Plasma Vitamin D3 Research Articles

Diet induced obesity modifies vitamin D metabolism and adipose tissue storage in mice

Low circulating levels of total and free 25-hydroxyvitamin D (25(OH)D) indicative of vitamin D status have been associated with obesity in humans. Moreover, obesity is thought to play a causal role in the reduction of 25(OH)D levels, and several theories have been put forward to explain this relationship. Here we tested the hypothesis that obesity disrupts vitamin D homeostasis in key organs of vitamin D metabolism. Male C57BL6 mice were fed for 7 or 11 weeks on either a control diet (control, 10% energy from fat) or a high-fat diet (HF, 60% energy from fat) formulated to provide equivalent vitamin D3 intake in both groups. After 7 weeks, there was a transient increase of total 25(OH)D together with a significant decrease of plasma vitamin D3 that could be related to the induction of hepatic genes involved in 25-hydroxylation. After 11 weeks, there was no change in total 25(OH)D but a significant decrease of free 25(OH)D and plasma vitamin D3 levels. We also quantified an increase of 25(OH)D in adipose tissue that was inversely correlated to the free 25(OH)D. Interestingly, this accumulation of 25(OH)D in adipose tissue was highly correlated to the induction of Cyp2r1, which could actively participate in vitamin D3 trapping and subsequent conversion to 25(OH)D in adipose tissue. Taken together, our data strongly suggest that the enzymes involved in vitamin D metabolism, notably in adipose tissue, are transcriptionally modified under high-fat diet, thus contributing to the obesity-related reduction of free 25(OH)D.

Simultaneous determination of Vitamin A, 25-hydroxyl vitamin D3 α-tocopherol in small biological fluids by liquid chromatography-tandem mass spectrometry

A sensitive method for the simultaneous analysis of vitamin A (VA), 25-hydroxyl vitamin D3 (25-OH VD3) and α-tocopherol (VE) in children plasma by liquid chromatography-tandem mass spectrometry (LC–MS/MS) has been developed and validated. Sample preparation chose the solid phase extraction. 100 μL of plasma was mixed with 300 μL ethanol contained 4 μL isotope-labelled analytes. After a series operation, the supernatant was applied to the solid phase extraction (SPE) plate (HLB μElution plate). The eluate was evaporated, and reconstituted in 100 μL methanol. And then, 6 μL reconstituted sample was injected into LC–MS/MS. Quantitative analysis was carried out by multiple reaction monitoring (MRM) with a positive mode electrospray (ESi + ). Separations of VA, 25-OH VD3 and VE were performed on an Acquity UPLC reversed-phase Phenyl-Hexyl analytical column (CSH, 2.1 × 50 mm, 1.7 μm). Gradient elution was used at a flow rate of 0.4 mL/min with a mobile phase consisting of 0.1% formic acid solution and 0.1% formic acid, 5 mM ammonium formate in acetonitrile. The total time of analysis was 10 min. The method had a limit of quantification (LOQ) of 10.03, 1.20, and 0.04 ng/mL for VA, 25-OH VD3 and VE in methanol, respectively. The linear calibration curves were fitted over the range of 0.14–14.32 μg/mL, 1.80–180.29 ng/mL, and 6.03–602.99 ng/mL for VA, 25-OH VD3 and VE in methanol. The correlation coefficients were greater than 0.998 for all analytes. The recoveries for all analytes were between 80 and 120% with the inter- and intra-day precisions (presented as relative standard deviation, RSD%) less than 10.0%. Analysis of VA, 25-OH VD3 and VE in recurrent respiratory tract infection children plasma and anemic infants’ fingertip blood was then carried out using this method and statistical analysis of the data with statistic package for social science 20.0 (SPSS 20.0). Using this method, multiple fat-soluble vitamins could be detected at the same time. Solid phase extraction was used to simplify sample pretreatment. μElution plate used here could reduce the sample volume, only 100 μL sample was used in this method, and 6 μL reconstituted sample was injected into LC–MS/MS. This makes the method appropriate for larger sample pretreatment, and suitable for children, especially infants and newborns’ sample detection, in whom the circulation blood was low.

