Is sunscreen the new margarine? (2019) | Hacker News Reader

Is sunscreen the new margarine? (2019)

outsideonline.com

118 pointsmarkgavalda138 comments

Wow, it feels like nobody read the article. Findings:

- high blood pressure leads to a lot of deaths

- people that spend more time in the sun have lower blood pressure

- skin cancer is caused by sun exposure, but it kills far, far less people than high blood pressure

- people that spend more time in the sun have a lower rate of dying from skin cancer than people who spend less time in the sun!

Summary: more sun exposure makes you less likely to die on at least two fronts!

It's really very simple. You skin adapts to sunlight and doesn't burn if you increase your exposure gradually, and then you get some amazing benefits from it!

I did[1], and would be curious if anyone is familiar with the underlying study. How did they attempt to control for other factors? (I assume that they did, and am interested to know how)

Also do you have to get a sunburn for sun damage to increase the risk of skin cancers? My understanding was accumulated sun exposure was the issue.

[1] Lindqvist tracked the sunbathing habits of nearly 30,000 women in Sweden over 20 years. Originally, he was studying blood clots, which he found occurred less frequently in women who spent more time in the sun—and less frequently during the summer... decided to look at overall mortality rates, and the results were shocking. Over the 20 years of the study, sun avoiders were twice as likely to die as sun worshippers.

The article cites another study by Richard Weller:

> Sure enough, when he exposed volunteers to the equivalent of 30 minutes of summer sunlight without sunscreen, their nitric oxide levels went up and their blood pressure went down.

I can't find information on the methods for this particular study. So I'm curious if he just set up UV lights on a timer and sat his subjects under them. That's something anyone can set up in their home office if they live somewhere gloomy. Instead of taking a vitamin D pill, turn the timer switch on for 30 minutes of a properly calibrated and positioned low-dose UV light (and out of direct line of sight to anyone not under it)

Or just take a nitric oxide supplement :)

> turn the timer switch on for 30 minutes of a properly calibrated and positioned low-dose UV light (and out of direct line of sight to anyone not under it)

Gosh. Or just go outside! It has the added benefit of being somewhat enjoyable.

Or gosh, just read my comment! I said in somewhat gloomy places. Sometimes people are working when the 10 minutes of sunlight comes out. Often that's not enough time to get down the elevator and get outside before the sun hides behinds the clouds again, even if you can take the daytime break.

Correction. More sun exposure is CORRELATED with being less likely do die. I don't think there's a single causal connection in this article.

> Sure enough, when he exposed volunteers to the equivalent of 30 minutes of summer sunlight without sunscreen, their nitric oxide levels went up and their blood pressure went down.

That is a causal connection.

Sorry for challenging here, I don’t remember the actual study being linked, and it seems I’m now paywalled and can’t check myself: did he do the same experiment with folks wearing sunscreen? Did he control for relaxation effects? I’d expect both blood pressure to go down and nitric oxide to go up as folks relax, e.g. in a sunny garden or on a tanning bed.

Not sure the “causal connection” is fully established.

NO2 and blood pressure is not the same as death

You are technically correct. The best kind of correct.

Or active people spend more time outside and have a lower rate of heart disease, regardless of whether the sun is shining.

That’s not what the article said though. It had nothing to do with physical activity. Ironic considering the comment you replied to

What I got from this is if we mandate the hospitals open their rooms to the sun, the new correlation will cause people to avoid the sunlight because "it leads to more deaths"

I read the article and it conjectures a bunch of stuff but fails to prove it or link relevant studies.

So consider then: we just did a round of "gloves are contaminating basically all micro plastics research" - it might be worthwhile to be slightly skeptical of a suspiciously anti-sunscreen adjacent narrative (coz "sunscreen might be bad for you" is in the article too).

And we should absolutely be suspicious of narratives which have the benefit of confirming someone should do what they already wanted to do: nobody likes putting on sunscreen.

And how strange the conclusion is mostly "you don't need sunscreen" versus "use a lower SPF".

I agree, that article is suspicious. One thing, what if you are not at risk of heart disease? I'm not fat, fairly active, have a low blood pressure and use sunscreen to slow down skin aging. Lots of health advice does not apply to me, cause it is meant for the overweight population. There are the biggest possible health gains to have, so statistically everything that makes people less fat is going to "be healthy for humans".

