Small Intestinal Bacterial Overgrowth (SIBO)

If you often experience bloating, gas or unpredictable bowel habits despite watching your diet, then you could be dealing with small intestinal bacterial overgrowth (SIBO), a condition where too many bacteria grow in the small intestine, disrupting digestion. The good news is that with proper medical evaluation and targeted treatment, SIBO can be effectively managed, helping you regain digestive comfort and energy.

What Is Small Intestinal Bacterial Overgrowth?

Small intestinal bacterial overgrowth occurs when bacteria that usually reside in the large intestine migrate into or excessively multiply within the small intestine. These bacteria ferment carbohydrates prematurely, producing gases and by-products that disrupt normal digestion and irritate the intestinal lining.

Over time, this abnormal bacterial activity can impair the absorption of essential nutrients, such as vitamin B12, iron and fat-soluble vitamins. Unlike temporary digestive upset, SIBO often requires medical assessment to identify underlying contributors and guide treatment, as recurrence is common if root causes are not addressed.

Causes and Risk Factors for Small Intestinal Bacterial Overgrowth?

SIBO typically develops when normal intestinal defence mechanisms are disrupted, allowing bacteria to accumulate in the small intestine. These contributors can broadly be grouped into underlying causes and predisposing risk factors.

Common Causes

• Impaired gut motility – slowed movement of food and bacteria through the small intestine allows bacteria to multiply instead of being cleared effectively.
• Structural abnormalities – surgical changes such as bowel resections, strictures or adhesions can create areas where bacteria stagnate.
• Reduced stomach acid – long-term use of acid-suppressing medications or low gastric acid levels reduces the body’s ability to limit bacterial growth.

Risk Factors

• Functional bowel disorders – conditions, such as irritable bowel syndrome (IBS), are commonly associated with SIBO.
• Chronic medical conditions – diabetes, coeliac disease, Crohn’s disease, chronic pancreatitis and hypothyroidism can impair digestion or motility.
• Previous gastrointestinal infections – post-infectious changes may disrupt gut function and bacterial balance.
• Age-related changes – natural decline in gut motility with ageing increases susceptibility.

How is Small Intestinal Bacterial Overgrowth managed in Singapore?

Managing SIBO requires a structured and individualised approach that addresses both symptoms and underlying causes. This typically entails:

• Dietary strategies – diets such as the low-FODMAP diet, specific carbohydrate diet or low-fermentation diets may help reduce symptoms. These should be implemented under a dietitian's supervision to avoid unnecessary restrictions.
• Addressing underlying causes – improving gut motility, managing hypothyroidism or diabetes, reviewing long-term acid suppression and addressing structural issues are essential to prevent recurrence.
• Nutritional support – supplementation of vitamin B12, iron, folate and fat-soluble vitamins may be required if deficiencies are present due to malabsorption.
• Antibiotic therapy – targeted antibiotics are often used to reduce bacterial overgrowth and should be prescribed and monitored by a specialist.