Why is iron from plants useless and leads to SIBR?

Trivalent plant iron is significantly less absorbed by the human body compared to divalent iron of animal origin. Let's break this down further.

Forms of Iron

• Fe²⁺ (divalent iron) — easily absorbed by the body. Found in heme iron (meat, fish).
• Fe³⁺ (trivalent iron) — an unabsorbable form for humans in isolated form. Found in plant foods (spinach, legumes, grains, etc.).

For Fe³⁺ to become bioavailable, it must be reduced to Fe²⁺ — a process influenced by stomach acidity and the presence of reducers (e.g., vitamin C).

Why is Fe³⁺ not effectively absorbed?

1. Requires reduction to Fe²⁺, with gastric acid (HCl) participating. In cases of reduced acidity (hypoacidity), this process is disrupted. Also, in older age or when taking PPIs (proton pump inhibitors), reduction is practically impossible.
2. Trivalent iron easily binds with phytates, tannins, fiber, forming insoluble complexes. These complexes do not break down in the gastrointestinal tract and cannot be absorbed.

What happens to unabsorbed iron?

When iron is not absorbed in the small intestine, it:

1. Reaches the lower parts of the intestine, including the small and large intestines.
2. Serves as a nutrient medium for pathogenic and conditionally pathogenic microflora.
3. Provokes bacterial imbalance.

SIBO (Small Intestinal Bacterial Overgrowth) is a condition where the microflora, usually residing in the large intestine, excessively proliferates in the small intestine.

There can be many causes for SIBO, but unabsorbed iron is one of the key provocateurs. Because:

• Iron is a primary limiting factor for bacterial growth.
• When there is an excess of iron in the intestinal lumen, it stimulates the growth of bacteria, including conditionally pathogenic ones.
• This disrupts normal digestion, fermentation, causes bloating, diarrhea, flatulence, and malabsorption syndrome.

How to avoid this:

• Use divalent iron from animal sources (liver, meat, eggs).
• Take vitamin C along with plant sources of iron to increase absorption.
• Ensure that stomach acidity is normal.
• Do not abuse iron-containing supplements without indications.
• In case of signs of SIBO — first eliminate bacterial imbalance, and only then prescribe iron.