SCD is often promoted for people with inflammatory bowel diseases (IBD), but very few studies support its effectiveness.

Over the last decade, the incidence of IBD has increased worldwide. Symptoms are often painful and include diarrhea, bleeding ulcers, and anemia.

Elimination diets, such as SCD, have gained traction as potential treatments for IBD and other inflammatory and autoimmune disorders.

While SCD was introduced in the 1920s by gastroenterologist Sidney Haas, it was expanded and popularized in the 1980s with Elaine Gottschall’s book “Breaking the Vicious Cycle.”

SCD is an elimination diet that emphasizes removing certain types of carbohydrate-containing foods based on their chemical structure.

The governing theory behind SCD is that complex carbs encourage an overgrowth of unhealthy bacteria in your small intestine if you have IBD.

As these bacteria grow, they produce byproducts that promote inflammation and eventually lead to reduced absorption of nutrients in your digestive tract.

SCD proponents claim that it inhibits the growth of such bacteria and restores digestive function by eliminating all carbohydrate food sources with two or more linked sugar molecules.

Though many carbs are prohibited, the SCD does permit carb sources that have single, unbound sugar molecules — or monosaccharides — as your digestive tract absorbs them more easily.

The diet labels any food or additive containing two or more chemically linked sugar molecules “illegal.” The SCD guidebook, “Breaking the Vicious Cycle,” collectively refers to these foods as complex carbs.

In scientific terms, any food with disaccharides, oligosaccharides, or polysaccharides will appear on the list of illegal foods.

As you can imagine, the list of banned foods is extensive. Common examples include:

The general structure of SCD is very rigid and intended to be followed exactly as outlined in the guidebook — with little to no room for flexibility.

While some people may reintroduce certain banned foods after symptoms subside, this will vary depending on your response to the diet.

SCD-approved foods are collectively called “legal.” Most of the foods on this list are unprocessed, whole foods that don’t offer many complex carbs.

The main sources of approved or “legal” carbs in the SCD come from the monosaccharides glucose, fructose, and galactose.

Common examples include:

  • Fruits: Most fresh or frozen fruits and juices. Canned fruits may be allowed if they don’t have added sugar or starch.
  • Vegetables: Most vegetables, except for potatoes, yams, plantains, and some other high-starch vegetables
  • Meat: Most fresh meats, as long as they don’t contain any fillers or additives
  • Eggs
  • Some dairy: Homemade yogurt fermented for at least 24 hours and some natural cheeses
  • Certain legumes: Some dried legumes, as long as they’re soaked and prepared according to the directions outlined in the guidebook
  • Nuts and nut butter: Most nuts, as long as they’re free from added starch or sugar
  • Herbs and spices: Most dried or fresh herbs and spices. Prepackaged blends may contain additives and are typically discouraged

The SCD guidebook recommends eating only the explicitly legal foods to avoid inadvertently ingesting something banned.

SCD was originally designed as a therapy for people with celiac disease and IBD, an umbrella term that includes ulcerative colitis and Crohn’s disease.

These diseases can hamper your ability to digest and absorb nutrients from food. Thus, SCD aims to heal intestinal tissue in order to restore its functions.

SCD’s promoters claim that some people are less adept at digesting foods — such as grains, legumes, refined sugar, and high-starch food additives — that result from settled agricultural practices and the modern food industry.

Supporters assert that continued ingestion of these carbs leads to an overgrowth of unhealthy bacteria in your gut, which promotes inflammation and eventually diminishes your ability to digest.

Strict adherence to SCD will purportedly starve these bacteria by depriving them of food, allowing your gut tissue to heal. To this day, SCD is primarily used to treat intestinal disorders — but with varied success.

One of the major criticisms of this diet is its lack of concrete scientific evidence.

Most available data is weak and limited to very small studies or anecdotal evidence, which isn’t enough to state whether or not the SCD works definitively.

Ultimately, more research is needed to determine whether SCD is truly an effective treatment for IBD.

SCD is also marketed for people with other medical conditions, including autism spectrum disorder (ASD) and cystic fibrosis (CF).

Early research suggests that gut bacteria may be crucial in treating some behavioral and inflammatory conditions, such as CF and ASD.

SCD is believed to balance your digestive tract, leading its proponents to theorize that it may be an effective therapy for these conditions, too.

However, the scientific understanding of these disorders is limited. Beyond anecdotal reports, there is no research to suggest that SCD treats diseases outside of IBD — if that.

In fact, it’s still unclear whether the SCD impacts gut bacteria at all. More research is needed to understand if SCD affects ASD or CF.

When well planned, the SCD can be balanced, complete, and healthy. However, SCD eliminates large groups of nutrient-dense foods that are beneficial for most people, including whole grains, some legumes, and most dairy.

Eliminating these foods without replacing their key nutrients could result in poor diet quality and subsequent nutritional deficiencies.

Maintaining good nutrition may already prove difficult if you have IBD. Adopting an extremely restrictive diet like SCD could increase your risk of malnutrition and associated complications.

If you’re considering this diet, consult with a registered dietitian or qualified healthcare professional to make sure you’re meeting your nutritional needs.

While anecdotal evidence indicates that SCD may improve IBD symptoms in some people, there’s no guarantee that it will work for everyone.

Medical conditions like IBD are complex, and specific interventions may pan out differently for different people.

With current evidence, it remains unclear if the diet plays any role in IBD treatment.

That said, a well-planned elimination diet may be worthwhile, especially if you want to avoid the more serious risks associated with certain long-term medications and surgeries.

While dieting is a personal decision, you should discuss SCD with a qualified healthcare professional before making any major lifestyle changes.

SCD is an elimination diet designed to treat symptoms of IBD and restore digestive function by purging many carb-containing foods.

While some people may notice improvements in their IBD symptoms, very little research supports its effectiveness beyond a placebo effect.

Due to the restrictive nature of the diet, it could increase your risk of malnutrition.

If you’re considering SCD, discuss it with a healthcare professional or dietitian first to reduce possible risks and ensure a balanced diet.