What we've learned over at FTA (freetheanimal.com) from Tatertot, Dr. Grace, and others, is that a variety of fibers need to co-exist in the diet. RS alongside Inulin, FOS, GOS, MOS, etc. And this is because RS2 alone
ferments quite rapidly in the caecum (although, interestingly, RS3 from cooked/cooled starchy foods
ferment slow and more distally, which is what we want). In other words, it's rapidly fermented. But eating RS2 alongside other fibers helps move the fermentation more distally and helps slows its rate of fermentation down.
After seeing people having some mixed — or in some cases underwhelming — results with Potato Starch (PS) alone, I recommended people start experimenting with other prebiotic fibers like Larch Arabinogalactan (LAG) and Beta Glucans and other polysaccharides — and ideally some of those found in medicinal mushrooms like Turkey Tail, Reishi or chaga.
However, this is where caution needed to be exercised. The feedback I got on those who tried LAG and medicinal mushrooms is that some found them to be too stimulating to the immune system if they went too fast. So, I believe there has been some merit in going very slowly so as not to cause an overwhelming blowback of endotoxins.
[...]
I could be wrong, but I got the sense that some people were hesitant to try too many probiotics. I can't remember though. I believe Prescript Assist was popular, and AOR-Probiotic 3. Many people seemed to have their own favorites though.
[...]
I'd like @
Vegas to clarify, but I believe most of his benefits are coming from small amounts of Larch Arabinogalactan (LAG). I know he used some PS as well, but the LAG seemed to be the key if I recall. I believe he said that LAG actually helped him tolerate PS better.
@
Gestalt was very adventurous, at one point trying 20g a day of LAG (early in the day, as it is energizing) in addition to the 3-4tbsp of PS (taken 5 hrs before sleep). I don't even think I could tolerate that much LAG

He had very good results if I recall, but he's had some regression due to an experimental stint with NAG/chitin (which we now know might apparently can feed candida).
So... I think LAG is showing some promise. And truth be told, LAG is actually
advertised to help CFS patients (one of the reasons I mentioned it in the first place). The makers of LAG claim that it
increases NK cells and enhances the immune response while supporting the lymphatic system, and this was believed to be beneficial for ME/CFS patients. (Here's a little layman's
cartoon explaining how LAG works, for those who are interested). The amazing thing is that you don't need that much. But, LAG is a bit complicated in that there are different kinds of LAG
with different molecular weights offering different kinds of targets.
I believe @
Gestalt recommends a low molecular weight LAG (ResistAid or Thorne's Arabinex... they are the same thing) for dealing with immune issues. The larger molecular weight (FiberAid) LAG is
supposedly a better LAG for general gut health. But if I recall, @
Vegas is using FiberAid so whatever benefit appears to be found in both kinds of LAGs to some degree.
More info:
http://www.nutritioninnovation.com/agpaper.pdf
I do recall @
Gestalt saying he's tried a number of LAGs and preferred ResistAid for their quality (smells like fresh pine trees) and for its preservation of antioxidants. ResistAid is manufactured by Lonza, and they are just a supplier. If you want ResistAid, you need to find out which LAG products are supplied by ResistAid in your country. Thorne's Arrabinex is ResistAid, but it is $40 for 100g (a normal dose is 2g if I recall). NaturalDoctor ResistAid is the exact same product (again, it's also just ResistAid by Lonza), but sells for $20/100g and is only available in the US — though they seem to be out of stock at the moment. Lonza is a big Swiss company, from what I understand, so ResistAid products should be available worldwide.
FiberAid sells for under $20 for 250g, but the normal dose is supposed to be 4g I believe (though, I think @
Vegas uses much less than that).
[...]
My guess is all these products are on a sliding scale based on their molecular weights (i.e. "
polydisparity") and their individual quality controls.
It's probably best to experiment with different brands of LAG and see what works for you. But,
don't automatically buy the cheapest one. The molecular weights are all different (each purportedly promoting different effects), the doses are different (skewing the cost effectiveness of
seemingly cheaper products), and the potency is different. So, the best approach may be to experiment.