Synergistic effect of vitamins A and D

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Very important article by Chris Masterjohn.   Based on the recent Chinese paper using human stem cells in-vitro.  The paper demonstrated that vitamin A acts synergistically in triggering expression of neurogenin-3.  Neurogenin-3 is necessary for activation of stem cells development, in that case - for replacing the damaged insulin-producing islet cells such as in diabetes type 1.

I think that study is important for several reasons:

- Adequate intake of both A and D3 is one of the critcial factors in tissue regeneration, propably not only limited to pancreatic islets but generally to all other organs,

- Supplementation of only one of the vitamins is inadequate because both act synergistically.

- I suspect (speculating) that beta carotene might not be adequate if vitamin D3 level is low, and vice versa - supplementation of D3 might not be effective in the absence of A.  We shall keep in mind that beta carotene (pro-vitamin A)  from plants is NOT the true vitamin A!   This may explain a curious fact of difficult to treat vitamin A or vitamin D3 depletions frequently reported by vegans.