PS 05-63 PRO- AND ANTI-INFLAMMATORY FACTORS AND VASCULAR STIFFNESS IN END-STAGE RENAL DISEASE PATIENTS

Objective: Vascular calcification (VC) has crucial importance in the accelerated arteriosclerosis of chronic renal disease patients. The aim of this study was to assess the extent of arteriosclerotic lesions and to relate vascular stiffness parameters to pro-inflammatory markers (hsCRP, TNF-α, TGF-β1) and to protective factors (α-Klotho, fetuin-A, vitamin D3) in patients on chronic hemodialysis. Design and Method: 96 consecutive patients in stable condition were enrolled. 20 healthy individuals served as controls. Beside routine biochemical parameters, TNF-α, TGF-β1 α-Klotho and fetuin-A were measured with ELISA. Carotid-femoral pulse wave velocity was measured using applanation tonometry (SphygmoCor, AtCor Medical Australia) before hemodialysis sessions. Carotid-femoral pulse wave velocity (cfPWV) was calculated. Results: Pro-inflammatory (pro-calcigenic) biomarkers (hsCRP, TNF-α, TGF-β1) were elevated (p < 0.01), whereas anti-inflammatory (anti-atherosclerotic) factors (fetuin-A: p < 0.05, α-Klotho: p < 0.01, vitamin D3 p < 0.01) depressed compared to controls. cfPWV correlated positively with total cholesterol (r = 0.244, p < 0.05) and fetuin-A (r = 0.282, p < 0.05) but inversely with the time spent on dialysis (r = -0.262, p < 0.05). hsCRP was negatively influenced by plasma vitamin D3 (β = −0.23, p < 0.01), sodium (β = −0.26, p < 0.00) and albumin levels (β = −0.36, p < 0.00), positively by BMI (β = 0.76, p < 0.00). TNFα and TGFβ1 as dependent variables were found to correlate with α-Klotho (β = 0.41, p < 0.00) and plasma creatinine (β = 0.30, p < 0.003), as well as with fetuin-A (β = −0.24, p < 0.02) and plasma albumin (β = 0.33, p < 0.002), Fetuin-A showed significant negative correlation with age (β = −0.225, p < 0.05), TGF-β1 (β = −0.228, p < 0.02), and dialysis time (β = −0.26, p < 0.01), while positive relationship was found between fetuin-A and triglyceride levels (β = 0.43, p < 0.00). α-Klotho correlated positively with TNF-α (β = 0.44, p < 0.00) and negatively with plasma calcium (β = −0.24, p < 0.01). Conclusions: Our study confirmed that the pro-inflammatory cascade of arteriosclerosis was activated and inflammatory biomarkers (hsCRP, TNF-α, TGF-β1) prevailed over protective factors (vitamin D, α-Klotho, Fetuin-A) in patients on hemodialysis. We demonstrated that PWV was significantly affected by total cholesterol, fetuin-A and dialysis time. Several clinical and laboratory factors were associated with pro- and anti-inflammatory biomarkers rather than PWV.

Relationship between vitamin D-binding protein polymorphisms and blood vitamin D level in Korean patients with COPD.

BackgroundIn chronic obstructive pulmonary disease (COPD), the blood vitamin D3 level is generally low, and genetic polymorphisms of vitamin D-binding protein encoded by the GC gene are associated with COPD development. In this study, we examined the relationship between GC polymorphisms and plasma vitamin D3 level in Korean patients with COPD.MethodsThe study included 175 COPD patients from the Korean Obstructive Lung Disease Cohort. Multivariate analysis was conducted with adjustment for age, body mass index (BMI), lung function, smoking status, smoking amount, and seasonal variation in blood vitamin D level. Vitamin D deficiency was defined as a plasma 25-hydroxyvitamin D3 level lower than 20 ng/mL.ResultsThe mean plasma vitamin D3 level was 17.5 ng/mL. The GC1F variant (44.3%) and genotype 1F-2 (27.4%) were the most common. The plasma vitamin D3 level was lower in patients with the GC2 variant (estimated =−3.73 ng/mL) and higher in those with genotype 1F-1S (estimated =4.08 ng/mL). The GC2 variant was a significant risk factor for vitamin D deficiency (odds ratio =2.41). Among COPD clinical parameters, vitamin D deficiency was associated with a lower ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) regardless of GC polymorphisms. FEV1/FVC was higher in patients with genotype 1F-1F (estimated =3.61%) and lower in those with genotype 1F-2 (estimated =−3.31%). The 6-minute walking distance was shorter for patients with the GC1F variant (estimated =−38.91 m) and longer for those with the GC2 variant (estimated =26.98 m). The emphysema index was higher for patients with the GC1S variant (estimated =6.56%) and genotype 1F-1S (estimated =9.86%), regardless of the vitamin D level.ConclusionThe GC2 variant is a risk factor for vitamin D deficiency, and genotype 1F-1S is a protective factor against vitamin D deficiency. GC polymorphisms and vitamin D deficiency correlate with clinical outcomes for Korean patients with COPD.

