The author of this paper, Michael Holick, was a professor of mine and is highly controversial due to his industry conflicts of interest that he didn't disclose (<a href="https://www.nytimes.com/2018/08/18/business/vitamin-d-michael-holick.html" rel="nofollow">https://www.nytimes.com/2018/08/18/business/vitamin-d-michae...</a>) and his seemingly perverse testimony in child-abuse cases (<a href="https://www.propublica.org/article/michael-holick-ehlers-danlos-syndrome-child-abuse-contrarian" rel="nofollow">https://www.propublica.org/article/michael-holick-ehlers-dan...</a>). I regard his research with high suspicion.
Wow,<p>I find this funny because through the 50-70's letting kids sleep outside for a nap in the day time was normal in Scandinavian countries.<p>I remember the 1980's photo of kids getting a solar bath in some Hoth like area of Russia in the winter.<p>I like this study because it's starting to add "Sensible sun exposure" into the mix. I suspect that we're going to add "physical activity" to that next.<p>We didn't evolve for 100k years to work at desks for 8 hours a day and hide in houses. Persistance hunting was an outdoor day time activity. Foraging was an out door day time activity. Heading animals was an out door day time activity. Farming was an...
The CDC does not recommend seeking sunlight to promote the production of endogenous vitamin D[1]:<p>> <i>The skin can produce only a limited amount of vitamin D at one time. Once the body has reached this limit, spending more time in the sun will not continue to increase vitamin D levels. However, continued time in the sun will increase your skin cancer risk. There is no known level of UV exposure that would increase vitamin D levels without also increasing skin cancer risk. Vitamin D can be obtained safely through food and dietary supplements without the risks associated with overexposure to UV.</i><p>Same thing with the EPA[2]:<p>> <i>Get Vitamin D safely through a diet that includes vitamin supplements and foods fortified with Vitamin D. Don't seek the sun.</i><p>[1] <a href="https://www.cdc.gov/cancer/skin/basic_info/outdoors.htm" rel="nofollow">https://www.cdc.gov/cancer/skin/basic_info/outdoors.htm</a><p>[2] <a href="https://www.epa.gov/sunsafety/sun-safety-tips" rel="nofollow">https://www.epa.gov/sunsafety/sun-safety-tips</a>
Australia recently updated its sun exposure guidelines to allow for the fact the some sun exposure is required to generate vitamin D. It's a balance, with influences from genetics, including skin colour.<p>The advice is tailored for Australian conditions. Australia is the melanoma capital of the world[1], so it puts a fair bit of effort into trying to get this advice correct.<p><a href="https://www.theguardian.com/australia-news/2024/feb/13/australias-sun-safety-guidelines-updated-to-take-account-of-diverse-skin-types" rel="nofollow">https://www.theguardian.com/australia-news/2024/feb/13/austr...</a><p><a href="https://www.assc.org.au/wp-content/uploads/2023/01/Sun-Exposure-Summit-PositionStatement_V1.9.pdf" rel="nofollow">https://www.assc.org.au/wp-content/uploads/2023/01/Sun-Expos...</a><p>[1] <a href="https://www.cancer.org.au/about-us/policy-and-advocacy/position-statements/sunsmart" rel="nofollow">https://www.cancer.org.au/about-us/policy-and-advocacy/posit...</a>
Well, that review is quite old and out of date now. We now know that vitamin D doesn't in fact protect against these diseases (from the results of large vitamin D supplementation trials). However, a number of large studies show that sunlight itself does give significant protection against cancer and cardiovascular disease, and reduces all cause mortality. It is thought that this effect is due to skin-derived nitric oxide rather than vitamin D.<p><a href="https://onlinelibrary.wiley.com/doi/full/10.1111/joim.12251" rel="nofollow">https://onlinelibrary.wiley.com/doi/full/10.1111/joim.12251</a>
This paper is from 2013. It is out-of-date. More recent large scale studies of Vitamin D supplementation show no benefit, except in cases of substantial deficiency.<p><a href="https://www.nature.com/articles/s41574-021-00593-z" rel="nofollow">https://www.nature.com/articles/s41574-021-00593-z</a><p>Sunlight, however, does show benefits. This suggests that Vitamin D is just a side effect of sunlight exposure, and does not by itself do any good.
