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PubMed1980

Renal parathyroid hormone-dependent adenylate cyclase activity after repletion of vitamin D-deficient rats with vitamin D-2.

Rats fed a diet deficient in both vitamin D and Ca2+ exhibited a greater depression of the renal parathyroid hormone (PTH)-dependent adenylate cyclase than was observed in rats fed diets deficient in either vitamin D or calcium. Total serum Ca2+ was decreased from a control level of 11.2 mg/dl to 8.5 mg/dl in rats fed the diet deficient in calcium alone, and to 5.4 mg/dl in rats fed the diet deficient in vitamin D. Serum calcium was decreased further to 4.3 mg/dl in rats fed the diet deficient in both vitamin D and Ca2+. Serum immuno-reactive PTH was significantly elevated over control levels when rats were fed the test diets; however, there were no significant differences between the elevated levels in the three experimental groups. Repletion of rats deficient in vitamin D only with a single oral dose of 3200 I.U. vitamin D-2 resulted in restoration of serum calcium to normal levels, a return of serum PTH to the control state, and an associated increase in PTH-dependent adenylate cyclase activity to the control level by 72 h. Repletion of rats deficient in both vitamin D and Ca2+ with the same dose of vitamin D-2 raised serum Ca2+ to 7.2 mg/dl by 72 h, but did not cause a reduction in circulating PTH, nor did it result in any significant improvement in the responsiveness of the membrane adenylate cyclase to PTH. These results suggest that elevated PTH is a factor in the down regulation of the PTH-dependent adenylate cyclase, but do not rule out a role for calcium as a regulatory factor.

Adenylyl Cyclases↗
PubMed1982

Release of vitamin B-12 in vitro from intrinsic factor-vitamin B-12 complex. Purification and characterization of a releasing factor from rat ileal brush border.

Vitamin B-12 is released from the purified gastric intrinsic factor-[57Co]vitamin B-12 (intrinsic factor-[57Co]vitamin B-12) complex, when incubated with rat intestinal mucosa. Maximum specific activity for splitting the complex is localized in ileal brush border. Release of [57Co]vitamin B-12 is not due to its mere exchange during incubation with endogenous non-radioactive vitamin B-12. The splitting process has specific requirement for Ca2+ and ATP and it is thermolabile, time- as well as temperature-dependent. It is also inactivated by the presence of p-chloromercuribenzoate. Further, the vitamin B-12-releasing factor has been isolated from solubilized brush border and is purified 70-fold by (NH4)2SO4 precipitation, gel filtration and Con. A-Sepharose 4B affinity chromatography. In SDS-polyacrylamide gel electrophoresis, it is resolved into a single band of about 25 kDa, indicating its purity. The releasing factor exhibits maximum activity at pH 7.4; isoelectric focusing reveals only one major form with pI 7.52. With intrinsic factor-[57Co]vitamin B-12-complex as the substrate, apparent Km and Vmax values obtained are 128.2 X 10(-12) M/I and 117.6 pg X h-1 100 micrograms protein, respectively. Amino acid and carbohydrate analyses reveal the glycoprotein nature of the factor. Intrinsic factor-[57Co]vitamin B-12 complex is not susceptible to unspecific proteolytic digestion. Similarly, the releasing factor does not hydrolyse other proteins. Thus, the observed substrate-specificity of the releasing factor differentiates it from other known proteolytic enzymes of ileal brush borders.

Adenosine Triphosphate↗
PubMed1995

[Vitamin D and pubertal maturation. Value and tolerance of vitamin D supplementation during the winter season].

