The specific carbohydrate diet (SCD) is an elimination diet that is grain free, starch free, sugar free and avoids most dairy (except for hard, aged cheese and homemade yogurt that has been fermented for over 24 hours.) The SCD focuses on natural, nutrient rich foods that includes vegetables, low-sugar fruits, eggs, meats and nuts. Essentially, the specific carbohydrate diet is very similar to what our ancestors ate.
The origins of the SCD can be traced back over a hundred years when early Coeliac disease researchers recognised that their patients did better when they removed grains from their diet. At the time, all starches (not just ‘gluten’) were singled out. In the late 1920’s, Dr. Sidney Hass, a paediatrician in New York, took the findings and experimented with diet as a therapy for his young patients. By simply excluding specific carbohydrates, Haas claimed to cure children of Coeliac disease and other gut conditions, such as inflammatory bowel disease.
In the 1950’s, Haas was treating a young girl by the name of Judy Gottschall, who was very sick with Ulcerative Colitis. After Judy’s steady recovery from UC, her mother, Elaine Gottschall, returned to study so that she could dedicated her life to researching the diet and the effects of food on the gut. At 47 she had earned degrees in biology, nutritional biochemistry, and cellular biology. In 1987, she published ‘Food and the Gut Reaction’, which was republished in 1994 as definitive SCD text “Breaking the Vicious Cycle - Intestinal health through diet”.
Advocates of the SCD quickly followed in her footsteps to spread the word of its efficacy; creating cookbooks and recipe websites for others to benefit from. Gottschall’s book and ongoing research continues to inspire people in the dietary management of inflammatory bowel disease, Coeliac disease and other gastrointestinal diseases.
Foods on the SCD are classified by their chemical structure – either monosaccharide, disaccharide, or polysaccharide. On the diet, only monosaccharide carbohydrates are permitted. Disaccharides include lactose, sucrose, maltose, and isomaltose and white sugar. Polysaccharides and are found in grains, starches and starchy veggies.
“These allowed carbohydrates are monosaccharides and have a single molecule structure that allow them to be easily absorbed by the intestine wall. ‘Complex carbohydrates’ which are disaccharides (double molecules) and polysaccharides (chain molecules) are not allowed. Complex carbohydrates that are not easily digested, feed harmful bacteria in our intestines causing them to overgrow producing by-products and inflaming the intestine wall. The diet works by starving out these bacteria and restoring the balance of bacteria in our gut.” Read more here
Not everyone’s digestive tract has evolved to optimally digest some modern food sources. So when complex carbohydrates, refined sugar and other synthetic ingredients found in our diet are removed from the diet of these people, digestive processes improve, toxins are reduced, inflammation subsides and overall health improves.
The rationale behind the SCD diet is that many digestive disorders stem from “an overgrowth and imbalance of intestinal microbial flora”. In other words, there are too many harmful types of bacteria, yeast and fungus residing within the body (mostly within the gut) where the majority of the immune system is located. Elaine Gottschall explains,
“When carbohydrates are not fully digested and absorbed, they remain in our gut, and become nutrition for the microbes we host. The microbes themselves must digest these unused carbohydrates, and they do this through the process of fermentation. The waste products of fermentation are gases, such as methane, carbon dioxide & hydrogen, and both lactic & acetic acids, as well as toxins and all serve to irritate and damage the gut.”
Foods allowed on the diet are easily digested and absorbed by the body and leave little behind for bad bacteria to enjoy. She says,
"As the microbial population decreases due to lack of food, its harmful by-products also decrease, freeing the intestinal surface of injurious substances. Malabsorption is replaced by absorption. As the individual absorbs energy and nutrients, all the cells in the body are properly nourished, including the cells of the immune system, which then can assist in overcoming the microbial invasion.”
In this way, the SCD targets both the underlying problems within the digestive tract that can lead to serious disorders as well as symptoms related to inflammation, bacterial overgrowth and poor nutrient absorption.
A key part of the SCD is to repopulate the gut with healthy bacteria by including foods rich in healthy bacteria. Yogurt is the first fermeneted food introduced on the diet.
While milk is not allowed on the diet, yogurt made from milk and fermented for a minimum of 24 hours is encouraged. Introducing 24-hour SCD yogurt repopulates the gut with beneficial bacteria which soon outnumber the bad bacterial overgrowth. This fermentation time is enough for the bacteria in the yogurt starter culture to break down the lactose (disaccharides) in milk, into galactose (a monosaccharide). It is essential that the yogurt is properly prepared so it must be homemade, as commercially available yogurts are simply not fermented long enough.
Foods on the diet are classified as either legal (allowed foods) or illegal (not allowed foods). A printable infographic can be found here.
The SCD is most often recommended to people with Coeliac disease, inflammatory bowel diseases (such as Crohns disease, ulcerative colitis) and diverticulitis. If you don’t have a diagnosable digestive disorder but suffer from persistent irritable bowel syndrome symptoms (like constipation, diarrhoea, gas, bloating) or food sensitivities, the SCD diet can also help. Simply removing hard to digest carbohydrates will help lower fermentation in the gut which leads to these symptoms. In turn, the diet will help prevent gut permeability (leaky gut) which could lead to more serious health issues down the track. More recently, it’s even been suggested that the SCD can help with learning disabilities such as autism. More on this in ‘Introduction to the GAPS diet’ coming soon.
With continued research into the gut and new nutritional and dietary therapies being prescribed, people are now commonly choosing to combine SCD with other gut healing protocols such as the GAPS diet, anti-inflammatory diets, Low FODMAP diet, low histamine to name a few.
For further reading, I highly recommend Elaine Gottschall’s book: 'Breaking the Vicious Cycle: Intestinal health through diet'or start at the official website.