Determination of dietary vitamin B-6 intake: is it accurate?
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Chromatography, High Pressure Liquid↗
Biomedical subjects
R D Reynolds
Publications and source records attributed to R D Reynolds.
Vitamin B-6 intakes of lactating women: analyzed vs calculated values.
Results of our study suggest that calculation of vitamin B-6 content of diets using a current database can provide a reasonably good estimation of the vitamin B-6 intakes of a population of lactating women. Our study also demonstrates that the mean vitamin B-6 intake of this group of lactating women 2 months after they had given birth, who were not using vitamin B-6 supplements, was 1.45 mg, which is less than 70% of the RDA. However, on the basis of guidelines for the assessment of vitamin B-6 status using dietary vitamin B-6:protein ratio (15,20), the women appeared to be consuming adequate amounts of vitamin B-6.
Adolescent↗
Acute aflatoxicosis in feeder pigs, resulting from improper storage of corn.
Aflatoxicosis was diagnosed in 600 feeder pigs, of which 400 died, 150 were destroyed, and 50 were marketed. The pigs were exposed to 2,500 to 3,500 micrograms of aflatoxins/kg of feed. Drought-stressed damaged corn infected with Aspergillus flavus was stored under ambient conditions in a glass-lined silo, and this storage environment provided conditions that favored rapid fungal growth and mycotoxin production.
Aflatoxins↗
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)
Adult↗
Dietary intake of total and glycosylated vitamin B-6 and the vitamin B-6 nutritional status of unsupplemented lactating women and their infants.
The mean dietary intakes of total and glycosylated vitamin B-6, determined from analysis of 3-d diet composites collected from 30 lactating women, were 8.63 +/- 4.04 and 1.33 +/- 0.85 mumol/d (mean +/- SD), respectively. A comparison of linear regression models that either included or excluded dietary glycosylated vitamin B-6 content indicates that the intake of glycosylated vitamin B-6 had little, if any, effect upon maternal plasma pyridoxal 5'-phosphate concentration and maternal urinary excretion of total vitamin B-6 and 4-pyridoxic acid. On the basis of guidelines from the literature for evaluating biochemical indices of vitamin B-6 nutriture, the women appeared to be consuming adequate amounts of the vitamin. The mean breast-milk concentrations of total and glycosylated vitamin B-6 were 733 and 18 nmol/L, respectively. Infant plasma pyridoxal 5'-phosphate concentration was 54 +/- 44 nmol/L (mean +/- SD) and all infants had lengths and weights appropriate for age.
Adult↗
Phenelzine treatment of panic disorder: lack of effect on pyridoxal phosphate levels.
Earlier reports indicated that phenelzine treatment may result in clinically significant reductions of vitamin B6 in some individuals. Sixteen subjects, ages 21-59 years (seven men, nine women) with panic disorder with or without agoraphobia were treated with an average of phenelzine 53.5 mg/day for an average of 10 weeks in an open treatment study. No significant effects on plasma levels of pyridoxal phosphate, the active form of vitamin B6, were discernible in this group, nor was there any clear relationship between pyridoxal phosphate levels and symptoms in the subgroup of five patients who did develop deficiency-type symptoms. Pyridoxine replacement had unclear effects in symptomatic patients.
Adult↗
Preliminary evaluation of a pulsed 2.15-micron laser system for fiberoptic endoscopic surgery.
There is a need for lasers that are compatible with fiberoptic endoscopes and that provide greater cutting precision than currently can be produced by the widely used Nd:YAG (1.06 micron) laser. Recently available lasers that operate in the 2-micron region fill this need. This laser light energy can be transmitted by low OH- silica fibers and has much less tissue penetration than radiation at 1.06 micron. We have been evaluating a prototype solid state laser system that produces pulses of 2.15 microns light that is delivered by a silica based fiberoptic delivery system with negligible transmission losses. This system is based on a thulium-holmium-chromium doped YAG (Tm-Ho-Cr: YAG) rod that lases at 2.15 micron. The laser does not require cryogenic cooling, toxic gases, or custom utilities and should be practical in a clinical environment. In vivo animal testing of this laser confirms that it provides greater ablating precision than does the Nd:YAG laser at 1.06 micron.
