Using the production of preD3 of an 8 year old as the standard (100%), an 18 year old produces 80%, while a 77 year old only produces 37%. Curiously, an 82 year old did better than the 77 year old (40%).
Source study below.
https://www.jci.org/articles/view/112134/pdf
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Dr. Mark Hyman weighs in on D supplements.
He Recommends just over 3000 IU daily.
AnUser
#23
I take 4000 IU a day because my ALP was high and I havenāt been supplementing much. Will adjust once I test my vitamin D levels so serum levels are optimal.
The causal decrease risk of MS (via MR), is worthwhile as well. Might be immune mediated?
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I donāt know, guys. There really is a lot of controversy. I know people have strong opinions, but we have to follow the science. And there is no agreement at all around higher levels being optimal, as optimal itself has to be individualized. This is explored here:
And FWIW, UCLA, for example sees anything above 50 ng/mL as potentially having adverse effects:
āIngestion of high levels of biotin in dietary supplements may lead to falsely increased results. Deficiency: less than 12 ng/mL Inadequate: 12-19 ng/mL Adequate: 20-50 ng/mL Potential adverse effects: greater than 50 ng/mL.ā
They donāt try to specify āoptimalā, and see as low as 20 ng/mL as adequate. My last level from a test couple of weeks ago was 38 ng/mL, at 66yo. I take 1000IU daily in a supplement, and donāt spend much time in the sun, have salmon once a week, mushrooms regularly.
I feel no need and have no plans to boost my vit. D levels. But of course everyone is in their own special situation and must do what is right for them, so, as always YMMV.
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I think it is best to be between 30-50. I was at 30 after supplementing with 5000 IUs daily. Iām taking 10000 IUs now to get to 50. Thereās not much benefit after that level.
The problem is that 90% of the non-supplementing population is deficient and below 20. That is a problem.
The issue AIUI is that the body has a limited ability to convert D3 (cholecalciferol) into 25OHD (which is what is measured and how the body stores vitamin D). Hence perhaps the first 1,000 or so massively increases 25OHD production and after that it dies down.
I take 25OHD as well as D3 to maintain my 25OHD, but it strikes me a that a vitamin D rich foodstuff would also provide 25OHD which might be better than D3 capsules.
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Very interesting. While the table from the paper jumped from 8 to 18 years, then 77 years, it also included a graph showing the decline.
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I just had MOHS surgery for a basal cell carcinoma, stitches will come out tomorrow. Not really feeling like the sun is my friend tbh. Especially because the doc told me that having had a bcc once makes it more likely that Iāll have it again.
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Thatās amazing. Iām guessing you are a stubborn fellow. I havenāt used much sunscreen because I thought it caused me to get acne flare ups (when I was susceptible). But I had to put on some sunscreen strategically where I could (lips, nose) to avoid getting eaten alive while playing on the sunny mountains of Colorado.
Now I just wear a hat and long sleeve shirt when Iām in the sun for hours.
I agree that sunlight is good for health but too much UV is a mistake. I aim for NIR mostly (in shade, through clothes). The good thing about sunlight is the full spectrum vs the narrow band we get indoors (LED lights, filtering glass windows). We evolved in a sunlight rich environment; stuff goes wrong without it.
Bicep
#30
Stubborn probably, but I would say the true reason is that I just wasnāt cared for much as a youth and worked on open tractors too.
My ancestors were scotch Irish and lived about as far north as possible. Where my pants cover, my legs are so white it would hurt your eyes to look at them. I donāt tan I just get freckles and as my skin sees more sun the freckles get closer together until my arms are solid freckle, so very dark and they can be in the sun all during our long summer days and they donāt care. So even though Iām not really made to be at this latitude, still we have a solution here and it works quite well.
Iām in the same boat. I had a BCC diagnosed in 2011, removed in 2012 (single, small, on my back). Thankfully nothing since. I still have yearly derma full body exams. Iām not super concerned that Iāll have more BCCs. A more unpleasant is a different concern - having a BCC is associated with having more cancer of all kinds overall, I believe with the exception of pancreatic cancer where the association is less chance of getting it; the elevation in risk of other cancers is not very high, but not desirable obviously.
