About SCD

Breaking the Vicious Cycle

Many diets have been used to improve and control gastrointestinal problems, schizophrenia, autism and countless other disorders. The common denominator of the successful diets are the type of carbohydrates that are eliminated and the ones that are allowed. The Specific Carbohydrate Diet is a highly nutritious and well-balanced diet that consists of simple sugars to allow proper digestion. It also helps rids toxins out of the body, which has also improved many neurological and physical ailments! This diet can be used to manage Crohn’s disease, Ulcerative Colitis, Irritable Bowel Syndrome, refractory constipation as well as other gastrointestinal disorders. It can also help alleviate muscle aches, stiff joints and even arthritis, chronic skin rashes, psoriasis and general fatigue. It can even help autism and schizophrenia!

Scientific Evidence Relating to Diet

Medical literature is abundant with reports sharing favorable effects of dietary changes on intestinal disease. In 1745, Prince Charles, the Young Pretender to the throne of England, had ulcerative colitis and cured himself by following a milk-free diet. The early 1900’s was filled with new discoveries about the effect of diet on intestinal problems. Dr. Christian Herter, a physician and professor at Columbia University, observed that in cases where children were experiencing diarrhea and depletion, proteins were well tolerated, fats were handled fairly well, but carbohydrates (sugars and starches) were poorly tolerated. Dr. Gee, a world-renowned children’s specialist, claimed that if intestinal disease could be cured at all, it would have to be through diet. He insisted that milk was the least suitable food during intestinal problems and that food with high amounts of starches like rice, corn, potatoes and grains were unfit. Dr. Gee stated, “We must never forget that what the patient takes beyond his power to digest does harm.” Therefore, any food given to a person with intestinal problems should require little or no digestion so that the digestive process itself will not inhibit the absorption of the carbohydrates. Unlike what many people may think, undigested (therefore, unabsorbed) carbohydrates are not passing harmless through the small intestine and colon and out in the feces but rather causing problems and damage in the digestive tract.


In order to understand why items are either illegal or legal on the diet, you must first understand the different carbohydrates that can make up food. Carbohydrates are made up of either one, two, or multiple sugar molecules. The Specific Carbohydrate Diet allows carbohydrates that are made up of one sugar, monosaccharides and forbids carbohydrates that are made up of more than one sugar, disaccharides and polysaccharides.

  1. Single sugars (monosaccharides)

These sugars require no further splitting in order to be transported from the intestine into the bloodstream. These include glucose and fructose, which can be found in honey, fruits, and some vegetables.

  1. Double sugars (disaccharides)

These sugars require splitting by intestinal cell enzymes. There are four main disaccharides: lactose, sucrose, maltose, and isomaltose. Lactose is found in milk, dried milk powder, commercial yogurt, homemade yogurt which has not been fermented for twenty-four hours, processed cheese, cottage cheese, cream cheese, ice cream, some sour creams, whey, and many products which have added milk solids or whey. Many drugs and vitamin and mineral supplements have added lactose. Sucrose is table sugar and is found in processed foods such as gelatin desserts, ketchup, cereals, many canned foods and some frozen preparations. Maltose and isomaltose are found in sources such as corn syrup, malted milk, and candies.

  1. Starch (polysaccharides)

Starch can be of two types called amylose and amylopectin. Most vegetables contain both types in various proportions. These can be found in rice, corn, sweet potatoes, yams and many other vegetables and all grains 


Normal Function

In order to understand why certain items are allowed or not allowed on this diet, you must also understand how the digestive process works in a normal state versus a state with disease. Before birth, the human intestine has no microbes. However, from the moment of birth, an attack of the gastrointestinal tract takes place and it quickly becomes filled with various types of microbes. The stomach and most of the small intestine typically have only a scarce population of microbes. However, the amount of microbes typically increases at the lowest part of the small intestine, the ileum, due to its close proximity to the microbial-rich colon. In a healthy intestinal tract, intestinal microbes live in a state of balance. An overpopulation of one type is avoided by the actions of other types, preventing any type of microbe from overpowering the body with its harmful waste products.

The last step in carbohydrate digestion occurs at the small projections on the intestinal surface called microvilli. Enzymes located in the microvilli break down and process carbohydrates so they can cross over the barrier and enter the bloodstream to nourish the body.

healthy cell

This is where lactose, sucrose and other starches and grains are broken apart and absorbed. However, monosaccharides like glucose are considered a “predigested” sugar because they don’t need to be broken down by enzymes and can move through the intestinal absorptive cells, enter the bloodstream and nourish the body with ease.

Disease Function

There are many places in the gastrointestinal tract where problems could lead to malabsorption: (1) if food travels too rapidly through the intestinal tract (as happens most often when diarrhea is present), there is not enough time for large food molecules like starch, fat and protein to be broken down by various enzymes and, therefore, their absorption into the bloodstream is seriously impaired; (2) if a poorly functioning pancreas does not deliver enough digestive enzymes to the small intestine to break down large molecules of protein, fat, and starch, absorption of these nutrients will not occur. However, research suggests a later step in digestion as the source of malabsorption in many intestinal disorders. As discussed before, this last step occurs at microvilli. The structure of the intestinal surface is dramatically altered during intestinal disease and, as a result, digestive activity is seriously inhibited. This makes the last step in the digestion of these carbohydrates difficult, if not impossible.

