Is low vitamin d more likely to cause depression than fatigue?and the depression causes fatigue?

Chicken vs. egg: Good question. Both depression and fatigue are common symptoms of D deficiency. I know of no data on which is more common, but you're correct that depression often causes fatigue, but fatigue and other symptoms of low D such as chronic pain can cause depression. Each can cause the other; everything is connected. Either way it's simple to correct low D. See http://tinyurl.com/2chkcer

Vit D depression: Is low Vitamin D more likely to cause depression than fatigue?And the depression causes fatigue? ANS: I am not aware that low Vit D can cause depression or fatigue that is reversed when Vit D is taken. Fatigue is common as symptom of depression. Talk to your Dr.