Small Intestinal Bacterial Overgrowth (SIBO)
The Wrong Low-carb Answer for Bowel Troubles

I recently received the following email: "I am writing to you about my 44-year-old niece who has been told by her doctors that she has SIBO. They have put her on a NO CARB diet, just protein and fat, as well as a second course of antibiotics. She is doing miserably and is very upset with her constant constipation, bloating, and GI distress." 

The newest fad diagnosis for explaining why people feel poorly for no apparent reason is called Small Intestinal Bacterial Overgrowth (SIBO)—meaning there is an overgrowth of bacteria in the small intestine; the section of the intestine beginning just below the stomach and ending at the start of the large intestine. We consume large amounts of bacteria with our foods and found naturally in the saliva in our mouth. Our stomach acids kill most of these bacteria before the remnants of the chewed and partially digested food pass into the small intestine. Thus, in a normal state, relatively few bacteria reside in this part of the gut.

An increasingly popular dietary theory is that carbohydrates make intestinal bacteria multiply in the small intestine. Only plants synthesize carbohydrates, therefore, in the minds of promoters of low-carb diets the solution is to avoid completely or restrict starches, vegetables, and fruits in an effort to starve the bacteria. The recommended low-carbohydrate diet focuses on animal foods: meat, poultry, cheese, fish, and eggs. (Mammalian milk contains the sugar, lactose, and so is not allowed; however, cheese is very low in this sugar, so it is okay to eat.)

Like the 44-year-old niece I introduced to you above, following a low-carb approach does not make people feel better, and often makes them feel worse. In most instances, in reality they never had SIBO. In addition, most who go low-carb can add constipation to the list of their troubles with 68% of people following the original Atkins Diet reporting this bowel distress. Plus the detrimental effects of following this advice to eat more animal foods can be as consequential as colon cancer, ulcerative colitis, Crohn's disease, diabetes, heart disease, and obesity.

The truth is that overgrowth of bacteria is found in very few people with abdominal distress who receive this diagnosis of SIBO. Taking a sample of the intestinal fluids and finding an excess of bacteria in the small intestine makes diagnosis. However, this is a complicated procedure; so instead the hydrogen breath test is used to make the diagnosis. The hydrogen breath test is highly unreliable and produces many false positive diagnoses of SIBO. Antibiotics are often used to treat this disorder, but the benefits of this approach are limited, with recurrence being common.

Real cases of SIBO are rare. This condition is found in patients who have problems such as diverticula (small pouches) off the intestinal wall, changes in intestinal flow that may result from surgeries of the bowel, and inflammatory bowel disease (IBD). Taking powerful antacids called proton pump inhibitors (for example, Prilosec, Prevacid, Nexium) prevents the stomach acids from naturally killing these bacteria and so SIBO develops.

Diseases Claimed to Be from SIBO

The range of problems claimed to be due to SIBO include: autoimmune diseases, vitamin deficiencies, malnutrition, weight loss, arthritis, fatigue, rashes, acne, eczema, asthma, depression, and rosacea. Nausea, bloating, vomiting, and diarrhea are common results of SIBO.

Irritable Bowel Syndrome (IBS) is most often ascribed to being caused by SIBO by healthcare givers who believe in restricting carbohydrates. (IBS is also classified as a functional gastrointestinal disorder.) People with this condition suffer with chronic abdominal pain or discomfort and diarrhea, constipation, or alternating bouts of the two. SIBO has also been linked to more serious Inflammatory Bowel Diseases (IBD), including Crohn's disease and ulcerative colitis.

Diet Changes Bowel Bacteria: Do Not Eat Low-Carb

Most people think of bacteria as dangerous and dirty. Our intestinal tracts contain a complex and diverse society of disease-causing (pathogenic) and "friendly" bacteria, referred to as our "microflora." In addition to digesting remnants of our meals and synthesizing vitamins, the helpful bacteria play an important role in the development of the immune system and the production of hormones. In short, "friendly" bacteria prefer to dine on plant-food remnants, and pathogens thrive when the diet is low in plant foods and high in meat, poultry, dairy, eggs and other "junk food."

