Vitamin D Stability in Milk

A method was developed to determine vitamin D₃ in milk. It includes saponification, solid phase extraction and HPLC. Recovery of added vitamin D₃ was 93%. Vitamin D₃ concentrations in commercial milks were variable. Stability studies showed that on exposure to light, there was a slight loss of vitamin D₃ from fortified milk. Air exposure did not affect stability in milk. Upon standing there was some stratification of the vitamin in milk containers with slightly more vitamin D₃ in the top layer of milk than at the bottom.     

Vitamin D and multiple sclerosis

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system and characterized by neurological and cognitive manifestations. The disease is more common in populations living in high altitudes with low sun exposure, women more than men, and certain ethnic backgrounds more than others. The etiology of MS is yet unknown, although several factors have been implicated in its development. These include genetic factors and environmental factors as well as dietary components and their interactions. Among the dietary components that have recently attracted the attention is vitamin D. This mini-review summarizes current knowledge on the potential use of vitamin D in the protection and treatment of MS. In addition, the mechanism(s) by which vitamin D plays a role in the development and/or protection from MS are discussed.     

Vitamin D status and glucose metabolism in youth

This study aimed to review and synthesize the available scientific evidence on the relationship between serum 25(OH)D concentrations and glucose metabolism among adolescents. A total of 19 studies were included. Many studies did not find a relation between 25(OH)D concentrations and insulin sensitivity, but most studies have shown that vitamin D status influences glucose dysregulation in youth due to particularities of this life stage. Considering the prevalence of vitamin D deficiency and insufficiency were high among adolescents, the importance for vitamin D status correction in this young group, in which chronic diseases are not expected but getting every day more common, is mandatory.     

Vitamin D3 toxicity in dairy cows

Large parenteral doses of vitamin D3 (15 to 17.5 x 10(6) IU vitamin D3) were associated with prolonged hypercalcemia, hyperphosphatemia, and large increases of vitamin D3 and its metabolites in the blood plasma of nonlactating nonpregnant and pregnant Jersey cows. Calcium concentrations 1 day postpartum were higher in cows treated with vitamin D3 about 32 days prepartum (8.8 mg/100 ml) than in control cows (5.5 mg/100 ml). None of the cows treated with vitamin D3 showed signs of milk fever during the peripartal period; however, 22% of the control cows developed clinical signs of milk fever during this period. Signs of vitamin D3 toxicity were not observed in nonlactating nonpregnant cows; however, pregnant cows commonly developed severe signs of vitamin D3 toxicity and 10 of 17 cows died. There was widespread metastatic calcification in the cows that died. Because of the extreme toxicity of vitamin D3 in pregnant Jersey cows and the low margin of safety between doses of vitamin D3 that prevent milk fever and doses that induce milk fever, we concluded that vitamin D3 cannot be used practically to prevent milk fever when injected several weeks prepartum.     

Vitamin A intoxication from reef fish liver consumption in Bermuda

We report three historical cases of severe vitamin A intoxication in anglers who had consumed reef fish liver caught in Bermuda. The subsequent analyses of 35 fish livers from seven different fish species revealed that very high concentrations of vitamin A exist in tropical fish liver, even in noncarnivorous fish species. Large variations in concentrations were observed between specimens and between species. The angling population and (especially) pregnant women should be advised of this potential health threat.     

Vitamin D binding factors in bovine blood.

Both 25 [25,26-hydrogen-3] hydroxycholecalciferol and [1alpha,2alpha-hydrogen-3] cholecalciferol were added to bovine plasma in vitro. Analysis by gel-filtration and ion exchange chromatography, electrophoresis, ultracentrifugation, competitive binding specificity studies, and plasma stripping showed that vitamin D circulated with a protein of alpha-globulin mobility. This globulin had a much higher affinity for 25-hydroxycholecalciferol while vitamin D3 appeared to be associated first with an alpha-lipoprotein and with time because associated with the alpha-globulin. This alpha-globulin had a molecular weight of approximately 70,000 as determined by gel-filtration. Cholecalciferol appeared to bind tightly to the alpha-lipoprotein and resisted being stripped from the plasma. Thus, alpha-globulin appears to be the major carrier of vitamin D in the blood while the alpha-lipoprotein may aid in the transfer of cholecalciferol from the gut to the liver via the lymph system.     

