Sunscreens and Skin Aging

Skin cancer considerations notwithstanding, many if not most of us contemplate use of sunscreens to reduce the signs of aging to our skin, as attested by the fact that anti-aging remedies such as creams, lotions and the like accounted for several billion dollars of purchases last year. Yet just how effective is use of sunscreen for reducing skin aging? That's what Rick and I discuss on PodMed this week, based on a study in Annals of Internal Medicine.  The results may convince even me to slather the stuff on daily.

Investigators from Down Under (aka Australia) recruited over 1600 volunteers to be randomized into four groups:  one used daily broad-spectrum sunscreen, another did the same with the addition of oral beta-carotene supplements, one did the sunscreen and an oral placebo, and the final group used sunscreen as the spirit moved them.  The sunscreen using groups were asked to apply the lotion to their head, neck, arms and hands daily in the morning, and to reapply if they went swimming, sweat profusely, or spent more than a few hours outside. Participants were followed from 1992 to 1996 and all were younger than 55 years of age at recruitment.  In addition, each had assessments of their skin performed using silicone-based skin surface replicas taken from the back of the left hand, so-called 'skin microtopography.' These impressions were taken at baseline and study completion.

Periodically during the 4 year study period study subjects were queried on adverse events and adherence to the sunscreen regimen. Data on smoking habits and sun exposure was also gathered at intervals.

Only the daily sunscreen group showed no additional signs of photoaging as assessed by microtopography at four years of follow-up.  This group was 24% less likely to show signs of photoaging as compared with the discretionary sunscreen use group.  So for those fountain of youth seekers, does this mean sunscreen is the answer?  Maybe, but one thing is known from this study: beta carotene provided no additional benefit with regard to avoiding sun damage to skin, so that at least can be given a miss.

What about the ongoing debate regarding SPF and UVA and UVB wavelengths of light and protection against them?  Sunscreen products available in the US are limited in some of the claims they make with regard to protection, for example, they can no longer use 'waterproof' and must instead use 'water resistant' as well as admonish users to reapply after swimming, and they must identify 'broad spectrum' coverage for UVA rays.  As far as SPF is concerned, the authors of this paper make the point that people may be misled by higher SPF numbers, and stay out in the sun longer or fail to reapply, both no-no's when it comes to protecting skin.  Anyone for a public health campaign to advocate sunscreen application along with flossing and tooth brushing? That may very well be the only way I'm likely to remember it.

Other topics this week include a look at various vegan diets and their impact on mortality in JAMA Internal Medicine, and two from JAMA: metabolic surgery for diabetes and the health effects of fructose.  Until next week , y'all live well.

 

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Sunscreens and Skin Aging | jhublogs
June 7, 2013 at 12:53 pm

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Stephen Knows Cancer June 20, 2013 at 12:43 am

Since learning more about skin cancer awareness month last month, I have been much more conscientious of the risks that unprotected sun exposure holds, especially when it comes to melanoma. While this is the least common form of skin cancer, it is the most aggressive and deadly type as well. This means that it is crucial to be mindful of the initial signs of melanoma, because early diagnosis and treatment could mean the difference between life and death.

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Robert in Birmingham June 11, 2013 at 11:54 pm

Hey, I think that this is great that you took the time to share this post. Skin cancer is something that should be discussed more often if you ask me. Last month, it was Skin Cancer Awareness Month, but I feel like I didn't really hear much about it on the television or other sources of popular media. Science and research are helping to develop better ways to protect our skin while we are out in the sun (such as these pills that can replace the need for putting on sun screen....), but knowledge of the risks of skin cancer is still very important.

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