She blamed hair loss, gas and low ferritin on different things. Then doctors joined dots, found gut bacteria

Nobody seemed to be connecting the dots. “This kind of symptom cluster is indicative of small intestinal bacterial overgrowth, or SIBO. Patients often show up with mixed symptoms like gas, abdominal bloating, feeling heavy after eating, and unexplained nutritional deficiencies,” says Dr Harsh Kapoor, Chairman, Gastroenterology, Metro Hospital, Noida.

What is SIBO?

SIBO means there is an abnormal increase of bacteria in the small intestine, where bacterial numbers are normally much lower than in the colon. “When bacteria grow abnormally, they can ferment too early and break down carbohydrates or other nutrients that produce gas, i.e. hydrogen and methane,” explains Dr Harsh Kapoor, Chairman, Gastroenterology, Metro Hospital, Noida.

This early fermentation can result in bloating, abdominal pain, excessive flatulence, belching and a feeling of fullness or heaviness after meals. For patients, the experience can become a frustrating cycle: eating leads to discomfort, discomfort leads to food restriction and persistent symptoms lead to repeated attempts at self-treatment.

Why do the bacteria overgrow?

According to Dr Kapoor, the presence of bacteria is only part of the story. The more important question is what allowed them to accumulate in the small intestine.

Normal intestinal function helps prevent excessive bacterial growth. Problems that slow down the movement of food through the intestine, changes in the structure of the digestive tract, previous gastrointestinal surgery and other digestive conditions can increase the risk of SIBO. “Diseases causing weakening of the intestinal function, anatomically impaired intestines, past surgical operations and gastrointestinal diseases may contribute to SIBO occurrence,” he says.

This is important because SIBO can recur if the underlying problem remains untreated.

What about low ferritin?

SIBO may affect how nutrients are processed and absorbed. Excess bacteria can utilise nutrients before the body absorbs them, and bacterial overgrowth may contribute to malabsorption in some patients. But low iron or ferritin should never automatically be blamed on SIBO. Iron deficiency has many possible causes, including inadequate dietary intake, menstrual blood loss and gastrointestinal conditions that interfere with absorption. Gastrointestinal blood loss also needs to be considered in appropriate patients.

“Not every low iron or ferritin level should be connected with SIBO,” Dr Kapoor cautions.

There is another complication: oral iron itself can cause gastrointestinal side effects. “So, if gas or abdominal discomfort increases after starting iron, that does not prove that bacteria are consuming the iron or that SIBO is responsible,” he explains.

And the hair loss?

Hair shedding can occur in the presence of nutritional deficiencies, including iron deficiency in some patients. But hair loss should not automatically be attributed to SIBO. “The commonly repeated claim that women need ferritin levels of 40–70 ng/mL to stop hair loss is not a universally accepted medical rule. There is no single ferritin level that guarantees shedding will stop. A low ferritin may warrant investigation, but the patient’s overall clinical picture matters more than chasing one number,” says Dr Kapoor.

How is SIBO diagnosed?

One commonly used non-invasive approach is a hydrogen and methane breath test. The patient consumes a specified carbohydrate substrate and then provides breath samples at set intervals to measure hydrogen and methane production. Dr Kapoor stresses that the test results must be considered together with the patient’s clinical presentation, history and symptoms.

What about treatment?

Depending on the individual case, treatment may include antibiotics to reduce bacterial overgrowth and appropriate nutritional management. But treating the bacteria is only part of the process.

“The underlying condition also needs attention. Otherwise, the symptoms may return. Thus, it does not mean that the recurrent condition should be treated with the help of antacids only,” says Dr Kapoor.

Diet may also have a role in managing symptoms, but repeatedly eliminating foods—including gluten—without establishing the underlying diagnosis can lead to unnecessary restriction and may complicate existing nutritional deficiencies.

The right approach is to look at the whole picture: investigate persistent digestive symptoms, establish the cause of iron deficiency, assess hair loss appropriately, use breath testing when clinically indicated and, if SIBO is diagnosed, look for the reason it developed.