Vitamin D3 fortification and quantification in processed dairy products

The purpose of this research was to examine the fortification and retention of vitamin D₃ added to lab-scale Cheddar cheese-like matrix, yogurt and ice cream, using two means of incorporation: pre-dissolved crystalline vitamin D₃ and emulsified vitamin D₃. An improved extraction method was developed, which yielded near total recovery from all samples, and in particular, from difficult-to-extract cheese samples. With the cheese, the loss of vitamin D₃ into whey was 7–9% (w/w). Storage stability of the vitamin in the cheeses differed: over three months, the emulsified form was more stable than the crystalline form. Conversely, both forms of vitamin D₃ were stable in experimental yogurts and ice creams during the expected shelf life of these products. These processed dairy products appear to be suitable for vitamin D₃ fortification.     

Effects of Vitamin D3‐Enriched Diet on Egg Yolk Vitamin D3 Content and Yolk Quality

A 40‐wk experiment was conducted using Hy‐Line W‐36 laying hens (19‐wk old) to investigate the impact of feeding cholecalciferol‐enriched diets on egg yolk quality. Feeds were enriched with 4 cholecalciferol levels, 9700 (diet 2), 17200 (diet 3), 24700 (diet 4), and 102200 (diet 5) IU/kg feed. The control (diet 1) contained 2200 IU cholecalciferol/kg feed. Eggs from each replicate group of enriched diets were collected daily and the yolks were pooled into 2‐d period during the first 2 wk. During weeks 3, 4, 6, 8, 12, 16, 20, 24, 28, 32, 36, and 40, pooled samples were generated by daily collection of 3 consecutive days of egg production. The cholecalciferol content of egg yolk from the enriched diets increased rapidly during the first 3 wk. The peak cholecalciferol concentrations in egg yolk that occurred at week 3 were 865, 1641, 2411, and 34815 IU/100 g egg yolk (wet basis) from diet 2 to 5. The average cholecalciferol concentration in yolk during weeks 3 to 40 and the deposition rate of cholecalciferol during the first 3 wk were both linearly increased with the dietary cholecalciferol level when the feed contained no more than 24700 IU/kg cholecalciferol. Egg yolk lipid profile (total lipid content, fatty acid composition, phospholipid composition, and unsaponifiables), physical and functional properties (yolk viscosity and emulsifying property), and sensory quality of hard‐boiled egg yolk were not affected by the cholecalciferol enrichment in the feed. Practical Application: A linear dose‐response relationship between dietary vitamin D₃ level and egg yolk vitamin D₃ content was established at relatively low enrichment levels. Such relationship can be used to formulate feed to achieve a target egg vitamin D level. High vitamin D yolk showed no difference from the conventional yolk in other compositional, functional, and sensory properties.     

Vitamin D3 and D3 metabolites in young goats fed varying amounts of calcium and vitamin D3

Twenty-four male goats, 2 to 4 wk of age, were allotted to four dietary treatments in a 2 X 2 factorial design and, for 20 wk, were fed a milk diet at 12.5% body weight. Treatments varied in amounts of supplemental calcium and vitamin D3. Daily allowances per kilogram body weight were: 9.4 IU vitamin D3 (basal), 9.4 IU vitamin D3 plus 406 mg calcium carbonate (basal plus Ca), 940 IU vitamin D3 (basal plus D3), and 940 IU vitamin D3 plus 406 mg calcium carbonate (basal plus Ca plus D3). At the end of wk 7, a corn supplement was added to all diets at 1% body weight daily. Addition of vitamin D3 to the diet resulted in a dramatic increase in plasma concentrations of vitamin D3. Goats in the basal plus D3 and basal plus Ca plus D3 groups had nearly 100 X greater concentrations of vitamin D3 than goats in the basal and basal plus Ca groups. When greater amounts of vitamin D3 were fed, dietary calcium interacted to decrease plasma vitamin D3 concentrations. Plasma concentrations of 25-hydroxyvitamin D3 were unaffected by additional dietary calcium but were increased by dietary vitamin D3, increasing sixfold to seven-fold in the basal plus D3 and basal plus Ca plus D3 groups. Supplemental calcium resulted in decreased plasma 1,25-dihydroxyvitamin D3. No signs of vitamin D toxicity were noted. The physiological responses reported implicate the goat as a potential animal model for vitamin D research in dairy cattle.     

