Does taking Vitamin A actually lower vitamin D?

I know from Caustic Symmetry that there is an important ratio between Vit A and Vit D and that one should consume them at as close to a 1/1 ratio as possible for optimal effect. (with health, with hair)

My question is will having excess amounts of Vitamin A actually lower vitamin D?

This would be for a strategy when someone has overloaded their D so high that is now toxic and is immuno-suppressive and it's taking a long time to bring it down.

I know the whole world is on the "take more D3" bandwagon at the moment and I agree but in this case this person took 200,000 IU of D3 per day for a few weeks and is now having autoimmune related inflammatory issues.

You're actually missing the MOST IMPORTANT catalyst in the middle of your vitamin A and D see-saw equation... vitamin K2. Vitamin K2 (MK-4 and MK-7) keeps calcium out of the arteries and in the bones/teeth where it belongs.

Too much vitamin D creates an abundance of Vitamin K dependent proteins leading to soft tissue calcification. Too much A leads to elevated phosphorus and hence bone loss due to low calcium. Vitamin K2 helps mediate between A & D keeping both in check, no matter their ratio.

Also add magnesium and silica for proper calcium absorption.

I think the answer to your question is yes. If you are really considering "excessive" amounts. The problem is many people are low in both of these vitamins to begin with. So at first, I think it might confer some benefits to take relatively higher doses to up your levels.

But these two vitamins can interact with the same receptors. Theres evidence out there that retinoic acid can interact with the VDR, and its thought that it might inhibit vitamin D interaction with the receptor. But this is really only going to be a problem when your intakes are very out of whack. For example, if your are D deficient and you're taking 15,000 IU vitamin A daily, you might have an issue. But if you are sufficient in both of these vitamins, then an intake that is balanced is actually optimal. Vitamin D requires vitamin A for proper function.

I think CS was accurate and an intake of approximately 1:1 is probably optimal. But again, without knowing your levels of these its hard to tell where a good starting point would be.

And that dose you mentioned is insane. I believe there were tolerance studies done about mid 20th century where there weren't adverse effects up to 50,000 IUs in men. I think that is still too high of a dose, but 200,000 is ridiculous. I'd stick around 5,000. Maybe 10 for a short period of time if you are really deficient. This all depends on your sunlight exposure/latitude.