Vitamin D: Physiology, clinical applications, dietary sources, and requirements

ABSTRACT

Vitamin D, the sunshine vitamin, is essential for bone health and reducing risk of acute and chronic diseases, including autoimmune diseases, cancers, heart disease, type II diabetes, neurocognitive dysfunction and infectious diseases including COVID-19. Vitamin D deficiency is one of the most common nutritional deficiencies worldwide. Vitamin D status is determined by measuring 25-hydroxyvitamin D in the blood. To maintain a normal level of at least 30ngmL−1 (75nmolL−1) as recommended by the Endocrine Society Guidelines on Vitamin D, infants up to 1 year need 400–1000IUs, children 600IU–1000IU, adults 1500–2000IU of vitamin D daily. Obese adults require 2–3 times more vitamin D to satisfy their requirement because of the vitamin D being diluted in the body fat and not available. This can be accomplished by receiving sensible sun exposure in combination with ingesting foods that either naturally contain or are fortified with vitamin D along with a vitamin D supplement. © 2023 Elsevier Ltd. All rights reserved