4 Sneaky Signs to Look For & Strategies

A diverse microbiome is essential for overall health. However, having an excessive amount of bacteria in the small intestine can cause serious problems. Small intestinal bacterial overgrowth (SIBO) can cause a number of unpleasant digestive side effects and affect other areas of the body as well. “SIBO can be tricky to identify because its symptoms can mimic other digestive disorders,” says Kaytee Hadley, M.S., RDN, IFMCP, a functional medicine dietitian specializing in SIBO and founder of Holistic Health and Wellness in Richmond, Virginia. In fact, the only way to know whether you have SIBO is by getting tested. “The most accessible way to test for SIBO is through a breath test, which measures levels of hydrogen, methane and hydrogen sulfide gases produced by bacteria in the small intestine,” says Hadley. 

In addition to digestive symptoms, there are less-obvious signals that you may have SIBO and should make an appointment with a health care provider. “While the classic signs include bloating, gas and altered bowel habits, many people experience more subtle symptoms like fatigue, brain fog or nutrient deficiencies, such as low vitamin B12 or iron,” says Ritu Nahar, M.D., a gastroenterologist with Allied Digestive Health. Here’s a closer look at four sneaky signs to be aware of. 

1. Nutrient Deficiencies 

SIBO can result in malabsorption of nutrients, including iron and vitamins A, D, E and B12. The small intestine is where the majority of nutrient absorption occurs. However, because it interferes with bile acids, which are needed to break down and absorb fats, SIBO can make it harder for your body to absorb fat-soluble vitamins A, D, E and K. Bacterial overgrowth can also affect iron levels, as up to 20% of iron is absorbed in the small intestine. As for vitamin B12, SIBO can both reduce the absorption and increase the use of this essential vitamin. Plus, because SIBO can cause nausea and loss of appetite, it may result in a more limited diet, which further increases the risk of nutritional inadequacies or deficiencies.

Changes in mood, brittle nails, thinning hair and increased fatigue are common symptoms of vitamin and mineral deficiencies, though the only way to know for sure is by having blood work done by a health care provider.

2. Brain Fog

The gut and brain are strongly connected, so it’s no surprise that SIBO can affect cognitive functioning. Brain fog is defined as periods of mental confusion, impaired judgment, poor short-term memory and difficulty concentrating that come and go. People with SIBO may experience these symptoms shortly after eating, or on and off throughout the day. A small study found that among people with unexplained gas, bloating and abdominal pain, those who also experienced brain fog were more likely to have SIBO and D-lactic acidosis—a condition caused by the accumulation of D-lactic acid due to an overgrowth of certain bacteria.

3. Fatigue After Eating

In addition to brain fog, SIBO can lead to extreme fatigue, which may be especially noticeable right after eating. While this fatigue may be linked to brain fog, it could also be caused by low vitamin B12 levels, resulting from impaired absorption.

4. Rosacea or Dry Skin

Rosacea is a skin disorder that can cause flushing and persistent redness and dryness on the face. While certain foods may exacerbate symptoms, the cause of rosacea is unknown. That said, research suggests that the condition may be tied to your gut. “Rosacea has been associated with SIBO and may improve once you get rid of the bacterial overgrowth,” says Hadley. 

Strategies to Manage SIBO

Once you’ve confirmed with your doctor that you have SIBO, what can you do? The experts we spoke with recommend a multifaceted approach that may include some combination of antibiotics, herbal antimicrobials and dietary changes. “Long-term success also depends on addressing the root cause, whether that’s impaired gut motility, previous surgeries or other contributing factors,” says Nahar. 

Here are some potential strategies your doctor or dietitian may suggest: 

• Use Medications to Reduce the Bacterial Count: “Managing SIBO starts with getting rid of the bacterial overgrowth itself,” says Hadley. Your doctor may prescribe an antibiotic or herbal antimicrobial to reduce the amount of bacteria in your small intestine.
• Try a Short-Term Elemental Diet: A short-term elemental diet, which includes packaged medical-grade food products, works by starving the bacteria in the small intestine. While shown to be effective, elemental diets should only be done under close medical supervision.
• Space Out Meals and Snacks: “Activating the migrating motor complex allows bacteria and food to be swept through the small intestine and is helpful for symptom management and preventing SIBO from recurring once it’s gone,” says Hadley. This cycle can take anywhere from 113 to 230 minutes, so waiting at least four hours between eating can allow the cycle to complete.
• Follow a Short-Term Elimination Diet: Another dietary approach is an elimination diet. “Short-term elimination diets, including the low-FODMAP and low-fermentation diet, can significantly reduce bloating, gas and discomfort by limiting the types of carbohydrates that feed bacteria in the gut,” says Hadley. That said, research is limited on whether the low-FODMAP diet is effective for SIBO. Because elimination diets can cause nutrient deficiencies when not done carefully, it’s best to work with a registered dietitian rather than implementing one on your own.

The Bottom Line

SIBO may start in the small intestine, but its effects don’t stay there. Digestive discomfort, bloating, diarrhea, constipation and gas are common side effects. However, you may also experience more subtle signs of SIBO, including nutritional deficiencies, rosacea, brain fog and fatigue. If you’re concerned that you may have SIBO, talk with your doctor about testing and treatment options to manage and resolve SIBO and its effects. After all, as Nahar says, “Early identification and a comprehensive approach can make a significant difference in symptom relief and quality of life.”