Unexpected benefits of sun exposure on skin
theguardian.com
theguardian.com
While I am a big fan of the scientific method, it is difficult to do studies that don't have lots of confounding variables in this area, so when in doubt, use common sense is my rule. We evolved with the sun, so the most likely probability is we have at least some defense to it, and more than likely we evolved so that at least some exposure has benefit.
But it is fairly intuitive that sunlight's ultraviolet radiation at any strength is going to degrade your skin over long periods of time.
Except for the 'sitting in office all year and then sit in the sun for two weeks straight and get 14 sun burns is not good, so you should use sunscreen' message, which is not very helpful and could conclude also that one 'should expose to sun moderately, e.g. at least an hour a day if possible'.
As an example of this, see this delivery truck driver who had the sun hitting mostly the left side of his face for twenty-eight years:
* https://www.cbsnews.com/news/trucker-accumulates-skin-damage...
MedCram has some easily digestible reviews on the topic:
- The ability for light to influence glucose metabolism: https://www.youtube.com/watch?v=6Win49aeh8A
- Light's effect on immune response and other processes: https://www.youtube.com/watch?v=5YV_iKnzDRg
“The ‘Slip, Slap, Slop’ guidance is appropriate for the descendants of white-skinned north Europeans living in high-UV environments such as Australia, where they have a lot of skin cancer. But it is not appropriate for white-skinned Brits here in Scotland, and it is absolutely inappropriate for dark-skinned Brits, who have made the reverse migration from Africa or India,” says Weller.
Just be aware of latitude differences and the rest is commonsense.
Right from the beginning i had felt that the whole Sun Exposure/Skin Cancer/Sunscreen debate was nonsensical without understanding the "original adaptations" of the people involved.
I remember an article which i read a long time ago that posited that all of our modern health/medical dosage "standards" (eg. BMI) are suspect because they were derived from a sample of European Males and hence are not universally applicable across the world. Given what we know today about genetics/epigenetics/adaptation i have always felt that this should be the first thing doctors should consider when treating patients.
What coping mechanisms would that be?
Right from the beginning i had felt that the whole Sun Exposure/Skin Cancer/Sunscreen debate was nonsensical without understanding the "original adaptations" of the people involved.
What "original adaptations" are you referring to?
I remember an article which i read a long time ago that posited that all of our modern health/medical dosage "standards" (eg. BMI) are suspect because they were derived from a sample of European Males and hence are not universally applicable across the world. Given what we know today about genetics/epigenetics/adaptation i have always felt that this should be the first thing doctors should consider when treating patients.
How about you give us a reference to this article before paraphrasing from memory?
One example; King of the Mountains: Tibetan and Sherpa Physiological Adaptations for Life at High Altitude - https://journals.physiology.org/doi/full/10.1152/physiol.000...
> What "original adaptations" are you referring to?
That should have been obvious from the context. A people's "native and niche" geographical area in which they evolved to adapt. Eg. Chukchi in the Arctic (tolerance to extreme cold by increased basal metabolic rate and blood pressure), Bajau Freedivers of Indonesia (much larger spleen) etc. More prosaically darker skin as you get closer to the equator and lighter skin as you go away from it.
> How about you give us a reference to this article before paraphrasing from memory?
How about you understand what is meant when i have said "which i read a long time ago"? I myself have been searching for this for a while now but i don't recall the title and hence am unable to find it. However, One very good example of BMI vs. Fat is this video about the epidemic of diabetes in poor countries that aren't overweight where the British and Indian scientists measure their fat content (the wai wai paradox at 7:40) - https://www.youtube.com/watch?v=aGuED1JczbI
I just hate that SPF stuff on my skin. It makes it sticky and makes me feel dirty. Instead I just try to avoid burning. I do bring some for when it does start but it almost never does. What I do to avoid it works well enough.
What I tend to do is just take the shady side of the road wherever possible and for the rest of the time just not worry too much unless I really feel I start getting burned. I check that by scratching my skin with my nail, once it starts burning it feels sharper. Then I'd put on the lotion. And by the time I get home my skin will be slightly red but not seriously burned. Which is pretty rare because I tend to tan naturally. By the time spring starts I already have a light brown shade and it protects me during summer. Most of the time I don't even burn at all.
What I do think is bad is someone living in a dark nothern country going on holidays for 2 weeks and spending 2 weeks lying on the beach in the full mediterranean sun. Sunblock or not. My ex used to do that and she got totally burned on the first day even with the sunblock and then spent the rest of the weeks complaining :) I used to live in such a country and I was always more careful during holidays.