Animals↗
Dietary pyridoxine interaction with tryptophan or histidine on brain serotonin and histamine metabolism.
We studied the metabolic effects of high dietary intakes of pyridoxine and of the substrate-cofactor interaction between dietary histidine or tryptophan and pyridoxine in rat brain. In the substrate-cofactor interaction study, histamine and serotonin levels were determined in rats fed elevated or requirement levels of substrate (histidine: 0.3% and 0.8%, tryptophan: 0.15% and 0.6%) and excess or requirement levels of pyridoxine HCl (7 mg vs. 3,000 mg/kg). Excess pyridoxine intake caused a differential effect on brain histamine concentration--inhibitory with the requirement level of histidine (-29%), and stimulatory (+21%) with the elevated level of histidine. When dietary tryptophan was fed at the requirement level, excess pyridoxine caused essentially no changes in hypothalamic serotonin and 5HIAA (-2%, -2%). With elevated tryptophan intake, excess pyridoxine significantly increased serotonin and 5HIAA (+32%, +20%) in the hypothalamus. These results indicate a clear interaction between substrate and coenzyme precursor which influences brain metabolism of histamine and serotonin.
Animals↗
Decreased vitamin B-6 status of submariners during prolonged patrol.
We investigated the effects of a 3-mo submarine patrol upon several vitamin B-6 indices in 23 male submariners. While on patrol, 12 subjects received a multivitamin-mineral supplement that provided 0.5 mg/d vitamin B-6 and 11 subjects received a placebo. The concentrations of plasma pyridoxal 5'-phosphate, total vitamin B-6, and urine 4-pyridoxic acid were significantly reduced during the patrol in both the placebo and the supplemented groups. The hematocrit of both groups also decreased by approximately 10% during the patrol and was not restored to prepatrol concentrations until several weeks postpatrol. Mood depressions, as measured by the Beck inventory and the depression adjective check list, were most pronounced during the 30 d before and at the beginning of the patrol. These depression measures did not correlate with the vitamin B-6 status indices, indicating that the mood depressions during a patrol do not appear to be related to the vitamin B-6 status of the submariners.
Adult↗
Nutritional and medical status of lactating women and their infants in the Kathmandu valley of Nepal.
In six villages in the Kathmandu valley of Nepal, an intensive health and nutrition study was conducted on 26 lactating women and their 2--6-month-old infants. Analysis of 24-h duplicate diet composites indicated that the mothers were consuming approximately 2100 kcal energy/d. The diets contained approximately 62 g protein (11.6% of the calories), 392 g carbohydrate (73.3% of the calories), and 20.9 g fat (8.6% of the calories) and a mean of 24 g neutral detergent fiber. Although anthropometric measurements indicated that the mothers had mild protein malnutrition and inadequate energy reserves, their infants exhibited low-normal weight and length for age. All the mothers had hepatitis A antibodies; 92% had tropical eosinophilia, indicating intestinal parasites; 16% had cheilosis and angular stomatitis, indicating a possible B-vitamin deficiency; and 8% had elevated urinary nitrite, indicating urinary tract infection. There were no unusual physical findings on the infants. Although the children appeared healthy, the mothers showed evidence of multiple infections and possible nutrient deficiencies.
Adolescent↗
Copper, iron, zinc, and selenium dietary intake and status of Nepalese lactating women and their breast-fed infants.
The dietary intake of copper, iron, zinc, and selenium of 26 Nepalese lactating mothers was estimated from chemical analysis of 24-h food and beverage composites. Fasting blood and milk samples were obtained from the mothers and blood samples were obtained from the infants. The Nepalese mothers consumed significantly more Cu, significantly less Fe and Se, and similar amounts of Zn as compared with American lactating women. Blood Fe status indices and plasma concentrations of Cu, Zn, and Se were lower in the Nepalese mothers than in the American mothers. These lower values may in part be related to the high neutral detergent fiber and phytate content of the Nepalese diet, which could make these minerals less available for absorption. The high exposure to infections in Nepal may also depress Fe status indices and plasma Zn concentrations. The lower dietary Se intake of the Nepalese mothers was reflected in lower milk concentrations.
Beverages↗
Calcium and magnesium dietary intakes and plasma and milk concentrations of Nepalese lactating women.