My approach with the sun is not to have any exposure during high UV intensity hours - no sunscreen use, only clothing protection - and small amounts of exposure early and late in the day. Importantly, consume food, beverages and supplements that are skin protective. All my sun skin damage was done during childhood summers before age 10, where every year weād vacation in mediterranean countries, and Iād regularly fall asleep on the beach and get skin peeling sunburns (Iām northern scandinavian); this was back in the 60ās so sunscreen was not a big thing and skin peeling was a common summer vacation rite of passage. So the damage was done, but Iāve been careful and sun shy since the 80ās.
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Same here except it was childhood in Australia and Arizona. Parents / grandparents regarded terrible sunburn with complacency. 
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Vitamin D and cardiovascular health - āHowever, in the latest randomized controlled trials no benefits of vitamin D supplementation for CVD have been confirmedā:
MR doesnāt seem to support any connection between vit. D and cancer:
Quote:
āResults from MR analyses do not support causal associations between 25-hydroxyvitamin D and risk for cancer incidence or mortality.ā
Based on the UK Biobank data, for diabetics and prediabetics, it is better to have at least adequate vit. D levels - above 30ng/mL - for all cause as well as CV mortality:
https://diabetesjournals.org/care/article/45/5/1219/144610/Association-of-Serum-25-Hydroxyvitamin-D-With
Diabetics and prediabetics. Serum levels present is not the same as levels achieved by supplementation
Koreans, but perhaps true for others. For ACM, it is better to have adequate vit. D levels - 30ng/mL at least, but no association with cancer, yet again, plus some for CV:
Quote:
āBased on the quartile cutoffs of serum 25(OH)D concentration, the highest quartile of serum 25(OH)D concentration (ā„21.8 ng/mL) was associated with the lowest all-cause mortality (HR, 0.72; 95% CI, 0.60-0.85; P trend < .001), and CVD mortality (HR, 0.60; 95% CI, 0.42-0.85; P trend = .006). No association with cancer mortality outcome was found. In conclusion, higher serum 25(OH)D levels were associated with lower all-cause mortality in the general Korean population. An additional association was found between higher quartile of serum 25(OH)D and lower CVD mortality.ā
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nikney
#34
Almost everyone is low in vitamin D because it is almost non-existent in foods. It is almost impossible for modern people to achieve normal vitamin D levels through sunlight. Therefore, vitamin D supplementation is especially critical for older individuals. There is not a single cell in the body, especially the immune system, that does not have a vitamin D receptor. In fact, vitamin D is not a vitamin but a hormone. When it was first discovered, it was called a vitamin and its name stuck.
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KarlT
#35
Why is it that we donāt get enough?
Bicep
#36
UVB doesnāt go through windows, clouds, clothes and barely makes it through the skin. Mornings and evenings are out because it canāt come through the atmosphere sideways. Gotta be naked at noon and thatās inconvenient.
People spend most of their time indoors because itās climate controlled and the computer is interesting.
UVB lamp like the sperti is a good solution, but it takes time and money. I predict this problem wonāt be solved for most people.
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nikney
#37
For example, 10 thousand years ago, people would walk around naked in the sun from morning to night. It is very difficult for us to live like this. Moreover, it is harmful to stay under the sun for such a long time.
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KarlT
#38
Sorry, but Iām Gonna have to say youāre probably wrong. Didnāt see any scientific data to back that up.
My guess is my 90 minute bike ride once or twice a week here in Arizona gives me all the vitamin D I need.
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I think we can all agree that a vitamin D deficiency is bad for health and that a lot of people are deficient. You can address it by sunlight or supplementation. Both work and both are effective.
I am deficient in vitamin D, have a family disposition towards skin cancer and live near the equator, so Iām going to go with the supplement. 
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KarlT
#40
There are other big benefits to even brief sunlight exposure.
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