Vitamin B-6 status of breast-fed neonates: influence of pyridoxine supplementation on mothers and neonates.

Vitamin B-6 concentrations in human milk are known to respond rapidly to changes in maternal vitamin B-6 intake. In this study, mothers were supplemented during the first 28 d of lactation with 2 or 27 mg pyridoxine (PN)-HCl/d and a subgroup of breast-fed infants of the 2-mg/d-supplemented mothers were supplemented with 0.4 mg PN-HCl/d. Vitamin B-6 intakes of breast-fed infants reflected the amount of their mother's supplement; intakes were highest for the vitamin-supplemented infants. Vitamin B-6 intake of mothers was a strong indicator of infant vitamin B-6 status. Vitamin intake of infants correlated significantly with five measures of vitamin B-6 status. Plasma pyridoxal-5'-phosphate (PLP) concentrations and birth weight were the strongest predictors of infant growth that were examined. Alkaline phosphatase activity in the mother's milk and infant plasma reflected pyridoxal-PLP ratios in these fluids, suggesting that the enzyme acts in regulating circulating vitamer concentrations.     

Pyridoxine supplementation of lactating mothers: relation to maternal nutrition status and vitamin B-6 concentrations in milk

Vitamin B-6 status, assessed by plasma pyridoxal phosphate (PLP) concentrations, and vitamin B-6 concentrations in breast milk were examined in 47 lactating mothers supplemented with different amounts of pyridoxine.HCl (PN.HCl) during pregnancy and the first 6 mo of lactation. PLP concentrations in cord blood and maternal plasma at 2 d postpartum and vitamin B-6 concentration in colostrum were positively correlated with the amount of PN.HCl supplementation prenatally (r = 0.71, p less than 0.001; r = 0.74, p less than 0.001; and r = 0.78, p less than 0.001, respectively). Correlations between the amounts of PN.HCl supplementation postnatally and plasma PLP concentrations increased with the length of supplementation. Plasma PLP concentrations were also correlated with vitamin B-6 concentrations of milk samples, which were obtained on the same day as plasma. PN.HCl supplements between 2.5 and 4.0 mg/d (2.1-3.4 mg PN equivalents) ensured vitamin B-6 adequacy of the mother and maintained relatively saturated concentrations of vitamin B-6 in breast milk.     

Vitamin B6 status of breast-fed infants in relation to pyridoxine HCl supplementation of mothers

The vitamin B6 nutritue of breast-fed infants was evaluated by vitamin B6 intake, plasma pyridoxal 5'-phosphate (PLP) concentration, and growth patterns during the infants' first 6 mo of age. Vitamin B6 intakes of 47 healthy, term infants were significantly correlated with four levels of maternal vitamin B6 supplements: 2.5, 4.0, 7.5, or 10.0 mg pyridoxine (PN) HCl/d and met the B6 Adequate Intake (AI, 1998) of 0.1 mg/d for infants 0 to 6 mo. Only infants whose mothers received 10.0 mg PN x HCl/d exceeded or met the Recommended Dietary Allowances (RDA, 1989) of 0.3 mg vitamin B6/d from 4 to 6 mo of age. Plasma PLP concentrations of infants, measured at 1, 4, and 6 mo of age paralleled their mother's vitamin B6 intake. Most infants showed normal growth. The findings indicated that a maternal PN x HCl supplement of 2.5 mg/d provided an adequate amount of vitamin B6 in breast milk (0.15 mg/d) for the vitamin B6 status parameters and the growth of breast-fed infants.     

