Vitamin D is an essential compound for growth and development throughout the human lifecycle. The deficiency of vitamin D is a major health problem worldwide in all age groups. It maintains normal level of calcium, Phosphorus and provide protection from the diseases and individual’s risk of developing, diabetes, multiple sclerosis, lupus, rheumatoid arthritis, heart failure, strokes, hypertension, peripheral vascular disease, coronary heart disease, muscle weakness, respiratory tract infection, skeletal deformities and others. Vitamin D deficiency is more prevalent in countries such as Saudi Arabia, Turkey, Korea, Japan, Canada, England, China, India and Australia. About 90% of the Vitamin D required for the body function is sourced from sunlight throughout the world. Upon sun exposure body synthesizes pre-vitamin D in the skin, which is then converted into active Vitamin D in the liver and kidney. In addition, the dietary sources including fish, cod liver oil, egg yolk, milk products are considered as rich sources of Vitamin D. However, an adequate amount of Vitamin D supplementation through dietary sources are not possible; therefore, sunlight exposure along with Vitamin D supplements proportionate to the age for adult and children are suggested by the medical care professionals to overcome Vitamin D deficiency. This review aims to provide an overview of Vitamin D level in various ethnic and geographical origins, including prevalence, causal factors and possible dietary & supplementary interventions in practice to combat the Vitamin D deficiency.
Key words: Vitamin D deficiency, Prevalence, Fortification, Sources, Functions, Health risks, Worldwide.