Interesting... What benefits does this have over vitamin D supplements?
I've seen this "optimising for some perceived negative effects" thing with toothbrushes/toothpaste, where "whitening" and stiff bristles actually just means removing more (irreplaceable) enamel from your teeth.
Vitamin D supplements are controversial on their own.
There is ample results on better health correlated with higher levels of Vitamin D, but the reverse is far more teneous: shoving in Vitamin D isn't guaranteed to be properly absorbed, and even when it is we don't see conparable results to people producing the Vitamin D themselves.
An example: https://academic.oup.com/jbmr/article/38/10/1391/7610360
The paper you linked is saying there is no benefit in Vitamin D supplementation in people who are not Vitamin D deficient. Which is not surprising.
Do you have research showing sunlight Vitamin D has benefit for someone who is not deficient?
Unless you are deficient it's not the vitamin D. It's a whole host of other processes that benefit your body from sun exposure and the activities that go along with it. The Vitamin D is just a marker that we can detect that can also be related to that same exposure. So there's a huge number of things for which people with high levels of Vitamin D do not suffer but supplementing has no effect because the vitamin D is only correlated not causative.
The paper covers a lot, some are administrating vitamin D as a prevention measure, most are on vitamin D deficient patients. e.g
> Even in the small subgroup of subjects with a poorer vitamin D status (serum 25OHD < 20 ng/mL), no effect on fracture risk was observed (hazard ratio [HR] = 1.07; 95% confidence interval [CI] 0.91–1.25).
> A large RCT in Mongolian children with severe vitamin D deficiency did not find a beneficial effect of vitamin D supplementation on the subsequent risk of subclinical or clinical tuberculosis.
Many people with inflammatory disease like IBD can't absorb oral vitamin D properly
Even in healthy people, oral vitamin D is not always sufficient (there was a study done in Japan where sunlight is low but Vitamin D from fish is high - can't find it right now) and sunlight exposure might have other benefits than vitamin D anyway
https://www.sciencedirect.com/science/article/pii/S0022202X2...
I have issues with low vitamin D and even really high supplement doses like 10,000iu/d do nothing at all- my level keeps dropping no matter how much I supplement. Sunlight brings it up quickly but not in the winter from Nov-Jan.
Vitamin D supplements don’t work consistently across different populations. Very few (~10%) of people can absorb dietary vitamin D. If you aren’t some form of Northern European, you probably need to take at least 10 times the daily recommended dose of vitamin D to influence your levels significantly.
Most people need sun!
Don't most people who take supplements just take 10X the RDA? It is still a tiny amount of supplement that is safer and costs a fraction of the indoor tanning or traveling often to somewhere with adequate Sun.
I’ve never talked to someone supplementing vitamin D who was aware at all.
I think that the correct approach would be start at 10x vitamin D with baseline bloodwork and adjust dosage from there.
But yeah I’m in the camp of “sun is good for you, in most cases.” I would be very unsurprised to find that there are precursor hormones released beyond vitamin D that impact efficacy. We don’t really understand the endocrine system very well.
I think that because we can see and understand the dermatological effects we overly weight them. Anecdotally older people I know who have not avoided the sun seem much better off mentally and physically, but I think because there isn’t a measurable reason we’re aware of, we completely discount any benefit.
Stiff bristles also damage your gum more easily and can lead to gum recessions. I needed gum transplants because of this and a wrong brushing technique. For me even medium stiffness is too hard.