Gut bacteria is all about balance, and we see from microbiome results that either
A) Testing is inconsistent
or
B) Microbiome between crohn's and UC patients vary within their respective diseases.
We see crohn's patience with bacteroidetes high and firmicutes low and vice versa. One tends to be linked to constipation and the other to diarrhea.
Other groups would see the same thing. If your lactobacillus is low, kefir will likely help.
If it's high then kefir will do little, or potentially be bad as it is with me.
Having high lactobacillus would explain both why I can have over half a gallon of milk a day without issue, and why high lactobacillus supplementation seems unproductive for me.
Having low lactobacillus would explain why many CD patients cannot ingest dairy.
You have to adjust your probiotic supplements to your deficiencies. The problem is that sometimes the way to bring one up is not to add more, or to feed that one, but to feed the bacteria which feeds it.
Many of our bacteria work by cross-feeding.
You're short in bacteria X.
Bacteria X feeds on biproduct of bacteria Y.
If you supplement bacteria X it dies off without bacteria Y to feed it.
So instead of just supplementing bacteria X, we need to supplement bacteria Y and eat foods that promote growth of bacteria Y.
The problem is the complexity of cross feeding is so huge we don't really know all the nuances to fix it.
This is why I believe we see that people taking probiotics will test positive for it in faecal testing, but when they stop taking the probiotics the tests come back negative. Their ecosystem is not able to support that bacteria naturally, so they can only maintain it through supplementation. That suggests to me the bacteria is not being fed, and if it's not being fed it's not doing its job of creating SCFAs or cross feeding other bacteria that do.
If you take kefir, but don't consume dairy, you'll maintain those bacteria only as long as you take kefir. Once you stop taking kefir, the bacteria will starve unless you start consuming dairy to feed it.