Effects of vitamin B6 intake on nutriture and growth of young infants

Vitamin B6 is critical to normal development; however, the requirement for adequate nutriture of the human infant is based on limited experimental data. In this study vitamin B6 intakes of breast-fed (BF) and formula-fed (FF), healthy, term infants were related to levels of pyridoxal phosphate (PLP) in their plasma at 1, 2, 4, and 6 mo of age. Mothers of BF infants were supplemented with either 2.5 or 15.0 mg pyridoxine . hydrochloride (PN . HCl)/d. Growth was similar for FF and BF infants and was within normal ranges over the 6 mo period. Plasma PLP in cord blood was similar in BF and FF infants; however, at 1-5 d of age and at each subsequent age studied, levels of plasma PLP were significantly higher in FF infants than in BF. Lowest PLP values were for BF infants of mothers who received 2.5 mg PN . HCl/d. Mean plasma PLP decreased with age and was not correlated to vitamin B6 intakes except at 1 mo of age. At this age, vitamin B6 intake of BF infants whose mothers received 2.5 mg PN . HCl/d was only 0.1 mg B6/d. The consequences of this are uncertain; however, plasma PLP levels of the infants were low and reflected their intakes of vitamin B6.     

Effect of maternal pyridoxine X HCl supplementation on the vitamin B-6 status of mother and infant and on pregnancy outcome

The effect of maternal pyridoxine X HCl (PN-HCl) supplementation on the vitamin B-6 status of pregnant women and their infants at birth and on pregnancy outcome was investigated. Volunteer subjects were randomly assigned a daily vitamin B-6 supplement containing 0, 2.6, 5, 7.5, 10, 15 or 20 mg of PN-HCl in a double-blind study. The mean dietary vitamin B-6 intake of the group was 1.43 +/- 1.28 mg/day as estimated from 24-hour dietary recalls. Maternal plasma pyridoxal 5'-phosphate (PLP) levels were positively correlated with vitamin B-6 supplementation at 30 weeks gestation (r = 0.55, P less than 0.0005) and at delivery (r = 0.54, P less than 0.01). Cord plasma PLP levels reached a maximum when maternal PN-HCl supplementation was 7.5 mg and greater. Supplemental PN-HCl at the 7.5-mg level was required to prevent a decrease in maternal plasma PLP at delivery. Apgar scores at 1 minute after birth were higher (P less than 0.05) for infants whose mothers took 7.5 mg or more supplemental PN-HCl than for infants of mothers who took 5 mg or less. These findings indicate that a vitamin B-6 intake between 5.5 and 7.6 mg/day (diet plus supplement as pyridoxine equivalents) was required to maintain maternal plasma PLP levels at term at a level comparable to initial values.     

Effects of maternal dietary restriction in vitamin B-6 on neocortex development in rats: B-6 vitamer concentrations, volume and cell estimates

Influence of the time of maternal restriction in dietary vitamin B-6 on vitamer concentrations and morphological development of neocortex was examined. Rats were fed ad libitum a vitamin B-6-free diet supplemented with 0.0 or 0.6 mg pyridoxine X hydrochloride (PN X HCl)/kg diet during gestation followed by a control diet (7.0 mg PN X HCl/kg) during lactation or were supplemented with 0.6 or 7.0 mg PN X HCl/kg diet throughout gestation and lactation. During postweaning offspring received the maternal diets fed during lactation. Neocortices of offspring were examined at 30 d of age by liquid chromatography and light microscopy. Vitamin restriction during gestation and 30 d postnatal was the only vitamin B-6-restricted treatment of the three administered that altered B-6 vitamer levels in neocortex; all vitamers were depressed equally. Brain weight and volume of neocortex were not changed significantly by the maternal restrictions imposed. However, each restriction adversely affected neurogenesis and neuron longevity of the neocortex and when expressed as percent reduction from control, neuron longevity was affected more severely than neurogenesis.     

Insensitivity of the tryptophan-load test to marginal vitamin B-6 intake in rats.