Agree, and this is the only brand I've tried that truly crosses the dry-touch threshold. It's a shame that it's more expensive and not commoditized yet (figured it would be by now since it's been on the market for several years).
The more convenient a sunscreen is, the more likely it is to be killing off coral.
Zinc oxide doesn’t give that chemical feeling, doesn’t stain clothes/etc, doesn't poison the environment, and is also more effective at blocking broad spectrum UV than the oxybenzones/etc.
Like everything else in life, "moderation in all things" is the best rule to follow. If you spend your life getting deep dark tans or don't take sensible precautions against sunburns, expect melanoma. If you avoid sunlight like a cave dweller, expect deficiencies in everything from vitamins to mental health.
- Octocrylene (endocrine disruptive + might cause sun allergies)
- Butylated Hydroxytoluene (endocrine disruptive)
- Homosalate (https://health.ec.europa.eu/system/files/2022-08/sccs_o_244....)
Evolution doesn't work like that, as long as you procreate you may die at 40 or 120 and genes would not care. Probably a lot more important to get vitamin d from the sun by reducing skin pigmentation when you live near the poles (getting stronger bones and muscles) than slightly reducing your chances of getting skin cancer at 50+ years (most of your peers die a lot sooner of unrelated causes anyways)
evolution doesn’t work like this, either: lifespan can well be selected for on grounds of communal care/ altruism.
If they really have controlled for that factor, shouldn't we see similar results from people with sedentary lives, but high UV exposure? (possibly by regular use of tanning beds or the like?) Being prescribed UV exposure is an interesting idea for the future.
[0] https://www.medrxiv.org/content/10.1101/2023.07.11.23292360v...
Broad-spectrum vs tanning.
And outside also gets lower CO2 and VOC.
I was held in cells without windows for five years. The other five the cells had windows but were so dirty that practically no sunlight entered. Never went outside. Maybe a total of 10 hours outside in 10 years. The first five years in a facility where they didn't design any outside into it because it was built in the middle of a downtown area and there wasn't space. The other five in a facility that had large outside areas but no staff to organize corralling a whole cellblock of inmates, getting them through the corridors of the buildings to the outside, monitoring them so they didn't escape and then getting them back. That requires a lot of staff, and most jails and prisons are vastly understaffed.
Here's what I wrote about the sunlight:
As a general just-so-story rule of thumb to be discounted in the face of evidence to the contrary, stimulus or stress that's a consequence of doing stuff generally acts as a "growth factor" even if it causes slight damage, including exercise, heat and cold shock, and sunlight.
If you are at all active over age 30 — by which I mean you EVER run, jump, or otherwise put pressure on your spine — you need to get lots of sunlight.
Most people have insufficient if not downright deficient levels of vitamin D. Spondylolysis and eventual spondylolisthesis is not a prognosis you want for your back.
The old folk saying is to take d-vitamin supplements in all months that has an R in them. Probably sound advice
This is just wrong.
Per capita vitamin D defficiency and insufficiency in the US are estimated at about 30% and 40%, respectively [0] compared to about 50% insufficiency worldwide [1].
Lack of exposure to sunlight is a major predictor of vitamin D insufficiency, even in western countries [1]. Sunlight produces more bioavailable vitamin D than dietary sources, and the recommended daily vitamin D can easily be obtained from sunlight alone, while it is hard to obtain from diet alone.
> Just a couple of slices of cheese per day and some milk is all the d-vit you need here apparently.
Daily intake of cheese [2] and milk [3] fortified with vitamin D at the recommended daily value is insufficient to make up for a lack of sun exposure.
[0] https://pubmed.ncbi.nlm.nih.gov/29644951/
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/
https://www.sciencedaily.com/releases/2015/03/150317122458.h...
2. while there's plenty of evidence that vitamin D levels is associated with positive health outcomes, AFAIK evidence that vitamin D supplementation being associated with positive outcomes isn't very good.
edit:
3. I dug further and found there was a response to the study that you linked[1]. The response points out that the standard used by the original study (ie. supplementation levels that's needed for 97.5% of the population to achieve adequate serum levels of vitamin D) would cause people on the lower end to consume too much. Therefore the recommendation of 8000 IU (or any single number, really) is bad, and we should instead have different recommendations according to body weight:
>With this approach we estimated, for example, that doses of 1885, 2802 and 6235 IU per day are required for normal weight, overweight and obese individuals respectively to achieve natural 25(OH)D concentrations (defined as 58 to 171 nmol/L).