When standing up from a longer squat I tend to blacken out a bit (never fully fainted) and this gets much worse with sun exposure. So I can totally confirm the underlying scientific finding of this article. Sun exposure does seem to lower blood pressure, but the rest is all conjecture and lacks differentiation.

I guess all the grandmas on the beach that look like they have a leather hide for a skin didn't get the memo that the sun doesn't cause damage after all.

In all seriousness: don't listen to OP, use sunscreen whenever possible.

It depends on what you use for sunscreen. A lot of sunscreens have aluminum in them and there are many that have it but it is not listed as an ingredient. Zinc oxide sunscreen is a much safer sunscreen.

You are still missing the point. Leathery skin is (by current beauty standards) undesirable but avoiding sunlight is deadly. Pick your poison

There are other ways to lower blood pressure than sun exposure. Article is insane and confuses necessary and sufficient conditions.

You seem to be missing what part of that implies "spending time in the sun with sunscreen is risky". Wearing sunscreen doesn't magically make you not exposed at all to the sun. I also think you're assuming it's easy to calibrate your exposure to gradually ramp it up, when I suspect it would probably vary quite a bit by person; some people burn extremely quickly in the sun. Some people who are relatively pale will often need to apply sunscreen hourly to avoid burning.

> Summary: more sun exposure makes you less likely to die on at least two fronts!

Is the “more sun exposure” with or without wearing sunscreen?

That logic is extremely broken. People who spend more time outside do so because of more physical activity. The sun exposure is a side effect. Drawing the conclusion that sun exposure is therefore safe is just totally bonkers.

The study in the article controlled for that

He specifically mentions sunbathers. Not landscapers or construction workers

That is also selection bias. People who spend more time outside relaxing may have lower stress levels? Stress definitely contributes to cardiovascular illness.

Ok, so stop worrying about the exact mechanism, stop arguing on the Internet, and just get outside!

Sigh.

Correlation != causation

It could be that people that spend more time in the sun are busy getting exercise. Which lowers blood pressure.

It could be that people that spend a lot of time in the sun know that they have skin damage, and are more likely to detect melanomas due to more frequent checks of their damaged skin.

Summary: More sun exposure may or may not lead to lower risk of death on two fronts. It seems far more likely that getting exercise and frequent melanoma checks lead to better outcomes, and both of those are correlated with being in the sun, but by no means necessary to the outcome.

Sigh indeed, since that's patently obvious and the study thus controlled for it.

I made a small little web app calculator for myself and my family to figure out how long we could stay outside without needing sunscreen based on current UV and skin type. I use it daily in the summer and a couple thousand people use it every month also. You can check it out at https://sunburntimer.com. It's also free and open source software, github link in footer.

It would be useful to have an option to change the time of day, rather than always using the current time; e.g. for planning at night what to do tomorrow.

I came here to post this so glad I'm not the only one looking for specific time of day. Or at least give the user the estimated time they can be outside before getting burned? The timer feels great to fire and forget but I might want to plan and I couldn't figure out from the UI what the duration is "safe"

It looks like the "Skin Damage Over Time" chart is the same information as the timer.

This is neat if you are avoiding the "getting red". My understanding is that the damage occurs with or without the sunburn but maybe this goes without saying.

Denver, CO, USA resident here -- this looks _super_ useful and I'm likely to start using it heavily. Our weather here is usually very outside-encouraging (if getting hotter over the years) and our UV is _ridiculous_; I see the index hit 11 and 12 with some regularity. Thanks for the link!

laughs in Australian

https://www.bom.gov.au/climate/maps/averages/uv-index/?perio...

The map isn’t too far off for July[1] considering how far Australia is from the Equator[2].

My area is similar to Sydney in your map. For Denver it’s the elevation that’s exposing them to more UV rays.

[1]https://www.epa.gov/sunsafety/sun-safety-monthly-average-uv-...

[2]https://www.reddit.com/r/MapPorn/comments/cd1t54/relative_la...

Yep, this—we aren’t as close to the equator, but there’s less atmosphere to filter UV. Not so much in terms of beach days, of course, so sunburns here tend to be less than full-body.

All that said: a daily mean of 13-14 is past what we’d see here—and yeah that is some serious burning.

Awesome project! I wanted its Home Assistant equavelant and there's an official integration for it: https://www.home-assistant.io/integrations/openuv/

Looks like the weather might be a bit off, I imagine from your upstream provider. In Indianapolis, all stats look correct except it says we have thunderstorms. Couldn't be a clearer day and nothing on the radar.