BACKGROUND: In France, several cases of vitamin D-deficiency rickets among adolescents have been reported, but no prophylaxis measure has been systematically recommended at this age. The aim of this study was to measure 25-hydroxyvitamin D (25-(OH)D) levels and to search for biological signs of vitamin D deficiency during adolescence. Moreover, the effects of a unique oral dose of 100,000 IU of vitamin D3, given during the winter, were analysed. POPULATION AND METHODS: Circulating levels of 25-(OH)D, 1,25-dihydroxyvitamin D, intact parathyroid hormone (iPTH), alkaline phosphatase activities, calcium and phosphate were measured in 53 adolescents aged 10-17 years (81% of metropolitan origin), seen during the winter. The effect of a single oral dose of 100,000 IU of vitamin D3 or of placebo was studied in 15 of these subjects. RESULTS: 24.5% of the adolescents had low 25-(OH)D concentrations (< 6 ng/ml), this frequency being even more elevated (38%) at the end of pubertal maturation (stages 4 and 5). An increase in iPTH concentrations was found in subjects with lowest 25-(OH)D levels (< 3 ng/ml). An oral dose of 100,000 IU of vitamin D3 resulted in a significant increase in the 25-(OH)D levels; yet, these levels remained within the normal range during the 1-2 month follow-up of the nine treated subjects. This dosage made it possible to correct the low calcium concentrations (2.20-2.24 mmol/l) found before treatment in three adolescents. CONCLUSIONS: The high frequency of low vitamin D status observed during puberty and its normalization after a 100,000 IU vitamin D3 supplementation show the interest and safety of this intermittent 100,000 IU vitamin D3 supplementation to adolescents during the winter season.

Adolescent↗
PubMed1992

Effect of vitamin C and vitamin E on prostaglandin synthesis by fibroblasts and squamous carcinoma cells.

Dietary levels of vitamins C and E have been associated with cancer prevention and to a lesser extent with therapeutic enhancement of cancer treatment. Inhibition of prostaglandins (PGs) by pharmacological agents has been demonstrated to enhance immunocompetence, and to suppress growth of tumors in animals and humans. We report here on the effect of vitamins C and E on PGE2 production by human gingival fibroblasts and SCC-25 oral squamous carcinoma cells. The results indicate: 1. vitamins C and E exert a dose-dependent effect on arachidonic acid (AA) release and PGE2 synthesis; 2. vitamin E has a biphasic effect which is stimulatory at 1 and 10 microM and inhibitory at 100 microM; 3. vitamin E is considerably more potent than vitamin C in its inhibitory effect on AA and PGE2 in both cell types; 4. a combination of the two vitamins has a consistent dose-dependent inhibitory effect on AA and PGE2; 5. vitamin C stimulates PGE2 synthesis from exogenous AA in fibroblasts, and inhibits it in SCC-25 cells. The in vivo significance of these findings requires further investigation.

Adult↗
PubMedDate not supplied

The prevalence of Vitamin D deficiency and effects of ultraviolet light on Vitamin D levels in elderly Turkish population.

Vitamin D deficiency is commonly found in the elderly and is associated with osteoporosis and hip fractures. In this study, Vitamin D status of 138 female and 87 male subjects living in old age homes (OAH) and 171 female and 24 male subjects living in own homes (OH) from Central Anatolia were assessed. A questionnaire was applied to collect information about wearing features and degree of sunlight exposure and benefiting from ultraviolet index calculated (BFUI). We have found Vitamin D deficiency in 33.4% among our subjects. Also, 40.1% of subjects living in OAH (54.1% of females and 18.4% of males) and 24.4% of subjects living in OH (27.9% of females and 4.2% of males) were Vitamin D deficient. Vitamin D deficiency was significantly higher in subjects living in OAH than subjects living in OH (P = 0.001) and also higher in females than males (40.7% versus 15.3%, P < 0.001). Subjects with Vitamin D deficiency were older (P < 0.001), BFUI was lower (P < 0.001) and parathyroid hormone (PTH) was higher (P < 0.001) than those having normal level of 25(OH)D. There was a significant negative correlation between 25(OH)D levels and age (P < 0.001, r = -0.248) PTH and 25(OH)D (P = 0.004, r = -0.340), and positive correlation between 25(OH)D and BFUI (P < 0.001, r = 0.340). Vitamin D deficiency is very common in Turkish elderly subjects especially living in OAH and there is a significant low exposure to sunlight among them. Simply by asking clothing habits and exposure to sunlight, we can able to identify risk of Vitamin D insufficiency in elderly subjects.

Age Factors↗
PubMed2004

Vitamin C or Vitamin B6 supplementation prevent the oxidative stress and decrease of prostacyclin generation in homocysteinemic rats.

