I was just found to have low levels of Vitamin D for the third time in the last year and a half. I've been having various symptoms during that time, including joint pain, eyes that are sensitive to light and generally a little poorer vision than before, and heartburn or acid reflux (though that symptom has improved a lot). I received numerous tests for those symptoms, and the vitamin D deficiency was the only thing that the tests found. The previous two times I tested low for vitamin D, my doctor had me take 50,000 units once a week, for 8 weeks the first time and 12 weeks the second time. I never noticed any improvement in my symptoms after taking the vitamin D, though my vitamin D level improved to a normal level. I take a multivitamin daily which contains vitamin D, and also drink orange juice fortified with vitamin D and calcium, but that hasn't seemed to prevent my vitamin D level from becoming low again after I stop taking the high doses of vitamin D.
I was wondering if I should be taking a relatively high level of vitamin D all the time, rather than just for a couple months at a time. Is it normal to have low levels of vitamin D even when you are getting some from a multivitamin and fortified juice, or might that indicate I'm not absorbing it well? Also, since I never saw any improvement with my symptoms after taking high doses of vitamin D, could that be because my vitamin D level wasn't in the normal range for a long enough time for my symptoms to improve, or might that mean that the vitamin D deficiency isn't the actual cause of the symptoms? Could the vitamin D deficiency itself be a symptom of whatever is causing the other symptoms, or is it more likely that it is the root cause of the problem?