What to do or look for when supplementation doesn't raise Vitamin D levels? I'm 52, in relatively perfect health, eat better than 99% of Americans, 5'9" 155lbs, don't exercise much except for a 2-3 mile run 2-3 times a week but am outdoors every day in the summer for at least an hour. No other supplementation or drugs save for a chewable magnesium/calcium/D3 occasionally. In June I tested 21 ng/ML so I started a 1K IU to 5K IU daily regimen. Total weekly supplementation was about 12K IU for the past 36 weeks. This week I retested and the results were only 23.5 ng/ML. Of course it is winter but I expected a much higher number. I also had a complete blood workup done and no other levels were out of range.
Any ideas what could be the issue? What should I be looking for as the cause? Should I increase the dosage of D3 supplementation? IF so, approx. how much? As a note I went "off" supplementation for three days before this latest D3 test to try and get a solid number. Not sure if that made any difference.