I would like to ask two questions:
1. One is about vitamin D's impact on the immune system. Since vitamin D levels have been found to be low in a number of autoimmune diseases and vitamin D supplementation has been found to be beneficial, does that mean that vitamin D suppresses the immune response and thus "deactivates" an overactive immune system and would that mean that normal immunity in an otherwise healthy person, i.e. free of autoimmune diseases, would be compromised by vitamin D supplementation?
2. Can vitamin D supplementation be addictive? If a person starts supplementing with vitamin D, would they always have to supplement to maintain their level or would they be able to stop supplementing sometimes and still maintain the level reached just by tanning, for example?
Thank you very much!