Is this about Vitamin D or Vitamin D supplements? We already know taking supplements does not equate to the body actually being able to make use of the vitamin.

Is this about Vitamin D or Vitamin D supplements? We already know taking supplements does not equate to the body actually being able to make use of the vitamin. I'd be interested if this study also discounts Vitamin D produced by the body, or if some extra ingredient is needed to allow the body to benefit from the vitamin.