The Specific Carbohydrate Diet (SCD) is a century-old diet that was originally created to treat children with inflammatory bowel disease. Today, adults and children alike follow SCD to manage their symptoms of various gut issues.
But what is the SCD diet, and how can it improve your gut health? In this article, we’ll take a look at SCD’s history, general rules, and efficacy based on research.
What Is the SCD Diet?
The SCD diet was developed in the 1920s by Dr. Sidney Haas, a pediatric gastroenterologist who sought an effective way to manage celiac disease in children. In the 1950s, Dr. Haas published Management of Celiac Disease with his son, Dr. Merrill Haas.
In the 1990s, Dr. Haas’ protocol was revised and published in biochemist Elaine Gottschall’s book, Breaking the Vicious Cycle. Gottschall’s daughter was a patient of Dr. Haas who followed SCD to manage her ulcerative colitis.
The general structure of the SCD diet is free of:
- Complex carbohydrates (starches)
- Added sugars
- Processed foods
The SCD eliminates foods that may cause digestive system inflammation for some people. Monosaccharides — also known as simple sugars — are the only carbohydrates allowed under SCD.
Complex carbohydrates (disaccharides, oligosaccharides, or polysaccharides) are restricted because they may be more difficult for your body to break down. Undigested food can promote an overgrowth of bad bacteria, which can cause bloating, constipation, and other symptoms.
SCD places foods into two categories: “legal” and “illegal.” Legal foods are allowed on the diet while illegal foods are not.
- Fresh fruits and vegetables such as bananas, blueberries, cucumbers, and eggplants
- Nuts and nut flours such as pecans, macadamia nuts, and sugar-free peanut butter
- Legumes such as lentils and split peas
- Fermented dairy products such as homemade yogurt, dry curd cottage cheese, and cheddar cheese
- Beef, poultry, and seafood
- Starchy vegetables such as sweet potatoes, yams, and corn
- Canned fruits and vegetables
- Processed meats such as cold cuts
- Most dairy products such as ice cream, milk, and commercial yogurt
- Sweeteners such as maple syrup, cane sugar, and high-fructose corn syrup
For a full list of foods allowed on the SCD diet, click here.
How To Follow the SCD Diet
Similar to other elimination diets, you begin the SCD diet withan introductory phase that lasts a maximum of five days. During this phase, eat mainly chicken broth, eggs, and meat. After that, gradually introduce other SCD-legal foods like cooked fruits and vegetables, and note how your body responds.
Keeping a food journal can help you identify which foods are your worst triggers. You can also work with a dietitian or health coach to come up with a sustainable eating plan.
Since it’s a very restrictive diet that excludes many healthy foods, SCD is not intended to be a long-term eating plan. Once your gut health improves, you will slowly re-incorporate healthy, whole foods from outside of the SCD plan back into your diet.
Remember that any diet framework must be tailored to fit your body’s needs, so expect to experiment to find what works best for you.
Effects of the SCD Diet on Common GI Disorders
Although anyone can follow the SCD diet to help improve an unhealthy gut, this protocol was originally designed to improve the symptoms of celiac disease in children. Since then, it’s been recommended for patients of various GI disorders and autoimmune diseases.
SCD and Celiac Disease
Celiac disease is a chronic autoimmune disorder that affects the small intestine, leading to poor digestion and malabsorption of key minerals. It’s triggered by gluten, a protein found in bread and cereal.
Celiac disease is a genetically-predisposed condition that affects nearly 1% of the world’s population . Diagnosis can take place in early childhood or late adulthood, and patients may not always show overt symptoms [2, 3].
Common symptoms of celiac disease:
Non-digestive symptoms of celiac disease:
How SCD helps manage celiac disease:
- SCD restricts gluten, a trigger for celiac symptoms. A systematic review and meta-analysis of 16 approved studies shows celiac patients experience an increase in health-related quality of life via a gluten-free diet .
- However, outside of Dr. Haas’ research on children from the 1950s , there is little modern scientific research to support the benefits of SCD for celiac disease.
- Note that celiac disease may coexist with inflammatory bowel diseases [12, 13]. Current studies regarding the effects of SCD on IBD are more readily available (see below.)
SCD and Ulcerative Colitis
Ulcerative colitis (UC) is an inflammatory bowel disease that’s characterized by small ulcers in the lining of the colon. In more severe cases, UC can spread to the rectum. It’s a chronic condition that can be managed through appropriate lifestyle changes.
Genetics and family history play key roles in the likelihood of a UC diagnosis, which is often made between 15-30 years of age . It’s most prevalent among North Americans and northern Europeans because of the Western diet [15, 16].
Common symptoms of ulcerative colitis include:
- Abdominal cramping and pain
- Chronic diarrhea
- Blood or pus in the stool
- Weight loss
Non-digestive symptoms of ulcerative colitis include:
How SCD helps manage ulcerative colitis:
- A systematic review showed that elimination diets like SCD yielded significant improvements in IBD symptoms .
- Additional research — in particular, large controlled studies — are still needed. However, a couple of N-of-1 (single patient) experiments show some promise in SCD’s ability to improve UC symptoms [23, 24].
SCD and Crohn’s Disease
Crohn’s Disease (CD) is an inflammatory bowel disease that attacks the GI tract. It’s often situated between the end of the small intestine (ileum) and the beginning of the colon. However, CD can sometimes reach as far as the mouth in the form of canker sores.
Common symptoms of Crohn’s disease include:
- Excessive gas
- Pain in the abdomen or rectum
Non-digestive symptoms of Crohn’s disease include:
How SCD helps manage Crohn’s disease:
- To reiterate an earlier point, a systematic review showed that elimination diets like SCD yielded significant improvements in symptoms of IBD .
- Meanwhile, a systematic review of eight studies showed that SCD can improve symptoms, lab results, and remission rates in CD patients. However, there is a need for testing among larger, more varied groups to provide stronger evidence of SCD’s efficacy .
Is the SCD Diet Right for You?
The SCD diet may help you manage symptoms associated with autoimmune disorders or inflammatory bowel disease. Preliminary studies show promise for SCD in improving symptoms of celiac disease, ulcerative colitis, and Crohn’s disease. However, more varied testing and concrete evidence are needed. That said, an elimination diet like SCD could help determine which foods are triggering inflammation in your body.
SCD is not suitable as a long-term diet since it deprives your body of key nutrients that are found in many of SCD’s “illegal foods.” Ease into SCD with the introductory diet, then slowly reintroduce other whole foods over time.
Remember that when implementing this or any other gut-healing diet, it’s important not to get caught up with following it perfectly. Stress can heighten existing digestive problems, so it’s important to relax and allow some room for flexibility. Keep track of your progress with a food journal and the aid of your nutritionist and gastroenterologist.
More on maintaining your intestinal health through diet:
- Learn more about becoming Dr. Ruscio’s patient..
- Discover the link between diet and gut health in Dr. Ruscio’s book, Healthy Gut, Healthy You..
- Learn more about SCD in our interview with SCD expert Steven Wright..