III.2

Fibre: the food of the good bacteria

The freshly engrafted flora needs food day after day, and its favourite food is fibre. This week you learn what kinds of fibre exist, why they matter, and how to bring them into your diet gradually and gently.

Összefoglaló

If your new gut flora is a freshly planted garden, then fibre is the water that keeps it alive. Fibre is the plant component that we ourselves cannot digest — but our beneficial bacteria can, and they live on it. This week we raise the fibre intake step by step, gently, so that you can feed the engrafting flora without overloading your sensitive digestion. The goal is not the perfect diet in a single day, but for every meal of yours to have a little plant-based base.

What is fibre, and why is this exactly what your flora eats?

Fibre^[G] is that part of plant foods — the fibrous structure of vegetables, fruit, whole grains, pulses — that our digestive system does not break down. We used to think this was "useless ballast" that simply passes through us. Today we know that this is precisely the most important food of the beneficial bacteria^[G] living in the colon. What we cannot digest, they regard as a feast.

When these bacteria digest the fibre, they produce valuable substances from it that feed and strengthen the gut wall. Fibre of this kind, which deliberately feeds the good bacteria, we call a prebiotic^[G]. It is important that this is not the same as a probiotic: a probiotic contains bacteria themselves, while a prebiotic provides the food of the bacteria. During your course we avoid shop-bought probiotics, but we build in prebiotic fibre gradually and consciously — because this feeds the flora you received with the FMT.

There are two kinds of fibre, and you need both. Soluble fibre (for example in oats, apple, pulses) swells in water, becomes a soft gel, and is a particularly favoured food for the bacteria. Insoluble fibre (in whole grains, vegetable skins) helps the bowel movement more. The point is that, from colourful, varied plant foods, both naturally end up on your table.

There is a special kind of fibre that deserves attention in its own right: resistant starch. This is a starch that "resists" our digestion — it is not absorbed in the small intestine, but reaches the colon intact, where the good bacteria feast on it. This is exactly what makes it valuable: it is an excellent source of butyrate, that is, the basis of the substance that feeds and strengthens your gut wall. The good news is that it comes from simple household sources: if you cool cooked rice or potato (even if you reheat it afterwards), part of the starch in it turns resistant; the firmer, green banana is also rich in it. A small portion of cooled rice or a slice of cooled cooked potato is therefore not just a side dish — it is targeted food for your engrafting flora.

How to raise the fibre so that it does not hurt?

Fibre is a wonder substance, but it has a pitfall: if you eat too much of it too quickly, it can temporarily cause bloating and gas formation — especially now, while your gut is still healing. This is why the golden rule is graduality. A little more every day, and always with enough water, so that the fibre passes easily through your system.

Start with the easily tolerated sources: cooked oats, peeled apple or pear, steamed carrot, well-cooked pulses in a small portion. Most healing guts tolerate these well. Leave the raw, coarse fibres — raw cabbage, a lot of onion, a large portion of bran — for later for now. Cooking, steaming and peeling all "pre-digest" the fibre a little, making it gentler this way.

Watch your body's signals, and write them down too. If you feel strong bloating after a particular fibre source, it does not mean that the fibre is bad — only that you need a smaller portion of it for now. The bloating eases over time, as your flora grows stronger and "gets used to" the new food. Your diary is worth its weight in gold here: you see which food affects you how.

🩺 Klinikai blokk

Fermentable dietary fibre is the primary energy source of the colonic microbiota; during its bacterial fermentation, short-chain fatty acids^[G] (SCFA) — acetate, propionate, butyrate^[G] — are produced. Butyrate is the main energy substrate of the colonocytes, strengthens gut barrier integrity and has an anti-inflammatory effect; in an SCFA-deficient, fibre-poor environment, microbial diversity declines (Sonnenburg et al., 2016). The loss of diversity was demonstrable even transgenerationally on a fibre-poor diet.

Among the prebiotic fibres, inulin^[G] (from chicory) selectively stimulates the bifidobacteria; it is noteworthy that inulin and potato starch (a resistant-starch source) are also among the excipients of the DiffBiome formulation, which provides a prebiotic substrate for the inoculated community even within the capsule. A gradual increase in fibre is warranted: a sudden, large quantity of fermentable fibre (FODMAP^[G]) causes transient gas formation and discomfort until the adapted fermenting community develops.

