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Comment by Aurornis | Hacker News Reader

> But I don't understand why people seem so resistant to the idea that some sun is probably beneficial.

There are some people who believe this, but Vitamin D and sun exposure have been a popular topic for a very long time now. It’s getting harder to find people who think that avoiding all sun exposure is a good idea.

The most confusing part appears to be the idea that wearing sunscreen is equivalent to avoiding UV exposure. Sunscreen reduces UV exposure, but does not completely eliminate it. This misconception has produced a lot of people who think “sunscreen bad” because “UV good”. You can get moderate UV exposure while wearing sunscreen.

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But some people think that just popping a vitamin D pill gives you all the benefits of sun exposure without the downsides.

Research on all cause mortality disagrees. Some sun exposure reduces all cause mortality even if you already take vitamin D.

But what doses did they take in the research? Vitamin D RDA has been increased by like 5-10x recently in some countries (others are still lagging behind), because the RDA that we've used for decades had a calculation error.

If the studies dosed vitamin D based on recommendations then it shouldn't be surprising that supplementing vitamin D didn't work. Considering that only a few countries have updated their vitamin D RDA in the past few years, and most haven't, then I think it's likely that most studies on the topic will have too low of a dose of vitamin D supplementation.

The vitamin D error: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210929/

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It's also possible that some of the health benefits don't come from vitamin D or UV exposure, but instead from something like red light exposure or some other wavelength. (Red) light therapy is a popular topic for example. It's mostly touted to improve skin aging and it's being studied as a help with myopia in children. Does it work? No idea.

Vitamines cannot be patented by pharmaceutical firms. So their supplements could be made by anyone. Also having vitamine D deficit makes you potential customer of all kind alternatives made by pharma because of your weak immunity.

Agenda against vitamine D is strong and make me sceptical everytime I hear about danger of sun exposing or how vitamine D is not working.

>Research on all cause mortality disagrees. Some sun exposure reduces all cause mortality even if you already take vitamin D.

Some sun exposure is correlated with lower all-cause mortality. That is a very long way from establishing causation, particularly considering all of the other plausible explanations for that correlation.

I wonder if it’s just correlation, with the actual cause of both being physical activity. Physical activity likely makes you go out into the sun more, and it also likely reduces mortality.

Would be great if you provided a source so we could check whether they controlled for physical activity.

One of the things I love most about HN - you think of a hypothesis, and right after you see someone else who has already posted it. Very curious about this one as well. Though I don't imagine it being the "actual cause", just a big cofactor. I'd still put some money on the direct effect of sunlight absorption by your skin in itself having additional positive benefits (in appropriate doses).

I would be very surprised if the research you’re pointing to suggests causation.

I’m not saying causation doesn’t exist. But the reason why this issue is hard to resolve is precisely because causation one way or another is hard to establish.

Causation for specific effects of Sun exposure is much easier to establish (for example skin cancer due to exposure, or lower depression due to exposure).

> some people think that just popping a vitamin D pill gives you all the benefits of sun exposure without the downsides.

No one with any cursory research would still think that. Nitric Oxide benefits have been known for awhile.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6830553/

How do you control for sun exposure versus outdoor physical activity and any of the other factors?

> You can get moderate UV exposure while wearing sunscreen.

Indeed, some of us count on it. My wife loves the beach/pool. So we take a fair number of vacations like that.

I’m a natural redhead. Sun and I are strangers.

But, sunscreened-up, and under an umbrella, I can sit outside and enjoy tropical drinks and reading a book. And still get what passes as a tan for me.

> It’s getting harder to find people who think that avoiding all sun exposure is a good idea.

Not in Asia.

I mean, I want to agree with you, but it is easy to see that everyone says any tanning of your skin is indication that you have skin damage. Which, frankly, feels extremely stated to me.

Pale skin from living in a cave looks just as unhealthy as leather tan skin from all day sun exposure over years. Moderate tan from being outside, though? I have a hard time thinking it is as dangerous as stated. Feels like saying "soreness is your muscles recovering from damage and you should avoid it."

> Feels like saying "soreness is your muscles recovering from damage and you should avoid it."

Except this is an analogy not a true comparison of the systems. The act of growing muscles is due to muscle damage and regrowth (to really handwave), and that action causes soreness. It’s not cumulative damage to the muscles, ideally it should heal in between. The same experience is not true for skin. You’re not “improving the health” of your skin by being tan, and we know that damage to the skin is cumulative.

The health benefits of being in the sun seem to be a combination of mental-health (sun=happy) and chemical-release when skin is exposed to sun (eg vitamin D). This seems more like “certain side affects of sun expose are positive to the overall body, despite the growing damage to the skin”.

Agreed that it is an analogy. I'll go farther and agree that I could flat be wrong! :D

In the analogy, though, I do know people have a hard time distinguishing between pain and soreness. Such that it is not uncommon for people to exercise too hard and trigger pain, which will slow them down. As such, I expect that sun exposure is likely the same. I even agree that it is probably easier to jump over any threshold that there may be and to get too much sun. I have a hard time thinking any darkening of skin is a sign of damage, though.

I also think it is tough to distinguish between damage versus wear. Which, is probably just my not liking the language of "damage" here. Do we say that guitar players have damaged their skin to build calloused finger tips? (Genuine question.)

The skin suffers (permanent?) damage from the sun. Not wear. Not darkening. Not “kinda in pain that does away”. Damage-like-negative-connotation-damage. (Yes it also tans and wrinkles and calluses).

This damage is mostly ignored until it manifests as cancer of the skin. Then it’s too late to undo the damage, and its treat-the-cancer time. But you can use tools at dermatology offices to see the damage more clearly, and you can take action to slow the damage (eg Sunscreen). But it’s absolutely suffering damage that one day may manifest as potentially lethal cancer.

I don't want to dig out the reference, but it seemed pretty credible when I read it.

It states that while it is true that people exposed to the sun get skin cancers more often, their outcomes are also usually far better.

So are their outcomes to all other forms of cancer. Thus, overall, the benefits are substantial.

This is not to say you should go out and lay in the sun for hours and get your skin dark brown - instead, it is about not being afraid of normal and regular sun exposure. It is good for you.

Things that mildly damage cells are not necessarily bad for you. They trigger apoptosis, a renewal of these cells. This is why fasting is beneficial, why exercise is beneficial, and why challenging your cells is beneficial. Many of the famous mud and water treatments that help arthritis have waters that are ever so slightly radioactive (well within safe limits but far higher than normal background radiation) for example.

You get new and more resilient, and better cells.

Except we have hard proof that tanning your skin raises your risk of melanoma. And, in fact, tanning regularly is more harmful than getting burned rarely.

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