Most people know that D2 is not as potent as D3 (it takes more D2 to raise vitamin D levels). However, to my knowledge, no one has shown that D2 is more dangerous than D3, except in total mortality. Recently, researchers from England and Australia collaborated on an interesting study looking at childhood D2 and D3 levels and subsequent psychotic experiences later in life.
Anna-Maija Tolppanen, Adrian Sayers, William D. Fraser, Glyn Lewis, Stanley Zammit, John McGrath, Debbie A. Lawlor. (2012) Serum 25-Hydroxyvitamin D3 and D2 and Non-Clinical Psychotic Experiences in Childhood. PLoS ONE 7(7): e41575. doi:10.1371/journal.pone.0041575
Dr. Anna-Marija Tolppanen and colleagues from the England and Australia, including two of my heroes, John McGrath and William Fraser, simply measured 25(OH)D2 and 25(OH)D3 in 5346 subjects at age 9 and then assessed for psychotic experience, such as hearing voices or seeing things that are not there,3 years later. Such psychotic experiences are associated with a higher risk of developing schizophrenia in later life.
What they found was nothing short of astounding. Children with higher 25(OH)D3 levels had fewer psychotic experiences in later life. Unbelievably, children with higher 25(OH)D2 levels had more, not fewer, psychotic experiences at age 12.
To my knowledge, other than potency data, this is the second study showing D2 is dangerous. As we have reported before, Bjelakovic et al found that D3 reduced mortality, while D2 did not (which may even increase mortality).
Obviously, studies comparing D2 and D3 are urgently need although I’d never agree to take D2 given the two studies above. Furthermore, it is not human vitamin D.
One last thing, the kids with higher 25(OH)D3 got it from the sun, not supplements. The idea we can replace sunshine with a bottle of vitamin D3 is a dangerous assumption. Get some sunbathing in or proceed at your peril.