Sun protection is the anti-aging intervention with the best evidence
The anti-aging market is enormous and most of it rests on mechanism, marketing, and before-and-after photographs. One intervention in that category has an actual randomized controlled trial behind it, costs very little, and is available at every pharmacy. It is sunscreen.
Most facial aging is sun damage
The wrinkles, mottled pigmentation, broken capillaries, and leathery texture that people describe as looking older are largely photoaging — cumulative ultraviolet damage to collagen and elastin — rather than chronological aging. Estimates commonly put UV exposure behind roughly 80% of visible facial aging.
The clearest demonstration is not a study but a photograph. A 2012 case report in the New England Journal of Medicine showed a truck driver who had spent 28 years with one side of his face at the window. The two halves of his face looked decades apart. Same man, same genetics, same number of birthdays.
Living in a coastal Southern California town raises the stakes. The UV index here stays meaningfully high most of the year rather than collapsing in winter, and water and sand reflect additional UV upward — which is why the underside of the chin and nose burn on the water.
There is a randomized trial
This is what separates sun protection from the rest of the anti-aging category.
In the Nambour trial in Queensland, adults were randomized to daily broad spectrum sunscreen or to using it at their own discretion. After four and a half years, the daily-use group showed no detectable increase in skin aging, while the discretionary group did — published in Annals of Internal Medicine in 2013. Randomized, prospective, measured on skin microtopography rather than opinion.
The same cohort produced the skin cancer findings: regular sunscreen use reduced squamous cell carcinoma, and follow-up showed reduced melanoma incidence as well.
Almost nothing else sold for aging skin has evidence of this quality.
The order of operations is not what people assume
Sunscreen gets the attention, but it is the last line rather than the first.
Timing. UV intensity peaks in the middle of the day. Shifting a run, a walk, or a session in the water toward early morning or later afternoon removes exposure rather than filtering it.
Shade. Physically blocking the sun outperforms any product.
Clothing. A tightly woven long sleeve does not wash off, does not need reapplication, and does not get applied too thinly. UPF-rated fabric makes this explicit, and a long-sleeved rash guard in the water is doing more work than the sunscreen underneath it.
Hats and sunglasses. A broad brim protects the areas where skin cancers actually cluster — nose, ears, cheeks, scalp. Sunglasses matter for the eyelid skin and for the eye itself.
Then sunscreen, for what the rest did not cover.
Sunscreen is mostly used wrong
Two failures account for most of the gap between the SPF on the bottle and the protection people get.
Quantity. SPF is measured at an application density of 2 mg/cm², which for an adult works out to roughly a shot glass for the body and something like a generous teaspoon for face and neck. Most people apply a quarter to a half of that. Protection does not scale linearly, so an SPF 50 applied at half density does not deliver anything like SPF 25.
Reapplication. Every two hours of continued exposure, and immediately after swimming, heavy sweating, or towelling off. “Water resistant” means the tested SPF held for 40 or 80 minutes of immersion, not that reapplication is optional.
Two other things worth knowing: SPF describes UVB protection, so broad spectrum on the label is what indicates UVA coverage — and UVA is the band most implicated in photoaging. And the difference between SPF 30 and SPF 50 is smaller than the numbers suggest, which matters far less than whether enough was applied at all.
The first new US filter since the 1990s
The United States has had a narrower and older set of sunscreen filters than Europe, Japan, or Australia, because new active ingredients enter the OTC monograph slowly. That changes this month.
On June 9, 2026 the FDA issued a final administrative order adding bemotrizinol to the sunscreen monograph, effective August 9, 2026. It is the first new sunscreen active ingredient permitted in the US since the late 1990s.
It is permitted at up to 6%, determined generally recognized as safe and effective for adults and children six months and older, and is a broad spectrum filter with strong UVA coverage and very low absorption through the skin. That last property is relevant given the systemic absorption findings that prompted questions about several older chemical filters.
Practically, expect it to appear gradually in reformulated products rather than all at once. It does not make existing sunscreen ineffective. What it does is narrow a long-standing gap between what Americans could buy and what was available elsewhere.
Skin cancer, and an honest note on screening
Sun protection reduces skin cancer risk, and that is the more consequential benefit — appearance is the reason people comply.
What is worth being straight about is screening. Recommendations here are more qualified than most people expect. The U.S. Preventive Services Task Force recommends counselling about UV exposure for fair-skinned people aged 6 months to 24 years, and selectively for fair-skinned adults over 24. But it concluded that the evidence is insufficient to assess the balance of benefits and harms of routine whole-body visual skin examination in asymptomatic adults, and likewise for counselling adults on skin self-examination.
That is not an argument against getting a changing lesion looked at — it is a statement about screening people with no findings. A new, changing, bleeding, or asymmetric lesion warrants examination regardless of what the screening evidence says about the well.
The distinction is the same one that runs through preventive care generally: the case for prevention can be strong while the case for routinely screening everyone remains unsettled.
What about vitamin D
The usual objection. Casual incidental exposure produces vitamin D for most people, and where a deficiency exists it is straightforwardly correctable with supplementation. Deliberately accumulating UV damage is an inefficient way to solve a problem that a cheap tablet solves — and the damage is cumulative and permanent in a way that a low vitamin D level is not.
The summary
Sun protection is the rare intervention that is cheap, available, supported by randomized evidence for both appearance and disease, and largely ignored by an industry that would rather sell something proprietary.
Shade and clothing before sunscreen. Enough sunscreen, reapplied. Broad spectrum. Start early, because the damage accumulates over decades and the benefit compounds the same way.