1,25-二羟维生素D3与慢性淋巴细胞性甲状腺炎

1,25-二羟维生素D3[1,25(OH)2D3]是维生素D的活性形式,除了具有调节钙和骨新陈代谢的功能外,还具有调节免疫系统的作用,这种作用在多种自身免疫性疾病的动物模型中已得到证实,如1型糖尿病、多发性硬化症、类风湿关节炎、系统性红斑狼疮、Graves病等[1].慢性淋巴细胞性甲状腺炎(CLT)亦是常见的自身免疫性疾病,其与维生素D的相关报道相对较少,现就维生素D与CLT的相关研究进行综述.     

维生素D缺乏与儿童疾病表观遗传学研究

维生素D不仅对骨代谢有着经典的作用,同时在免疫、细胞增殖和分化中有重要的作用。最近的研究发现,孕期维生素D水平也可能通过表观遗传修饰影响到后代儿童期非骨骼系统疾病的易感性,如哮喘,自身免疫性疾病和神经精神疾病等。本文将综述维生素D缺乏与儿童疾病表观遗传学的研究进展。     

儿童血清维生素D水平、自噬、免疫调节及机体各系统疾病的相关性综述

维生素D对人体作用广泛且复杂,是一种与特异性受体相结合而发挥作用的一类脂溶性类固醇激素,其受体在多种组织细胞中都有分布,含量最多的器官为小肠、肾脏、甲状旁腺及骨骼,此外,心血管、胃肠道、中枢神经系统等其他脏器也有维生素D受体的表达。血清维生素D水平异常时,机体会出现相应的病理改变,如:呼吸道疾病、消化道疾病、泌尿系统疾病、风湿免疫疾病、自身免疫性疾病、肥胖等疾病,本文就维生素D水平、自噬、免疫调节及各系统疾病的相关性进行综述。     

中国人群维生素D营养状况

20世纪30年代人工合成维生素D后,维生素D一直被认定为是微量营养素,参与钙磷代谢,促进骨骼发育。但是近年来对维生素D代谢有了深入的研究,维生素D需要在体内转化成具有活性的维生素D,即25-OHD3和1,25-(OH)2D3后,才能发挥生理作用。几乎在身体各种器官组织内都有维生素D受体,维生素D通过这些受体发挥作用,因而维生素D被认定是激素类物质。维生素D具有广泛的作用:如提高免疫、预防自身免疫性疾病、骨关节炎、Ⅰ型糖尿病和Ⅱ型糖尿病、心血管病、抗肿瘤,甚至与改善肺功能、哮喘、脑发育及精神疾病有关[1],而调节钙磷代谢仅仅是它的一种营养功能。我国开展以血清25-OHD3水平评价维生素D营养的资     

铜陵市婴儿维生素D制剂服用情况调查分析

正维生素D是维持机体正常功能所必须一类脂溶性维生素,维生素D的缺乏在全世界范围内非常普遍,已成为公共卫生问题[1],维生素D缺乏不仅可使小儿患佝偻病,而且还与心血管疾病、呼吸系统疾病、自身免疫性疾病、肾脏、精神疾病等密切相关[2]。合理补充维生素D,对维持体内维生素D水平有重要意义。由于维生素D的应用在不同人群都存在不合理情况,为了解铜陵市婴儿维生素D服用情况,促进维生素D的合理服用,本文对铜陵市     

“维他命”的毒副作用

“维他命”是维生素的早期译名。顾名思义,维生素即维持生命的要素。然而,这类人体必须的且广泛存在于各种食品中的营养素,如使用不当,也能置人于死地。维生素分为两大类,一类是水溶性维生素,如维生素B_2、B_2、B_6、B_12、C等;另一类是脂溶性维生素,如维生素A、D、E等。一般人认为维生素是人体的营养素,多吃有益无害。甚至也有不少医生对病人     

维生素D营养状况与儿童疾病

血清25-(OH)D 水平可以作为维生素D营养状况的客观指标,一般认为血清25-(OH)D≥75 nmol/L是维生素D较为理想的水平。儿童是维生素 D缺乏的潜在高危人群,维生素 D缺乏不仅可使儿童患佝偻病,而且还与心脑血管疾病、呼吸系统疾病、自身免疫性疾病、肾脏疾病、神经精神疾病、肿瘤、糖尿病等密切相关。本文就此方面的研究进展进行系统综述。     

