Preface

Vitamin D deficiency has been noted in people worldwide and thus it is a global problem. As such, there is growing interest from scholars and health practitioners in the function of vitamin D in human health and diseases, especially in its pleiotropic outcomes. It is generally accepted that vitamin D is an essential substance for the homeostasis of calcium and phosphorus in the human body. It is a neuroactive secosteroid that may be implicated in the development of various pathological disorders. The functionally active form of vitamin D (1.25-OH-VD 2) reveals both genomic and non-genomic effects.

The book presents new insights into the role of vitamin D deficiency in the development of various chronic diseases, including COVID-19. It is organized into four sections: "Introduction", "Vitamin D Status and Childhood", "Vitamin D Status and COVID-19", and "Vitamin D Status and Non-Hormonal/Hormonal Disorders".

After the first section, which is the introduction, an important theme developed in Section 2 is vitamin D status in the neonatal and postnatal periods in children. Chapters in this section examine the consequences of vitamin D deficiency in children and discuss strategies for addressing this deficiency. Section 3 discusses the profound role of vitamin D deficiency in the era of COVID-19. Finally, Section 4 reviews the implication of vitamin D deficiency in the physiological and biochemical processes of renal, endocrine, and cardiovascular diseases.

> **Julia Fedotova, MD, Ph.D., Dr. habil, Sc.D.** Associated Professor, Laboratory of Neuroendocrinology, Pavlov Institute of Physiology RAS, St. Petersburg, Russia

National Research South Ural State University, Chelaybinsk, Russia

**1**

Section 1

Introduction

Section 1 Introduction

## **Chapter 1**