学龄儿童维生素D水平与矿物元素相关性分析

目的:了解广西学龄儿童维生素D(VD)营养状况与矿物元素含量关系,为防治儿童微量营养素缺乏提供科学依据。方法:采用随机整群抽样方法,抽取广西融水县1所中心小学512名6—14岁儿童,采集静脉血,用酶联免疫吸附法测定血清25-羟维生素D[25-(OH)D]浓度,测量身高、体重,计算体质指数(BMI),测定全血铜(Cu)、锌(Zn)、钙(Ca)、铁(Fe)、镁(Mg)元素含量。结果:研究对象血清25-(OH)D平均浓度为22.86±9.37ng/mL,存在男女性别间差异(P0.05)。血清25-(OH)D水平、Cu、Zn、Fe在各年龄组间差异有统计学意义(P0.05),Ca、Mg含量差异不明显(P0.05)。血清25-(OH)D水平与全血钙或铁含量呈负相关(P0.01);与全血镁含量呈正相关(P0.01);与全血铜或锌含量关系不明显(P0.05)。血清25-(OH)D水平与BMI相关性无显著性意义(P0.05),男生BMI高于女生(P0.05)。维生素D缺乏率随年龄增长呈下降趋势(P0.05)。各年龄组钙、铁、锌缺乏率差异不明显(P0.05)。结论:维生素D营养状况与全血钙、铁、镁含量关系密切,儿童维生素D水平受年龄和性别影响,应定期监测,以保障儿童健康成长。     

VD强化及其稳定性研究进展

近年来,国内外VD缺乏的现象越来越受到人们的重视。本文对目前VD的补充、强化、强化载体以及在强化载体中的稳定性方面的研究进展作一综述,以期为加强我国VD强化食品研发力度和增加VD的有效摄入量提供一定的参考。     

维生素D_2微囊的制备与研究

以明胶和环糊精为壁材 ,采用凝聚法制备VD2 微囊 ,通过真空干燥制得微囊成品。研究中发现 ,采用真空干燥法制备的微囊粒径较小 ( 0 1～ 0 5mm) ,稳定性好 ,经过 7d的高温 ( 60℃ )加速试验 ,微囊中VD2 的含量超过 83 5 % ,较好地增加了VD2 稳定性 ,可以作为食品的营养添加剂。     

Vitamin D and calcium metabolism in relation to different levels of vitamins B6 and D]

The influence of vitamin B6 deficiency on some vitamin D-dependent processes was studied in animals. The following parameters changing in relation to the level of vitamin D providing were investigated: activity of alkaline phosphatase in the serum and small intestine mucosa, the levels of Ca, P and parathormone, concentration of vitamin D metabolites and enzyme activity; and only 25-hydroxyvitamin D (25-OVD) concentration in the blood serum, under conditions of combined vitamin B6 and D deficiency was significantly lower as compared to cases with vitamin D deficiency alone. In the presence of vitamin B6 deficiency recovery of 25-OVD level in the blood serum, after vitamin D administration to the animals, had a tendency to delay as compared to that in the animals provided with vitamin B6. Vitamin B6 deficiency produced similar effect on 25-OVD 1-hydroxylase activity. The data obtained have evidenced a possibility of vitamin B6 influence on vitamin D metabolism.     