Lactose Intolerance, calcium, vitamin D and parathyroid hormone levels in type 2 diabetic patients

BackgroundType 2 diabetes mellitus is a chronic metabolic disorder. Common gastrointestinal symptoms in type 2 diabetic patients are nausea, vomiting, flatulence, constipation and/ or diarrhea. Reason for these symptoms may be lactose intolerance. Vitamin D, calcium and parathyroid hormone further regulate the bone mineralization in our body.AimThe present study was planned to measure lactose intolerance, levels of vitamin D, calcium, and parathyroid hormone in type 2 diabetic patients.Material and Methods150 patients and 150 age and sex matched healthy controls attending Endocrinology Clinic in PGI, Chandigarh were enrolled. Lactose intolerance was measured using non‐invasive lactose breath test. 25‐hydroxyvitamin D3 and Parathyroid hormone were measured in plasma using immunoassay. Plasma calcium was measured using auto analyzer. T score was recorded from DXA scan for bone mineral density measurement.ResultsLactose intolerance was observed in 89/150 (59.3%) diabetic patients and 63/150 (42%) in controls. Levels of vitamin D3, calcium and parathyroid hormone were significantly less in diabetic patients as compared to controls. Furthermore, levels of plasma vitamin D3, calcium and parathyroid hormone were more decreased in lactose intolerant diabetic patients than lactose tolerant patients. 67% of diabetic patients suffered from osteoporosis and 20% of controls. 80% diabetic patients and 16% controls with osteoporosis suffered from lactose intolerance.ConclusionFrom this study we can conclude that measurement of lactose intolerance using non‐invasive lactose breath test is suggested for type 2 diabetic patients so that deficiency of vitamin D and calcium can be taken care off.Support or Funding InformationIndian Council of Medical Research, New Delhi, India

Patients with type 2 diabetes have reduced levels of plasma vitamin D3 and are well correlated with the oxidative stress parameters

Background: Diabetes has emerged as an epidemic in this country as well as worldwide. Increased oxidative stress and decreased antioxidant defense are established etiological factors of this multifactorial disease. Some of the recent studies reported deficiency of vitamin-D3 in type-2 diabetic patients. Aims and Objectives: This study was aimed to estimate the total oxidative stress (TOS), the total antioxidant defense (TAD) and the plasma 25-hydroxy vitamin D3 levels in patients of type-2 diabetes patients with an objective to elucidate if there is any significant correlation between the TOS, TAD and vitamin D3 levels.Materials and Methods: The study was conducted in forty patients recently diagnosed type-2 diabetic and the findings were compared with age/sex matched healthy controls. Total oxidative stress and TAD values was estimated by two simple colorimetric tests developed and standardized in our laboratory, plasma 25-hydroxy vitamin D3 by standardized ELISA method.Results and Discussion: The levels of vitamin D3 in patients was found to be 50.17 ± 15.85ng/ml which was significantly decreased (P&lt;0.001) when compared to healthy control group (75.42 ± 9.59 ng/ml). The plasma vitamin D3 levels show a significant positive correlation (r=0.564, P&lt;0.001) with the TAD values and a significant negative correlation (r=-0.561, P&lt;0.001) with the TOS values in the study subjects. There is significant positive correlation of 25-OH vitamin-D3 with antioxidant defense and significant negative correlation with oxidative stress observed in the current study, and the levels of vitamin D3 were significantly decreased in type-2 diabetes when compared to the healthy controls.Conclusion: The type-2 diabetes patients are usually associated with vitamin D3 deficiency which is significantly correlated with the oxidative stress conditions in this group of patients.Asian Journal of Medical Sciences Vol. 7(3) 2016 35-40