The tryptophan-load test for vitamin B-6 nutritional status was administered to adult female Long-Evans rats fed graded levels of pyridoxine hydrochloride (PN.HCl) in two experiments, and its sensitivity to marginal vitamin B-6 intake was evaluated. In Experiment 1, rats were 4-h meal-fed an AIN-76A (20% casein) diet devoid of PN.HCl for 3 wk, then repleted (n = 12) for 6 wk with 4-h pair-fed meals of either 0.25, 0.5, 1.0 or 7.0 (control) mg PN.HCl/kg diet. In Experiment 2, rats (n = 16) were pair-fed for 10 wk either 0.0, 0.5, 1.0 or 7.0 (control) mg PN.HCl/kg diet, with 24-h access to food. Vitamin B-6 nutritional status was assessed at the end of each experiment. Except in rats fed 0 mg PN.HCl/kg diet, mean body weights were not significantly different among diet groups of either experiment. Plasma pyridoxal phosphate (PLP), pyridoxal and total vitamin B-6 concentrations, determined by HPLC, were very sensitive to gradations in dietary PN.HCl concentrations (P less than 0.05). Red blood cell endogenous and PLP-stimulated alanine and aspartate aminotransferase activity did not statistically differentiate all levels of dietary vitamin B-6, although the calculated activity coefficient for each enzyme (stimulated/endogenous activity) did. Urinary xanthurenic acid excretion following a tryptophan load [24.5 mumol (5 mg) L-tryptophan/100 g body weight, injected intraperitoneally] was significantly (P less than 0.05) elevated compared with controls only in the group fed 0 mg PN/HCl/kg diet. At the tryptophan dose used here, the tryptophan-load test was not useful in detecting marginal vitamin B-6 intake in rats.     

Vitamin B-6 content of breast milk and neonatal behavioral functioning

OBJECTIVE: To determine if vitamin B-6 intakes of mothers influence the B-6 vitamer content of transition milk and if correlations exist between the vitamin B-6 content of the milk and the infants' neurobehavioral functioning. DESIGN: Transition milk samples were collected from mothers 8 to 11 days after delivery for B-6 vitamer analysis. Neurobehavioral functioning of the neonates was determined at that time. A 24-hour recall was used in estimating vitamin B-6 intakes of the mothers. SUBJECTS: A convenience sample of low-income, lactating women (n = 25) who had normal pregnancies. MAIN OUTCOME MEASURES: B-6 vitamers were measured in the mothers' transition milk samples. Neurobehavioral functioning was assessed using the Brazelton Neonatal Behavioral Assessment Scale (NBAS), and the Center for Epidemiologic Studies Depression Scale was used to evaluate maternal depression. STATISTICAL ANALYSES PERFORMED: Pearson correlation coefficients were used to assess if statistically significant relationships existed between variables. The Mann-Whitney test was used to determine if median group values were significantly different. RESULTS: The major B-6 vitamer in transition milk was pyridoxal. Mothers with vitamin B-6 intake greater than the median value had a significantly higher median pyridoxal level in their breast milk than did the mothers with intakes below the median value. All except one mother had a dietary vitamin B-6 intake that exceeded the Recommended Dietary Allowance. Infant scores on habituation (r = .94, P < .05) and autonomic stability (r = .34, P < .05) subscales of the NBAS were positively correlated with milk pyridoxal values. APPLICATIONS/CONCLUSIONS: Vitamin B-6 is important for normal behavioral functioning of infants. The mothers' vitamin B-6 intake affects vitamin B-6 levels of breast milk and the need for consuming recommended levels of vitamin B-6 should be emphasized to all pregnant and lactating mothers.     