维生素D和维生素D缺乏性佝偻病的研究

进入21世纪,维生素D缺乏性佝偻病又出现了上升趋势.该文探讨了其病因:纯母乳喂养时间过长而未添加维生素D,尤其是那些摄入母亲自身是维生素D缺乏者乳汁的婴儿;由于各种原因造成婴儿日照时间减少,从而使得婴儿体内由皮肤转化的内源性维生素D的量大大减少;在很多温带地区移民人群中佝偻病的高发病率.因此,维生素D缺乏可能是一项国际妇幼保健问题,需再次强调对儿童及孕妇额外补充维生素D及日照的重要性.     

维生素D缺乏与儿童呼吸系统疾病新进展

维生素D是维持人体生长发育和健康所必需的营养要素之一, 据统计全球50%的人口存在维生素D缺乏的风险, 儿童是维生素D缺乏的潜在高危人群。目前越来越多的研究发现维生素D除了被用作预防和治疗佝偻病外, 还与儿童呼吸系统疾病有着密切联系, 如毛细支气管炎、儿童反复呼吸道感染、哮喘、肺结核、肺炎等, 以下就近些年维生素D与儿童呼吸系统疾病的研究近况作如下综述。     

如何预防儿童维生素D缺乏

维生素D是人体所需的一种非常重要的营养物质,是儿童必需的营养物质之一,其主要由自身合成,部分可从食物中摄取。维生素D对人体吸收钙、磷等矿物质起关键作用,可维持骨骼正常生长发育,提高骨强度,若维生素D缺乏会引起小儿佝偻病、手足抽搐,影响小儿的生长发育。为预防儿童维生素D缺乏,应从胎儿期开始,以婴儿为重点对象并持续到青春期。因此,孕妇及婴幼儿应增加户外活动,均衡膳食,并注重补充外源性维生素D,预防维生素D缺乏。     

Vitamin D deficiency, muscle function, and falls in elderly people

An inadequate serum vitamin D status is commonly seen in elderly people as the result of various risk factors interacting in this population. Apart from the well-known effects on bone metabolism, this condition is also associated with muscle weakness, predominantly of the proximal muscle groups. Muscle weakness below a certain threshold affects functional ability and mobility, which puts an elderly person at increased risk of falling and fractures. Therefore, we wanted to determine the rationale behind vitamin D supplementation in elderly people to preserve and possibly improve muscle strength and subsequently functional ability. From experimental studies it was found that vitamin D metabolites directly influence muscle cell maturation and functioning through a vitamin D receptor. Vitamin D supplementation in vitamin D-deficient, elderly people improved muscle strength, walking distance, and functional ability and resulted in a reduction in falls and non-vertebral fractures.In healthy elderly people, muscle strength declined with age and was not prevented by vitamin D supplementation. In contrast,severe comorbidity might affect muscle strength in such a way that restoration of a good vitamin D status has a limited effect on functional ability. Additional research is needed to further clarify to what extent vitamin D supplementation can preserve muscle strength and prevent falls and fractures in elderly people.     

Skeletal and extra-skeletal consequences of vitamin D deficiency

Vitamin D is obtained from cutaneous production when 7-dehydrocholesterol is converted to vitamin D(3) (cholecalciferol) by ultraviolet B radiation or by oral intake of vitamin D. Rickets appeared to have been conquered with vitamin D intake, and many health care professionals thought the major health problems resulting from vitamin D deficiency had been resolved. However, rickets can be considered the tip of the vitamin D deficiency iceberg. In fact, vitamin D deficiency remains common in children and adults. An individual's vitamin D status is best evaluated by measuring the circulating 25-hydroxyvitamin D (25(OH)D3) concentration. There is increasing agreement that the optimal circulating 25(OH)D3 level should be approximately 30 ng/mL or above. Using this definition, it has been estimated that approximately three-quarters of all adults have low levels. In utero and during childhood, vitamin D deficiency can cause growth retardation and skeletal deformities and may increase the risk of hip fracture later in life. Vitamin D deficiency in adults can exacerbate osteopenia and osteoporosis, cause osteomalacia and muscle weakness, and increase the risk of fracture. More recently, associations between low vitamin D status and increased risk for various non-skeletal morbidities have been recognized; whether all of these associations are causally related to low vitamin D status remains to be determined. The discovery that most tissues and cells in the body have vitamin D receptors and that several possess the enzymatic machinery to convert the 25-hydroxyvitamin D3, to the active form, 1,25-dihydroxyvitamin D3, has provided new insights into the function of this vitamin. Of great interest is its role in decreasing the risk of many chronic illnesses, including common cancers, autoimmune diseases, infectious diseases, and cardiovascular disease. In this review I consider the nature of vitamin D deficiency, discuss its role in skeletal and non-skeletal health, and suggest strategies for prevention and treatment.     

