I will thus cut down on supplementation to avoid vascular calcification.
Current good practice is to also supplement with vitamin K when taking D. This is to promote carboxylation of osteocalcin, so calcium is directed into bones rather than soft tissues[1].
Additionally, please no one take vitamin K supplements without speaking with your physician first. They’re a direct reversal agent for a class of anticoagulants, the prime example of which is warfarin. It’d suck if you accidentally had a stroke or pulmonary embolism because of a random internet comment.
With regards to vitamin K, all the versions of the supplement I've seen have a specific warning on the bottle that they're not to be used if you're also taking anticoagulants.
UVB exposure does cause cancer, that much is undisputed [1]. However, with very short exposures following a correct schedule given by a doctor, UVB phototherapy can be an efficient treatment for Vitamin D deficiency in people with certain specific illnesses like cystic fibrosis or inflammatory bowel disease that cause digestive malabsorption of vitamins. This can also be an effective treatment e.g. for psoriasis. The increase in risk seems to be negligible when used like this [2], but for people without these specific diseases a normal Vitamin D supplement is unequivocally safer.
[1] https://www.cancer.gov/publications/dictionaries/cancer-term...
The original article seems to imply that the whole industry is just some sort of hype. I cannot say for certain how much of it is true given the author’s experience is not in the medical field
https://www.quora.com/How-long-does-it-take-for-a-vitamin-D-...
Last winter, I wound up sick due to low vitamin D. We are talking "had to sit while making a simple dinner" sort of sick, headaches and backaches and so on. Now, stronger vitamin D pills are prescription here, lower-dose aren't. I got prescription pills to take for 90 days. I had a blood test after 1.5 to 2 months (earlier than initially thought, but the doctor was curious.
Not only were my vitamin D levels good, but I felt much better. Better than I had in months. I still take the lower dose pills to prevent such a thing. I have the choice to get sun during the summer - at least 15 minutes a day with sun on more than just my face. Alas, I find the temperatures too cold to do that all the time (I live in Norway, summers are chilly). On the other hand, my levels are still good (had them tested last month per doctor's orders).
Now, it might take a bit longer to actually repair damage done by low vitamin D, but as far as how I felt - it was much quicker.
I read something a long time ago that suggested if you are in need of more sun exposure, it's best to get it near noon, because when the sun is low, it provides relatively more of the cancer causing UV and less of the therapeutic. Of course, in the northern parts of the world in the winter, that's not so easy.
The same thing happened to one of my friends earlier this year. He started getting all sorts of weird diseases when he used to never get sick. After getting a blood test and learning his vitamin D levels were low, he started taking it and he hasn't gotten sick since.
So even if there is big money behind it, I think it's worth getting tested if you spend a lot of time indoors.