A common mistake with supplements is taking them without food, or even the right kind of food. Certain vitamins and minerals come in a fat-soluble form, and taking them without some dietary fat accompanying them renders them completely inaccessible to your body, and they just pass through the urine.

Vitamin D falls into this category, so it's possible that this is still the result of a vitamin D deficiency, even though he's chewing his Flintstones every day.