Vitamin D has become the focus of huge interest in recent years, with an increasing number of studies identifying a high prevalence of deficiency. Vitamin D is widely regarded as being important for a healthy immune system and is implicated in the pathogenesis of cancer, autoimmune, cardiovascular and respiratory diseases as well as depression and cognitive impairment. More recently a large body of circumstantial evidence supports a role for vitamin D in ameliorating the symptoms or severity of Covid-19. In fact, to date there are nearly 1000 peer-reviewed studies published on the topic of ‘Vitamin D and Covid-19’. Vitamin D is not a nutrient in the traditional sense as it is a hormone that is largely derived from cutaneous synthesis after UVB exposure. Furthermore, dietary sources are limited and make a small contribution to overall intake but include fortified foods (milks, breakfast cereals), oily fish and eggs.
This has only been defined in relation to optimal bone health. A 25-hydroxyvitamin D level of less than 30 nmol/L is generally considered to represent deficiency and can cause rickets in children, osteomalacia in adults and result in secondary hyperparathyroidism. A level between 30-50 nmol/L represents possible deficiency and may be deleterious to bone health though other factors such as calcium and phosphate intake interact with vitamin D and play a role. For this reason, levels in the 30-50 nmol/L range are generally categorised as “insufficient”.
For verified healthcare professionals
Log in or register for free to read this article. HPN is for healthcare professionals, so new accounts are verified by our team.
