Quote from zerocool on September 11, 2021, 1:25 pm

So someone on here mentioned Anthony Mawson on Luke's progress report. I went digging around to see if I could find anything on him and vitamin A toxicity. Just wanted to start a discussion on him, because I don't know much about his work. I did come across this and read most of it...some of it was confusing...especially when he said retinoids could both inhibit and enhance viruses(he's talking about influenza in this particular instance)? But what I gather from this particular report is that he's saying as long as you keep your vitamin D levels up, and you keep your vitamin A to D ratio in balance, then vitamin A won't become toxic. The thing I learned from this is that everyone should probably be getting outside and getting sunlight...which seems like a no-brainer. I think he says 30 minutes of sunlight per day. He also talks about vitamin D supplements in winter, which I think is a bad idea.  Source link below. 

Quote from 15. Conclusion part of paper:

"The severity of influenza virus infection can perhaps be considered a function of two sets of opposing factors. On one side are the factors that fight infection, exerting inhibitory effects on the virus at different stages of the disease process. On the other side are the factors that drive the disease, allowing the virus to multiply, spread, and induce symptoms. There is evidence that retinoids play a central role in both processes. It has been proposed that (1) reduced exposure to sunlight and/or preexisting vitamin D deficiency simultaneously increase the accumulation and potential toxicity of endogenous retinoids, while the decreased vitamin D-to-vitamin A ratio triggers viral activation or increases susceptibility to novel strains of influenza virus; (2) increased but normal physiological concentrations of retinoid effectively work with vitamin D to inhibit influenza pathogenesis; and (3) higher background concentrations of vitamin A (i.e., very low vitamin D : A ratios), for example, associated with diseases and conditions affecting the liver, enhance viral replication and increase the likelihood of severe or lethal complications of the disease. It is possible and indeed likely that, on the vitamin A side, different retinoid receptor isotypes (RARs, RXRs) will prove to be involved in the outcomes of altered vitamin D : A ratios, either enhancing or inhibiting infection and viral replication, depending on the background level of retinoids in the body. For instance, one group of retinoid receptor isotypes may facilitate and exacerbate influenza viral infections, while another set may come into play to inhibit viral proliferation and infection."

Source: https://www.hindawi.com/journals/isrn/2013/246737/