Inflammatory bowel disease (IBD) (e.g., Crohn's disease and ulcerative colitis) affects millions of US adults, causing symptoms like fatigue, abdominal pain, diarrhea, weight loss, and multiple daily bowel movements that are often bloody. Treatments include medications (to suppress inflammation or quieten the immune response) and surgery to remove damaged bowel.

Many people with IBD have tried the specific carbohydrate diet (SCD) to ease their symptoms. This diet eliminates specific carbohydrates like grains, bread, pasta, and cereals and is very low in sugar and milk sugar (lactose).

Keep reading to learn more about the SCD, what foods are permitted and prohibited on the diet, and the evidence behind it for helping those with IBD.

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What is The Specific Carbohydrate Diet?

The SCD is a dietary approach developed by Dr. Sidney Haas in the 1920s to help manage symptoms of celiac disease in children. The diet is based on the idea that certain carbohydrates are difficult to digest and lead to gut inflammation and digestive symptoms.

The diet is designed to be very restrictive, eliminating most grains, sugars, and processed foods. It only allows specific types of carbohydrates, such as certain fruits and vegetables, honey, some legumes, nuts, and seeds.

What are Monosaccharides?

Monosaccharides (simple sugars) are the simplest form of carbohydrates. They are composed of a single sugar molecule and cannot be broken down into simpler sugars. Monosaccharides are the building blocks for more complex carbohydrates and are the body's primary energy source.

Examples of monosaccharides include glucose, fructose, and galactose. Glucose is the body's primary energy source and can be found in foods such as fruits, vegetables, and grains. Fructose is the sugar found in fruits and honey. Galactose is found in dairy products and is a component of lactose.

The SCD allows only specific monosaccharides like glucose, galactose, and fructose, obtained from fruits, vegetables, honey, and other foods.

What are Disaccharides?

Disaccharides (double sugars) are a type of carbohydrate composed of two monosaccharides (simple sugars) linked together. Disaccharides are not as easily absorbed by the body as monosaccharides and require the action of enzymes to break them down into their monosaccharide components before they can be absorbed and used for energy.

Examples of disaccharides include:

• Sucrose: composed of glucose + fructose; found in table sugar and many sweet fruits.

• Lactose: composed of glucose + galactose; found in milk and dairy products.

• Maltose: composed of two glucose molecules; found in grains and cereals.

The SCD prohibits the consumption of disaccharides, such as sucrose, lactose, and maltose, as these sugars are challenging to digest and may contribute to gut inflammation.

What are Polysaccharides?

Polysaccharides (complex carbohydrates) are a type of carbohydrate composed of multiple monosaccharides (simple sugars) linked together. Polysaccharides are a source of energy for the body.

Examples of polysaccharides include:

• Starch: found in plants, especially in grains like wheat, corn, and rice. Starches are made up of long chains of glucose molecules and can be broken down into glucose by enzymes.‍
• Glycogen: found in animals, especially in the liver and muscles. Glycogen is also made up of long chains of glucose molecules and can be broken down into glucose by enzymes.‍

• Fiber: found in plants, especially whole grains, legumes, fruits, and vegetables. Fiber is not digestible by the body; instead, it passes through the digestive system.

The SCD allows only specific polysaccharides, like some fruits and vegetables and certain seeds, while prohibiting other polysaccharides like sugars, processed foods, and most grains.

Foods Allowed on The Specific Carbohydrate Diet

The following foods are allowed:

• Meat (including fish and shellfish)
• Eggs
• Certain legumes, including navy beans, lentils, peas, split peas, and lima beans
• Certain Cheeses (cheddar, Colby, Swiss, and dry curd cottage cheese)
• Homemade yogurt (fermented for at least 24 hours)
• Fresh, frozen, raw, or cooked vegetables and string beans
• Fresh, frozen, raw, cooked, or dried fruits with no added sugar
• Juice with no additives or sugars.
• Most nuts (e.g., unroasted cashews and peanuts) and nut flours (e.g., almond and coconut flour)
• Nut butters (e.g., all-natural peanut butter, almond butter, and cashew butter)
• Mustard, cider, white vinegar, and most oils
• Plain, weak tea and coffee
• Honey

Foods to Avoid on The Specific Carbohydrate Diet

The following foods are to be avoided:

• Sugar, molasses, maple syrup, sucrose, processed fructose, including high-fructose corn syrup, or any processed sugar
• Stevia, agave nectar
• Artificial sweeteners such as Splenda and Equal
• All types of grains (e.g., corn, wheat, wheat germ, barley, oats, rice
• Bread, pasta, and baked goods made with grain-based flour
• Canned fruits and vegetables
• Some legumes
• Seaweed and its byproducts (e.g., carrageenan)
• Starchy tubers (e.g., potatoes, sweet potatoes, and turnips)
• Canned and most processed meats
• Canola oil and mayonnaise
• Milk
• All dairy products that are high in lactose (e.g., mild cheddar, store-bought yogurt, cream, sour cream, and ice cream)
• Candy, chocolate, and products that contain fructooligosaccharides

How to Implement the Specific Carbohydrate Diet

It's essential to talk to your doctor before you begin the SCD to make sure you'll get the nutrients and calories you need. Due to its restrictive nature, the SCD may make it hard to get adequate intakes of certain nutrients and vitamins.

Here are some general guidelines to follow when implementing the SCD:

1. For an introductory period of 2 to 5 days, limit yourself to only a few of the allowed foods.
2. Cautiously and slowly add more foods from the allowed list.
3. Prepare your own food whenever possible to ensure you are not consuming any prohibited ingredients.
4. Be prepared to experiment with different foods and recipes to find what works best.
5. Consider using a food journal to monitor your symptoms closely. If you notice an improvement, continue with the diet. If you experience any adverse side effects or if your symptoms do not improve, consult your healthcare professional and consider alternative treatment options.

The SCD can relieve symptoms in some people, and they may be able to come off the diet without having an IBD relapse. Others may need to remain on the diet for an indefinite period.  

Evidence Supporting the Specific Carbohydrate Diet

The studies to date are small, but the evidence is promising for the role of the SCD in the treatment of IBD.

IBD Remission

A case report on a single patient demonstrated remission of Crohn's disease after one year of following the SCD.

Another case report demonstrated ulcerative colitis remission after two years on the SCD.

A more extensive study surveyed over 400 patients with IBD who were following the SCD. One-third of respondents noted remission of IBD after only two months on the SCD, which increased to 42% of respondents at the six-month mark.

Symptom Resolution

A study on a cohort of 50 patients with IBD demonstrated that two-thirds of the participants had complete symptom resolution while on the SCD. The study participants found the diet to be greater than 90% effective in relieving acute IBD flare-up symptoms.

Summary

The SCD is a dietary approach developed by Dr. Sidney Haas in the 1920s to help manage symptoms of celiac disease in children. It was later promoted as a possible treatment for IBD. More robust research studies are needed to formally evaluate the SCD in patients with IBD, but the results to date are promising.

The SCD can lead to specific nutrient and vitamin deficiencies, so it's best to consult a functional nutritionist or healthcare practitioner before attempting the diet.