We hypothesize that homocysteinemia causes oxidative stress, decreases the aortic ability to generate prostacyclin and that antioxidants have a protective role. Four groups of eight rats each were fed for 8 weeks the control diet (group A), control diet with folic acid omitted and excess methionine (Me) added to drinking water (group B), diet B + 500 mg/kg of Vitamin C (group C) or diet B + 60 mg/kg Vitamin B6 (group D). The three groups of rats fed folic acid deficient (FD) diets (groups B, C and D) were homocysteinemic as indicated by the significant increase in their serum homocysteine (HC) concentration. Rats fed diet B had oxidative stress as indicated by an increase in serum thiobarbituric acid reactive substances (TBARS) and advanced oxidation protein products (AOPP) and urinary isoprostanes and had a decreased ability of their aortas to generate prostacyclin. Homocysteinemic rats fed a FD diet + Vitamin C (group C) or Vitamin B6 (group D) also had high levels of serum homocysteine but the oxidative stress markers and the ability of their aortas to generate prostacyclin returned to normal. This indicates that the homocysteinemic effect is through an oxidative mechanism and that Vitamin C as a free radical scavenger prevents these effects. Serum Vitamin C and liver glutathione concentrations significantly increased in rats fed excess Vitamin B6 compared to the control or FD rats. This may explain why Vitamin B6 has an antioxidative effect.

Animals↗
PubMed2006

Plasma holotranscobalamin compared with plasma cobalamins for assessment of vitamin B12 absorption; optimisation of a non-radioactive vitamin B12 absorption test (CobaSorb).

BACKGROUND: A recently developed non-radioactive vitamin B(12) absorption test (CobaSorb) was further explored to identify the best marker for reflection of vitamin B(12) absorption and to determine the duration of the test. METHODS: Seventy-eight healthy individuals (age 21-81 years) were given three oral doses of 9 microg vitamin B(12) per day for 5 successive days. Non-fasting blood samples were collected on days 1 to 5 before administration of vitamin B(12) and on day 8. Cobalamins and holotranscobalamin were measured. RESULTS: Performance of the vitamin B(12) absorption test was evaluated in individuals with holotranscobalamin or cobalamins below the 75% percentiles. We used a change greater than 2xCV(day-to-day) in holotranscobalamin (22%) and cobalamins (12%) to indicate a change caused by absorption of vitamin B(12). Among individuals with a baseline holotranscobalamin below the 75% percentile (<75 pmol/L, n=57), 98% had an increase in holotranscobalamin >22% from day 1 to day 3. In contrast, only 72% of the individuals with baseline cobalamins below the 75% percentile (<335 pmol/L, n=57) had an increase in cobalamins >12%. CONCLUSIONS: In healthy individuals with baseline holotranscobalamin <75 pmol/L, vitamin B(12) absorption is well reflected by an increase in holotranscobalamin after 2 days administration of oral vitamin B(12).

Adult↗
PubMed2005

Dietary intake of vitamin C and vitamin E and the development of hypertensive disorders of pregnancy.

OBJECTIVES: To explore the relationship, if any, between dietary intake of the antioxidant vitamins C and E, and the development of pre-eclampsia and gestational hypertension. STUDY DESIGN: A prospective cohort study of pregnant women attending the antenatal clinic of the Women's and Children's Hospital in Adelaide, Australia, was carried out between April and July 2001. Women completed a semi-quantitative 116-item food frequency questionnaire (FFQ). Women's medical records were viewed after birth to collect data on pregnancy outcomes. Relationships were explored through cross-tabulations, chi-square analysis, and adjustments were made for potential confounders using binary logistic regression. RESULTS: A total of 299 women completed the FFQ. Median intake of vitamin C was 188 mg and for vitamin E was 6.74 mg. There was no relationship between the intake of vitamin C and hypertensive disorders of pregnancy. For vitamin E, being in the lowest quartile of intake, was associated with an increased risk of hypertensive disorders (RR 1.75, 95% CI 1.11-2.75, P = 0.02). This relationship was confirmed after adjusting for the confounding factors of maternal age and parity. CONCLUSIONS: Little support was found for a relationship between dietary intake of vitamin C and the development of hypertensive disorders of pregnancy. Low vitamin E intake was associated with a significant increase in the risk of hypertensive disorders of pregnancy, even after adjustments were made for confounding factors. Further research is required to investigate whether supplementation above dietary intake of antioxidant vitamins influences the risk of hypertensive disorders of pregnancy.

