The syndrome of excessive bacterial growth is dangerous precisely because a large number of bacteria proliferate in your body, which begin to take vitamins and minerals from food. Thus, you will not receive the necessary nutrients and you will develop deficiencies.
The small intestinal bacterial overgrowth syndrome (SIBO) is dangerous because bacteria actively colonize the small intestine. Several adverse mechanisms occur:
Competition for nutrients. Bacteria begin to "intercept" vitamins and minerals before they can be absorbed in the walls of the small intestine.
Mucosal damage and inflammation. The overgrown bacteria release toxins and fermentation products. This irritates the mucosa, triggers chronic inflammation, and increases the permeability of the intestinal wall. As a result, even those nutrients that reach the absorption site pass through the damaged barrier less effectively.
Digestive disruption. Due to bacterial activity, bile acids and enzymes work less effectively, disrupting the breakdown of fats, proteins, and carbohydrates. This not only reduces nutrient absorption but also increases gas production, bloating, diarrhea, or, conversely, constipation.
Metabolic consequences. Bacteria can synthesize their own substances, including D-lactic acid. Its accumulation in some individuals causes symptoms similar to neurological disorders—fatigue, "brain fog," and decreased concentration.
Thus, in SIBO, a vicious circle is formed: the more bacteria there are, the more nutrient deficiencies arise, and these deficiencies, in turn, weaken the function of the mucosa and the intestinal immune system, further facilitating microbial growth.
Which nutrients are affected by SIBO
Here are the main vitamins and minerals that are most often deficient.
Vitamin B12 (cobalamin). Bacteria actively capture B12 and use it for their own metabolism, leaving very little for the human host.
Iron. Bacteria alter the pH and damage the mucosa, hindering iron absorption. Additionally, during intestinal inflammation, the body "hides" iron in tissues, reducing its availability.
Vitamin D. Disruption of fat emulsification in SIBO reduces its absorption.
Vitamin A (retinol). It is also affected by impaired fat absorption.
Vitamin K. Normally produced partly by the microbiota of the large intestine. SIBO disrupts the balance and synthesis.
Calcium. Its absorption is directly related to vitamin D and the healthy state of the mucosa. SIBO disrupts transport across the intestinal wall.
Magnesium. Chronic diarrhea and intestinal inflammation lead to its loss.
Zinc. Bacteria also compete for it, plus inflammation worsens transport.
