Autoimmune diseases often are due to suboptimal vitamin D3 softgel intake (typically 4-5K IU) or suboptimal magnesium intake (300-400 mg). Bringing both to highly optimal levels should minimize the risk of development of new or worsening autoimmune diseases, although it won't revert any existing ones. Low dosing either one doesn't work in this context.
Those who reject this even after reading the following 100% deserve to suffer, but worse yet, they make others suffer, often due to their conflict of interest as shills for pharma. The general commitment to truth is well below zero for those who stand to gain from its suppression.
https://medicalxpress.com/news/2024-10-vitamin-d-deficiency-...
https://medicalxpress.com/news/2022-01-vitamin-d-supplements...
https://medicalxpress.com/news/2018-02-magnesium-vitamin-d-i...
Whilst I agree that there's a lot of people with D3 deficiency (at least during winter), it's also worth being careful of taking too much D3. Typical signs of too much D/D3 are nausea, loss of appetite, more frequent urination, thirst, weakness, confusion or brain fog.
It's worth being aware of that as the recommended limits for vitamin D are laughably too small, so it's common for people to take much larger amounts. I believe that 4k IU is considered a safe adult dosage.