The Specific Carbohydrate Diet (SCD) is a strict elimination diet that removes most complex carbohydrates, including grains, starchy vegetables, and refined sugars, while allowing simple sugars the body can absorb easily. It was originally developed for digestive disorders and is most commonly used today by people with inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis.
How the Diet Works
The core idea behind the SCD is that certain carbohydrates are harder to digest and end up sitting in the intestines, where gut bacteria feed on them. When bacteria break down these undigested carbohydrates, they produce acids and inflammatory byproducts that can worsen symptoms like gas, cramping, and diarrhea. By eliminating those carbohydrates and eating only simple, easily absorbed sugars (called monosaccharides), the diet aims to starve off harmful bacterial overgrowth and reduce intestinal inflammation.
In practical terms, this means the SCD allows foods like fruits, vegetables without starch, nuts, meats, fish, eggs, certain legumes, honey, and some cheeses. It excludes all grains (wheat, rice, corn, oats), most dairy products, refined sugar, potatoes, and anything containing starches or complex sugars.
Origins of the Diet
Dr. Sidney Haas, a pediatrician, developed the diet in the 1920s as a treatment for celiac disease. It remained relatively obscure until 1987, when Elaine Gottschall published “Breaking the Vicious Cycle” after her daughter’s inflammatory bowel disease improved dramatically on the diet. Gottschall’s book became the foundational guide, and the SCD gained a dedicated following among people with IBD, irritable bowel syndrome, and other gut-related conditions.
What You Eat (and What You Don’t)
The SCD divides carbohydrates into two categories: those your body can absorb directly through the intestinal wall (monosaccharides like glucose, fructose, and galactose) and those that require additional digestion (disaccharides and polysaccharides like lactose, sucrose, and starches). Only the first category is allowed.
Foods typically permitted include:
- Proteins: unprocessed meats, poultry, fish, and eggs
- Fruits: most fresh and frozen fruits
- Vegetables: non-starchy options like spinach, tomatoes, carrots, and squash
- Nuts and seeds: almonds, walnuts, pecans, and nut flours for baking
- Fats: olive oil, butter, and coconut oil
- Sweetener: honey (the only permitted sweetener)
- Dairy: homemade 24-hour fermented yogurt and certain aged, low-lactose cheeses
The yogurt is one of the diet’s most distinctive features. Standard commercial yogurt still contains significant lactose, a disaccharide the SCD prohibits. By fermenting yogurt at 100 to 110 degrees Fahrenheit for a full 24 hours, the bacterial cultures break down virtually all the lactose while producing far more beneficial bacteria than store-bought varieties.
Foods that are off-limits include all grains and grain-based products, potatoes, table sugar, maple syrup, corn syrup, most commercial dairy, canned vegetables with added ingredients, and processed foods of any kind.
Getting Started: The Intro Phase
Gottschall’s book recommends starting with an introductory period of two to five days where you limit yourself to a handful of easy-to-tolerate foods. This typically includes homemade chicken soup, eggs, and the 24-hour yogurt. After that initial phase, you slowly add new permitted foods one at a time, watching for any symptom flare-ups. Many followers keep a food journal during this period to identify which foods they tolerate well and which cause problems. The gradual reintroduction process can take weeks or months depending on individual responses.
What the Research Shows
Small studies in children with IBD have produced encouraging results. In one pediatric study, 7 out of 8 patients who completed 12 weeks on the SCD achieved clinical remission based on symptom scoring, lab work, and clinical assessment. Six of those eight children gained weight on the diet, showing that despite its restrictive nature, most were able to get enough calories to support growth even while dealing with active disease.
In adults, the picture is more nuanced. A randomized trial comparing the SCD to a Mediterranean diet in adults with Crohn’s disease found no significant difference between the two. About 46.5% of SCD participants reached symptomatic remission at six weeks compared to 43.5% on the Mediterranean diet. By week 12, remission rates were essentially identical: 42.4% for SCD and 40.2% for the Mediterranean diet. Markers of inflammation in the gut showed similarly comparable responses between the two groups.
This is an important finding. It suggests the SCD can help, but it may not be uniquely effective compared to a generally healthy, whole-foods diet like the Mediterranean approach, which is considerably less restrictive and easier to maintain long-term.
Nutritional Concerns
Because the SCD eliminates grains and most dairy, calcium intake is a genuine concern. In one study of children following the diet, 9 out of 10 participants had inadequate calcium intake. Calcium was the only nutrient where a standard unrestricted diet clearly outperformed the SCD. Vitamin D intake also tends to run low, with 40% of SCD followers in one study falling below adequate levels.
For most other nutrients, the SCD actually performs reasonably well. Its emphasis on whole foods, meats, fruits, vegetables, and nuts means that people following it carefully tend to meet their needs for protein, iron, zinc, and most vitamins. The key gap is calcium, and anyone on the SCD long-term should pay close attention to calcium-rich permitted foods (like the 24-hour yogurt and certain aged cheeses) or discuss supplementation with a provider.
Where It Stands in Medical Practice
The SCD is not part of standard treatment guidelines for IBD. The Crohn’s and Colitis Foundation does not endorse any single diet for managing IBD, noting that while people report symptom improvement on the SCD, the scientific evidence base remains limited. The foundation also flags that the diet is very restrictive and difficult to follow.
That said, interest in dietary therapy for IBD is growing, and gastroenterologists increasingly recognize that food choices play a role in managing symptoms. Many practitioners are open to patients trying the SCD, particularly when conventional treatments alone aren’t providing relief. The diet works best when paired with professional guidance to ensure nutritional adequacy, especially for children who are still growing.
For people who find the SCD too difficult to sustain, the randomized trial data comparing it to a Mediterranean diet offers a practical alternative. Both approaches showed similar remission rates, meaning a less restrictive whole-foods diet may provide comparable symptom relief with fewer sacrifices at the dinner table.