Evaluation of vitamin B-6 status and function of rats fed excess pyridoxine

We compared the vitamin B-6 status of 12-wk-old rats (n = 12) fed excess (1400 mg/kg diet) or the recommended level (7 mg/kg diet, control) of pyridoxine (PN) hydrochloride to test if excess vitamin B-6 would cause tissue depletion of pyridoxal phosphate (PLP), the active coenzyme form of vitamin B-6. Plasma PLP, tryptophan-load test results, food intake, and tissue and body weights were not different at wk 6. Red blood cell endogenous alanine aminotransferase activity and PLP concentration were elevated (P less than 0.01) in rats fed 1400 mg PN.HCl/kg diet. In contrast, PLP concentration in muscle was significantly lower (P = 0.01) in rats fed excess vitamin B-6 (9.7 +/- 0.8 nmol/g, mean +/- SEM) than in controls (14.9 +/- 1.4). PLP concentration in other tissues, including plasma, was not affected. In rats fed excess vitamin B-6, pyridoxal was increased in all tissues examined (P less than 0.05), and total vitamin B-6 was increased in plasma, red blood cells and kidneys (P less than 0.05). Total glycogen phosphorylase (a + b) activity in the gastrocnemius was not affected, but phosphorylase a activity was increased in rats fed excess vitamin B-6 (P = 0.025). Concentrations of dopamine and metabolites in the caudate nucleus of the basal ganglia were not affected. A transient, but significant, elevation in acoustic startle response, a central nervous system reflex, was observed in rats fed excess vitamin B-6. The depletion in muscle PLP could not hae been predicted by either plasma or red blood cell PLP concentration, although the latter did reflect vitamin B-6 intake.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determination of vitamin B-6 estimated average requirement and recommended dietary allowance for children aged 7-12 years using vitamin B-6 intake,nutritional status and anthropometry

The Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) of vitamin B-6 for children were recently estimated by extrapolating from adult values because of limited available information. To determine vitamin B-6 requirements and provide recommendations for intakes, vitamin B-6 intake, nutritional status and anthropometry of 168 healthy children (79 boys and 89 girls) were studied in Tainan, Taiwan. Direct and indirect vitamin B-6 status indicators were measured in plasma, erythrocytes and urine. Anthropometric data of children in this study were similar to those of the first Nutrition and Health Survey in Taiwan (NAHSIT) conducted in 1993-1996. The plasma pyridoxal phosphate (PLP) concentration of each child was >/=30 nmol/L, indicating an adequate vitamin B-6 status. Daily dietary vitamin B-6 intakes of boys and girls were 0.80 +/- 0.16 and 0.74 +/- 0.16 mg/d, respectively. Daily dietary vitamin B-6 intakes of children who had adequate urinary 4-pyridoxic acid (4-PA) (>3.0 micro mol/L), erythrocyte alanine aminotransferase activity coefficient (EALT-AC) (<1.25) and aspartate aminotransferase activity coefficient (EAST-AC) (<1.8) were not different from those of children who had adequate plasma PLP, although the percentages of adequacy for urinary 4-PA, EALT-AC and EAST-AC ranged from 20 to 91%. Vitamin B-6 status indicators were strongly correlated with vitamin B-6 intake. Adequate values of PLP, EALT-AC, EAST-AC and urinary 4-PA were used to determine the EAR according to Dietary Reference Intake (DRI) committee methodology. We determined the vitamin B-6 EAR (RDA) for boys and girls aged 7-12 y to be 0.84 (1.01) and 0.75 (0.89) mg/d, respectively.     

Dietary vitamin B-6 intake and food sources in the US population: NHANES II, 1976-1980

Dietary vitamin B-6 intake and food sources were estimated from the Second National Health and Nutrition Examination Survey (NHANES II) dietary data for 11,658 adults aged 19-74 y. The average daily intake of vitamin B-6 was 1.48 +/- 0.01 mg (mean +/- SEM) for the total population, 1.85 +/- 0.02 for males and 1.14 +/- 0.01 for females. Seventy-one percent of males and 90% of females consumed less than the 1980 recommended dietary allowance (RDA) of vitamin B-6. Sixty-four percent of all survey respondents reported a ratio of vitamin B-6 to dietary protein of less than 0.02 (expressed as mg/g protein). Foods from animal and plant sources provided 48% and 52% of the total vitamin B-6, respectively. Vitamin B-6 intake decreased (P less than 0.0001) with increasing age and decreasing education and income status. Beef steaks and roasts, alcoholic beverages, potatoes, ready-to-eat cereals, and milk were important dietary sources of vitamin B-6.     