Adult↗
PubMed2004

Is vitamin D hypothesis for schizophrenia valid? Independent segregation of psychosis in a family with vitamin-D-dependent rickets type IIA.

The vitamin D hypothesis of schizophrenia is a recent concept bringing together old observations on environmental risk factors and new findings on the neurodevelopmental effects of vitamin D. Candidate genes related to the vitamin D endocrine system have not yet been fully explored for this purpose. The coexistence of vitamin-D-dependent-rickets type II with alopecia (VDDR IIA) and different forms of psychosis in the same inbred family has provided us with an opportunity to investigate the presumed relationship between vitamin D deficiency and psychosis. Psychiatric examination and molecular genetic studies were performed in this family overloaded with psychotic disorders and VDDR IIA. Forty members were evaluated in order to describe their phenotypic features. The family was tested for a linkage to the chromosome 12q12-q14 region where the vitamin D receptor (VDR) gene is located. Psychosis was the common phenotype in the 18 psychiatrically affected members. Pedigree analysis did not show a cosegregation of psychosis and rickets. Lod scores were not significant to prove a linkage between psychosis and VDR locus. The authors concluded that (1) the neurodevelopmental consequences of vitamin D deficiency do not play a causative role in psychotic disorders, (2) these two syndromes are inherited independently, and (3) vitamin D deficiency does not act as a risk factor in subjects susceptible to psychosis.

Adolescent↗
PubMed2003

The association between vitamin C and vitamin E supplement use before hematopoietic stem cell transplant and outcomes to two years.

OBJECTIVE: To examine the prevalence of supplement use in persons before receiving hematopoietic stem cell transplant (HSCT) and the association of select supplements with outcomes. DESIGN: This observational cohort study included a questionnaire on supplement use before HSCT. Nonrelapse mortality, recurrence/relapse, and mortality or relapse (the inverse of disease-free survival) were followed to two years. Subjects/Setting Persons receiving HSCT at the Fred Hutchinson Cancer Research Center between September 1994 and December 1997 were eligible (N=1,182). Statistical Analyses Performed Descriptive statistics and univariate and Cox regression analyses were conducted. RESULTS: Sixty-six percent of patients used supplements (31% vitamin C, 19% vitamin E, and 20% herbs or others preparations). Vitamin C at > or =500 mg/day was inversely associated with recurrence among persons with breast cancer (RR=0.11; 95% CI, 0.02-0.89; P=.03). However, among persons with acute leukemia, vitamin C at > or =500 mg/day was positively associated with nonrelapse mortality (RR=2.25; 95% CI, 1.33-3.83; P=.01) and mortality or relapse (RR=1.63; 95% CI, 1.09-2.44; P=.01), respectively. Vitamin E at > or =400 IU/day was positively associated with mortality or relapse (RR=1.77; 95% CI, 1.06 -2.96; P=.02). Applications/Conclusions Though this work was observational, the results suggest supplemental vitamin C before therapy may be beneficial in persons with breast cancer but both vitamin C and vitamin E may increase risk in persons with acute leukemia receiving HSCT. Practitioners should document supplement use in subjects receiving therapy for cancer.

Adolescent↗
PubMedDate not supplied

Three-dimensional structure-function relationship of vitamin D and vitamin D receptor model.