Independent and combined effects of exercise and vitamin D on muscle morphology, function and falls in the elderly

Regular exercise, particularly progressive resistance training (PRT), is recognized as one of the most effective strategies to prevent age-related muscle loss (sarcopenia), but its effects on muscle function are mixed. However, emerging data indicates that high velocity PRT (fast concentric muscle contractions) is more effective for improving functional outcomes than traditional PRT. In terms of falls prevention, high-challenging balance training programs appear to be most effective. There is also compelling evidence that supplemental vitamin D is an effective therapeutic option for falls prevention. The findings from a recent meta-analysis revealed that supplemental vitamin D at a dose of at least 700-1,000 IU/d or an achieved serum 25(OH)D level of at least 60 nmol/L was associated with reduced falls risk among older individuals. Based on these findings, it is possible that the combination of exercise and vitamin D could have a synergistic effect on muscle morphology and function, particularly since both interventions have been shown to have beneficial effects on type II "fast twitch" muscle fibers and systemic inflammation, which have both been linked to losses in muscle mass and function. Unfortunately however, the findings from the limited number of factorial 2 × 2 design RCTs indicate that additional vitamin D does not enhance the effects of exercise on measures of muscle morphology, function or falls risk. However, none of these trials were adequately powered to detect a "synergistic" effect between the two treatment strategies, but it is likely that if an exercise-by-vitamin D interaction does exist, it may be limited to situations when vitamin D deficiency/insufficiency is corrected. Further targeted research in "high risk" groups is still needed to address this question, and evaluate whether there is a threshold level of serum 25(OH)D to maximize the effects of exercise on muscle and falls risk.     

Should we be concerned about the vitamin D status of athletes?

A surprisingly high prevalence of vitamin D insufficiency and deficiency has recently been reported worldwide. Although very little is known about vitamin D status among athletes, a few studies suggest that poor vitamin D status is also a problem in athletic populations. It is well recognized that vitamin D is necessary for optimal bone health, but emerging evidence is finding that vitamin D deficiency increases the risk of autoimmune diseases and nonskeletal chronic diseases and can also have a profound effect on human immunity, inflammation, and muscle function (in the elderly). Thus, it is likely that compromised vitamin D status can affect an athlete's overall health and ability to train (i.e., by affecting bone health, innate immunity, and exercise-related immunity and inflammation). Although further research in this area is needed, it is important that sports nutritionists assess vitamin D (as well as calcium) intake and make appropriate recommendations that will help athletes achieve adequate vitamin D status: serum 25(OH)D of at least 75 or 80 nmol/L. These recommendations can include regular safe sun exposure (twice a week between the hours of 10 a.m. and 3 p.m. on the arms and legs for 5-30 min, depending on season, latitude, and skin pigmentation) or dietary supplementation with 1,000-2,000 IU vitamin D3 per day. Although this is significantly higher than what is currently considered the adequate intake, recent research demonstrates these levels to be safe and possibly necessary to maintain adequate 25(OH)D concentrations.     

Vitamin D and bone health: potential mechanisms

Osteoporosis is associated with increased morbidity, mortality and significant economic and health costs. Vitamin D is a secosteriod hormone essential for calcium absorption and bone mineralization which is positively associated with bone mineral density [BMD]. It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. Sub-optimal vitamin D status has been reported in many populations but it is a particular concern in older people; thus there is clearly a need for effective strategies to optimise bone health. A number of recent studies have suggested that the role of vitamin D in preventing fractures may be via its mediating effects on muscle function (a defect in muscle function is one of the classical signs of rickets) and inflammation. Studies have demonstrated that vitamin D supplementation can improve muscle strength which in turn contributes to a decrease in incidence of falls, one of the largest contributors to fracture incidence. Osteoporosis is often considered to be an inflammatory condition and pro-inflammatory cytokines have been associated with increased bone metabolism. The immunoregulatory mechanisms of vitamin D may thus modulate the effect of these cytokines on bone health and subsequent fracture risk. Vitamin D, therefore, may influence fracture risk via a number of different mechanisms.     

