Vitamin D plays an important part in modulation of the immune system and has been implicated in the aetiology of cancers, autoimmune diseases and cardiovascular disease. Actually a hormone, vitamin D is synthesised in the skin from cholesterol, and anything that interferes with the UV light reaching the skin will reduce cutaneous production. Those of us who live in high latitudes are prone to vitamin D levels dropping through the winter resulting in sub clinical deficiency. Supplementation of vitamin D3 is effective at maintaining blood levels and should be a first line of defence; however, it can be difficult to gauge the correct doses without blood tests. Regular sun exposure is an effective method of obtaining adequate production of vitamin D3, and so the question arises as to whether sun beds can supplement natural UV light.
The metabolism of vitamin D in the human body following sun exposure or ingestion of vitamin D3 in the diet.
According to a study published in the American Journal of Clinical Nutrition1 subjects from Boston, Massachusetts who regularly used a sun bed for tanning had concentrations of 25(OH)D3 (see figure 1) that were 90 % higher (116 nmol/L v 60 nmol/L) and parathyroid hormone levels that were 18 % lower than control subjects (PTH can increase to compensate for Vitamin D deficiency). The presence of vitamin D deficiency [25(OH)D3 ≤ 50 nmol/L] was significantly lower in tanners (8 %) that in non tanners (42 %) at the end of winter. More significantly, bone mineral density was higher in the tanners than the control group at the hip, and the researchers also recorded a small but not significant (statistically) positive correlation between serum 25(OH)D3 and bone mineral density at the hip and spine.
This study would suggest that regular use of a sub bed improves skeletal health. Sun beds that emit UV B radiation in the 290 to 315 nm wavelength are able to increase circulating levels of 25(OH)D3. Sunscreen with a sun-protective factor of greater than 8 reduces the amount of vitamin D3 produced by the skin by 95 %. Research has indicated that maintaining a blood level of 25(OH)D3 above 80 nmol/L is necessary to maintain optimal calcium absorption from the gut, and to produce 1,25-dehydroxyvitamin D3 in most tissues to regulate cell growth. Although chronic and excessive sun exposure has its dangers, it is clear that the avoidance of direct sun exposure is something that results in serious health consequences. Sensible sun exposure coupled with supplementation of vitamin D3 are important steps towards maintaining vitamin D sufficiency.
RdB