On the basis of conformational analysis of the vitamin D side chain and studies using conformationally restricted synthetic vitamin D analogs, we have suggested the active space region concept of vitamin D: The vitamin D side-chain region was grouped into four regions (A, G, EA and EG) and the A and EA regions were suggested to be important for vitamin D actions. We extended our theory to known highly potent vitamin D analogs and found a new region F. The analogs which occupy the F region have such modifications as 22-oxa, 22-ene, 16-ene and 18-nor. Altogether, the following relationship between the space region and activity was found: Affinity for vitamin D receptor (VDR), EA > A> F > G > EG; Affinity for vitamin D binding protein (DBP), A >> G,EA,EG; Target gene transactivation, EA > F > A > EG > or = G; Cell differentiation, EA > F > A > EG > or = G; Bone calcium mobilization, EA > GA > F > or = EG; Intestinal calcium absorption, EA = A > or = G >> EG. We modeled the 3D structure of VDR-LBD (ligand binding domain) using hRARgamma as a template, to develop our structure-function theory into a theory involving VDR. 1alpha,25(OH)(2)D(3) was docked into the ligand binding pocket of the VDR with the side chain heading the wide cavity at the H-11 site, the A-ring toward the narrow beta-turn site, and the beta-face of the CD ring facing H3. Amino acid residues forming hydrogen bonds with the 1alpha- and 25-OH groups were specified: S237 and R274 forming a pincer type hydrogen-bond for the 1alpha-OH and H397 for the 25-OH. Mutants of several amino acid residues that are hydrogen-bond candidates were prepared and their biologic properties were evaluated. All of our mutation results together with known mutation data support our VDR model docked with the natural ligand.

Animals↗
PubMed2001

Vitamin K-dependent and vitamin K-independent hypocoagulant effects of dietary fish oil in rats.

In rats, dietary fish oil causes a plasma triglyceride-lowering as well as hypocoagulant effect. The latter is apparent from reduced levels of vitamin K-dependent coagulation factors and a decreased thrombin-forming potential of the coagulating plasma. Here, we describe that intervention with low levels of n-3 polyunsaturated fatty acids (n-3 PUFAs, about 2.5% of digestible energy, en%) resulted in no more than a small reduction in coagulation factors, when supplied as part of a high-fat diet relatively rich in vitamin K. Plasma triglycerides also remained unchanged. On the other hand, when feeding rats with low- or high-fat diets restricted in vitamin K, intervention with 3 en% of n-3 PUFAs acids (fish oil) caused only a lowering in triglycerides in combination with high fat. The fish caused a reduction in coagulation potential and levels vitamin K-dependent coagulation factors (prothrombin and factor VII) that was most prominent with the low-fat diet. Fish oil, in combination with low fat but not with high fat, reduced the vitamin K levels in the liver of the animals. In addition, regardless of the fat content, the vitamin K-independent coagulation factor V was decreased in the fish oil groups. Taken together, these results indicate that, in the rat, the hypocoagulant effect of a low dose of n-3 PUFAs is most apparent at low intakes of both vitamin K and fat, is not linked to the triglyceride plasma level, but involves modulation of both vitamin K-dependent and -independent coagulation factors.

Animals↗
PubMed2000

Salubrious effect of vitamin C and vitamin E on tamoxifen-treated women in breast cancer with reference to plasma lipid and lipoprotein levels.

Tamoxifen, a non-steroidal antiestrogen, has been used in the hormonal treatment for breast cancer. The hepatic estrogenic effect of tamoxifen causes severe triglyceridemia. The combined effect of tamoxifen, vitamin C and vitamin E on plasma lipid and lipoprotein is important, since, vitamin C and vitamin E encumbered the lipid abnormalities instigated by tamoxifen. Therefore supplementation of vitamin C (Celin 500 mg) and vitamin E (Evion 400 mg) for 90 days along with tamoxifen (10 mg twice a day) to postmenopausal breast cancer patients was ventured. In tamoxifen-treated patients, total cholesterol (TC), free cholesterol (FC), phospholipids (PL), free fatty acids (FFA), low density lipoprotein cholesterol (LDL) levels were decreased and the triglycerides (TG), ester cholesterol (EC), high density lipoprotein cholesterol (HDL) and very low density lipoprotein cholesterol (VLDL) levels were increased. Combination therapy reduce all the cholesterol level and VLDL, LDL. TG levels were significantly decreased and HDL, EC levels were significantly increased. These results suggested that tamoxifen treatment is the most effective during co-administration of vitamin C and vitamin E in that they reduce the tamoxifen-induced hypertriglyceridemia.

