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Is this more vitamin D evidence or is there something more going on?
Is this more vitamin D evidence or is there something more going on?
That is absolutely the right question to ask. If the results are not adjusted for vitamin D levels, and it does not appear that they are, then the results are largely useless because vitamin D is very easy to supplement. Note: Adjusting by vitamin D levels is not the same as adjusting by supplemental intake. Even adjusting for supplemental intake must be a linear adjustment, not a binary one.
"The health effects of vitamin D supplementation: evidence from human studies"
https://www.nature.com/articles/s41574-021-00593-z
I do think the question is complicated by the fact that humans have wildly different skin tones. What is applicable for skin types that are very pale is quite different than darker skin tones. This question has been complicated even more by recent migration of humans into zones their skin was never meant to be exposed to. It feels like the dermatologists all made their guidelines based on people with porcelain skin that live at the equator. The truth is more complicated than that, people with darker skin develop low vitamin D status follwing those guidelines. Humans love to have blanket rules they can follow without regard to extenuating circumstances like different skin tones, but that isn't reality.
The selected cohort of people is pretty specific from a global perspective. In particular, if you live in a higher UV location (i.e. closer to the equator), intentionally increasing sun exposure like they measured in this study may not be necessary or helpful. For instance, the entire lower 48 states in the USA are below the same latitude as the UK.
Earlier quoted context omitted.
That is absolutely the right question to ask. If the results are not adjusted for vitamin D levels, and it does not appear that they are, then the results are largely useless because vitamin D is very easy to supplement. Note: Adjusting by vitamin D levels is not the same as adjusting by supplemental intake. Even adjusting for supplemental intake must be a linear adjustment, not a binary one.
Vitamin d supplementation studies are a lot more ambiguous than this though. And this also matches my "feel". Getting sun makes me feel good in a way that vitamin D supplementation never does. I was once at a dinner and sitting at the table with the head of the Office of Dietary Supplements for the US government and asked him this question- "How should I get vitamin D and how much should I take?" He answered quite qu…
Listening to such people in power is a path to getting yourself killed, in this case by diseases. Their interest is in preserving their power, first by taking it away from you.
They always have to say "don't supplement" because asking everyday people to supplement will force the officials to admit that the food and/or environment has recently been made inadequate. This will put the officials in a corner that they cannot get out of.
The study you linked is defective by design. It uses a threshold of 50 nmol/l which is a pathetically low 20 ng/ml. Such studies are engineered to show a null result.
Higher ultraviolet light exposure is associated with lower mortality... for white people residing in the United Kingdom. The selected cohort of people is pretty specific from a global perspective. In particular, if you live in a higher UV location (i.e. closer to the equator), intentionally increasing sun exposure like they measured in this study may not be necessary or helpful. For instance, the entire lower 48 stat…
"The UK Biobank has data from which behavioural and geographic UV exposures can be estimated. Firstly, participants were asked ‘how many times a year would you use a solarium or sunlamp?’ We recoded the responses to create a solarium use variable (solarium user or solarium non-user, defined as one or more times per year versus never or less than one time per year)."
and
"Secondly, we estimated an annual average residential shortwave radiation (SWR; kJ/m2) over the follow-up period variable for each participant. Downward SWR is the total incoming solar energy over the Earth's surface in the shortwave spectrum and comprises both UVA and UVB radiation, (Yu et al., 2021) the components solar radiation that have effects on human health. The Japan Aerospace Exploration Agency (JAXA) calculates half-monthly average of daily downward SWR (250 nm–2500nm) measurements using daily data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua and Terra satellites, considering cloud and aerosol thickness (Murakami, 2010). These measurements are available at a 0.05°x.0.05° spatial resolution."
So, "Did you use a sunroom at least once?" and "How much solar radiation does where you live according to our model?"
Is this more vitamin D evidence or is there something more going on?
Did you (and those who so far responded to you) actually read the article? The Vitamin D question is addressed throughout, e.g. "Linear regression models were fitted for the UV exposures and vitamin D serum levels, adjusted for the same confounders for each UV exposure described above, plus vitamin D supplementation."
That's entirely the opposite of adjusting the results for vitamin D levels. It's biasing the results by vitamin D levels.
Higher ultraviolet light exposure is associated with lower mortality... for white people residing in the United Kingdom. The selected cohort of people is pretty specific from a global perspective. In particular, if you live in a higher UV location (i.e. closer to the equator), intentionally increasing sun exposure like they measured in this study may not be necessary or helpful. For instance, the entire lower 48 stat…
Accounting for UV intensity of your home country is crucial. Don’t just go out and frolic without precautions just because a study from the UK found sun exposure was good. Their sun isn’t built the same.
Mid day UV index in SF is 9 as I type. Compare what the paper says about the UK UV index:
“ The UV index [in the uk], which measures the erythemal intensity of sunlight, rarely exceeds 6 (where 3–5 is classified as moderate and 6–7 high)”
Make good decisions people! I got some sun when the UV was 2 early in the early morning. Now it’s 9 at midday. All sun is not equal.