Vitamin D Supplementation in Patients with Juvenile Idiopathic Arthritis

Vitamin D has been implicated in the pathogenesis of skeletal disorders and various autoimmune disorders. Vitamin D can be consumed from the diet or synthesized in the skin upon ultraviolet exposure and hydroxylation in the liver and kidneys. In its bioactive form, vitamin D exerts a potent immunomodulatory effect and is important for bone health. Juvenile idiopathic arthritis (JIA) is a collection of inflammatory joint diseases in children that share the manifestation of inflamed synovium, which can result in growth arrest, articular deformity, bone density loss, and disability. To evaluate the potential effect of vitamin D on JIA disease manifestations and outcomes, we review the role of vitamin D in bone metabolism, discuss the mechanism of vitamin D in modulating the innate and adaptive immune systems, evaluate the clinical significance of vitamin D in patients with JIA, and summarize the supplementation studies.     

Hypovitaminosis D-induced pain

Vitamin D deficiency is a problem of considerable magnitude that has reemerged as a major public health issue in the United States and several other developed countries. Vitamin D plays a crucial role in calcium homeostasis in the body. Hypovitaminosis D leads to osteomalacia and increased risk of fractures, especially in the elderly. Preliminary research suggests that vitamin D can prevent certain types of cancer and autoimmune diseases. A recent large study has shown the association between severe hypovitaminosis D and persistent, non-specific musculoskeletal pain, further suggesting that patients with no apparent cause of pain should be assessed and possibly treated for vitamin D deficiency.     

Sarcopenia and Vitamin D Deficiency in Patients with Crohn’s Disease: Pathological Conditions That Should Be Linked Together

Sarcopenia is a prevalent condition in patients with Crohn’s disease (CD), representing an independent predictor factor for the development of major postoperative complications. Thus, a proper assessment of the muscle strength, by using different validated tools, should be deemed an important step of the clinical management of these patients. Patients with CD are frequently malnourished, presenting a high prevalence of different macro- and micro-nutrient deficiencies, including that of vitamin D. The available published studies indicate that vitamin D is involved in the regulation of proliferation, differentiation, and regeneration of muscle cells. The relationship between vitamin D deficiency and sarcopenia has been extensively studied in other populations, with interesting evidence in regards to a potential role of vitamin D supplementation as a means to prevent and treat sarcopenia. The aim of this review was to find studies that linked together these pathological conditions.     

Vitamin D: an overview of its role in skeletal muscle physiology in children and adolescents

Many children may have insufficient serum concentrations of vitamin D, which could prevent optimal muscle development and function. Vitamin D deficiency in animal models results in negative effects on muscle fiber structure and calcium/phosphorus handling, suggesting an integral role of vitamin D in skeletal muscle function. While there is a dearth of data in humans, the available evidence demonstrates a positive association between vitamin D status and muscle function. This review focuses on the important role of vitamin D in muscle function in children and adolescents who live in North American regions where exposure to ultraviolet B radiation is limited and who are thus at increased risk for vitamin D insufficiency. The effects of vitamin D on muscle cell proliferation and differentiation, muscle fiber structure, and calcium and phosphorus handling are discussed. Moreover, the roles of vitamin D and the vitamin D receptor and their genomic and nongenomic actions in muscle function are explored in depth. Future research should aim to establish a vitamin D status consistent with optimal musculoskeletal development and function in young children.     

Fortification of food with vitamin D is a reasonable approach to fracture prophylaxis

Vitamin-D deficiency is common in immobile elderly and non-Western immigrants and has been related to muscle weakness in these populations. When serum calcidiol concentrations are below 50 nmol/l, parathyroid hormone concentrations increase, causing bone resorption. Bone mineral density and proximal muscle strength increase as the serum concentration ofcalcidiol increases. Vitamin-D supplementation is reported to reduce the incidence of fractures in nursing home residents. Dutch guidelines recommend vitamin-D supplementation for nursing home residents and for those who are house-bound. Fortification of milk and other foods with vitamin D in the United States and Sweden has led to a better nutritional state with respect to vitamin D than in the Netherlands. Therefore the dairy industry should be allowed to add vitamin D to dairy products to prevent fractures.