Yet nearly every controlled trial supplementing Vitamin D has limited or no effect, except maybe in the most deficient people. Many many trials have been conducted. Vitamin D advocates always have an excuse — it’s too little vitamin D; no, actually you also have to add Vitamin K2; etc<p>Part of the problem of all the observational trials looking at vitamin d is that low vitamin d is a biomarker for being less healthy. People who are ill spend less time outdoors. People who spend more time outdoors are already healthier and are also getting other benefits from their outdoor activities.<p>You can try to control for all of these things, but every time we actually try to test what happens if you give people Vitamin D, we find almost no benefit.
I have had psoriasis for over 30 years now. The only consistent thing that makes it go into regression is getting a lot of sun in the late spring / summer. Unfortunately I live in a northern state, so over half of the year I do not get UVB from the sun and my psoriasis starts coming back in the mid-late fall. I have tried Vitamin D supplements but they don't seem to work for me. Even at high dosages.
If you decide to supplement vitD in winter time note that US government recommendations are way too low [1][2] compared to normal practices in Nordic countries: should be daily 3000 IU for kids (toddlers and up) and 8000 IU for adults.<p>[1] It's not sufficient for kids to take the bare minimum that avoids rickets. (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3476526/" rel="nofollow">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3476526/</a>)<p>[2] Statistical error in estimation of the recommended dietary allowance (RDA) for vitamin D (<a href="https://www.jpmph.org/journal/view.php?number=1915" rel="nofollow">https://www.jpmph.org/journal/view.php?number=1915</a>)
> It has been estimated that as much as 25% of health care dollars could be saved just by improving the world’s vitamin D status.<p>Seems like a low hanging fruit for the government.
Is sunlight really very bad for you? There seems to be extra obsession to protect against sun in the US. Everyone is plastering their kid with sunscreen.
I just do not know how much of it is true. If it was really bad for you places like Italy and Spain would be heavily impacted by it.
Mushrooms when exposed to ultraviolet light can then have considerable amounts of dietary Vitamin D<p><a href="https://en.wikipedia.org/wiki/Edible_mushroom#Vitamin_D" rel="nofollow">https://en.wikipedia.org/wiki/Edible_mushroom#Vitamin_D</a><p>Otherwise there really isn't much in the diet that naturally or regularly contains it other than milk that has been supplemented.
One thing I've found helpful is that you can find out the current UV levels for your location, e.g. <a href="https://www.arpansa.gov.au/our-services/monitoring/ultraviolet-radiation-monitoring/ultraviolet-radiation-index" rel="nofollow">https://www.arpansa.gov.au/our-services/monitoring/ultraviol...</a><p>I live in the antipodes (near the ozone hole), am fair skinned, burn easily, and have had low vitamin d levels when I've had them checked.<p>I cover up or am very careful with sunscreen when the UV is high, then try to do the opposite (no sunscreen, lots of exposure) when UV is at lower levels. The idea is to generate vitamin d at safer times while avoiding skin cancer.<p>I also supplement with vitamin d pills.
The gist:
> As a result 1,25-dihydroxyvitamin D influences a large number of biologic pathways which may help explain association studies relating vitamin D deficiency and living at higher latitudes with increased risk for many chronic diseases including autoimmune diseases, some cancers, cardiovascular disease, infectious disease, schizophrenia and type 2 diabetes
>A three-part strategy of increasing food fortification programs with vitamin D, sensible sun exposure recommendations and encouraging ingestion of a vitamin D supplement when needed should be implemented to prevent global vitamin D deficiency and its negative health consequences.
I'm fair skinned and the ozone layer is very thin where I live, so I have to cover up a lot when I go outside.<p>Which reminds me, I should take some vitamin D.