SIBO Diets - GAPS diet and SCD

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Small Intestinal Bacterial Overgrowth or SIBO as it is commonly referred to is when there is an increase of bacteria in the small intestine. Normally the amount of bacteria is greatest in the large intestine and a smaller amount can be found in the small intestine but SIBO patients have a greater quantity of bacteria within the small intestine. The types of bacteria normally differ in the two intestines but SIBO characteristically has similar bacteria in the small intestine that can be found in the large intestine. SIBO is sometimes called Small Bowel Bacterial Overgrowth Syndrome or SBBOS.

What Causes SIBO

Normally food is digested continuously through the digestive tract from the help of coordinated muscle action. This action helps flush out excess bacteria as well as preventing some bacteria from entering the small intestine. If a condition that causes SIBO interferes with the normal action of the gastrointestinal tract then bacteria stays longer and can grow in number within the small intestine. SIBO can affect the structure and function of the small bowel by interfering with digestion and the absorption of nutrients which is mainly due to damage to the cells that line the small bowel. This can then leak onto a “leaky gut” where various toxins and germs pass through the bowel into the bloodstream. There are various conditions that can cause SIBO such as:

  • Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD)
  • Crohn’s Disease
  • Fibromyalgia
  • Chronic fatigue syndrome (CFS / ME)
  • Neurological and muscular diseases
  • Diabetes

Symptoms of SIBO

Symptoms of SIBO are similar to other gut related conditions such as IBS so it is always important to seek the advice of your doctor who will be able to help with the diagnosis and treatment of the condition.

Many patients with Small Intestinal Bacterial Overgrowth have symptoms from the following:

  • Diarrhea
  • Weight loss
  • Abdominal bloating and abdominal pain
  • Excess wind
  • Nausea

When food is digested in the intestines the bacteria produces gas which can then accumulate within the abdomen and lead to bloating as well as abdominal pain. The bacteria can convert the food into wastes that are irritating to the gut which produces diarrhea or even constipation due to production of methane gas.

Diagnosis of SIBO

Diagnosis can be done in a number of ways but commonly there are two tests that would be used to help with diagnosis. The first is culturing the bacteria to see how much bacteria is present in the gut and the other common method is the hydrogen breath test (HBT). The culturing method can be quite uncomfortable and requires a degree of skill from the doctor as a long tube is inserted through the nose, through the stomach and into the intestines. Conversely HBT is quite a simple test where the patient fasts for at least 12 hours then inflates a balloon with a single breath of air and ingests a small amount of sugar. Breath samples are then taken at set periods to analyse the methane and hydrogen produced. These tests help aide your doctor to make a good diagnosis by taking these results and other factors such as patient symptoms and history.

Treatment of SIBO

SIBO can be treated with antiobiotics but the underlying cause would need to be determined and treated as well or the symptoms would return after the antibiotics are stopped. Probiotics is another way to treat the SIBO, doctors are more likely to prescribe this over antibiotics as there can be long term consequences of taking antibiotics. Probiotics can be used in conjunction with antibiotics where a short course is used then probiotics is used long term. One other way to treat SIBO is to try a diet that is tailored to help reduce the symptoms of bacterial overgrowth. Three common diets that has seen success are the GAPS Diet, Specific Carbohydrate Diet and the Low FODMAP Diet. Sometimes a combination of these diets can provide effective relief.


The GAPS Diet was developed by Dr Natasha Campbell-McBride and the book Gut and Psychology Syndrome, where the acronym comes from, provides in depth information on the diet. The diet was inspired by the Specific Carbohydrate Diet (SCD), which was developed by Dr Sidney Valentine Haas in the 1920s. The diet was developed to help treat digestive conditions such as SIBO, IBS, IBD and leaky gut as well as neurological issues such as ADHD, autism, anxiety and depression.

The diet is comprised of a meal plan that helps repair the gut wall and restore gut health. There are two parts to the diet - the introduction diet and the full GAPS diet. The introduction diet has six stages, you start with stage one and work your way through the stages. This part helps ease you into the diet and tackles symptoms such as diarrhea, constipation and abdominal pain. You should try the introduction diet if your condition is particularly severe such as having chronic diarrhea, ulcerative colitis or severe neurological conditions including schizophrenia, bipolar or autism. If your symptoms are not severe it is okay to skip the introduction and go to the full GAPS diet.

The diet is basically a grain-free diet and is easy to digest to help your gut recover. The foods you eat are low in carbohydrates and sugar and high in healthy fatty acids. It is similar to the Specific Carbohydrate Diet but with a few changes such as fewer beans and cultured vegetables are given more value than yogurt. The introduction phase has been altered and includes more stages.

You begin stage 1 with homemade meat or fish stock. You can make some homemade soups with this stock. Probiotics should be introduced from the start of the diet. Through the stages you will be introduced to the following foods:

GAPS Diet Introduction Foods

  • Ginger tea with honey
  • Fermented vegetables and juices from sauerkraut
  • Raw organic egg yolks
  • Fermented fish
  • Homemade ghee
  • Ripe avocado
  • Pancakes with organic nut butter, squash marrow or zucchini/courgette
  • Roasted and grilled meats
  • Olive oil
  • Freshly pressed juices
  • Cooked apples for apple puree
  • Raw vegetables and peeled cucumber
  • Peeled raw apple

After you complete the six stages of the introduction diet you move onto the full GAPS diet where a larger variety of foods are can be consumed. Fresh meats, animals fats and organic eggs should be consumed frequently and you will find that this part of the diet is less restrictive as there is a greater variety of foods that can be eaten. Take note to avoid baked goods that consist of nut flours and fruit as this can hinder the healing process.

The introduction diet can take around 3-6 weeks to complete and then the full GAPS diet should be followed for a minimum of 18-24 months. For more information on the diet with a full breakdown of the stages and detailed information on the full GAPS diet consult the Gut and Psychology Syndrome book.

Specific Carbohydrate Diet (SCD)

The Specific Carbohydrate Diet is an elimination diet that reduces the amount of complex carbs consumed from certain sources. Grains are eliminated as well as most starches such as potatoes and lactose containing dairy products. The diet is effectively gluten-free due to the no grains aspect. The diet aims to reduce digestion to help reduce inflammation and decrease gut related problems. The diet was developed by Dr Sidney Haas in the 1924 for the purpose of treating celiac disease. This diet has been effective in helping other conditions such as SIBO, Crohn’s disease and IBD. For more information on the diet the book “Breaking the Vicious Cycle” by Elaine Gottschall offers a full breakdown of the diet as well as recipes geared to the diet.

Common Good and Bad Food for SCD

Foods Types Not Allowed

  • Foods containing simple sugars
  • Grains
  • Starches
  • Most dairy

Foods Allowed

  • Vegetables, not canned
  • Meats, unprocessed
  • Fish, unprocessed
  • Eggs, unprocessed
  • Some natural cheeses
  • Fruit
  • Nuts
  • Olive oil and coconut oil
  • Vinegar and mustard

The diet is quite restrictive, difficult to follow and you need to be careful you get your daily nutrients and vitamins that this diet provides a lack of. Looking past these issues the diet has found praise and many sufferers of SIBO as well as other conditions have found their symptoms have decreased.

Where to Get Advice and Support For SCD

The official website to the diet offers helpful information and a list of websites, blogs and support lists can be found at