This is a clever idea.

Unfortunately, UV exposure is cumulative. So your skin is still getting damaged by the UV rays even if you're not getting burnt.

Cumulative but with a repair mechanism. There's not necessarily "rollover exposure".

There are temporary as well as permanent effects and the repair mechanism can be overwhelmed: photoaging, age spots, mutations.

Right but there are common precautionary rule-of-thumb heuristics which lead normal people to believe that every sun exposure brings them a little closer to death. That's exaggerated. Or at least, the claims are widely contested.

Lets be honest here, every additional sun exposre means you lived longer which directly leads you closer to death sooooo ;P

That part really is cumulative

So how many Joules can you safely sustain in say, a month, or a lifetime ?

I don't think it's really helpful (nor possible) to get into this level of specificity.

Generally, just apply sunscreen and limit prolonged sun exposure when possible (particularly when UV index is high).

Avoiding sunburns (i.e. prolonged sun exposure, particularly when skin is unprotected) is probably the main thing to focus on as I believe studies have shown there is a high correlation between getting burnt and developing skin cancer.

Amazing idea! A little Feedback: I tan easily but still have freckles.

This is awesome thank you for making this!

The article seems to be a meta analysis of a bunch of conflicting research to support a narrative that we don’t really know shit.

And fair, we don’t.

But a couple of things we do know that weren’t covered - egregiously so - is that aging is UV damage. Sometimes called photoaging, wrinkles, sun spots, discoloration, fine lines, grey hair, all of that shit that you associate with someone visibly looking old is sun damage.

So the picture that the article paints of some pasty nerds in offices shielding themselves from all UV and thus: they might as well be smoking… it doesn’t even touch on why people might be doing this.

Both kurgezadt and veritasium did some really great videos on photoaging and it’s worth checking out if this is new information to you.

I often embarrass my daughter when she has some new friend over. If the topic comes up, I give a demonstration. I'm 62 and I've never tried to get a tan and work indoors, and I haven't had a serious sunburn in close to 40 years. On the other hand, I lived spent the last 20 years in Austin, TX. I mow the yard and I ride a bike and in the summer months I put on sunblock before doing the bike rides an sometimes mowing.

The exposed parts of my arms look like I'm 62 -- freckles, some age spots, the skin has lost a lot of elasticity. But then I roll up my T-shirt sleeve to expose my shoulder and my skin is like it was when I was 25: not just pale, but no freckles, no age spots, still supple.

Photo claiming to be a 92 year old woman who used suncream on her face, but not her neck, for 40 years:

https://i.ytimg.com/vi/ITlo7TAy_Hs/maxresdefault.jpg

(She also appears to have Frank's Sign: https://en.wikipedia.org/wiki/Frank%27s_sign )

and then staying in the sun too long, over and over again.

Don’t forget that step.

I see no mention of that in the picture I linked for me to have 'forgotten'? Or in the longer article where it appears: https://onlinelibrary.wiley.com/doi/full/10.1111/jdv.17660

That seems to be something you have 'hallucinated'?

You think that happened to her from a single exposure?

A handful of exposures?

She looks like a football! Who’s hallucinating?

92 years is 33,000 days of being alive, that's plenty of time to rack up damage without doing anything for "too long".

If she had tooth decay or dentures would you say she must have been "chewing for too long"?

Chewing bacteria and or acid for too long, yeah. Like most people.

It’s easy to explain away degenerative effects as primarily age-related - until you look at healthy old people.

About whom the model just says “statistical outlier” and moves on.

the culprit is not the sun-- but overdoing it. If you overdrink water, it is fatal, too.

The sun is responsible for benefiting over 200 processes in the body. And you don't need to be out in the sun all day to get the benefits (if your job does not demand it).

It's far harder to overdrink water than it is to overstay in the sun.

Pro golfers look a good 10-20 years older than their real age sometimes fwiw. In contrast to most other pro athletes in indoor disciplines who generally look better than their age. There's also examples of truckers who spent most of their career with the window rolled down and you can tell straight up what side of the road they drove on.

I first took sun exposure seriously after backpacking and spending time with other young travellers in hostels. It was apparent who spent their time exposed to the sun, I remember a girl my age who was in the middle of a multi-year cycle tour, and although I envied her journey, her skin looked quite rough. I decided that if I ended up doing that, I'd get one of those cycle helmet brim visors and would probably just cover my face during a lot of the riding portions.

