Do Sunscreens protect skin cancer at cost of developing Vitamin D deficiency ?

Are sunscreens necessary evil- protecting skin cancer at the cost of causing Vitamin D deficiency is a million-dollar question.

Sunscreens are used to protect skin from harmful ultraviolet (U.V) rays emitted by the Sun which can cause skin cancer. Sunlight contains UVA and UVB radiation, and the latter is essential for vitamin D synthesis. Few studies, therefore have shown that Sunscreens may increase vitamin D deficiency if not used in a proper fashion. Sunscreens can prevent sunburn and skin cancer, but there has been a lot of uncertainty about the effects of sunscreens on vitamin D.

The best way out will be to devise a method so that the benefits of sunscreen use can be obtained without compromising vitamin D levels. The concern of individuals that they are not getting enough vitamin D from sunlight due to use of sunscreen can be addressed by eating more foods that contain vitamin D or by taking vitamin D as a supplement. Vitamin D is found in fatty fish, egg yolks, spinach, and vitamin D–fortified milk.

Read also: Home made Sunscreen recipes unscientific and unsafe, feel experts

Sunlight although, has got a bad reputation when it comes to skin cancer and tan but the Ultraviolet B (UVB) radiation produced the sun is essential for vitamin D synthesis. In a study published in the British Journal of Dermatology, scientists have compared two sunscreens with the same SPF. Sunscreen with a high UVA protection factor enabled significantly higher vitamin D synthesis than a low UVA protection factor sunscreen, likely because it allows more UVB transmission.

In a study published in the European Journal of Pediatrics, 29 sunscreen use was categorized into 'regular ' and nonregular 'regular ' was defined as always applying a sunscreen with an SPF of 15 or higher at least 30 minutes before exposure to sunlight and reapplying every 2 hours after swimming. Despite the stringent definition, 41% of children and 30% of adolescents reported regular use. Among those in the highest sun exposure category, the 25(OH)D concentration was approximately 20 nmol/L lower in regular versus non-regular sunscreen users (47 nmol/L versus 66 nmol/L).

A systematic review of all experimental studies, field trials, and observational studies on the same, conducted by Australian researchers , however, reported a lack of adequate evidence regarding the use of the very high SPF sunscreens that are now recommended and widely used, the study was published in the British Journal of Dermatology.

Sunscreens are designed to prevent erythema. The action spectra for vitamin D production and erythema overlap considerably in the UVB region. Thus, in theory, sunscreens that are effective at preventing erythema should also decrease vitamin D3 production and circulating 25(OH)D3 concentration. However, vitamin D production and change in serum 25(OH)D concentration are affected by factors such as the starting concentration of 25(OH)D and, critically, the body surface area exposed (unlike erythema which is a local effect at the site of exposure).

If sunscreen does decrease vitamin D production to an extent that is clinically important, the risks and benefits of sunscreen application need to be considered.