medicalxpress.com/news/2015-12-vitamin-quells-severity-preemie-gi.html"After observing that some gastrointestinal disease in premature human and mouse infants progresses only when certain immune system white blood cells go into inflammatory overdrive, Johns Hopkins researchers have found that giving large doses of vitamin A to mice converts those blood cells into inflammation suppressors and reduces the severity of the disease, compared to untreated mice."
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Not Crohn's or UC but none the less the anti-inflammatory effect might apply.
I had great success with the addition of 10,000 to 20,000 i.u. of vitamin A (Cod liver oil source) daily - so two gel caps, one in the morning and one before bed. For me it was the light switch between mucus and no mucus, but I was well on my way to remission when I added it. However the effect was almost overnight in my case. Mucus with each BM was the one thing I was having trouble getting rid of.
To much on the other hand can also be a bad thing.