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Comment by Hendrikto | Hacker News Reader

> According to Richard Weller, who co-led the study, most uv exposure guidance has thus far been firmly focused on preventing melanoma skin cancer. But, he says, “Many times more people die from other cancers and diseases. We have to think about how uv radiation could help them avoid illness.”

> The exact mechanism whereby uv light might lengthen lives is unknown. The authors, for their part, believe part of the explanation may lie in vitamin D’s ability to boost the immune system and improve bone health. They also point to nitric oxide, a potent blood-vessel widener capable of reducing the risk of cardiovascular disease.

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another effect - collagen mixed with vitamin B polymerizes in UV, thus eyes and skin repairs for example.

The biggest issue is non-managing mismatch between your geographically evolved skin type and the Sun in the geography you're residing - thus white people living south get a lot of skin cancer while for example Somali immigrants in Minnesota and Sweden have widespread severe vitamin D deficiency (and associated issues)

Tangential - a pet theory of mine is that 40K years ago when magnetic field flipped, and there was short period (1K years or so) of highly increased UV it led to large number of early eyes issues in those large eyed (most probably the result of evolutionary adjustment to the more northern light) Neanderthals living in Europe - early damaged vision, cataracts, blindness - while Cro-Magnon's eyes with Cro-Magnon just coming out from Africa, faired much better with that northern, even temporarily increased, level of UV and thus the Cro-Magnon quickly replaced the Neanderthals.

So why can't we just eat more Vitamin D supplements?

The sunlight is free. :-)

There are 4 beneficial effects of sunlight I know of that have nothing to do with vitamin D.

I know 5.

My 4:

Light that is brighter than is possible inside most homes makes you more alert (almost immediately), and if done during the first 3 hours of wakefulness has benefits that last throughout the day according to Andrew Huberman.

Specific qualities present in sunlight when the sun is very low in the sky (or under the horizon, namely yellow-blue contrasts detected by the intrinsically-photosensitive retinal ganglion cells) entrain the body's clock, making it easier to get to sleep at a consistent and suitably early time of day.

UVB exposure triggers a skin-brain-gonadal axis through skin p53 activation (nothing to do with vitamin D). I.e., 20 or 30 min every other day of strong sunlight on bare skin and into your eyes increases your levels of the sex hormones.

Certain red and infrared wavelengths help cytochrome c oxidase turn serotonin into melatonin, which is a potent antioxidant right where antioxidant activity is most needed (in the mitochondria).

What's the fifth one?

ADDED. It just occurs to me that with "I know 5" the conversation might have jumped from the object level to a comment on the social and emotional effects of my comment. D'oh!

They seem a bit remote for someone at high risk of skin damage due to skin type and location. I am surprise the immune system does not get more attention in discussions like this. I would put it high on the list.

There is an interesting wtf correlation between incidence and severity of multiple sclerosis and latitude. Sunlight (or alternatively narrowband UVB in a controlled clinical setting) can be an effective treatment for some skin conditions.

THERE ARE FOUR LIGHTS

The 6th reason is being smarter than the other two guys.

For one, your body absorbs an abysmal fraction of supplements, nearly all of it comes back out the other end. This isn't unique to vitamin D, naturally, but for practically all food supplements. Your body is pretty good at taking care of itself so long as you give it the tools it needs. If you live in a northern climate, vitamin D supplements may be a part of it, but for most part, spending some time outside and getting your movement in is a reasonable baseline.

> your body absorbs an abysmal fraction of supplements, nearly all of it comes back out the other end

This is irrelevant when the supplements are available in high enough doses to overcome poor availability.

It’s not hard to exceed the upper limits of serum Vitamin D with common higher-dose off the shelf supplements if taken long enough.

You can, and it’s quite possible that provides most of the benefit. But very few systems in the body operate in total isolation, and it’s equally possible something else depends on vitamin D synthesis or on UV absorption, and that thing might matter for health.

In short, because the body and the mind is a very complex system.

I know almost nothing about this apart from being vitamin D deficient and taking supplements. My doc says that vitamin D absorption through the gut is much less efficient than vitamin D created by the body.

because its a reductionist view of the value of sunlight exposure

>They also point to nitric oxide, a potent blood-vessel widener capable of reducing the risk of cardiovascular disease.

This paper, "Insufficient Sun Exposure Has Become a Real Public Health Problem" [1] states "thus, serum 25(OH)D as an indicator of vitamin D status may be a proxy for and not a mediator of beneficial effects of sun exposure".