Then I met a man who did kayak tours of a city. He was awesome, but really leathery due to the 20 years in a boat without shade and having the UV reflections off the water. Your skin cancer risk is off the charts at that point.

I used to work on boats in the Caribbean.

After my first few months there I realized that the people who didn't look like an old leather bag wore long sleeve shirts and big hats pretty much constantly.

Truckers, plural? Is there an example that isn’t William McElligott from the famous photo[1]?

Edit: self answer, yes[2] (left side!)

[1]: https://www.cbsnews.com/news/trucker-accumulates-skin-damage...

[2]: https://www.mirror.co.uk/news/health/lorry-driver-ages-drama...

Those drivers don't even need to have the window rolled down as far as I know. That's because most door auto glass lets UVA rays through and that's what causes premature aging. If you want to block those UVA rays, you would need to apply some kind of additional film to the side window.

The sunny side of the road?

> kurgezadt

I suffered with German too, in fact, still do :)

As a trivia: "kurz gesagt" -> kurz: short, gesagt: said. "sagen" is the verb "to say", "ge"+"t" is to form the past participle. (but not always :)

I've not heard that grey hair is sun damage.

Do you have any sources for that?

There’s plenty, though please evaluate the veracity of their claims for yourself, I’m not a scientist nor do I excel at parsing scientific articles. Here’s one I’ve come across after a few minutes which references many others https://www.sciencedirect.com/science/article/abs/pii/S10111...

After a quick skim, that article seems to be talking about something other than typical age-related greying. More photobleaching.

From the conclusions:

> Sun radiation affects hair properties as color, luster, mechanical resistance, the content of proteins and others.

TLDR Yes it impacts color. Further reading can be found in the 75 studies that can be found in the references section.

If hair greying was mostly caused by UV damage, I would expect that the pattern of greying would be even, and begin on the top of the head.

In contrast (based on my own unscientific observations!) greying typically begins in small areas, and often on the temples - not what I'd expect if caused by UV damage.

Now I'm curious why it starts on the temples (it's where mine started too, then my fringe)

When most people think of age-related hair greying (which you referenced in your original post), they think of the phenomenon whereby hair follicles stop producing pigments that colour hair.

This is distinct from UV bleaching of the pigments in the hair.

Which grows out. So if it was substantial, you can just stay inside a while and eventually your hair will grow out and replace the faded hair.

If you compare President Obama photos (2008) to President Obama photos (2016) you may conclude that he spent most of his time lounging on the beach?

https://commons.wikimedia.org/wiki/File:20081217_PRESSER-504...

https://commons.wikimedia.org/wiki/File:President_Obama_and_...

I'd rather look old than be one of those lunatics who goes for a summer walk in a longsleeve shirt, gloves, and a hat with built-in veil (a pretty common sight in the Bay Area)

Sounds like my parents, I would always sweat our beach walks with my mom wearing a nose protector that resembled a beak

Who cares about your skin looking a little older when it prevents cardiovascular related deaths??

Current guidelines for sun exposure are unhealthy and unscientific – research (2019) - https://news.ycombinator.com/item?id=31471416 - May 2022 (335 comments)

>These rebels argue that what made the people with high vitamin D levels so healthy was not the vitamin itself. That was just a marker. Their vitamin D levels were high because they were getting plenty of exposure to the thing that was really responsible for their good health—that big orange ball shining down from above.

Yeah, it's not just UV. Infrared light has beneficial effects on deep tissue, including the brain. There's no way to get that from a pill.

> Homo sapiens have been around for 200,000 years. Until the industrial revolution, we lived outside. How did we get through the Neolithic Era without sunscreen? Actually, perfectly well. What’s counterintuitive is that dermatologists run around saying, ‘Don’t go outside, you might die.’”

At least in Australia a big difference is that there is a hole in the ozone layer that stone age people did not have. Sun exposure is much more harmful now.

> How did we get through the Neolithic Era without sunscreen?

By reproducing at 15 years old long before cancer is a problem? Skin cancer was probably at the very bottom of causes of death back then, by a fat margin.

They also didn't have tooth paste, tooth brush, soap, antibiotics, vaccines, so go ahead and live like a caveman... I'm 100% positive it'll have a negative impact on your lifespan

So everything in moderation? Cool, glad my philosophy still applies.

