The Specific Carbohydrate Diet (SCD): a comprehensive overview for people with Crohn’s disease and ulcerative colitis

Should you do the Specific Carbohydrate Diet for your Crohn’s or ulcerative colitis?

Current diet guidelines do not recommend the SCD for induction or maintenance of remission in individuals with Crohn’s disease or ulcerative colitis due to lack of research supporting its use at this time.^

What is the Specific Carbohydrate Diet?

The specific carbohydrate diet is a whole foods diet that eliminates all grains, certain starches (such as potatoes, okra, and sugars), most milk products (except hard cheeses and yogurt that has been fermented for 24 hours), and processed foods.^

Background on the Specific Carbohydrate Diet

The Specific Carbohydrate Diet was originally developed by Dr. Sydney Haas in 1924 to treat celiac disease.^ It was later popularized by biochemist Elaine Gottschall after she wrote the book, Breaking the Vicious Cycle, in 1994.

The book claims the diet is helpful for individuals with Crohn’s disease, ulcerative colitis, diverticulitis, cystic fibrosis, chronic diarrhea, and autism. However, it’s important to note that there was no research at the time the book was published that supported the author’s claims about the benefits of the diet for people with IBD. 

What are carbohydrates?

Carbohydrates are a macronutrient that plays an important role in the health of the human body.^ Foods that contain carbohydrates include sugar, fruits, vegetables, legumes, grains, and dairy. There are two main types of carbohydrates:^{ }

• Simple carbohydrates - Simple carbohydrates are carbohydrates that are digested quickly by your body. Examples of simple carbohydrates include white bread, soda, pastries, sugar. 
• Complex carbohydrates - Complex carbohydrates are carbohydrates that are digested more slowly by your body. Examples of complex carbohydrates include whole grains, vegetables, fruits, and legumes.

How the SCD works:

The theory behind the specific carbohydrate diet is that since complex carbohydrates are poorly digested, they feed bad gut bacteria in the intestines leading to an overgrowth of this bacteria, which harms the intestinal wall.^

The SCD, therefore, aims to starve out the bad gut bacteria and restore the balance of bacteria in our intestines by only allowing certain types of simple carbohydrates.^ 

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Who the diet is for/not for:

Who may benefit from following the SCD:

• Individuals with mild to moderate Crohn’s disease who want to use a structured diet to potentially improve their symptoms

Who may not benefit from following the SCD:

• Individuals with mild to moderate ulcerative colitis or Crohn’s disease who want to use diet for induction of remission - currently there’s insufficient evidence to support this outcome.
• Individuals with moderate to severe ulcerative colitis or Crohn’s disease - currently there’s insufficient evidence to support the SCD in this population group
• Individuals with a history of eating disorders or disordered eating - if your relationship with food isn’t in a good place, extra consideration should be taken to the benefits vs drawbacks of implementing any restrictive diet as a therapy 
• Individuals wanting to keep their diet as expansive as possible - this diet is restrictive so if you want to keep your diet as expansive as possible, this may not be the right choice for you
• The SCD may be inappropriate for patients with stricturing Crohn’s disease (as there may be a risk for obstructions)

Is it hard to stick to the Specific Carbohydrate Diet? 

One randomized controlled trial that included 99 patients following the specific carbohydrate diet found that 67% of patients were able to adhere to the diet for 6 weeks while 40% of patients were able to adhere to the diet for 12 weeks.^ In another study with 208 patients, 71% of those following the SCD adhered to it 90% of the time, and of those patients, 70% had been following the diet for more than 1 year.^ 

Some of the barriers that prevented patients from sticking to the diet include^

• Dietary restrictions
• Perceived lack of variety
• Taste fatigue
• Psychosocial impacts
• Financial burden
• Time commitment
• Inconsistent clinical responses

Does the Specific Carbohydrate Diet work?

Current nutrition guidelines for inflammatory bowel disease do not recommend the use of the Specific Carbohydrate Diet for induction or maintenance of remission in individuals with Crohn’s disease or ulcerative colitis.^{ }

The highest quality study conducted to date compared the Mediterranean diet to the Specific Carbohydrate Diet and found that there were no significant differences between the diets in reducing symptoms or inflammatory markers^

Given the similar results, fewer diet restrictions, and the health benefits associated with the Mediterranean diet, researchers recommend trying the Mediterranean diet over the SCD for patients with mild-to-moderate Crohn’s disease.^

To date, no high quality studies have been published that look at the effectiveness of the SCD in people with ulcerative colitis or microscopic colitis. 

Summary of higher quality studies/randomized trials:

High quality studies compare two or more diets to each other and include a sufficiently large number of patients so that researchers can determine if the results are statistically significant and not just due to chance or bias. 

1. A 2021 study of 194 Crohn's disease patients compared the Specific Carbohydrate Diet to the Mediterranean diet over the course of 12 weeks. There were no significant differences in the number of patients achieving symptom remission, fecal calprotectin response, or CRP response between the two diets. Both diets were helpful for achieving symptom remission in about 45% of participants.
2. A 2022 study of 54 children with IBD compared the Specific Carbohydrate Diet to the Modified Specific Carbohydrate Diet over 8 weeks. Neither diet helped to significantly improve symptoms or markers of inflammation such as fecal calprotectin
3. A 2020 study of 18 children with mild-to-moderate Crohn's disease compared the Specific Carbohydrate Diet to the Modified Specific Carbohydrate Diet and a whole foods diet over 12 weeks. Only 10 out of 18 patients completed the study. All 10 achieved symptom remission and had lower CRP levels, however the change in CRP was not statistically significant. 

