According to the study in the other HN link here, they made an error in calculating how much Vitamin D you need. The medical community also seems to think that

According to the study in the other HN link here, they made an error in calculating how much Vitamin D you need. The medical community also seems to think that 20 ng/ml is when the deficiency starts, when in reality it's more like 40. Some studies have shown that you can see benefits upwards of 60 ng/ml. Other research has shown that Vitamin D helps with sleep in the 60-80 ng/ml range. I've seen many people on Reddit say that their blood tests level came out at 5-10. That's crazy. Get your 25(OH)D level checked. Some of the studies that have shown "no improvement" from Vitamin D saw that result mainly because they were still prescribing far too little Vitamin D (yet still higher than the RDA). 10,000 IU may be necessary just to maintain your level. However, you also have to keep in mind that you won't be getting D only from the supplement, so throughout the year you should actually increase your Vitamin D level as you get more sun exposure. Meanwhile the 10,000 IU (which by the way is "only" 250 micrograms) will maintain those high levels. Then, in the second year, you may further increase your Vitamin D level as you once again get more exposure in the sunny days. So you should check your Vitamin D at least after a year, to ensure your levels aren't too high. After you're stabilized you should need around 5,000-7000 IU, but it's really dependent on each person's needs, so you'll have to figure out on your own through trial and error. However, you also need to keep in mind that not everyone uses Vitamin D as efficiently. You may have undiscovered gallbladder issues for instance, or your gut bacteria is not well balanced, or your stomach doesn't have enough acid, or you're not taking Vitamin D with enough fat, and all of these factors which could impact how easily you're absorbing Vitamin D. This is part of the reason why the FDA can't just recommend "everyone should take 10,000 IU". Plus, people of color need much more Vitamin D, so if the FDA recommends everyone 2,000 IU as a higher minimum, that may still not be enough for them. https://www.youtube.com/watch?v=v3pK0dccQ38&feature=youtu.be&t=5m33s https://www.youtube.com/watch?v=v3pK0dccQ38&feature=youtu.be... https://www.youtube.com/watch?v=xF24xmJQK1k https://www.youtube.com/watch?v=xF24xmJQK1k https://www.foundmyfitness.com/vitamin-d https://www.foundmyfitness.com/vitamin-d https://www.vitamindcouncil.org/i-tested-my-vitamin-d-level-what-do-my-results-mean/ https://www.vitamindcouncil.org/i-tested-my-vitamin-d-level-... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5541280/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5541280/