Extreme tension leads to breakage. Something something in buddhism about not trying to put too much tension in a bow or it'll break.

Also known as the middle way.

Moderation is a great philosophy.

> something in buddhism about not trying to put too much tension in a bow or it'll break

Perhaps you are referencing AN 6.55 Sona Sutta.

https://www.accesstoinsight.org/tipitaka/an/an06/an06.055.th...

Moderation is good, just don't overdo it...

Sunlight does way more than just produce vitamin D:

Photo-neuro-immuno-endocrinology: How the ultraviolet radiation regulates the body, brain, and immune system

https://www.pnas.org/doi/10.1073/pnas.2308374121

https://www.sciencedirect.com/science/article/pii/S135382922... this is better source on the underlying study

Since biological evolutionary forces have forever been fighting the sun are our bodies MORE or LESS suited to dealing with UV damage vs oxybenzone damage? Since oxybenzone can intercalate DNA rungs under extremely high local concentrations (forcing some molecules into cavities), or by photo-oxidation converting to radical cation, or in the presence of ethanol which lowers DNA hydration layers and can widen the inter-pair base gaps, then is it causing MORE DNA damage or LESS DNA damage than the Sun's ultraviolet radiation which can contribute to cancer under real world conditions?

Either way it doesn't matter, use mineral sunscreen. Of course if you use bottom tier sunscreen formulated in the 60s you're asking for troubles

Does anyone know whether UVA or UVB is more conducive to producing vitamin D naturally? A quick search shows me that it is mainly UVB that's responsible for that, but unfortunately, this is what gets blocked out by glass windows and sunscreen. On the other hand, UVA is what causes early aging.

So this is just an unfortunate situation because I don't think there's a way of just getting UVB into you in a safe way.

UVB makes it.

UBA denatures it[1], which I thought was how we avoid overdose levels building up in the skin when outside, but can't find a source for that.

Suggested as a reason why fair-skinned indoor workers are getting more melanomas, (ref glass blocking UVB and passing UVA): https://www.sciencedirect.com/science/article/abs/pii/S03069...

Offhand, what was the overdose level? Because 150ng/ml (adjust if I messed units up) isnt an overdose and most people are around ~50 unless they supplement (I mean people outside the 25th parallel.) I think even approaching 300ng/ml is possibly safe as long as you're accounting for the calcium.

I aim to be around 105ng/ml.

I have no idea what the numbers were, I took it in as a system idea: more time in sunlight, more UVB, more Vitamin D. Then UVA breaks it down slowly, so more builds up in the skin, more is being broken down, acting as a control-feedback brake on the increase.

> "unless they supplement"

I have seen plenty of claims that low levels of Vitamin D correlate with many diseases and overall mortality, but that supplementing Vitamin D hasn't been proven to help. Is there any consensus on that?

> "as long as you're accounting for the calcium".

Vitamin D helps bodies absorb calcium but has concerns about high blood levels of calcium. Taking Vitamin K2 as well helps redirect that calcium to the bones instead of the artery walls, apparently. But high levels of Vitamin A could also be causing loss of bone calcium into the blood:

"""in the industrialized world excess of vitamin A has been suggested to be a risk factor for secondary osteoporosis and enhanced susceptibility to fractures. Preclinical studies unequivocally have shown that increased amounts of vitamin A cause decreased cortical bone mass and weaker bones due to enhanced periosteal bone resorption. Initial clinical studies demonstrated a negative association between intake of vitamin A, as well as serum levels of vitamin A, and bone mass and fracture susceptibility. In some studies, these observations have been confirmed, but in other studies no such associations have been observed. One meta-analysis found that both low and high serum levels of vitamin A were associated with increased relative risk of hip fractures.""" - https://pmc.ncbi.nlm.nih.gov/articles/PMC11070503/

which could be a confounding factor with Vitamin A and its precursors in so many animal and plant foods and fortified into more, and in daily multivitamin supplements, skin creams, moisturisers and such.

> Is there any consensus on that?

I'm not sure. there's two doctors that i based my supplementation of D3+K2 on, but i cannot remember their names or link the videos. The assertion made was that blood serum 25OH Dwhatever of 100ng/ml (or dl, i always forget, but the one that makes sense) is enough to prevent most disease, like colds, flu, etc.