It is typically accepted among physicians and researchers that a normal state of balance between intestinal microbes living in our gastrointestinal tract is lost during intestinal upsets and chronic intestinal disease. Once the normal equilibrium of the colon is disturbed for any reason, microbes can migrate into the small intestine and stomach hindering digestion, competing for nutrients, and overwhelming the intestinal tract with their harmful waste products. Although the normal intestine controls the growth of bacteria, cases with intestinal abnormality prevent this normal regulatory control.

Overgrowth of bacteria in the stomach and small intestine may happen for multiple reasons including:

  • interference with the high acidity of the stomach through the continual use of antacids
  • a decrease in the acidity of the stomach such as occurs in the aging process
  • malnutrition or a diet of poor quality, and the resulting weakening of the body’s immune system
  • antibiotic therapy which can cause a wide range of microbial changes. A microbe commonly residing in the intestine without harmful effects may undergo a wide range of changes as a result of antibiotic therapy.

When bacteria multiplies within the small intestine, the chain of events develops into a vicious cycle with an increase in the production of gas, acids and other products of fermentation, which further the malabsorption problem and the intestinal disorder. It is difficult to pinpoint where this vicious cycle starts exactly.


When undigested carbohydrates are present in the small intestine and cannot be broken down by the required enzymes, microbes will ferment these carbohydrates and produce harmful by-products such as carbon dioxide gas, hydrogen gas, methane gas, alcohol, lactic acid, acetic acid and more.

The rising levels of irritating by-products given off by the growing microbial population cause intestinal cells to defend themselves. Their form of defense is the production of excessive mucus where the intestinal tract attempts to “lubricate” itself against the injury caused by the damaging microbial population. If the cells of this mucus layer become wearied, the bare intestinal surface is exposed to more damage. At this point, it is possible that ulceration of the intestinal surface, as seen in ulcerative colitis, can happen. An abnormally thick layer of mucus produced by the intestinal cells can prevent contact between the microvilli enzymes and the carbohydrates that need to be broken down.

The main reason patients need to adopt this diet is because they have lost the ability to digest disaccharides due to excessive mucus production by intestinal cells. Since the sugar-splitting enzymes are in the membranes of the intestinal cells, they are very vulnerable to damage. Also, irritating or toxic by-products produced by yeast, bacteria, or parasites which have invaded the small intestinal tract can cause damage to the intestinal cell membranes, destroying their enzymes. An abnormally thick layer of mucus prevents contact between the disaccharides and the digestive enzymes of the intestinal cells. For this reason, sugars that need digestion cannot be broken down and will not be absorbed to provide nourishment. Countless conditions involving the small intestine are frequently associated with deficiencies of lactase (enzyme that splits lactose) as well as other disaccharidases (enzymes that splits disaccharides). When the intestine is injured, the enzymes embedded within the intestinal cell membranes simply cannot do their job: to make contact with and split certain sugars in the diet.


The damage on the small intestine from bacterial growth appears to destroy the enzymes on the intestinal cell surface, preventing carbohydrate digestion and absorption and making carbohydrates available for further fermentation. Undigested and unabsorbed carbohydrates within the small intestine can encourage microbes from the colon to take up residence in the small intestine and to continue to multiply and cause injury. Undigested and unabsorbed carbohydrates remaining in the intestine (because there are no enzymes available to break them down) provide energy and encourage the growth of microorganisms involved in intestinal disorders. Undigested sugars in the interior space of the small intestine even causes a reversal of the normal nutritional process. Instead of nutrients flowing from the intestines into the bloodstream, water is drawn into the intestinal space. The water (carrying nutrients) is lost via diarrhea and the cells of the body are deprived of energy, minerals, and vitamins. Even worse, the sugars still remaining in the intestinal space are of course providing energy for further fermentation and growth of intestinal microbes. This fermentation produces harmful by-products, injures the intestines and keeps this vicious cycle going.

Why SCD Works

The purpose of the Specific Carbohydrate Diet is to deprive the harmful microbes of the food it needs to overpopulate and disrupt a healthy balance. By adopting a diet, which contains mainly “predigested” carbohydrates, the individual can be maximally nourished without supporting the intestinal microbial population.

A basic approach to get rid of the undesirable activities of intestinal microbes is the use of antibiotics. This approach is often tried in most chronic intestinal disorders, but it has limitations. Antibiotic therapy is limited while others drugs of the cortisone and sulfa families have side effects if used too long. A reasonable and safe form of intervention on the unwanted intestinal microbes is to control their energy supply through diet. The Specific Carbohydrate Diet is based on the idea that specifically selected carbohydrates, requiring minimal digestive processes are absorbed and leave virtually none behind to be used for microbial growth in the intestine. By stopping the growth of the microbial population, the vicious cycle can end. As the microbial population has a lack of food, its population decreases and its harmful by-products also decrease, freeing the intestinal surface of injurious substances. As the individual absorbs energy and nutrients, all the cells of the body are properly nourished, including the cells of the immune system, which then can assist in overcoming future microbial invasion.


Gottschall, Elaine Gloria. Breaking the Vicious Cycle: Intestinal Health Through Diet. Kirkton, Ont.: Kirkton, 1994. Print.