Therefore, what we choose to eat determines the predominance of the bacteria species that will live in our gut. By switching from a diet based on animal foods and highly processed foods to a whole food, plant-based diet, you can suppress the growth of harmful bacteria and stimulate those that are beneficial. Major alterations in the microflora take place within one to two weeks of changing a person's diet.

Bowel bacteria are fundamental players in the cause of diseases as apparently dissimilar as coronary artery disease and Inflammatory Bowel Disease. The intestinal bacteria that grow from a diet of meat, dairy, and eggs contribute to development of atherosclerosis by producing trimethylamine (TMA), which is then oxidized into an artery-toxic substance (TMAO) . Both meat and milk have been shown to cause the growth of bacteria that produce toxic sulfur-based compounds that damage the cells of the intestine, causing Inflammatory Bowel Disease. Sources of dietary sulfur include high-protein products with sulfur-containing amino acids (red meat, cheese, and eggs).

Restricting Specific Carbohydrates for SIBO

Over the past 10 years, diets that restrict foods high in specific carbohydrates (not all carbohydrates) have become popular. The most popular SIBO treatment diets are the Specific Carbohydrate Diet (SCD) and the Low FODMAP Diet (LFD). . However, other diets blaming specific sugars (carbohydrates) for bowel problems are cropping up.

The rules for these diets are very complicated, and thus, they are difficult to follow. Any benefits achieved, I believe, are simply due to patients paying closer attention to what they eat in general, resulting in the elimination of junk foods, such as cookies, cakes and candies. I would not promote the approaches of restricting specific carbohydrates even if they worked, because these diets continue to promote the consumption of animal foods and vegetable oils, and fail to emphasize the central importance of starch in the prevention and treatment of common Western diseases, including most bowel diseases.

For example, IBS, as discussed above, is "a condition of chronic abdominal pain or discomfort and diarrhea, constipation, or alternating bouts of the two." Consider that cow's milk (the protein) is a very common cause of constipation, and fats and oils themselves can cause severe diarrhea. Both the Specific Carbohydrate and the FODMAP diets allow dairy proteins as well as fats and oils. Plus these diets promote foods entirely lacking in dietary fiber (animal foods and oils). Fiber, synthesized by plants only, makes up the bulk of a bowel movement. Fiber deficiency results in small, rock-hard marbles that are passed infrequently into the toilet, requiring body-damaging straining. Hemorrhoids, varicose veins, and hiatal hernia are a few of the consequences of the straining caused by constipation.

The McDougall Diet Is Right for the Bowels

What we eat and, therefore, send down into our intestine can cause disease not only of this organ, but the entire body. Over the past 35 years, underdeveloped countries, such as Asia (where rice is a staple food) and Central America (where corn and beans are staples), have switched to diets high in meat, dairy, and vegetable oils. These "newly rich" populations have, with a change of their diets, developed epidemics of diabetes, obesity, cancers, and bowel diseases.

One recent study found 92% of people with Crohn's Disease maintained in remission of their disease for two years with a semi-vegetarian, mostly rice, diet. More information on IBS and IBD is found on my website. Also read about star mcdougaller, Andrew Neuman, and his recovery from severe ulcerative colitis, and listen to Sondra Berk tell of her recovery from Crohn's Disease. My experience with more than 6,000 patients in my live-in programs has found that the first organ to respond to a healthy diet is the intestine. Constipation, GERD, and acid indigestion are usually gone within two days.

This dietary change is a simple, cost-free approach with no downsides, like trading IBS for IHD (ischemic heart disease). The benefits begin for most people within hours. My challenge for any of you who are suffering is a one-week-long experiment with simple instructions laid out in 66 pages of my Color Picture Book on Food Poisoning. (Diet is powerful medicine. It is appropriate to discuss an impending diet change with your private medical doctor, especially if you are on medications.)