of 9.4 (2.4, 14.3) years. The median (IQR) vitamin B6 concentration was 223.4 (74.2, 392.8) nmol/L measured a median (IQR) of 9 (4, 16.5) months following commencement of dialysis. None of the children had vitamin B6 deficiency. Vitamin B6 concentrations were raised in 17 (61%), eight of these received a supplement. Nineteen (68%) received vitamin B6 and/or a supplement containing vitamin B6 whilst 11 (39%) received an enteral feed and a supplement. In those with normal vitamin B6 concentrations who were not receiving an enteral feed or an oral nutritional supplement (n = 6), all achieved normal concentrations without need for vitamin B6 supplementation. There were no differences between those on PD versus IHD (269.2 nmol/L vs. 130 nmol/L, P = 0.65). CONCLUSIONS: We report no children with vitamin B6 deficiency although > 50% had elevated vitamin B6 concentrations. We suggest if dietary assessment of vitamin B6 intake indicates insufficient intake, measurement of blood concentrations will help confirm if supplementation is required. Routine vitamin B6 supplementation and monitoring is currently not indicated in children on chronic dialysis.

Suboptimal maternal and cord plasma pyridoxal 5' phosphate concentrations are uncommon in a cohort of Canadian pregnant women and newborn infants.

Vitamin B6 is important in fetal development, but little is known of the vitamin B6 status of pregnant women and newborns in North America and potential modifying factors. This prospective study determined maternal and cord plasma concentrations of pyridoxal 5' phosphate (PLP; an indicator of vitamin B6 status) in a convenience sample of 368 Canadian pregnant women and their newborns. The association of maternal intake of vitamin B6 and fetal genetic variants with cord plasma PLP and homocysteine concentrations was also examined. Dietary and supplemental intakes of vitamin B6 were assessed in early and mid to late pregnancy. PLP concentrations were measured in maternal plasma in early pregnancy and at delivery, and in cord plasma. Six fetal variants of the MTHFR and CßS genes were assessed for their association with cord plasma PLP and homocysteine concentrations. Geometric mean (95% CI) PLP concentrations were 107 (98, 116) nmol/L in early pregnancy and 58 (53, 62) nmol/L at delivery, respectively, and 296 (275, 319) nmol/L in cord blood (p < .0001). During early pregnancy and at delivery, 3.6% and 5.5% of women had plasma PLP concentrations <20 nmol/L, respectively. Ninety eight percent of the women with supplemental B6 intake of at least the recommended dietary allowance had PLP concentrations >20 nmol/L. Fetal genetic variants were not associated with cord PLP and homocysteine concentrations. Vitamin B6 deficiency is uncommon in a cohort of Canadian pregnant women due largely to prevalent vitamin B6 supplement use.

Interventions with vitamins B6, B12 and C in pregnancy.

The water-soluble vitamins B6, B12 and C play important roles in maternal health as well as fetal development and physiology during gestation. This systematic review evaluates the risks and benefits of interventions with vitamins B6, B12 and C during pregnancy on maternal, neonatal and child health and nutrition outcomes. Relevant publications were identified by searching PubMed, Popline and Web of Science databases. Meta-analyses were conducted for outcomes where results from at least three controlled trials were available. Potential benefits of vitamin B6 supplementation were reduction in nausea and vomiting, improvement in dental health, and treatment of some cases of anaemia. In meta-analysis based on three small studies, vitamin B6 supplementation had a significant positive effect on birthweight (d = 217 g [95% confidence interval (CI) 130, 304]). Interventions with vitamin C alone or combined with vitamin E did not systematically reduce the incidence of pre-eclampsia, premature rupture of membranes, or other adverse pregnancy outcomes. In meta-analyses, vitamins C and E increased the risk of pregnancy-related hypertension (relative risk 1.10 [95% CI 1.02, 1.19]). Effects of vitamin B6 or C intervention on other neonatal outcomes, including preterm birth, low birthweight, and perinatal morbidity and mortality, were not significant. Data on child health outcomes were lacking. Despite the prevalence of vitamin B12 deficiency amongst populations with limited intake of animal source foods, no intervention trials have evaluated vitamin B12 supplementation before or during pregnancy. In conclusion, existing evidence does not justify vitamin C supplementation during pregnancy. Additional studies are needed to confirm positive effects of vitamin B6 supplementation on infant birthweight and other outcomes. While vitamin B12 supplementation may reduce the incidence of neural tube defects in the offspring based on theoretical considerations, research is needed to support this hypothesis.

[Vitamin B-6 in chronic renal insufficiency]. / Witamina B-6 w przewleklej niewydolnosci nerek.

Chronic diseases, including chronic renal insufficiency, predispose to deficiency of vitamin B-6. Prevalence of that phenomenon, the need and appropriate level of supplementation remain controversial. The paper is a review of literature concerning those topics. Causes of deficiency, as well as advantages and dangers of supplementation were referred.

Dietary intake of vitamin B6 and concentration of vitamin B6 in blood samples of German vegans.