Resistant starch (RS) ferments in the colon and is more pronouncedly butyrogenic than the other prebiotic substrates: it selectively increases the production of butyrate, which is the primary energy source of the colonocytes and a key mediator of barrier integrity and anti-inflammation (Sonnenburg et al., 2016). Its dietary sources: the retrograded starch (RS3) of heat-treated then cooled starchy foods (rice, potato), green banana and pulses (RS2). In the post-FMT period, targeted SCFA supply, particularly butyrate, strengthens colonisation resistance against C. difficile.

Day 28 – The first conscious fibre day

Today there will be a little plant-based base at every meal — gently, from well-tolerated sources. This will be the foundation on which the week is built.

For breakfast, a portion of cooked oats (with water or plant-based milk), with a little peeled apple on top
For lunch or dinner, a portion of steamed vegetables (carrot, courgette, squash)
Drink a large glass of water with every fibre-rich meal
Diary: stool count, Bristol, bloating, fluids; note down the fibre sources of the day

Day 29 – Soluble fibre in focus

Today we put soluble fibre to the fore — this is the flora's favourite, and it is gentle on the gut.

For breakfast oats again, or a small portion of well-cooked red lentils during the day
A peeled pear or ripe banana as an afternoon snack
Keep the fluid intake high (6–8 glasses), so the fibre moves easily
Diary: stool count, Bristol, bloating, fluids; which fibre source you tolerated and how

Day 30 – A little variety

Today we bring in a new, gentle fibre source not tried before — carefully, in a small portion. The goal is gradual expansion.

Try a new, well-tolerated fibre in a small portion (e.g. steamed green beans, baked sweet potato without the skin)
Bring in a small portion of resistant starch as a butyrate source: cooled cooked rice or potato, or perhaps a riper but still firm banana
Keep the already proven sources too — the point is variety, not replacement
If any new food causes strong bloating, reduce its portion, do not leave it out entirely
Diary: stool count, Bristol, bloating, fluids; the tolerability of the new fibre

🍽️ Eating during these days

In these three days fibre is at the centre — the daily food of the freshly engrafting flora — and you raise the fibre intake gradually and gently. Your tasks: on day 28 have a little plant-based base at every meal (for example oats in the morning, steamed vegetables at lunch), on day 29 put soluble fibre to the fore (oats, well-cooked red lentils, ripe banana), and on day 30 bring in a new, well-tolerated fibre source in a small portion. Drink a large glass of water with every fibre-rich meal; if a food causes strong bloating, reduce its portion, do not leave it out entirely — the secret is graduality.

For these days, the Plant Calendar, still in the firming foundation phase, recommends gentle, digestion-soothing sources: on day 28 ginger (a small amount as a tea, digestion-soothing), on day 29 cinnamon (a blood-sugar-friendly spice), and on day 30 chokeberry (aronia) — in moderation — which contains tannin and polyphenols. Alongside these, it is worth keeping the already proven, gentle fibre sources too, since the goal is gradual expansion, not replacement. Build the plant of the day into at least one meal; if you do not tolerate one of them well, try it in a small portion, or return to it later.

📊 Adat

This week, record daily:

DiffBiome dose (capsules/day) and LOT number, if the course is still ongoing;
daily stool count;
stool Bristol scale (1–7), watch the trend heading towards 3–4;
bloating (0–5);
bloody stool (yes/no);
fluid intake (litres);
the fibre sources of the day and their tolerability;
wellbeing (1–5).
Movement: type + minutes, step count (target/actual)
Stress level (1–5) and mood (1–5)
Sleep (hours + quality 1–5)

Why does this matter?

The engrafted flora only stays and grows stronger if it receives food every day — and this food is fibre. This week you have learned that fibre is the bread of the good bacteria, that there are two kinds of fibre, and that the secret is graduality: a little more every day, always with enough water. If the bloating appears now and then, it is not a fault but a sign of the flora adapting. Next week we will build further on the variety of fibre sources.