Antineoplastic Agents, Hormonal↗
PubMed2002

Supplementation with vitamin C and/or vitamin B(6) in the prevention of Depo-Provera side effects in adolescents.

BACKGROUND/OBJECTIVES: Depo-Provera-induced menstrual irregularity is believed to be secondary to relative estrogen deficiency. Weight gain associated with this contraceptive method is believed to be due to Depo-Provera's steroid-like appetite stimulation effect and to an altered tryptophan metabolism. We examined whether vitamin C, an important factor in uterine estrogen binding, and vitamin B(6), a glucocorticoid antagonist and an important coenzyme in the tryptophan-serotonin pathway, might alleviate menstrual irregularities and weight gain associated with Depo-Provera. METHODS: Fifty-five adolescent girls (age 16 +/- 1 yr, gyn age 4 +/- 1 yr, body mass index 25.2 +/- 0.9) who decided to initiate Depo-Provera (150 mg intramuscularly every 3 months) were randomly assigned to one of four groups (group 1: vitamin B(6) 50 mg plus placebo pill/day; group 2: vitamin C 500 mg plus placebo pill/day; group 3: vitamin B(6) 50 mg plus vitamin C 500 mg/day; group 4 (control): 2 placebo pills/day) for 6 months. Participants were assessed by their care providers every 3 months. SETTING: Two urban hospital-based adolescent clinics. RESULTS: Number of days of bleeding during the first interval (first 3 months) as well as during the second interval (months 4-6) among groups 1, 2, and 3 did not differ statistically from days of bleeding in control group. There were no significant body mass index (BMI) changes among groups 1-3 (-0.15 +/- 0.18, 0.34 +/- 0.56, 0.01 +/- 0.31) compared with control (-0.38 +/- 0.38) during the first interval as well as during the second interval (0.68 +/- 0.37, -0.39 +/- 0.21, 0.45 +/- 0.32, compared with 0.28 +/- 0.43). When data from all 55 participants were collapsed, there was no significant change in BMI during the first 6 months of Depo-Provera use. About 48% at 3 months and 44% at 6 months were very or somewhat concerned about menstrual irregularity; 41% at 3 months and 18% at 6 months were very or somewhat concerned about weight changes. More than half (57%) at 3 months and 74% at 6 months reported less tampon/pad use, and 77% at 3 months and 78% at 6 months reported decreased menstrual cramps. Overall, 59% at 3 months and 70% at 6 months were very satisfied with Depo-Provera; 97% at 3 months and 96% at 6 months said that they would recommend Depo-Provera to a friend or a relative. CONCLUSIONS: This study does not support a role for vitamin C in the prevention of Depo-Provera-induced menstrual irregularities or for vitamin B(6) in the prevention of weight changes associated with Depo-Provera. The unchanged BMI during the first 6 months of Depo-Provera use in the present study suggests that raising awareness and close follow-up may prevent weight gain among adolescent girls using this contraceptive method.

Adolescent↗
PubMed1990

Effect of vitamin A supplementation on haemoglobin and vitamin A levels during pregnancy.

About 450 pregnant women from a low-income group were recruited to study the effect of vitamin A supplementation on plasma vitamin A levels in the mother and cord and on the birth weights of the neonates. Results showed that supplementation with 1800 micrograms vitamin A/d for more than 12 weeks prevented the decline in plasma vitamin A that otherwise occurs during the last few weeks of pregnancy. This improvement in maternal values for vitamin A at a critical time of development favourably affected availability to the fetus, as reflected by the marked elevation in cord levels. Supplementation for a period of 12 weeks was found to be sufficient, since subsequent discontinuation did not alter the beneficial response. Apart from increasing maternal and cord vitamin A levels, vitamin A supplementation along with iron prevented, in this study, the significant decline in haemoglobin occurring at 26-28 weeks of gestation. The birth weights were not altered by vitamin A supplementation.

Birth Weight↗
PubMed1990

Effects of food or nutrient restriction on milk vitamin A transfer and neonatal vitamin A stores in the rat.