Impact of Vitamin D Supplementation on Gross Motor Development of Healthy Term Infants: A Randomized Dose-Response Trial

ABSTRACTIn addition to benefits for bone health, vitamin D is implicated in muscle function in children and adults. Aims: To determine if vitamin D dosage positively correlated with gross motor development at 3 and 6 months of age. We hypothesized that higher doses would be associated with higher scores for gross motor skills. Methods: A consecutive sample of 55 healthy, term, and breastfed infants from Montreal, Canada were recruited from a randomized trial of vitamin D supplementation between 2009 and 2012. Infants were randomized to 400 International Units (IU) (n = 19), 800 IU (n = 18) or 1,200 IU (n = 18) vitamin D3/day. Motor performance at 3 and 6 months was quantified by the Alberta Infant Motor Scale (AIMS). Plasma vitamin D3 metabolites were measured by tandem mass spectrometry. Results: AIMS scores did not differ at 3 months. However, total AIMS scores and sitting subscores were significantly higher at 6 months in infants receiving 400 IU/day compared to 800 IU/day and 1,200 IU/day groups (p < .05). There were weak negative correlations with length and C-3 epimer of 25(OH)D. Conclusions: In contrast to our hypothesis, gross motor achievements were significantly higher in infants receiving 400 IU/day vitamin D. Our findings also support longer infants being slightly delayed.

Host vitamin D status is dependent on the microbiota. (MUC9P.747)

Abstract Vitamin D deficiency is linked to susceptibility to inflammatory bowel disease (IBD). Mice deficient in vitamin D are more susceptible to experimental colitis than supplemented mice. Vitamin D alters the microbiota suggesting some of the effects of vitamin D on IBD are due to changes in the microbiota. Here we explored how the microbiota affect vitamin D metabolism using germ-free (GF) mice. Vitamin D is converted to 25D3. 25D3 is converted primarily in the kidney to 1,25D3, by 1α-OHase (Cyp27B1), or to 24,25D3 for degradation. Expression of Cyp27B1 was significantly higher in conventional (CV) versus GF kidneys. GF mice were given vehicle or 5μg vitamin D3 for 14 days and then conventionalized while maintaining their respective treatments for another 14 days. Liquid chromatography mass spectrometry was used to measure plasma vitamin D3, 25D3, 24,25D3, and 1,25D3 from GF mice before and after conventionalization. Vitamin D supplementation was less effective in GF mice. Conventionalized mice absorbed more vitamin D and had higher 25D3, 1,25D3, and 24,25D3. Furthermore, after correcting for differences in absorption between GF and CV mice, 1,25D3 was still significantly decreased in GF mice. This indicates GF mice neither absorb nor metabolize vitamin D normally. Differences in vitamin D metabolism between GF and CV mice suggest the microbiota play a role in regulating host vitamin D status, which could affect host immune responses and susceptibility to diseases like IBD.

Simultaneous determination of oxysterols, cholesterol and 25-hydroxy-vitamin D3 in human plasma by LC-UV-MS.

