Vitamin D
Background
Vitamin D is well known for its role in bone health, however research now shows a critical role for vitamin D in the modulation of immune function and its importance in maintaining a healthy immune system.
Vitamin D has been found to be an important regulator of innate immunity, the body’s first defence against infection, through:
Enhancing the production of antimicrobial peptides
Reducing inflammatory proteins called cytokines
Reinforcing the physical barrier function of epithelial cells (the cells that act as a barrier between the inside and outside of the body).(1)
Vitamin D status of Australians
Nearly one quarter of Australian adults have low vitamin D levels (<50nmol/L), with higher rates during winter when sun exposure is reduced.
Groups at greatest risk include housebound, and other people who regularly avoid sun exposure.(2)
Meeting vitamin D requirements
Vitamin D is obtained through the direct action of sunlight on the skin (90%) or through dietary nutrition (10%), in particular dairy products, eggs and fish.
Increasing vitamin D levels through diet alone is very difficult. When sun exposure is minimal, vitamin D intake from dietary sources and supplementation of at least 600 IU (15 μg) per day for people aged ≤ 70 years and 800 IU (20 μg) per day for those aged > 70 years is recommended.(3)
(1)Sassi F et al. Nutrients 2018;10:1656-69
(2)Australian Health Survey, 2011-2012
(3)Nowson C et al Med J Aust 2012; 196 (11): 686-687