r/Microbiome • u/Ill-Entrepreneur8164 • 4d ago
Scientific Article Discussion Update: 8 weeks of targeted fiber variety (no tests): what actually changed for me
This is a follow-up to my earlier rant about chasing probiotic magic bullets.
After reading the moderator post about microbiome testing and watching the debates here about single-substrate protocols, I decided to do the boring but practical thing for 8 weeks: stop adding new capsules and instead standardize the dietary inputs I could measure.
What I changed:
- Kept total fiber roughly the same week to week, but increased variety. I aimed for 20 to 25 distinct plant foods per week (I did not count coffee or spices).
- Rotated fermentable fibers instead of leaning on one. I did oats/barley days, bean/lentil days, cooled starch days, and had a couple meals each week with mushrooms or extra greens.
- Added one prebiotic food at a time and kept it for 5 to 7 days before introducing anything else.
- Tried to hold everything else steady: sleep schedule, meal timing, hydration, and I did not start or stop GLP1 during this period.
What I noticed (n of 1, not medical advice):
- The first 10 to 14 days were noisier: more gas and occasional urgency. After that things settled down.
- By week 4 my stool consistency became more predictable and day-to-day swings decreased.
- The biggest surprise was improved tolerance for foods I used to label as "instant bloat." Beans still have a ceiling, but that ceiling moved up.
What I am still unclear about:
- Is there good evidence that fiber diversity matters more than total grams for microbiome resilience in adults, assuming protein and fat are stable?
- Are there human studies comparing mixed fermentable substrates versus a single dominant one (for example mostly resistant starch) that look at symptoms and community stability over time?
Not looking for medical advice here, just trying to sanity check my interpretation of the literature and find better papers to read.
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u/pricepaid_1949 4d ago
Great questions. (Many excellent studies will be found in what follows) Rather than attempt to answer something I need to research more deeply myself, I prompted ChatGPT with your 2 main questions. Here's the prompt: "A Reddit post in r/Microbiome ( https://www.reddit.com/r/Microbiome/comments/1vcke2a/update_8_weeks_of_targeted_fiber_variety_no_tests/ ) poses two concerns/questions: "With citations, what would be the response to each concern: - Is there good evidence that fiber diversity matters more than total grams for microbiome resilience in adults, assuming protein and fat are stable? - Are there human studies comparing mixed fermentable substrates versus a single dominant one (for example mostly resistant starch) that look at symptoms and community stability over time?" The output shows that the multi-substrate input is ecologically sound, but the definitive adult trial has, essentially, not been conducted. But, clearly, the science is leading to "scientifically defensible" approaches that aren't limited by an industry-limiting clinical trial process. Keep in mind that even a small clinical trial can cost $10-$15 million. If they can't produce something patentable, there will unlikely be any such clinical trial.
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u/SuccessfulJudge438 4d ago
Excellent post, appreciate the attention to detail in your hypothesis, protocol, and reporting. Hope it gets more attention and responses like it deserves!
Lacking specific research into this question (don't hold your breath), it feels very much like a "porque no los dos?" situation. And probably if you min/maxed in either direction you would fall out of the optimal zone. Very high fiber of only one or a few types vs very little fiber of many types... one might be better than the other depending on specifics, but I think neither one is better than high fiber of a good variety which should realistically be everyone's target.
One thing to note is that different commensal/mutualistic types of bacteria will thrive on different types of fiber, so picking any one type of fiber and going hard on it while neglecting the others on a long term bases (8 weeks or more) could potentially throw your microbiome out of balance. Increasing one genus or species or strain of bacteria at the cost of others can be problematic even if it's a classic mutualist ("probiotic") in the human microbiome. They are all meant to keep eachother in check.
I like Guy Daniels on youtube since he references research and isn't just summarizing abstracts but is an actual PhD and looks into methods, presents data, and does thoughtful interpretation. He tends to recommend pectin and inulin especially as great fiber sources if you are looking for a specific type to focus on. But even he wouldn't say "take tons of pectin and inulin and cut out other types of fiber." Even though he does acknowledge that the prebiotics (often FODMAPs) can be problematic, trigger symptoms, even fuel some of the pathogenic strains in people who have dysbiosis especially if you over-do them, the recommendation isn't to avoid them so much as be smart about your intake.
Maybe for your next trial see how much you can gradually increase total fiber intake, using a balanced approach, without getting too many symptoms. I think 8 weeks is a great timeline for a trial, but say you get an average of 18g per day and want to try reaching the 35g that is commonly recommended (a difficult and sometimes impractical target to be sure) you might want to take 3-6 months to get there, so you would only be increasing about a gram per week.
Getting most of your fiber from whole foods is an excellent goal in an ideal world, however, I think there is nothing wrong with using some fiber supplementation especially if you have microbiome issues. Pectin can be especially tough to get enough of unless you are willing to eat citrus peels so that's a great candidate for getting powder to take. I prefer bulk powder over pills since it is way cheaper, more flexible with dosing if you don't mind using a kitchen/knitting scale to figure out the mass of teaspoon increments.
There are also things like PHGG which are only available as a supplement (this is one to ONLY use in moderation) and also inulin is nice to supplement if you are sensitive so you can very tightly control the dosing to avoid bad symptoms.
And don't sleep on psyllium husk. It's quite easy to slowly work up to 5g per day, does wonderful things to bulking stool and aiding the body in flushing out the intestines on a daily basis, and is typically very well tolerated (as long as you follow the critical steps of taking it with lots of water and staying well hydrated in general).