After getting root canals, my health declined including a diagnosis of leaky gut. As well as having the root canals removed, high dose vitamin C is what has healed my body the most. Ascorbic acid powder is available cheaply online. It is pure vitamin C as it has the same molecular structure. I took it neat although some people prefer to add some Bicarbonate of soda to make it pH neutral.
Each morning I take it to bowel tolerance, 5 g at a time. Some people take 3 g at a time. When my stomach started to rumble or I felt gassy, that is bowel tolerance and I stopped. This is the vitamin C telling you that your body is saturated and that's when it is most effective.
As you heal you will need less to reach bowel tolerance. Initially I was taking 25 g at a time, now I need much less. After taking it just once, I already felt better with less pain from the dental infection in my neck. It gave me bloating and gas for 2 to 3 weeks as it went to work on the pathogens in my gut but that suddenly stopped and I felt noticeably better.
After five months I realised that I could stop my proctitis medication as I no longer needed it. Digestion was a lot better, I had a lot more energy and was feeling better than I had in years. I am still healing the dental infections but will continue to take vitamin C for the rest of my life, it is like having a superpower.