BackgroundOxysterols are promising biomarkers of neurodegenerative diseases that are linked with cholesterol and vitamin D metabolism. There is an unmet need for methods capable of sensitive, and simultaneous quantitation of multiple oxysterols, vitamin D and cholesterol pathway biomarkers.MethodsA method for simultaneous determination of 5 major oxysterols, 25-hydroxy vitamin D3 and cholesterol in human plasma was developed. Total oxysterols were prepared by room temperature saponification followed by solid phase extraction from plasma spiked with deuterated internal standards. Oxysterols were resolved by reverse phase HPLC using a methanol/water/0.1% formic acid gradient. Oxysterols and 25-hydroxy vitamin D3 were detected with atmospheric pressure chemical ionization mass spectrometry in positive ion mode; in-series photodiode array detection at 204nm was used for cholesterol. Method validation studies were performed. Oxysterol levels in 220 plasma samples from healthy control subjects, multiple sclerosis and other neurological disorders patients were quantitated.ResultsOur method quantitated 5 oxysterols, cholesterol and 25-hydroxy vitamin D3 from 200 μL plasma in 35 minutes. Recoveries were >85% for all analytes and internal standards. The limits of detection were 3-10 ng/mL for oxysterols and 25-hydroxy vitamin D3 and 1 μg/mL for simultaneous detection of cholesterol. Analytical imprecision was <10 %CV for 24(S)-, 25-, 27-, 7α-hydroxycholesterol (HC) and cholesterol and ≤15 % for 7-keto-cholesterol. Multiple Sclerosis and other neurological disorder patients had lower 27-hydroxycholesterol levels compared to controls whereas 7α-hydroxycholesterol was lower specifically in Multiple Sclerosis.ConclusionThe method is suitable for measuring plasma oxysterols levels in human health and disease. Analysis of human plasma indicates that the oxysterol, bile acid precursors 7α-hydroxycholesterol and 27-hydroxycholesterol are lower in Multiple Sclerosis and may serve as potential biomarkers of disease.

Hypovitaminosis D in children with familial Mediterranean fever.

Vitamin D deficiency or insufficiency plays a role in the initiation and perpetuation of certain autoimmune diseases. The purpose of this study was to measure the vitamin D status of children with Familial Mediterranean Fever (FMF) and compare it to their healthy peers. A total of 50 FMF patients and 49 healthy children were enrolled in this prospective study. Vitamin D levels were measured via HPLC. Demographic data, FMF symptom severity scores and the levels of other disease activity markers were retrieved from our hospital database. The mean age and gender balance of patients and controls were similar, being 8.4 ± 3.8 years and 19 male patients, and 9.1 ± 3.0 years and 25 male controls, respectively. The mean 25(-OH) vitamin D3 levels were 15.94 ± 9.66 µg/L in FMF patients and 41.22 ± 21.31 µg/L in controls. Vitamin D levels were normal in 12% of FMF patients, insufficient in 62% and deficient in 26%. No vitamin D deficiency was evident in any control subject; 30% had insufficient and 70% had normal vitamin D levels. Plasma vitamin D3 levels were similar in all patients despite varying FMF symptom severity scores. Vitamin D deficiency is frequent in children with FMF but is not associated with disease severity score.

Effects of Vitamin D3 Supplementation on Lung Function of Healthy Non-Smoking Young Iraqi Subjects

Background: There is an increasing evidence that vitamin D3 improves lung function in respiratory diseased subjects. Higher plasma vitamin D3 concentrations are also linked to better lung function in several communities. Objectives: To study the effects of single oral vitamin D3 supplementation (600 IU) on lung function in healthy non-smoking young Iraqi subjects. Methodology: Spirometric tests represented by forced vital capacity (FVC), forced expiratory volume in first one second (FEV1) and forced expiratory volume ratio (FEV%) were done for 82 healthy non-smoking young Iraqi college students (38 males and 44 females) in two occasions one month apart (first and second visits). They were divided into two main groups: Control group (CRL) and Vitamin D3 group (VTD). CRL group contained 42 subjects (18 males and 24 females) who didn't receive oral vitamin D3 supplementation. VTD group contained 40 subjects (20 males and 20 females) who received single oral vitamin D3 supplementation (600 IU). The ages of the study population were the same (20 years) and their heights were not significantly different within each sex. Results: It was found that FVC and FEV1 (but not FEV%) were significantly higher (of 80 ml to 130 ml) in the second visit than in the first visit in both groups (VTD and CRL) and in either sex (all p&lt;0.05). Conclusion: Depending on the results of present research; it is concluded that in healthy non-smoking Iraqi subjects; vitamin D3 doesn't seem to have positive effects on Spirometric measurements other than these observed in control subjects.

