One thing is the fat soluble vitamins (A, E, D & K2-mk4) are [cofactors]. Vitamin A (retinol) toxicity directly depends on Vitamin D3 status.
Vitamin A is used short term at high dose 50,000 IU to 100,000 IU adjunctly to augment cancer therapy as part of core integrative nutraceutical programs (incl natural beta-carotene, high dose vitamin D 25(OH)D 75ng/ml, high dose fish oil (4-20g/day), glutamine, butyrate, etc)
Why is Vitamin A used together with Vitamin D? Why are they found in potent quantities together in nature (ie, fish liver, oily fish, salmon, oysters, trout, catfish, egg yolk, zooplankton, butter, pate, fish eggs/roe/caviar, breastmilk)? All the best foods in life… (breastmilk—my kids were really into that stuff). Pasture-raised cows indeed produce butterfat brimming with a wealth of cardioprotective vitamins K2, A, D and E! I wonder why??
A synergistic effect has been observed for nearly all benefits studied. This makes absolute sense since they exist co-dependently physically located in the nucleus of our cells.
One thing is the fat soluble vitamins (A, E, D & K2-mk4) are [cofactors]. Vitamin A (retinol) toxicity directly depends on Vitamin D3 status.