Another interesting thing vis a vis overdose/excess D3 is that for covid there was a hospital protocol for 50,000 IU given three times to "knock covid out"

I never read a study, sorry, so i can't link.

I started on this path because my wife got cancer and afterward was getting sick and always tired, d3 serum test was 28ng/ml so we brought her up to 100ng/ml and she hasn't been "sick" in 5 years. Additionally she no longer has to supplement calcium, which her oncologist said she'd have to do the rest of her life.

I buy "Micro Ingredients Vitamin D3 10,000 IU + K2 MK-7 200 mcg, 600 Softgels with Virgin Coconut Oil (2 Pack)" - B0D7B94P8D, and have for years. consistently good, and the blood tests prove it's real. Not affiliated.

I supplement a lot of stuff because my diet sucks and it's something i have been working on this year.

The article explains that it is much safer than not getting UVB. Nothing in this universe is completely safe, but the evidence is that getting UVB is bar far safer than not getting it

Coming from the skin cancer capital of the world (Australia) - no, no it is not

Australia is kind of an exception. You’ve got a super outdoor culture, a bunch of fair-skinned people, thin ozone, and very clear skies.

Yeah, lack of Vitamin D may or may not be a problem (well, obviously in extreme cases it leads to rickets, but that's rare). But skin cancer unquestionably is a problem, and not infrequently a deadly one. Pick your battles.

Very infrequently. Total death rate per year in the US is something like 900 per 100,000 adults, of which less than 3 are from skin cancer. Heart disease, stroke, other cancers, accidents, are all much bigger.

The title is inadvertently correct only because modern margarine is healthier than alternatives such as butter.

Seed oil is healthier than milk fat? Going to need some framing definitions, here...

I had to look up the concept of a framing definition so I might have gotten these wrong but I would equivalently state:

1. Modern margarine is healthier than butter.

2. Seed oils are generally healthier than animal fats.

3. PUFAs are healthier than saturated fats.

4. In this case the industrial processed spread is healthier than the more natural less-processed spread.

PUFA vs saturated fats come with a lot of caveats. It's generally good advice to avoid saturated fats, but there are only certain conditions in which saturated fats are unhealthy and we don't fully understand those conditions yet. Saturated fats from dairy is even more complicated. It's may not be as bad as other saturated fats.

Recently there are very good studies tracking heart disease progression with extreme accuracy and it is very clear that you can eat high amount of saturated fat for a very long time with zero CVD progression. The mechanism depends on other factors.

Still, personally I think it's good advice to reduce saturated fat until we understand these mechanisms better. Eventually though, I suspect we will find other interventions that eliminate the CVD impacts of saturated fats.

I gotta imagine that margarine with EVO is a clear winner, EVO has several great benefits. Not saying processed seed oils are bad.. I'm not in that camp. Evidence for that idea seems very flimsy.

By all means please caveat away! This is HN after all. I was torn between pithyness and qualifying those statements myself. Obviously there's a lot of interesting variation that's not being captured by population means or the limited subgroups we've studied and I'm excited for us to learn more.

In the meantime, I use butter because it's tastier and for me that's worth it. I don't understand why that's not enough for some people.

So.... get a small reasonable amount of sun and use sunscreen whenever you are getting more ?

Do we really have to reapply every 2 hours?

I have heard that some Asian or European sunscreens have some UV blockers that are much more stable than the ones that are mainly used in sunscreens available in the USA. So if you’re using one of these, the need to reapply isn’t as much of a concern. The only thing is that they aren’t FDA approved.

Some examples I have heard of are “ethylhexyl triazone”, “diethylamino hydroxybenzoyl hexyl benzoate”, and “bemotrizinol”.

EDIT: The last chemical on my list was actually approved by the FDA this month (June 2026).

https://hidefromit.substack.com/p/there-is-no-evidence-you-s... <-- somebody claims that's kind of a ghost citation effect. (for what it's worth, I'm quite pro-sunscreen, it just seems to keep working over time better than this advice implies)

This is one of those things that will start a fight at a beach party so I'm just goongtto forget the two tenuous studies the FDA used to stand up the guidelines.

Yes. Most modern sunscreens are photostable, but even if you aren't going in water or sweating, just moving around (and thus scrunching and un-scrunching your skin on a micro level over and over again) is enough to mess up the sunscreen layer you put on your skin.

It depends what sunscreen you use: mineral vs chemical font behave the same, on how much you used, on what you're doing.

