Dietary Sources of Vitamin D, Vitamin D Supplementation, and Its Bio-Viability

The focus of this paper is to review the data on the dietary sources of vitamin D, vitamin D supplementation and its bio-viability. Vitamin D is a fat-soluble vitamin that plays an important role in human health. Low vitamin D levels (<75 nmol/l) have been reported worldwide in all age groups in recent years. Vitamin D deficiency is rising, mainly due to modern lifestyle and malabsorption disorders. There are two main sources of vitamin D; dietary source which includes food of animal and plant origin as well as dietary supplements and endogenous synthesis under the UVB radiation in the skin. Dietary sources rich in vitamin D are mainly fish oil, sea fish, eggs, and margarines fortified with vitamin D. As the adequate intake of vitamin D is hard to achieve through the diet alone, dietary supplements of vitamin D are recommended. However, there are different factors influencing the bioavailability of vitamin D and are explained within this review article. There is no universal consent on the amount and the frequency of vitamin D supplementation. Furthermore, there is still missing information for better understanding the vitamin D absorption, bioavailability, and metabolism in human. Conclusion – A brief mini review article on vitamin D summarizes the current knowledge about dietary sources of vitamin D, vitamin D supplements, and its bio-viability. The best source of vitamin D is in vivo synthesis in the skin under the UVB radiation. The main dietary sources of vitamin D includes food of animal and plant origin. Adequate intake of vitamin D through the diet alone is hard to achieve, therefore vitamin D supplementation is recommended.