Dietary calcium and magnesium intakes of 26 Nepalese lactating women were determined from analysis of 24-h duplicate food and beverage composites. In addition, blood, urine, and milk samples were collected. The mean Ca intake of these Nepalese mothers, 482 +/- 249 mg/d, was less than half that of American lactating women yet the Ca concentration of the milk was similar for the two groups of women. The Nepalese mothers appeared to maintain milk Ca concentrations by an increase in bone resorption as demonstrated by an elevated excretion of hydroxyproline. The Nepalese women had a mean Mg intake of 353 +/- 28 mg/d. Two locally available foods considered special for lactating women, jwano and gundruk, were examined for nutrient content and found to contain high concentrations of Ca and Mg. Increased consumption of these locally grown foods could add substantially to the Ca and Mg intakes of these lactating women.
Bone Resorption↗
Bioavailability of vitamin B-6 from plant foods.
The major factors that affect bioavailability of vitamin B-6 are formation of reaction products during food processing, fiber type and content, and presence of the conjugated pyridoxine glucoside. The bioavailability of vitamin B-6 from animal products is quite high, reaching 100% for many foods. In general the bioavailability from plant foods is lower. The presence of fiber reduces the bioavailability by 5-10% whereas the presence of pyridoxine glucoside reduces the bioavailability by 75-80%. This glucoside is found in a variety of plant foods, with the highest content occurring in the crucifers. The percent of total vitamin B-6 that exists as the glucoside has been suggested to be the best indicator of bioavailability. Data from Nepalese vegetarian lactating women suggest that the low vitamin B-6 status of these mothers and their infants, as determined by their concentrations of plasma pyridoxal phosphate, may be adversely affected by the dietary intake of the naturally occurring pyridoxine glucoside.
Biological Availability↗
Effect of age on changes in plasma, erythrocyte, and urinary B-6 vitamers after an oral vitamin B-6 load.
We investigated the effect of age on indices of vitamin B-6 metabolism in 36 fasting males aged 25-35, 45-55, and 65-75 y who ingested 17.15 mumol vitamin B-6. There were no significant differences among groups in dietary vitamin B-6 intake, base-line erythrocyte pyridoxal 5'-phosphate (PLP), and total vitamin B-6 concentrations, and 24-h and base-line urinary excretion of total vitamin B-6 and 4-pyridoxic acid (4-PA). Base-line plasma PLP and total vitamin B-6 were higher (p less than 0.05) in the youngest group. Increased serum alkaline phosphatase (AP) and decreased dietary vitamin B-6 intake were correlated with decreased base-line plasma PLP and total vitamin B-6. Changes in plasma and erythrocyte PLP concentrations and excretion of 4-PA and total vitamin B-6 postload were not different among groups. Indices of vitamin B-6 absorption, phosphorylation, and excretion were not affected by age.
Adult↗
Migration of lead in a glass-lined bottom-unloading silo.
Alfalfa, estimated to contain 25.89 mg lead (Pb)/kg of air dried sample, was ensiled in a glass-lined bottom-unloading silo. Three weeks later air dried haylage from the bottom of the silo contained 118.6 mg of Pb/kg. The concentration of Pb in the haylage was sufficient to induce saturnism in a dairy herd. During the disposal process, the concentration of Pb was determined in each 11.3 m3 load of silage. These data provide evidence that Pb migrated and concentrated in the bottom of the silo.
Animal Feed↗
Risk of breast cancer in relation to cigarette smoking.
To provide additional data on the smoking-breast cancer association, a case-control study of 456 cases of breast cancer and 1693 matched controls was conducted among participants in a cancer screening program. The adjusted risk of breast cancer for current smokers was 1.38 (95% confidence interval, 1.01 to 1.90). Analysis of smoking habits restricted to premenopausal women revealed a risk estimate of 2.33 (confidence interval, 1.10 to 4.96) among current smokers and increasing linear trends in risk for number of cigarettes smoked per day and for number of years of smoking. Although smokers had an earlier natural menopause than nonsmokers, there was no evidence of a protective effect of early menopause after adjustment for other factors. These findings suggest that smoking may increase the incidence of breast cancer, especially in premenopausal women.
Adult↗
Effect of dietary vitamin B-6 deficiency on calcium fluxes in rat enterocytes.
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Animals↗