CORRELATION BETWEEN VITAMIN D3 AND FASTING PLASMA GLUCOSE, A1C AND SERUM LIPIDS IN NON-DIABETIC SUBJECTS

Objective: To study the correlation between vitamin D3 and fasting plasma glucose, haemoglobin A1c, and lipids in non diabetic persons . Patients and methods: Eighty-eight healthy Saudi females; aged 18 to 50 years were recruited from an endocrine clinic in a tertiary care hospital in southern region of Saudi Arabia. Exclusion Criteria: Diabetes mellitus, malabsorption, significant cardiac, hepatic, oncologic, renal or psychiatric disease. Use of medications known to affect serum vitamin D3, plasma glucose or lipid profile. After an overnight fasting blood samples were collected for laboratory measurement of fasting plasma glucose, lipids, haemoglobin A1c (HbA1c) and vitamin D3 [25(OH)D3]. Results: Fasting plasma glucose inversely correlated to vitamin D3 level (p=0.034). No significant correlation was found between vitamin D3 and HbA1c (p=0.23) or any of the components of lipid profile. Conclusion: It seems that vitamin D3 affects glucose homeostasis. The lower the vitamin D3 level, the higher the blood sugar. Vitamin D3 level is not correlated to HbA1c in our study population of non-diabetic females. This may be attributed to age and ethnicity of the study group. Vitamin D3 level is not correlated to fasting lipid profile.

Altered Plasma Concentrations of Trace Elements in Ulcerative Colitis Patients Before and After Surgery

Ileal pouch-anal anastomosis (IPAA) is a classical surgery for ulcerative colitis patients. However, knowledge on trace element alteration in patients who had undergone this surgery is limited. This study was conducted to assess trace element alteration in patients with ulcerative colitis before and after ileal pouch-anal anastomosis. Preoperative (40) and postoperative (35) ulcerative colitis patients were studied. The dietary assessment of trace element intake was undertaken by a semiquantitative food frequency questionnaire. Patients' trace element status of zinc, copper, manganese, selenium, calcium, iron, and vitamin D3 was assessed by measuring their blood concentrations. We found that with the similar dietary intake, there was no statistical difference in the concentrations of plasma copper, iron, calcium, and vitamin D3 in the two groups (P > 0.05). Compared with preoperative patients, postoperative patients had higher concentrations of plasma zinc (14.51 ± 4.75μmol/l) and manganese (0.21 ± 0.11μmol/l) and lower concentrations of plasma selenium (0.86 ± 0.58μmol/l). Both preoperative and postoperative mean concentrations of plasma calcium and vitamin D3 were below their reference range, respectively. We conclude that IPAA does not seem to alter patients' abnormal trace elements completely. It is important to monitor and supply some specified trace elements even in postoperative patients.

PLASMA VITAMIN D LEVEL AMONG WOMEN WITH AND WITHOUT POLYCYSTIC OVARIAN SYNDROME

Polycystic ovarian syndrome (PCOS) is an endocrine problem in women of reproductive age. While Vitamin D is involved in calcium and phosphorus homeostasis, evidence indicates an association between vitamin D deficiency and metabolic syndromes in PCOS.This study evaluated plasma vitamin D levels in polycystic and non‐polycystic women following supplementation with long chain omega‐3 PUFA and Vitamin D3. Twelve polycystic and 8 non polycystic women consumed 2.3g n‐3 PUFA for three months and 1000IU of Vitamin D3 and n‐3 PUFA for an additional two months. Fasting blood samples were collected monthly with plasma Vitamin D levels assessed by HPLC.Plasma Vitamin D3 was not affected by supplementation in either group nor was there a difference in plasma Vitamin D3 between PCOS and non‐PCOS at baseline. Plasma Vitamin D2 was 2‐fold higher in PCOS than non‐PCOS at baseline. Plasma vitamin D2 was reduced with exclusive n‐3 PUFA ingestion and further reduced with Vitamin D3 supplementation. However, plasma vitamin D2 levels remained over 2‐fold higher in PCOS than non‐PCOS throughout (P≤ 0.05). Vitamin D3 supplementation may not be critical for women with PCOS. However, as Vitamin D2 was significantly higher in polycystic versus non‐ polycystic women, and was responsive to n‐3 PUFA ingestion, D2 supplementation may value in both groups.

Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementation

It is sometimes assumed that dietary fat is required for vitamin D absorption, although the impact of different amounts of dietary fat on vitamin D absorption is not established. This study was conducted to determine whether the presence of a meal and the fat content of the meal influences vitamin D absorption or the 25-hydroxyvitamin D [25(OH)D] response to supplemental vitamin D3 . Based on earlier studies in rats we postulated that absorption would be greatest in the low-fat meal group. Sixty-two healthy older men and women were randomly assigned to one of three meal groups: no meal, high-fat meal, or low-fat meal; each was given a monthly 50,000 IU vitamin D3 supplement with the test breakfast meal (or after a fast for the no-meal group) and followed for 90 days. Plasma vitamin D3 was measured by liquid chromatography-mass spectroscopy (LC/MS) before and 12 hours after the first dose; plasma 25(OH)D was measured by radioimmunoassay at baseline and after 30 and 90 days. The mean 12-hour increments in vitamin D3 , after adjusting for age and sex, were 200.9 nmol/L in the no-meal group, 207.4 nmol/L in the high-fat meal group, and 241.1 nmol/L in the low-fat meal group (p = 0.038), with the increase in the low-fat group being significantly greater than the increases in the other two groups. However, increments in 25(OH)D levels at 30 and 90 days did not differ significantly in the three groups. We conclude that absorption was increased when a 50,000 IU dose of vitamin D was taken with a low-fat meal, compared with a high-fat meal and no meal, but that the greater absorption did not result in higher plasma 25(OH)D levels in the low-fat meal group.

Expression of 1alpha-HYD and 24-HYD in bovine kidney mediated by vitamin D3 supplementation

In order to better understand vitamin D3 in cattle metabolism, we quantified 1alpha-HYD and 24-HYD gene expression. In the kidneys of 35 male Nellore cattle, these were divided into a control group and two treatment groups (2 x 10(6) international units of vitamin D3 administered for 2 or 8 consecutive days pre-slaughter). Vitamin D3 supplementation resulted in a significant increase in 1alpha-HYD gene expression; however, significantly increased 24-HYD gene expression was only detected in cattle that had 8 days of supplementation. The finding of upregulation of 24-HYD due to vitamin D supplementation is in line with the expected rise in 24,25-di-hydroxy-vitamin D3 synthesis observed when plasma vitamin D3 concentrations are high, stimulating excretion by the organism. On the other hand, upregulation of 1alpha-HYD was unexpected, since vitamin D3 supplementation has been reported to impact these two genes in opposite directions. We conclude that vitamin D3 metabolism in these animals is more complex than previously reported.

Vitamin D levels in Malawian infants from birth to 24 months

We measured longitudinal levels of vitamin D in unsupplemented Malawian infants at 0 (birth), 2, 12, 15, 18 and 24 months of age. Matched maternal plasma and breast milk vitamin...

Coronary artery vitamin D receptor expression and plasma concentrations of 25-hydroxyvitamin D: their association with atherosclerosis.

The aim of this study was to analyze coronary artery vitamin D receptor (VDR) expression, the plasma concentrations of 25-hydroxyvitamin D3 (25OHD3), and their relationship with coronary artery atherosclerosis. Premenopausal cynomolgus monkeys were fed atherogenic diets containing the equivalent of 1,000 IU/day of vitamin D3. Protein was derived from casein-lactalbumin (C/L, n = 10), soy protein isolate (soy, n = 10), or a combination (n = 19). After 32 months of consuming the diets, each monkey underwent surgical menopause. After 32 postmenopausal months, coronary atherosclerosis was measured in the left circumflex (LCX) artery and left anterior descending (LAD) artery. VDR expression was determined for the LAD, and 25OHD3 concentrations were assessed. Both the cross-sectional area of atherosclerotic plaques (in square millimeters) and plaque thickness (in millimeters) in the LCX as well as the LAD arteries were analyzed in these monkeys. Those with higher plasma vitamin D3 concentrations and higher VDR were compared with those with higher plasma 25OHD3 concentrations and lower VDR. Significantly smaller plaque sizes were noted with higher plasma 25OHD3 concentrations and higher VDR. For the LCX artery, there was also a significantly lower plaque size (both plaque thickness and cross-sectional area) in those with higher quantities of VDR and lower 25OHD3 concentrations versus those with lower quantities of VDR and higher plasma concentrations of 25OHD3 (P = 0.009 and P = 0.040, respectively). Cynomolgus monkeys with higher quantities of VDR have significantly less atherosclerosis than do those with lower quantities of VDR and higher plasma 25OHD3 concentrations. If these findings translate to human beings, it might explain why some individuals with higher plasma concentrations of 25OHD3 have more coronary artery atherosclerosis.