Chemical ones go bad with exposure to sun, mineral ones not as much, but either way they can both be rubbed off the skin

I'd suggest checking out Lab Muffin Beauty Science's videos and blogs. The tl;dr is that ideally yes, not because modern sunscreens break down (they're generally pretty photostable), but because your skin cells move over time and create gaps in coverage.

Side note: you can also buy a UV camera on Amazon that shows your suncreen application coverage!

There’s also UV exposure stickers. I haven’t used them, but the idea is that you put a small sticker on your skin, and apply sunscreen normally and over the sticker. Then when the sticker on you turns purple, you know that you have to reapply.

That's cool, do you have one?

I think this all stems from Baby boomers controlling the narrative. Baby boomers had an insane relationship with the sun. Getting crispy brown tan, using tanning oils, using that metal collar to blast sun directly into their face, and frequenting tanning beds were viewed as totally normal and healthy things.

Big surprise they all got skin cancer. Then they swung the pendulum all the way back and now preach 24/7 sunscreen and never letting the sun touch you.

The article doesn't make really controlled findings. There's an argument to be made that the increase to diseases isn't purely lack of vitamin D but lack of exercise.

Our ancestors got lots of Vit D but they also got lots of exercise while absorbing the sun.

I still don't think it's going to be wise to go out and just bake in the high UV of early afternoons but rather it's important to go outside early to mid morning or late afternoon and absorb some sun without copious amounts of sunblock.

No. It is terrible on noodles. Every brand.

Yeah, but it is better than margarine?

I can't believe it's not better.

(2019)

A bit unclear - it says

> Weller’s largest study yet is due to be published later in 2019

But in the header, it also says

> Updated May 31, 2024

I'd still love to know whether there has been further research in the meantime.

And https://web.archive.org/web/20260000000000*/https://www.outs... seems to suggest 2021. I guess we'll put that above, although we had 2019 in the 2022 thread (https://news.ycombinator.com/item?id=48715020) :)

It was published early 2019, maybe late 2018.

Searching for the title of the article ("Is sunscreen the new margarine?") makes it easy to pinpoint: there is a open letter responding to the article, dated January 15, 2019. https://www.asds.net/Portals/0/PDF/LetterToTheEditor-Outside...

Ok, let's go with 2019!

tl;dr you probably should get a few minutes of sunlight daily on your unexposed skin without sunscreen for the "health gains"

(you can also wear clothes to block sun instead of sunscreen so you don't necessarily need sunscreen at all)

You still need it at least on your face and hands. A hat won't completely protect against UV, and you're probably not going to wear gloves in the summer.

It’s great that people are finally talking about this. It should have been obvious that sun exposure without sunscreen is needed to some extent. If you’re blocking the UV all the time, then how could you possibly be getting the minimum UV exposure that you do need. But people have become absolutely obsessed with sun protection.

Sunscreen isn't a 100% block, though. In fact it's advertised by what proportion of the UV it blocks. And in general it's far more common to have too much sun exposure than too little, and in the areas where people have too little, it's not exactly the norm to wear sunscreen every time you step outside.

I don't know of anyone using sunscreen from the moment they wake up until they go to sleep. Guaranteed that even the best user will still receive a healthy amount of UV even if they refresh every few hours. As far as I'm concerned sunscreen is a 10am-5pm endeavor, not needed before or after

Worth noting here for any readers new to UV guidelines that the above rule isn’t necessarily helpful for you. I’m currently traveling in an area that is 8:30am-4:30pm and live in an area that’s 10-6 pm in the summer and shifts throughout the year.

The actual rule is derived from your location’s safe UV index zones, which is found out by determining what local time the UV Index <= 2. Above 2, wear some amount of protection.

That's basically sun up to sun down, here.

It's been completely grey, overcast, and raining here all day and the UV index sat between 3 and 5.

The worst sunburn I ever got was on a boat while overcast. I don't trust them clouds no more.

Clouds block a decent amount of UV on average, but it’s much less consistent than you might expect. 9/10 you might be completely fine with no sunscreen and then get a horrible sunburn the tenth, with no apparent visual distinction between them.

Ya, the relationship between UV and sunlight is strange and unintuitive. For that reason I use a UV widget on my lock screen.

I find that being exposed to the value (e.g. 4) while being able to see the suns effect (e.g. cloudy) gives me a better feel for conditions.

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