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.     

Contribution of various food groups to dietary vitamin B-6 intake in free-living, low-income elderly persons

Elderly persons are reported to have low dietary intakes of vitamin B-6. Knowing which foods are the primary contributors of dietary vitamin B-6 may be useful to health professionals working to improve the nutritional status of the elderly. Therefore, we examined the contribution of five food groups--flesh foods (including all meat/fish/poultry), grains/cereals, legumes/nuts, fruits/vegetables, and dairy products/eggs--to dietary vitamin B-6 intake in 198 free-living elderly persons aged 60 years or older. Subjects were primarily Caucasian, low-income non-smokers; their mean age was 72 years. Mean dietary vitamin B-6 intake, determined from 3-day diet records, was 1.6 +/- 0.6 mg/day. The fruit/vegetable group was the largest dietary contributor of vitamin B-6 (0.69 mg/day). Flesh foods and cereals/grains contributed equally to the vitamin B-6 intake (0.35 and 0.34 mg/day, respectively). The lowest contributors were dairy products/eggs and legumes/nuts. Approximately 96% of the vitamin B-6 intake could be accounted for by the five food groups. Twenty percent of the population (no. = 39) consumed less than 66% of the Recommended Dietary Allowance (RDA) for vitamin B-6; their vitamin B-6 intake from fruits/vegetables and grains/cereals was 0.36 and 0.10 mg/day, respectively. Individuals with vitamin B-6 intakes greater than or equal to 100% of the RDA (no. = 69) consumed greater amounts of fruits/vegetables (primarily bananas) and grains/cereals (primarily breakfast cereal) than did persons who consumed less than 66% of the RDA for vitamin B-6; their vitamin B-6 intake from fruits/vegetables and grains/cereals was 0.98 and 0.55 mg/day, respectively. In the elderly population studied, plant foods were the major dietary contributors of vitamin B-6.     

Effects of different levels of vitamin C intake on the vitamin C concentration in human milk and the vitamin C intakes of breast-fed infants

The influence of maternal intake of vitamin C on the vitamin C concentration in human milk and on the vitamin C intakes of breast-fed infants has not been demonstrated conclusively. This study examined these influences of diet and supplementation in 25 lactating women administered 90 mg of ascorbic acid for 1 day followed by 250, 500 or 1000 mg/day for 2 days or unsupplemented for 1 day followed by either 0 or 90 mg ascorbic acid supplement for 2 days. Vitamin C content in milk and urine was determined by the 2,4-dinitrophenylhydrazine method. Vitamin C intakes of infants were calculated from milk volume, as determined by the test-weighing method and from vitamin C levels in milk samples obtained at each feeding. Total maternal intakes of vitamin C, which exceeded 1000 mg/day or 10-fold the RDA for lactation (100 mg/day), did not significantly influence the vitamin C content in milk or the vitamin C intakes of infants. However, maternal vitamin C intake was positively correlated (r = 0.7) with maternal urinary excretion. These differences in milk and urine response to vitamin C intake suggest a regulatory mechanism for vitamin C levels in milk.     

Response of vitamin B-6 content of muscle to changes in vitamin B-6 intake in men

Previous reports indicated that in growing rats the vitamin B-6 pool in muscle was relatively stable during deficiency but increased in response to increased vitamin B-6 intake. To determine whether human muscle would show a similar response 10 college-aged males received a low vitamin B-6 diet (1.76 mumol/d) for 6 wk followed by 6 wk on a self-selected diet supplemented with 0.98 mmol pyridoxine HCl/d. During depletion, excretion of pyridoxic acid rapidly adjusted to approximate the intake. Plasma pyridoxal phosphate concentrations at the end of the baseline, depletion, and supplementation periods were 81 +/- 51, 9 +/- 3, and 455 +/- 129 nmol/L, respectively, whereas muscle concentrations were 21 +/- 9, 20 +/- 4, and 25 +/- 7 nmol/g, respectively and total vitamin B-6 in muscle was 28 +/- 10, 27 +/- 4, and 35 +/- 10 nmol/g, respectively. These data provide further confirmation that the vitamin B-6 pools in skeletal muscle are resistant to depletion. They also demonstrate that in humans with constant body weight, vitamin B-6 supplementation is not associated with marked increases in vitamin B-6 in muscle.     

