So what food contains it? Where can you buy it?
If you are not greatly immune compromised, the write up directly describes that three things are the problem. First, simple sugars in your gut. Second, unexpected oxygen in your gut. Third, good bacteria do not seem to be in your gut, any longer (could be from antibiotics or simply eating in such a way as to eliminate or reduce good bacteria populations to a level they can't help).
Step one would be to stop eating things that become, or are, simple sugars. Step two surrounds the oxygen issue, which seems to be from missing populations of gut bacteria that otherwise help pull out oxygen from the gut.
There is a picture at the website link. It states several times that butyrate is produced by Clostridia bacteria is a key, here. Note, I haven't read the study, but this makes sense, to me.
I have previously posted threads about how soluble fiber increases three short chain fatty acids, acetate, propionate, and butyrate. It does this by growing populations of bacteria that are still there. Given enough soluble fiber over a month or more, those populations should be providing you each needed substance, with whatever butyrate made preventing the candida issue.
Do note you may need a probiotic or kefir to provide bacteria you may not have at this time, but to better know this, the easy way is to see if you still have issues with candida in your gut. The more costly way to identify an issue is to have a poo sample analysis, which can cost a few hundred dollars, but can be ordered online.
This is how I would make it all practical, and my wife and I have done this, without intending to address any candida concern.