OBJECTIVE: The study aimed to evaluate the dietary vitamin B6 intake and determine the vitamin B6 concentration in blood samples of German vegans. DESIGN AND SETTING: Cross-sectional study with 33 examination sites all over Germany. Subjects Ninety-three vegans (50 females) with a mean (+/- standard deviation (SD)) age of 43.7 +/- 15.7 years who took no vitamin supplements. METHODS: Dietary intake was assed using a semi-quantitative food-frequency questionnaire. Erythrocyte aspartate aminotransferase activity coefficient (EAST-AC) was calculated as the ratio of stimulated (pyridoxal 5'-phosphate added) to unstimulated activity in blood samples that were provided after an overnight fast. RESULTS: Mean +/- SD vitamin B6 intake was 2.83 +/- 0.98 mg day(-1) and mean +/- SD protein intake was 56.6 +/- 21.7 g day(-1). Of the participants 4% showed vitamin B6 intakes lower than daily recommended intakes for Germany, 16% showed EAST-AC > 1.85, and a further 58% showed EAST-AC of 1.5-1-85. Moderate vegans were affected to a lesser extent than strict vegans. None of the established confounders was a significant predictor of EAST-AC. In logistic regression analyses the contribution of nutriments and cereals to pyridoxine intake was the only predictor of EAST-AC classified as < or = 1.85 and > 1.85, respectively. CONCLUSIONS: In spite of the high total intake of vitamin B6, an adequate concentration in blood samples could not be realised for a majority of the participants. Due to the health implications of a marginal pyridoxine status, vegans should be encouraged to include foods with a high bioavailability of pyridoxine, such as beans, lentils and bananas, in the daily diet.

[Isoniazid induced neuropathy: consider prevention]. / Neuropathie toxique induite par l'isoniazide: pensez à la prévention.

INTRODUCTION: Antituberculous treatment is effective but has numerous side effects. Among these isoniazid induced neuropathy is easily preventable. CASE REPORT: A female patient of 42 years, infected with HIV, presented with general deterioration associated with an interstitial pulmonary infiltrate and mediastinal lymphadenopathy. Tuberculosis was not confirmed bacteriologically but she responded to antituberculous treatment. Three months later she developed distal leg pains extending proximally. There was superficial sensory impairment up to the groins and loss of the ankle reflexes. The dose of isoniazid was reduced from 5 to 2.5 mg/kg/day on account of slow acetylator status and treatment with pyridoxine 250 mg/day commenced. The clinical signs resolved in a few weeks. CONCLUSIONS: Isoniazid neuropathy develops in the presence of risk factors (HIV, alcoholism, diabetes, renal failure, malnutrition, pregnancy and lactation, neurotoxic medication) and manifests itself initially by burning feet. Pyridoxine is preventative in low dosage and curative in high dosage. The development of symptoms should lead to measurement of acetylator status, and a reduction of the isoniazid dose to 3 mg/kg/day or even less in slow acetylators.

Water-soluble vitamins: research update.

For more than 50 years, the Food and Nutrition Board of the National Academy of Sciences has been reviewing nutrition research and defining nutrient requirements for healthy people, referred to as the recommended dietary allowances (RDA). As new nutrition research is published, the importance of vitamins as vital nutrients is underscored, and new physiologic roles and applications to human health are examined and considered with regard to updating the RDA. Each year a substantial amount of research is published on vitamins. This article examines and summarizes noteworthy research published on individual water-soluble vitamins (excluding vitamin C) in the past 12 months, provides relevant background information on these vitamins, and offers critical reviews as appropriate.

Vitamin B6 requirements in chronic renal failure.

According to our results the long-term daily oral supplementation of 6 mg vitamin B6 was sufficient for prevention of vitamin B6 deficiency in chronic renal failure, regular dialysis treatment and CAPD groups of patients. Haemodialysis and charcoal haemoperfusion have led to non-significant decrease of erythrocyte vitamin B6. A favourable effect was found of daily oral administration of 50 mg pyridoxine on electrophoretic mobility of peripheral blood lymphocytes and cellular immunity.

Vitamin B6 requirements of patients on chronic peritoneal dialysis.

Patients with chronic renal failure often develop vitamin B6 deficiency, which is of clinical concern because the multiorgan system manifestations are similar to those of uremia. Vitamin B6 deficiency in hemodialysis patients has been previously studied, but the need for daily pyridoxine supplementation in patients on chronic peritoneal dialysis (CPD) remains unclear. Therefore, we studied a group of 11 stable patients, nine on CAPD and two CCPD, to test for vitamin B6 deficiency and to establish daily requirements. Adequacy of vitamin B6 nutrition was assessed by measurement of plasma and dialysate effluent total vitamin B6 and pyridoxal 5'-phosphate (PLP), the latter using a very sensitive modification of the tyrosine apodecarboxylase enzyme assay. After four weeks without vitamin B6 supplements on a diet containing 1.3 +/- 0.2 mg vitamin B6/day (7.7 +/- 1.2 mumol/day), all patients had subnormal plasma PLP levels, 16 +/- 3 nmol/liter (nml 40 to 60), seven having a severe deficiency (less than or equal to 20 nmol/liter). Plasma total vitamin B6 levels (which includes non-PLP forms of the vitamin) were normal in all patients at baseline, 116 +/- 29 nmol/liter. Peritoneal losses were small, 8 +/- 2 nmol PLP/day and 545 +/- 61 nmol total vitamin B6/day. Supplementation with 5 mg/day oral pyrodoxine HCl for up to 16 weeks adequately repleted eight patients (65 +/- 7 nmol PLP/L), while three patients required 10 mg/day to achieve normal plasma PLP levels. During three episodes of peritonitis, dialysate losses of PLP did not increase.(ABSTRACT TRUNCATED AT 250 WORDS)

