Revolutionizing the Vitamin D recommended dietary allowance: Need for scientific evidence—A review

Abstract Vitamin D is an important vitamin required for maintaining good bone health. It is synthesised endogenously when exposed to sunlight, which converts it to 7-dehydrocholesterol to cholecalciferol (Vitamin D3). However, direct sunlight exposure poses skin cancer risks and other issues. There are continuous disputes due to different studies and their methodologies regarding the RDA and the uses of vitamin D in humans. Currently, all the RDAs vary globally. The Endocrine Society proposes 1,500–2,000 IU/day for adults, while the UK suggests 400 IU/day. Some studies advocate higher dosages(like 600-800IU) to maintain optimal levels. In the past, RDAs recommended 400–800 IU per day to prevent bone disorders. Given that vitamin D has functions other than bone health, recent research raises concerns about whether these values are sufficient. Evidence supports its significance in preventing cancer, diabetes, dry eyes, eye inflammation, and kidney disease despite scepticism. Research points to anti-angiogenic, immunomodulatory, and anti-inflammatory benefits as well as a possible drop in cancer-related mortality. Deficiency of vitamin D has been associated with various diseases, such as diseases of liver disease, celiac disease, cystic fibrosis, Crohn's disease, ulcerative colitis, obesity, eye diseases, and problems with bone density are all associated with vitamin D insufficiency. Guidelines should be reviewed to accommodate the wider range of health advantages linked to vitamin D while striking a balance to prevent excessive sun exposure. To determine the ideal vitamin D levels for general health and disease prevention, more research is necessary.