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I first became interested in vitamin D when I learned that it is not a vitamin. Instead, it is the only known substrate of a seco-steroid neuro-hormone that functions, like all steroids, by turning genes on and off.
That means it has as many different mechanisms of action as the genes it regulates. Moreover, vitamin D directly regulates hundreds, if not thousands, of the 21,000 coding genes of the human genome. Genes are responsible for making the proteins and enzymes the human body relies on for normal development and function.
Evidence that vitamin D is involved in the autism epidemic is mounting.
Vitamin D is a precursor of the steroid hormone calcitriol that is crucial for bone and mineral metabolism. Both the high prevalence of vitamin D deficiency in the general population and the identification of the vitamin D receptor in the heart and blood vessels raised interest in the potential cardiovascular effects of vitamin D. Experimental studies have demonstrated various cardiovascular protective actions of vitamin D, but vitamin D intoxication in animals is known to induce vascular calcification. In meta-analyses of epidemiological studies, vitamin D deficiency is associated with an increased cardiovascular risk. Findings from Mendelian randomization studies and randomized, controlled trials (RCTs) do not indicate significant effects of a general vitamin D supplementation on cardiovascular outcomes. Previous RCTs, however, were not adequately designed to address extra skeletal events, and did not focus on vitamin D-deficient individuals. Therefore, currently available evidence does not support cardiovascular benefits or harms of vitamin D supplementation with the commonly used doses, and whether vitamin D has cardiovascular effects in individuals with overt vitamin D deficiency remains to be evaluated. Here, we provide an update on clinical studies on vitamin D and cardiovascular risk, discuss ongoing vitamin D research, and consider the management of vitamin D deficiency from a cardiovascular health perspective.
Key points
The vitamin D receptor (VDR) and enzymes for vitamin D metabolism are expressed throughout the cardiovascular system
VDR and 1α-hydroxylase knockout mice have hypertension with myocardial hypertrophy and increased activity of the renin–angiotensin–aldosterone system
The molecular effects of VDR activation indicate various anti-atherosclerotic and protective effects on the heart and on common cardiovascular risk factors
Observational studies have shown that low 25-hydroxyvitamin D levels are associated with an adverse cardiovascular risk profile and significantly increased risk of cardiovascular events
Mendelian randomization studies and randomized clinical trials have not shown significant effects of vitamin D on cardiovascular events, but these trials were not designed to investigate cardiovascular outcomes in vitamin D-deficient individuals
Vitamin D supplementation is currently not indicated for the purpose of cardiovascular disease prevention, but treatment of vitamin D deficiency is critical for skeletal health
Introduction
The critical involvement of vitamin D in bone and mineral metabolism is historically known. The identification of the vitamin D receptor (VDR) in almost all human organs including the heart and the blood vessels, and observations that individuals deficient in vitamin D are at increased risk of various extraskeletal diseases, stimulated research on the role of vitamin D for overall and cardiovascular health. In this Review, we summarize the existing knowledge on the effects of vitamin D on cardiovascular diseases and associated risk factors, with a particular focus on meta-analyses of large, epidemiological studies and randomized, controlled trials (RCTs). First, we provide a short summary of vitamin D metabolism and current vitamin D guidelines, a historical perspective on vitamin D and cardiovascular diseases, and a brief overview on the mechanistic effects of VDR activation on cardiovascular risk factors, the blood vessels, and the heart. The principal aspect of this Review is an update on observational studies, Mendelian randomization studies, and RCTs on vitamin D and cardiovascular risk. Finally, we outline and discuss ongoing vitamin D research, including large RCTs, and present our conclusions on how to deal with the management of vitamin D deficiency from a public health and cardiovascular health perspective.
A protein activated by vitamin D could be involved in repairing damage to myelin in people with multiple sclerosis (MS), according to new research from the University of Cambridge. The study, published today in the Journal of Cell Biology, offers significant evidence that vitamin D could be a possible treatment for MS in the future.
Researchers, from the MS Society Cambridge Centre for Myelin Repair, identified that the ‘vitamin D receptor’ protein pairs with an existing protein, called the RXR gamma receptor, already known to be involved in the repair of myelin, the protective sheath surrounding nerve fibres.
By adding vitamin D to brain stem cells where the proteins were present, they found the production rate of oligodendrocytes (myelin making cells) increased by 80%. When they blocked the vitamin D receptor to stop it from working, the RXR gamma protein alone was unable to stimulate the production of oligodendrocytes.
Vitamin D (vitD) is known for its essential role in calcium homeostasis and bone health. VitD is made endogenously in the skin from UVB radiation from sunlight. VitD is now considered as a potent neurosteroid hormone, critical to brain development and normal brain function, and is known for its anti-inflammatory property affecting various aspects of human health. VitD ligand-receptor, a receptor that mediates much of vitD's biological actions, has been found throughout the body including the central nervous system. VitD deficiency is common in patients with severe mental illness such as schizophrenia. Schizophrenia is a debilitating chronic mental illness characterised by positive symptoms, such as hallucinations and delusions, and negative symptoms including flat affect and lack of motivation. Several environmental risk factors for schizophrenia, such as season of birth, latitude and migration, have been linked to vitD deficiency. Recent studies have suggested a potential role of vitD in the development of schizophrenia. For example, neonatal vitD status is associated with the risk of developing schizophrenia in later life obesity, insulin resistance, diabetes, hyperlipidaemia and cardiovascular disease, which are commonly seen in patients with schizophrenia. It has been well established that vitD deficiency is related to these metabolic problems. The biological mechanism is most likely related to vitD's action on the regulation of inflammatory and immunological processes, consequently affecting the manifestation of clinical symptoms and treatment response of schizophrenia. Potential benefits of vitD supplementation to improve schizophrenia symptoms as well as physical health in patients with schizophrenia should be further explored in future studies.
Introduction
Vitamin D (vitD), the 'sunshine' vitamin, is widely known for its essential role in calcium absorption and bone health. VitD is created in mammals after the epidermis comes into contact with UVB light. UVB radiation catalyses the conversion of 7-dehydrocholesterol to previtamin D3 in the skin, which is then quickly converted into vitamin D3 (cholecalciferol) by the body. 25-hydroxyvitamin D [25(OH)D], the main circulating form of vitD, is used by clinicians to measure vitD levels in the body. VitD is also obtained through dietary sources. Fatty fish, fungus and eggs naturally contain high levels of vitD. In many countries, cereal, milk and other everyday foods are fortified with vitD. VitD is also readily available as a dietary pill. However, since most individuals lack the necessary amount of exposure to UVB light and do not consume enough dietary vitD, vitD deficiency has become a global pandemic. While vitD has long been associated with bone health and related diseases, research in the past decade has uncovered its widespread effects on other aspects of the human body. Studies have identified links between vitD and a multitude of conditions including various cancers, autoimmune diseases, cardiovascular diseases, infectious diseases and mental disorders.
Studies have unveiled the presence of vitD, vitD receptors (VDR) and related enzymes (CYP 27B1, CYP 24A1) in various regions of the brain, leading researchers to establish vitD as a neuroactive/neurosteroid hormone critical to brain development and normal brain function. Furthermore, VitD's possible role in depression has led researchers to explore its potential benefits in other mental illnesses.
Schizophrenia is a severe and debilitating mental illness characterized by chronic positive (hallucinations, delusions) and negative symptoms (lack of motivation, speech issues).