[Action of pyridoxine on lipid metabolism in carbon disulfide-poisoned rats]. / Vozdeistvie piridoksina na obmen lipidov u krys pri intoksikatsii serouglerodom.

The author studied the influence of pyridoxine (8 mg/kg bw) on upset lipid metabolism in rats exposed to carbon disulfide (30 mg/m3) inhalation over 90 days. The content of total lipids, total esterified and free cholesterol, free fatty acids, phospholipids, triglycerides and beta-lipoproteins was measured in serum on days 15, 30 and 90 since exposure. Carbon disulfide alone caused a reduction in the level of some lipid groups on day 15, whereas on days 30 and 90 it provokes an elevation of the content of total fats and all lipid groups under study. Administration of pyridoxine alone brought about a decrease in lipid characteristics. The combined use of the vitamin and carbon disulfide made these characteristics return to normal. Pyridoxine is a possible active factor in the prophylaxis of atherosclerotic lesions in carbon disulfide poisoning.

Maternal plasma concentration of pyridoxal phosphate during pregnancy: adequacy of vitamin B6 supplementation during isoniazid therapy.

Vitamin B6 is an important supplement both for pregnant patients and for those receiving isoniazid. Therefore, we decided to monitor pyridoxal phosphate (PLP) concentrations in 12 pregnant patients who were receiving isoniazid to be certain that supplementation was adequate. Patients were given a prenatal vitamin preparation and 50 mg of pyridoxine hydrochloride daily. At 1 month 10 of the 12 patients had adequate PLP concentrations. Seven of these 10 patients had elevated PLP concentrations and 3 had normal concentrations. Supplementation with 52 to 60 mg per day of Vitamin B6 produces adequate PLP concentrations in pregnant patients who are also taking isoniazid.

Influence of pyridoxine supplementation on vitamin B-6 levels in milk of rats deficient in the vitamin.

Levels of vitamin B-6 in milk from pyridoxine deficient dams were used as an indicator of the ability of pyridoxine to protect offspring against the effects of the deficiency. Sprague Dawley rats were fed a basal diet containing 30.0 (control) or 1.2 (deficient) mg pyridoxine-HC1/kg diet from weaning throughout growth, gestation and until 5 days postpartum. At this time, deficient dams were supplemented by a single intraperitoneal injection of 600 mug pyridoxine-HC1, or by adding 30 or 60 mg pyridoxine-HC1/kg to the diet. The vitamin B-6 content in milk form the group supplemented by injection exceeded the control level of 38.8 mug/100 ml milk 30 minutes after the injection, and reached a peak level of 110.7 mug/100 ml at 4 hours with a subsequent decline to 27mug/100 ml at 20 hours. In rats supplemented orally with 30 or 60 mg pyridoxine-HC1/kg diet, the vitamin B-6 level in the milk reached the control value in 24 and 6 hours, respectively. At 120 hours, orally supplemented dams had significantly higher levels of vitamin B-6 in the milk than control animals. Vitamin supplementation of dams by a single injection of pyridoxine-HC1 was sufficient to overcome the pyridoxine deficiency syndrome in the pups, but was not adequate for optimum growth.

Maternal and fetal plasma levels of pyridoxal phosphate at term: adequacy of vitamin B6 supplementation during pregnancy.

The effect of different amounts of vitamin B6 supplementation during pregnancy on maternal and fetal plasma levels of pyridoxal phosphate (PLP) at term has been studied. Ten of 13 subjects given 2 to 2.5 mg. of vitamin B6 daily exhibited plasma PLP levels lower than 4.7 ng. per milliliter (the lower limit of normal for nonpregnant subjects). In contrast, only 4 of 11 subjects given a supplement of 10 mg. of vitamin B6 daily had plasma PLP less than this value. The mean plasma PLP level (64.4 ng. per milliliter) of 10 cord blood samples from newborn infants whose mothers exhibited plasma PLP levels greater than 4.7 ng. per milliliter was significantly higher (P less than or equal 0.005) than that (34.2 ng. per milliliter) from 14 newborn infants whose mothers had abnormally lowered plasma PLP concentrations. In cord plasma, an average venous-arterial gradient of 10.6 ng. per milliliter was observed, indicating that the fetus retains and/or degrades PLP. These results suggest that more than 2 to 2.5 mg. of vitamin B6 supplement daily is required for most pregnancies to restore normal vitamin B6 nutrition in the mother and, perhaps, also in the fetus.