i had the same thoughts with l glutamine added to enemas as I had tried the oral approach w no success. I had no problems with it and feel that it helped heal my ulcerative colitis rather quickly.
I have also supercharged coffee enemas with glutathione and MSM to support detox stages in combo with compounds in the coffee that do many things including dilation of biliary tubes.
The glutamine enemas lead me to add lysine, ornithine, and arginine... and this combo led me to be able to not only get back into the gym after years of undiagnosed lyme and co infections but within 4 months I was in the gym 5 days a week... 30 min intense hill climbing, followed by 30 min weights 3x week, with 2 intense flow yoga a week as well
before the enema supplementation I could only do about 10 min of aerobic exercise then spend the rest of the day in bed
I also put on alot of muscle that I had lost
There is a limit to how much irritation the colon can take... so go slow and take breaks... all IMO