But Cholcalciferol (Vitamin D3) is Cholcalciferol, whether ingested by mouth or manufactured within the skin via sunlight. The benefits are the same.
Sunlight manufactures approx' 10,000ius of Cholcalciferol in the skin over a half hour period: the body then stops production at a level determined by itself.
Supplemenation at this level is therefore identical when sunlight is absent.
The same can be said for Manufactured Ascorbate, which is chemically identical to its natural counterpart and which has been used at very high doses (Orthomolecular Medicine) in the complete cure of Eisenmenger Syndrome (amongst other diseases and ill-health conditions).