As such, even though there might be an error caused by "off by a factor of 10", everyone really shouldn't be upping their supplementation by a factor of 10.
However I also have low vitamin D.
My current strategy is to check the UV levels (I've got a widget on my personal dashboard) and whenever the UV levels are moderate or below, I try to get as much sun exposure as possible - shorts and t-shirt, or topless.
I then cover up when the UV levels are demonstrably high.
My theory is that low levels of exposure are very good - you get your vitamin D, whatever else you need, and your body starts to build an appropriate amount of melanin.
The worst thing to do is to avoid sun all the time, then suddenly get massive UV doses.
I've noticed that my hands very rarely get burned compared to other areas - my theory is due to constant exposure that part of my body is more resistant compared to the pasty areas.
My key point is that you can view the UV rating and protect yourself appropriately - e.g. high caution summer-midday, zero caution winter mid-day.
This is of course true, and it took me half a lifetime to realize I could get deep tans and stay out in the sun without any sunscreen, all it took was to "DCA" my way into sun exposure at the beginning of the summer. Concerted efforts to get 5, 10, 15, 20, 25, 30 minutes of unprotected sun exposure that slowly increase but not to the point of burning.
I also realized that sunscreen does not need to be so liberally or frequently applied- particularly mineral sunscreen, the thinnest possible film is all that is needed for hours of protection if you aren't swimming or sweating excessively.
Yeah it does. But we are also here at this article.
I'm glad I was forced to wear a helmet because otherwise my head would look weird ;)
And yet ... when it comes to sunblock ... I try to avoid sliding into a conspiratorial stance, but let's just say that I don't use it [0], and I am very curious about the reason(s) why so many of us do.
ps. yes, I do know about skin cancer and have several friends and family that experienced it.
[0] if am going to be outdoors all day after a long period of being mostly indoors, I'll use it for a few days to protect my nose, lips, cheeks, ears and neck. Then I'll stop. I prefer sunblocking sleeves for my arms if that sort of is necessary.
> ps. yes, I do know about skin cancer and have several friends and family that experienced it.
How are you still curious then?
It seems that the argument that solar exposure causes cancer, and if not cancer than weathered leathery skin when you're older, has been widely and effectively made, and this has been enough to get most people to hedge and just use sunblock anyway.
I'm not convinced they're wrong - I'm more interested in the way sunblock brings out my own inner "conspiracy" self, even if I don't feel inclined to defend that version of me. It's actually a way to have some empathy towards people I otherwise feel no empathy whatosever for (e.g. the anti-vax crowd).
Yes, that is literally it. That is why people wear sunblock, including "religiously". They don't want cancer or prematurely aged skin.
> m not convinced they're wrong - I'm more interested in the way sunblock brings out my own inner "conspiracy" self, even if I don't feel inclined to defend that version of me
Again I'm completely lost. Is the conspiracy that people don't want cancer?
I didn't actually just say that :)
Even if you doubt the efficacy against skin cancer, sun burns are easily observed in short time
Of course we do know that very heavy sun exposure and especially sunburn can cause cancer. It’s probably a case of moderation being good for you— not too little and not too much.
Severe vit d deficiency obviously is strongly negatively selective. So that by itself explains the evolution of white skin in northern climates. I dont think evolution can be used as evidence for other benefits, since vit d deficiency would cause that just by itself.
E.g. it snows more as you go towards the poles. There are a lot of pale creatures in climates with snow, for the even more obvious natural selection pressure of "can hide better".
Anyway, from all I have learned and done, the best health advice that I think applies to most people is moderation is the best. Trying too much and too hard on something will just backfire. Eating only meat and milk will cause cancer sure, but eating only vegetables and beans will also affect your health, namely nutritional deficiency. Etc. and etc.
I will just live normally while adjust things within limits and enjoy life while it is still good.
I wonder if future building codes will require some type of intermittent full spectrum or UV light in certain areas. Maybe in a bathroom with a timer that shuts it off a few seconds after someone enters.
The time when the ratio of UVB to UVA is highest (best time) between 10 am to 2 pm, or when your shadow is not longer than your height.
So 20 mins in the sun at noon without sunblock is best, and after that if you’re pale then slather on the sunscreen.
So far I play it by ear: I wear sunscreen when I go out any time before 330pm. I don't get sunburn this way, but it's really hard to tell if I'm damaging myself. I also migrated from center Italy to Canada, so my skin is a bit more resistant (Sicilian heritage), but it makes it way harder to figure out the balance, since the sun is still strong in the summer.
Sunscreen is full of pretty active chemicals, so I would not recommend using it, when you don't have to.