Remissionsspektrometrische Bestimmung von Vitamin D in di?tetischen Lebensmitteln

Zusammenfassung Es wird eine Analysenmethode zur Bestimmung von Vitamin D in diätetischen Lebensmitteln, speziell in Säuglingsnährmitteln, beschrieben. Nach 4 Reinigungs- bzw. Anreicherungsstufen (Extraktion, Verseifung, Säulenchromatographie, Dünnschichtchromatographie) wird der Vitamin-D-Gehalt auf der Dünnschichtplatte durch eine remissionsspektrometrische Bestimmung bei 265 nm ermittelt.

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Determination of vitamin D in dietetic food

Summary This method deals with the determination of vitamin D in dietetic food, specially in baby food. For this purpose normally 4 clean-up resp. enrichment steps are necessary (extraction, saponification, liquid-solid chromatography and TLC), followed by the determination of vitamin D by means of reflectance spectroscopy.

     

维生素D改善肥胖大鼠的脂代谢

本文研究维生素D改善肥胖大鼠脂代谢的作用。建立肥胖大鼠模型,正常组、模型组、高剂量组(2.40μg/mL)、中剂量组(1.20μg/mL)、低剂量组(0.60μg/mL)、奥利司他组(0.10 mg/mL)。统计体重、体长、Lee’s指数、附睾脂肪垫质量、脂肪体重指数,检测总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C),观察大鼠脂肪细胞形态学,检测过氧化物酶体增殖物激活受体γ(PPAR-γ)、瘦素、线粒体解偶联蛋白(UCP)蛋白表达。高剂量组大鼠体重250.76 g、Lee’s指数2.52%、附睾脂肪垫质量5.05 g、脂肪体重指数1.41 g、TC 1.96 mmol/L、TG 0.83 mmol/L、LDL-C 1.05 mmol/L低于模型组大鼠,HDL-C 0.59mmol/L高于模型组大鼠(p0.05)。高剂量组大鼠PPAR-γ、瘦素蛋白表达低于模型组大鼠,高剂量组大鼠UCP蛋白表达高于模型组大鼠(p0.05)。维生素D通过调控PPAR-γ、瘦素、UCP蛋白表达,改善大鼠脂代谢。     

Vitamin D Bioavailability: State of the Art

There has been renewed interest in vitamin D since numerous recent studies have suggested that besides its well-established roles in bone metabolism and immunity, vitamin D status is inversely associated with the incidence of several diseases, e.g., cancers, cardio-vascular diseases, and neurodegenerative diseases. Surprisingly, there is very little data on factors that affect absorption of this fat-soluble vitamin, although it is acknowledged that dietary vitamin D could help to fight against the subdeficient vitamin D status that is common in several populations. This review describes the state of the art concerning the fate of vitamin D in the human upper gastrointestinal tract and on the factors assumed to affect its absorption efficiency. The main conclusions are: (i) ergocalciferol (vitamin D₂), the form mostly used in supplements and fortified foods, is apparently absorbed with similar efficiency to cholecalciferol (vitamin D₃, the main dietary form), (ii) 25-hydroxyvitamin D (25OHD), the metabolite produced in the liver, and which can be found in foods, is better absorbed than the nonhydroxy vitamin D forms cholecalciferol and ergocalciferol, (iii) the amount of fat with which vitamin D is ingested does not seem to significantly modify the bioavailability of vitamin D₃, (iv) the food matrix has apparently little effect on vitamin D bioavailability, (v) sucrose polyesters (Olestra) and tetrahydrolipstatin (orlistat) probably diminish vitamin D absorption, and (vi) there is apparently no effect of aging on vitamin D absorption efficiency.

We also find that there is insufficient, or even no data on the following factors suspected of affecting vitamin D bioavailability: (i) effect of type and amount of dietary fiber, (ii) effect of vitamin D status, and (iii) effect of genetic variation in proteins involved in its intestinal absorption.

In conclusion, further studies are needed to improve our knowledge of factors affecting vitamin D absorption efficiency. Clinical studies with labeled vitamin D, e.g., deuterated or ¹³C, are needed to accurately and definitively assess the effect of various factors on its bioavailability.