Assessment of vitamin B-6 estimated average requirement and recommended dietary allowance for adolescents aged 13-15 years using vitamin B-6 intake, nutritional status and anthropometry

Because of limited available information, the Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) of vitamin B-6 for adolescents were recently estimated by extrapolation from adult values. To determine vitamin B-6 requirements and to provide recommendations for intakes, vitamin B-6 intake, nutritional status and anthropometry were studied in 134 healthy adolescents (63 boys and 71 girls) aged 13-15 y in Tainan, Taiwan. Direct and indirect vitamin B-6 indicators were measured in plasma, erythrocytes and urine. The anthropometric data of the adolescents in this study were similar to those of the first Nutrition and Health Survey in Taiwan (NAHSIT), conducted from 1993 to 1996, showing the normal growth and development of this adolescent group. All subjects had plasma pyridoxal-5'-phosphate (PLP) concentrations > or = 20 nmol/L, indicating an adequate vitamin B-6 status. The mean dietary vitamin B-6 intakes of boys and girls were 1.04 +/- 0.24 and 0.83 +/- 0.26 mg/d, respectively. Vitamin B-6 status indicators, including plasma PLP, erythrocyte alanine activity coefficient (EALT-AC), aspartate aminotransferase activity coefficient (EAST-AC) and urinary 4-pyridoxic acid (4-PA), were correlated with vitamin B-6 intake (r = 0.84, -0.84, -0.77 and 0.86, respectively, P < 0.01). Adequate values of plasma PLP (> or = 20 nmol/L), EALT-AC (<1.25), EAST-AC (<1.8) and urinary 4-PA (>3.0 micromol/d) were used to determine the EAR according to the Dietary Reference Intake committee methodology. The present study suggests that vitamin B-6 EAR (RDA) for adolescent boys and girls aged 13-15 y are 1.07 (1.28) and 0.90 (1.08) mg/d, respectively.     

Breast milk vitamin B-12 concentrations in Guatemalan women are correlated with maternal but not infant vitamin B-12 status at 12 months postpartum

In our previous studies, one-third of lactating Guatemalan women, infants, and children had deficient or marginal serum vitamin B-12 concentrations. Relationships among maternal and infant status and breast milk vitamin B-12, however, have not, to our knowledge, been investigated in such populations. Our purpose was to measure breast milk vitamin B-12 in Guatemalan women with a range of serum vitamin B-12 concentrations and explore associations between milk vitamin B-12 concentrations and maternal and infant vitamin B-12 intake and status. Participants were 183 mother-infant pairs breastfeeding at 12 mo postpartum. Exclusion criteria included mother <17 y, infant <11.5 or >12.5 mo, multiple birth, reported health problems in mother or infant, and mother pregnant >3 mo. Data collected on mothers and infants included anthropometry, serum and breast milk vitamin B-12, and dietary vitamin B-12. Serum vitamin B-12 concentrations indicated deficiency (<150 pmol/L) in 35% of mothers and 27% of infants and marginal status (150-220 pmol/L) in 35% of mothers and 17% of infants. In a multiple regression analysis, breast milk vitamin B-12 concentration was associated (P < 0.05) with both maternal vitamin B-12 intake (r = 0.26) and maternal serum vitamin B-12 (r = 0.30). Controlling for the number of breastfeeds per day and vitamin B-12 intake from complementary foods, infant serum vitamin B-12 was associated with maternal serum vitamin B-12 (r = 0.31; P < 0.001) but not breast milk vitamin B-12, implicating a long-term effect of pregnancy status on infant vitamin B-12 status at 12 mo postpartum.     