Simultaneous Quantification of Vitamin D-2, Vitamin D-3, and their 25- Hydroxy Metabolites in Human Plasma by High Performance Liquid Chromatography

A simple and reliable High Performance Liquid Chromatography (HPLC) method for simultaneous determination of vitamin D-2 (VD-2), vitamin D-3 (VD-3), 25-hydroxyvitamin D-2 [25 (OH) VD-2], and 25-hydroxyvitamin D-3 [25(OH) VD-3] in human plasma was developed and validated. Plasma samples were deproteinized with a mixture of methanol and 2-proponol, and extracted with hexane. After evaporation, the residue was dissolved in methanol:water (9.6:0.4, v/v), centrifuged, and then clear solution was injected onto Zorbax C18 column. The mobile phase (gradient elution mode) consists of methanol, acetonitrile, and water (pH = 3.0); the eluents were monitored by photodiode array detector (wavelength set at 265 nm). The relationship between the concentration of VD-2, VD-3, 25(OH) VD-2, 25(OH) VD-3 in plasma and their peak area ratio to the IS was linear over the range of 5 - 100 ng/mL. The coefficients of variation for inter-day and intra-day assay were all ≤ 9.7% and biases ≤ 13.1%. Mean extraction recoveries of VD-2, VD-3, 25(OH) VD-2, and 25(OH) VD-3 from plasma were all over 80%. The method was applied for the determination of vitamin D levels in plasma obtained from healthy subjects. Further, it was used to assess the stability of VD-2, VD-3, 25(OH) VD-2, and 25(OH) VD-3 in plasma under various conditions encountered in the clinical laboratory.

Identification of a mechanism for increased cardiovascular risk among individuals with low vitamin D concentrations.

The aim of this study was to investigate the plasma concentrations of vitamin D and its association with plasma lipid profiles. Plasma vitamin D3 and lipid concentrations were measured in 119 female cynomolgus monkeys (premenopausal, n = 49; ovariectomized, n = 70) consuming approximately 1,000 IU per day of vitamin D3. In a subset of the ovariectomized monkeys (n = 23), vitamin D3 was remeasured after 6 months. The concentrations of vitamin D3 were analyzed as a continuous variable and were divided at the median into high (≥48 ng/mL) versus low (<48 ng/mL) groupings. Among the 119 monkeys, the range of vitamin D3 concentrations was 24.0 to 95.2 ng/mL (mean ± SD, 48.5 ± 12.7 ng/mL). Plasma vitamin D3 concentration was positively associated with high-density lipoprotein cholesterol (HDL-C; P = 0.003). Monkeys in the high vitamin D3 group had a significantly greater plasma HDL-C concentration (57.9 mg/dL) than did those in the low vitamin D3 group (47.1 mg/dL; P = 0.001). Although the difference was not significant (P = 0.120), the monkeys in the high vitamin D3 group had a decreased total plasma cholesterol-to-HDL-C ratio compared with those in the low vitamin D3 group (5.4 and 6.2, respectively), potentially putting them at lower risk of atherosclerosis development. Given that the monkeys all consumed a diet replete in vitamin D3, it seems that individual differences in vitamin D absorption or metabolism may have determined whether the monkeys had high or low concentrations of vitamin D3. Lower vitamin D3 was associated with a more atherogenic lipid profile, a major risk factor for progressing to coronary artery atherosclerosis in monkeys and human beings.