We have investigated the effects of maternal diets low in fat or protein, or restricted in total food intake on vitamin A transfer from the dam to her pups. When animals were fed on diets moderately restricted in fat or protein, minimal differences in milk, serum, and liver vitamin A concentrations were observed compared with animals fed on a control diet. In a second study, dams were fed on diets more severely restricted in protein, or fat, or both, or were fed on a control diet equal to 50% of the intake of control rats but containing an equal amount of vitamin A. The quantity of milk obtained from these more severely restricted dams' nipples or the pups' stomachs was greatly reduced; however, there were no differences in milk vitamin A concentration. Body-weight, liver weight, and total liver vitamin A stores of undernourished pups were just half those measured for control pups, although serum vitamin A and serum retinol-binding protein were nearly normal in concentration. We conclude that (a) moderate restrictions in fat or protein in the maternal diet are insufficient to affect transfer of vitamin A to the suckling pup; (b) further dietary restrictions could cause decreased milk production with little change in milk vitamin A concentration and, hence, (c) the neonates' hepatic retinol accumulation during the suckling period is markedly reduced when maternal diets are severely deficient in fat or protein or of normal composition but restricted in amount.

Animals↗
PubMed2002

Plasma vitamin D and 25OHD responses of young and old men to supplementation with vitamin D3.

OBJECTIVES: This study was conducted to determine whether there are age differences in the plasma parent vitamin D and 25-hydroxyvitamin D (25OHD) responses to eight weeks of supplementation with 20 microg/day of vitamin D3. METHODS: Twenty-five healthy young men (age 18-35) and 25 healthy older men (62-79) were randomly assigned to supplementation with 20 microg/day of vitamin D3 or to no intervention and followed for eight weeks. Plasma vitamin D3 was measured by high performance liquid chromatography and 25OHD was measured by competitive protein binding. RESULTS: Both young and old men in the supplemented group had pronounced, rapid and similar increases in plasma vitamin D3, whereas vitamin D3 concentrations were stable in the control group. By the end of the eight-week adaptation period, plasma vitamin D3 of young and old men had increased by 4.3 and 6.2 nmol/L respectively. In the supplemented group, mean 25OHD concentrations of both the young and old men increased during the study, and the magnitude of the change after eight weeks was nearly identical in the two age groups (22.5 and 22.1 nmol/L in the young and the old men, respectively). In the control group there was a modest decrease in 25OHD of both the young and old men. CONCLUSIONS: There appears to be no age-related impairment among men in the absorption or metabolism of 20 microg/day of vitamin D3 taken orally for at least eight weeks.

Adult↗
PubMed1984

[Vitamin A requirement of growing swine. 1. Effect of vitamin A supply on growth of piglets and fattening swine].

For the purpose of ascertaining the vitamin A requirement seven experiments with 303 pigs in the live weight range between 6.5 and 114 kg were made. In three experiments under in practice conditions we checked the standard vitamin A supplement to the mixed feed with 1,732 pigs (live weight range between 8.5 and 110 kg). The supplement to vitamin-A-free rations and to those poor in or free of carotene amounted to between 0 and 8,000 IU/kg feed. Above that, between 0 and 16 mg beta-carotene and 1,000 mg nitrite/kg feed were supplemented. As long as the vitamin A store in the liver during weaning amounted to greater than 50 IU and greater than 100 IU/g at the beginning of fattening, feed intake, live weight growth and feed expenditure were not influenced by the supplement of vitamin and provitamin resp. The supplement of 250 IU resulted in the same weight growth from weaning to the end of fattening as that of 4,000 IU. Nitrite supplement had a negative effect at 250 IU, at 500 IU vitamin A consumption and weight growth tended to be only insignificantly lower. The methaemoglobin content decreasing in the course of the experiment reflects the adaptation of the pigs to the nitrite load. The consumption and growth depression caused by vitamin A deficiency could be observed from the 7th week of the experiment when casein-swelling starch rations were fed, but from the 13th week of the experiment only when cereal-soybean oilmeal rations were fed. The weight of liver, spleen, kidneys, heart and brain was not influenced by vitamin A supply. The same applies to the body composition and retention with the exception of two deficiency piglets, which contained less fat in the empty body than the control animals.

Animals↗