Consumption of a dehydrated ration for 31 days at moderate altitudes: status of zinc, copper, and vitamin B-6.

Intake of energy zinc, copper, and vitamin B-6 and indexes of zinc, copper and vitamin B-6 status were determined for eight men who consumed a high-carbohydrate dehydrated ration for 31 days of high activity at moderate altitudes (2,400 to 4,300 m). Data were collected 2 months before exposure (PRE), four times during the month at moderate altitudes (ALT), and 1 month after return (RET). Mean (+/- standard error) energy intake was 2,725 +/- 215, 3,430 +/- 79, and 3,370 +/- 215 kcal/day during PRE, ALT, and RET, respectively. Zinc and copper intakes averaged 10.6 +/- 1.6 and 1.0 +/- 0.1 mg/day during PRE and increased significantly to 16.9 +/- 0.7 and 3.5 +/- 0.1 mg/day during ALT; zinc and copper intakes were 15.5 +/- 1.6 and 1.9 +/- 0.3 mg/day for RET, respectively. Similarly, vitamin B-6 intake was significantly higher during ALT (PRE = 2.2 +/- 0.5 mg/day; ALT = 4.2 +/- 0.4 mg/day; and RET = 2.6 +/- 0.4 mg/day) as compared with PRE and RET. No significant changes were noted for plasma zinc, copper, or their related proteins or plasma or erythrocyte pyridoxal-5'-phosphate. Finally, no changes in urinary excretion of zinc were observed. The results indicate that dehydrated rations provide zinc, copper, and vitamin B-6 in amounts above the Recommended Dietary Allowances. Such diets may be consumed for at least 1 month without compromising status for these nutrients.     

Vitamin B-6-supplemented diets compared with a low vitamin B-6 diet suppress azoxymethane-induced colon tumorigenesis in mice by reducing cell proliferation

Male ICR mice were examined for the effect of vitamin B-6 [pyridoxine (PN) HCl] on azoxymethane-induced colon tumorigenesis. Mice were fed the diets containing 1, 7, 14 or 35 mg PN HCl/kg for 22 wk, and given a weekly injection of azoxymethane (5 mg/kg body) for the initial 10 wk. Compared with the 1 mg PN HCl/kg diet, 7, 14 and 35 mg PN HCl/kg diets significantly suppressed the incidence and number of colon tumors, colon cell proliferation and expressions of c-myc and c-fos proteins. For some variables, 14 and 35 mg PN HCl/kg diets were more effective than the 7 mg/kg diet. Supplemental vitamin B-6 had no influence on the number of colon apoptotic cells. The results suggest that elevating dietary vitamin B-6 suppresses colon tumorigenesis by reducing cell proliferation.     

Vitamin B-6 deficiency impairs interleukin 2 production and lymphocyte proliferation in elderly adults

The effect of vitamin B-6 deficiency on immune response was studied in eight healthy elderly adults. The protocol consisted of a 5-d baseline (BL) period; a vitamin B-6-depletion period of less than or equal to 20 d; three stages of vitamin B-6-repletion, each lasting 21 d; and a 4-d final phase. The amounts of vitamin B-6 ingested during the different phases of the study were 3.00, 15.00, 22.50, and 33.75 micrograms.kg body wt-1.d-1, respectively. During the final phase the subjects ingested 50 mg vitamin B-6/d. Fasting blood was collected at the end of each period. Vitamin B-6 depletion significantly decreased percentage and total number of lymphocytes, mitogenic responses of peripheral blood lymphocytes to T- and B-cell mitogens, and interleukin 2 production. These indices returned to BL values after the third vitamin B-6-repletion period, when the total vitamin B-6 intakes were 1.90 +/- 0.18 mg/d for women and 2.88 +/- 0.17 mg/d for men. Vitamin B-6 deficiency impairs in vitro indices of cell-mediated immunity in healthy elderly adults. This impairment is reversible by vitamin B-6 repletion.