The amount of Vit D in a dose is extremely minute.
It may be a coincidence...College kids always get viruses, and the food in the dorms can be awful....
Have him stop for 5 days, then take again. This time with food.
It might be the fillers or carrier in the capsule/tablet.
1000IU = 25mcg or .025mg of D. That is really a tiny amount and not likely to cause diarrhea.
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All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
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Weezie looking at petunias 8.25.2017
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