Intro 0:20 Vitamin D receptor binding requires vitamin A.  0:50 Retinol is found in animal-based products. Pre-vitamin A is from vegetables. 1:40 Pairing vitamin A and vitamin D supports immune system, brain, and blood sugar health. 2:40 Excessive supplemental vitamin A in pregnant women can affect fetal growth.   4:25 There are fewer micronutrients in your food. 5:45 Paired vitamin D and vitamin A balance the anti-inflammatory mechanisms of the immune system. 7:25 Mike suggests that you supplement with a retinol, not a beta carotenoid version of pre-vitamin A.