That is, while vitamin D can be used to deduce someone's amount of sun exposure, the benefits of sun exposure are not coming from the vitamin D.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400257/

In his TED talk, Weller gives a potential alternate benefit source in nitric oxide production which leads to potential cardiovascular benefits. So, the short answer is it may not be (just) vitamin-d. The bigger point though is that there are a lot of very complex things that happen when you go outside and benefits could come from many of them. We want an easy 'this one thing happens so we can replicate just that' but maybe it is actually a combination of many things so there may be no easy one pill replacement.

Two pills then: Daily 10,000 iu D and daily Cialis. Bonus: Bon-us.

Because studies into vitamin D supplementation haven't shown that it reduces mortality, and because there are other benefits of sunlight, such as nitric oxide.

Ok, just add L-Arginine supplementation then...

So how do you explain the reduction in cancer mortality with sunlight?

Did this study factor in supplementing for other things sunlight provides, i.e. the nitric oxide? If not, then it's a poor study in relation to supplementation as a means of obtaining the benefits of sun exposure.

No studies have shown that any of these supplements reduces mortality, whereas multiple studies show sunlight reduces mortality.

Did these studies that show that these supplements don't reduce mortality, were they done in such a way where they are measuring the multiple supplements that are received through sun exposure at the same time? No? Didn't think so.

No. There are no studies, other than for vitamin D. That is the point.

because the exact mechanism whereby uv light might lengthen lives is unknown

when your skin synthesizes vitamin d using sunlight, it synthesizes it from cholesterol. i wonder, does that lower serum cholesterol? if so, which serum cholesterol?

People who get plenty of vitamin D through their diet still benefit from sunlight exposure

Ecological study of solar radiation and cancer mortality in Japan https://pubmed.ncbi.nlm.nih.gov/15551791/

Something I've found rather curious is that my home state of New Mexico has the lowest cancer incidence rate out of any other state US state (Puerto Rico is lower, but technically not a state) (https://statecancerprofiles.cancer.gov/incidencerates/index....).

Now, granted, your risk of dying from heart disease is actually greater than that of cancer, so it's entirely possible that the low cancer rate is because everyone is dying from heart disease instead. It would make a lot of sense since New Mexico is one of the poorest states in the country.

Thing is though, the heart disease mortality rate is also low. (https://www.cdc.gov/nchs/pressroom/sosmap/heart_disease_mort...)

So I don't know, I'm kind of inclined to that our low mortality rates might be due to the sun instead. On top of being located further south than most states, we also get more UV exposure due to our higher elevations, and most days are relatively cloud free. Other theory of mine is a more Latin-influenced diet and exercise, but again, we're a poor state, poverty tends to be negatively correlated with exercise and diet.

It's a trend followed by most of the Mountain West, which is roughly as arid and sun-rich as New Mexico. I just find New Mexico so interesting because it definitely dispels any notion that people are healthier because they're richer or have access to better health care.

This is called the Hispanic Paradox, there's even a wiki page on it.

Hispanic people have better health outcomes despite being poorer, probably due to better diet, exercise, community structure etc.

He has a good TED talk on this from over a decade ago. https://www.ted.com/talks/richard_weller_could_the_sun_be_go...

I don’t understand how this is surprising for people.

We have evolved under the sun, of course we have adapted to its presence, and taking it away naïvely is unadvisable.

People are generally taught things like this through mildly hysterical news broadcasts from moralizing non-specialists. This is why it's surprising for people. They've been taught the sun is scary.

If you don't put sunscreen on your kids, it's tantamount to abuse. (I recently experienced this walking through the woods at 10 AM with a family member, no I don't need any sunscreen for a short hike through the trees)

Men are known to be callous dare-devils sometimes, but Women also exhibit a curious lack of good risk assessment that fits this pattern.

They either over-cautiously drink 8 bottles of water a day for dubious health benefits, or they uncaringly approach some wild animal that they cannot imagine goring to death them a few seconds later.

People evolved to live in a fairly small area of the world rather than flying to distant places with different amounts of sunshine than our ancestors likely dealt with in the areas where they spent generations.

I don't buy that as an argument. It's the same argument used to push all kind of hoaxes or fad stuff. We live longer than what we used to do, so not everything we did in the stone ages can have been beneficial.

Average lifespan has increased, meaning more people survive early deaths due to disease and injury that we can now prevent, but as individuals we haven't broken through any maximum age barriers.

That said, sun bathing is a modern phenomenon. Our ancestors knew enough to assess that painful sunburns were bad and mitigated their exposure by wearing large hats and clothing with long sleeves. I'm sure even primitive peoples would cover themselves when necessary. If you spend a lot of time working outside you also develop a very dark tan which helps quite a bit. Modern people seem to suffer mostly from spending so much time indoors that even moderate sun exposure on the weekend produces a damaging sunburn.

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