State-of-the-art expert reviews provide insights into vitamin D research

Vitamin D is essential for human health. Although much is known about its important role in bone metabolism and in certain areas of non-skeletal health, there are many open questions and topics of debate. With the help of guest editor, Terry Aspray, Calcified Tissue International has commissioned seven state-of-the-art expert reviews which provide insights into current consensus and new directions of research in a wide range of topics - including vitamin D's role in maternal health, rheumatoid arthritis, respiratory disease, and muscle.

Dr Aspray stated:

I am very impressed with the breadth of coverage of this topic, evident from these reviews, which cover a range of clinically relevant science relating to vitamin D from true experts in the field."

The reviews include:

Vitamin D Measurement, the Debates Continue, New Analytes Have Emerged, Developments Have Variable Outcomes

William D. Fraser, Jonathan C. Y. Tang, John J. Dutton, Inez Schoenmakers

This review describes developments in the measurement of the commonly analyzed vitamin D metabolites in clinical and research practice. It describes current analytical approaches, discusses differences between assays, their origin, and how these may be influenced by physiological and experimental conditions. An overview of the value and application of the measurement of 1,25 dihydroxyvitamin D, 24,25 dihydroxyvitamin D and free 25OHD in the diagnosis of patients with abnormalities in vitamin D metabolism and for research purposes is provided.

Vitamin D Deficiency: Defining, Prevalence, Causes, and Strategies of Addressing

Kevin D. Cashman

Vitamin D deficiency, even assessed at the most conservative thresholds, is widespread in both low- and high-income country settings. This review addresses environmental factors and personal characteristics which prevent or impede dermal synthesis of vitamin D and looks at a number of strategies for addressing low dietary vitamin D intake and consequently lowering the risk of vitamin D deficiency.

Vitamin D, and Maternal and Child Health

Rebecca J. Moon, Justin H. Davies, Cyrus Cooper, Nicholas C. Harvey

Vitamin D has important roles in calcium metabolism and in the prevention of rickets and osteomalacia. Low levels of 25-hydroxyvitamin D are common in the general population and amongst pregnant women. This paper reviews the evidence to support routine vitamin D supplementation in childhood and pregnancy and points to the need for future research to focus on individual characteristics and genetic factors which may influence the response to supplementation.

Vitamin D, Autoimmune Disease and Rheumatoid Arthritis

Stephanie R. Harrison, Danyang Li, Louisa E. Jeffery, Karim Raza, Martin Hewison

The overall aim of this review is to provide a fresh perspective on the potential role of vitamin D in Rheumatoid Arthritis (RA) pathogenesis and treatment. It explores the immune activities of vitamin D that impact autoimmune disease, with specific reference to RA. As well as outlining the mechanisms linking vitamin D with autoimmune disease, the review also looks at the different studies that have linked vitamin D status to RA, and the current supplementation studies that have explored the potential benefits of vitamin D for its prevention or treatment.

Targeting Vitamin D Deficiency to Limit Exacerbations in Respiratory Diseases: Utopia or Strategy With Potential?

Karen Maes, Jef Serré, Carolien Mathyssen, Wim Janssens, Ghislaine Gayan-Ramirez

This review focuses on vitamin D as a potential candidate to treat or prevent exacerbations in Cystic Fibrosis, COPD, and asthma. Patients with such respiratory diseases often experience an acute worsening of respiratory symptoms (termed exacerbations), mostly triggered by a respiratory infection. Exacerbations often require hospitalization and are an important cause of mortality. Many patients do not benefit from existing therapies and suffer from recurrent events, and vitamin D deficiency is extremely prevalent in these patients.

The Latest Evidence from Vitamin D Intervention Trials for Skeletal and Non-skeletal Outcomes

Arvind Sami, Bo Abrahamsen

Vitamin D has long been considered a central part of the treatment paradigm for osteoporosis. Initial studies in high-risk populations with widespread vitamin D deficiency found a reduction of both vertebral and non-vertebral fractures. Subsequent studies in the general population have yielded mixed but mostly disappointing results both for skeletal and especially non-skeletal outcomes. Recent sequential trial meta-analyses suggest that future studies are likely to be futile given the overall disappointing result. However, mega-trials are still in progress, and additional results have been released. This narrative review aims to evaluate new literature to determine if there has been any substantial change in the message.

Vitamin D and Skeletal Muscle: Emerging Roles in Development, Anabolism and Repair

Christian M. Girgis

This review focuses on morphologic and functional roles of vitamin D in muscle, from strength to contraction, to development and ageing, and will characterise the controversy of the vitamin D receptor's (VDR) expression in skeletal muscle, central to our understanding of vitamin D's effects on this tissue.