About SCD

Introduction

The Specific Carbohydrate Diet (SCD) is used to control conditions caused by inflammation in the gut, such as Crohn’s disease. The SCD achieves this by cutting out complex carbohydrates (grains, most dairy, refined sugar, etc.), which restores a good balance of bacteria in the gut and reduces inflammation. It is highly recommended to work with your doctor to treat your condition and you are encouraged to read the details of the diet outlined in the book Breaking the Vicious Cycle by Elaine Gottschall. Evidence and upcoming trials for the SCD can be found on the Research page. The information provided by Simply SCD is meant to give you an overview of the diet and act as a resource to help implement the SCD in your lifestyle.

How the SCD works

Carbohydrates are an important component of food that provide energy. All carbohydrates are made up of a single sugar molecule (monosaccharide). However, carbohydrates can also come in other forms such as two sugar molecules (disaccharide), or multiple sugar molecules (polysaccharide).

saccharide structure
Figure from Breaking the Vicious Cycle (Gottschall, 1994).

The walls of a healthy gastrointestinal (GI) tract are covered with little cell surface extensions called microvilli. These microvilli are the home of tiny proteins called enzymes which split chunks of food (like disaccharides and polysaccharides) into small pieces (like mono saccharides) to be absorbed through the intestinal wall. So as food moves through a healthy gastrointestinal tract, enzymes break down the food and the intestines absorb as many nutrients as possible. Once the food is digested and excreted, the GI tract is left with colonies of good bacteria that help the immune system and produce beneficial nutrients.

healthy microvili
Figure from Breaking the Vicious Cycle (Gottschall, 1994).

However, if there is inflammation in the intestines (such as in Crohn’s disease), the microvilli become damaged and the enzymes cannot function properly. This means that disaccharides and polysaccharides are not broken down into small enough nutrients to be absorbed through the intestines. In addition, an inflamed intestinal wall makes it even harder for nutrients to be absorbed to nourish the rest of the body.

unhealthy microvili
Figure from Breaking the Vicious Cycle (Gottschall, 1994).

This leaves a supply of undigested disaccharides (such as table sugar) and polysaccharides (such as potatoes) in the GI tract for “bad” bacteria to eat, grow and overpopulate “good” bacteria. The “bad” bacteria create harmful gases and compounds which cause inflammation in the intestinal walls. This creates a vicious cycle, which inspired the title of the book Breaking the Vicious Cycle .

vicious cycle
Figure from Breaking the Vicious Cycle (Gottschall, 1994).

This vicious cycle is stopped by not eating carbohydrates that need the help of enzymes to be broken down. The foods allowed on the SCD are made up of monosaccharides already small enough to absorb through the intestinal wall, leaving no food behind for “bad” bacteria to survive. This eventually gets rid of the “bad” bacteria, reducing the inflammation, and allowing the intestinal wall to heal. Next, visit the Food List page and read Breaking the Vicious Cycle to learn more about the foods that are allowed on the SCD.

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