We’ve discussed how UVB rays could harm skin via direct DNA damage. The subsequent chromosomal alterations and mutations can initiate skin cancers, particularly the squamous or basal-cell types associated with UVB. Even if we use a non-nano zinc oxide sunscreen daily to block UV rays, sunscreen alone just does not provide complete protection.
We’ve all heard that taking antioxidants protects the heart and brain. Less known is the understanding that, because production of free radicals is associated with the initiation phase of UVB-induced damage, antioxidants can act as skin protectants, especially when applied topically.
The Linus Pauling Institute has this to say about vitamin C: “While vitamin C is not a 'sunscreen' because it does not absorb light in the UVA or UVB spectrum, its antioxidant activity protects against UV-induced damage caused by free radicals. Topical application of vitamin C, alone or in combination with other compounds, may result in greater photoprotection than oral supplementation because of the more direct route of administration. In one mouse study, topical application of ascorbic acid delayed the effects of chronic high-dose UVB exposure on the skin, including a reduction in skin wrinkling and the development of skin tumors. In pig models, topical application of vitamin C reduced the number of sunburned cells, decreased erythema response and reduced DNA damage induced by UVA exposure.”
Even better, according to our same source, are vitamin C and vitamin E together.
“Topically applied combinations of vitamin C and vitamin E are more effective in preventing photodamage than either vitamin alone. In particular, this combination of antioxidant vitamins decreased the immunosuppressive effects of UV exposure, increased minimal erythemal dose (MED), and decreased cell damage.”
A new study offers hope that we may be on track to limiting UVB-induced damage with topically applied anti-inflammatories, in particular, sodium salicylate and aspirin.
Sodium salicylate is the salt of salicylic acid, and some people sensitive to salicylic acid find they can readily tolerate sodium salicylate. A study on hairless mice concluded that topical doses of NAS inhibited UVB-induced thymine dimer formation, thus inhibiting tumor formation via a sunscreen mechanism. The exciting discovery about NAS is that not only does it work as a sunscreen agent at the initiation stage, but it also can inhibit the promotion stage by preventing UVB-mediated signal transduction leading to AP-1 activation.
“The ability to act as a sunblock or screen and, at the same time being able to prevent UVB-induced signal transduction, may make NAS a more potent chemoprevention agent than some of the commercial sunscreens used now.” (From study, italics mine)
The same study also looked at the effects of topically applied aspirin and came to the following conclusion:
“The 40 µmol dose of aspirin significantly inhibited the rate of tumor formation (P < 0.05). To investigate the mechanism of this inhibition, we studied UVB-induced thymine dimer formation in the epidermis of the mouse skin. We found that NAS inhibited UVB-induced thymine dimer formation (P = 0.0001), whereas aspirin did not. Therefore, we conclude that NAS prevents UVB-induced tumor growth and formation through a sunscreen effect; whereas, the moderate inhibition of aspirin may be because of a molecular event, such as the inhibition of various UVB signaling pathways."
ABC News recently reported that aspirin users may get an added benefit—guarding against melanoma. A study of nearly 60,000 post-menopausal women found that those who used aspirin regularly were 21% less likely to be diagnosed with melanoma, while aspirin use for five years or more was tied to a 30% reduction in melanoma risk.
I believe studies like this represent real breakthroughs in skin-cancer prevention. Such groundbreaking research gives sunscreen developers opportunities to create new generations of more powerful sunscreens with fewer side effects. And consumers provisioned with more choices are not only more likely to adopt a daily protection routine, they are also much more likely to stick with it.