Summary of lower quality studies:

Low quality studies are observational (meaning they don’t compare one diet to another), contain a small number of patients, include significant sources of bias, do not consider the use of medications or external factors, or are poorly designed.

While these studies may be interesting, it’s important to use caution when interpreting their results due to the inherent limitations of each study. 

1. A 2016 study surveyed 417 IBD patients about their perceived benefit of following the Specific Carbohydrate Diet for 1 year. 33% of survey respondents reported symptom remission after 2 months on the diet while 42% reported symptom remission after 6 and 12 months.
2. A 2015 study surveyed 50 IBD patients about their perceived benefit of following the Specific Carbohydrate Diet for an average of 10 months. 66% of survey respondents reported symptom remission after an average of 10 months.
3. A 2016 study examined the medical records of 26 children with IBD. The authors found that the average symptom score of the study population decreased over the course of about 4 weeks on the Specific Carbohydrate Diet, though the results were not statistically significant.
4. A 2014 study of 16 children with Crohn's disease who followed the Specific Carbohydrate Diet looked at symptom scores and a marker of inflammation (the Lewis Score) after 12 and 52 weeks on the diet. 9 patients completed 12 weeks on the diet and there was a significant reduction in symptom and inflammation scores across the study population. These results were maintained in 7 patients who followed the SCD for 52 weeks.
5. A 2018 study of 12 children with IBD who followed the SCD found that average symptom scores and C-reactive protein levels of the study population decreased after 12 weeks on the diet.
6. A 2016 study of 11 children with Crohn's disease who followed the SCD for up to 14 months. The authors found that inflammatory markers including ESR rate improved during the study period however it's not clear if the changes were due to the diet or medication.
7. A 2014 study of 7 children with Crohn's disease who followed the SCD for an average of 15 months found that symptom remission was achieved in all patients after 3 months.

Reasons people start the Specific Carbohydrate Diet

There are many reasons individuals with Crohn’s disease or ulcerative colitis may want to start the SCD. Research suggests these are the most common reasons people with Crohn’s or colitis start the SCD:^{ }

• To avoid medications 
• To avoid long-term consequences of medications
• As an adjunct to medication therapy 
• Desire for integrative/alternative medicine approach
• Belief that the SCD was more effective than medications
• Belief that medications were not effective 
• History of adverse reaction due to a prior medication
• Read breaking the vicious cycle book
• Medication cost
• Need for surgery
• Fear of colon cancer
• Recommended by a medical professional 
• Recommended by a family member/friend 
• Recommenced by internet forums

Reasons people stop the Specific Carbohydrate Diet

There are many reasons individuals with Crohn's or colitis may want to stop following the SCD. Researchers found the following as the most common reasons individuals with IBD discontinue the SCD:^{      }

• Lack of IBD symptom improvement
• Increased symptoms 
• Lack of response to diet and requiring medication escalation
• Adverse effects including weight loss, lethargy, hunger, allergic reaction, or abdominal pain
• Lack of interest or desire to continue
• Limited support
• Restrictive food options/too restrictive of a diet 

11 tips for starting the SCD

One study suggested it was hard to adjust to the diet in the beginning^ so, prior to starting the SCD, it may be helpful to consider the following tips: 

1. Create a follow up plan - Prior to starting the SCD, talk to your (or your child’s) gastroenterologist and IBD care team about whether it’s safe for you or your child to follow the Specific Carbohydrate Diet. It could be helpful to develop goals of the diet, such as symptom remission, and when you will assess whether the diet is working. Regularly looking at your progress and goals of the diet will help you and your care team decide whether it makes sense to continue the diet. 
2. Get professional support - One of the reasons research suggests people stop the SCD is a lack of support in understanding how to follow the diet, so we suggest you find an IBD-focused registered dietitian that can help you implement the diet safely.^ This may help to reduce your or your child’s risk for nutrient deficiencies, weight loss, and malnutrition. 
3. Focus on substitutions - Try to keep things as simple as possible in the beginning. It may be helpful to adjust your expectations and avoid trying to recreate your or your child’s favorite meal.^ It may be easier to substitute ingredients in go-to recipes for alternatives instead of recreating a brand new meal.^ For example, instead of having rice or potatoes in a recipe, swap out the rice for more vegetables.
4. Plan out your meals - It may be helpful to plan out what you or your child will eat throughout the week while on this diet. Plan out both meals and snacks so that you can honor your hunger cues as they arise. 
5. Carve out time for cooking and/or meal prepping - It can sometimes be helpful to prep some of your meals or snacks for the week so that it’s not overwhelming/exhausting to plan and prepare your meals the day-of.  
6. Consider food waste - While on the Specific Carbohydrate Diet you may be consuming more fruits and vegetables than you’re used to, so it may be helpful to consider how you’ll keep your produce fresh throughout the week. Is it easier for you to go to the grocery store more often, or is it easier to prep and then freeze your vegetables ahead of time?
7. Get family support - Research suggests that it’s easier to stick to the SCD if your whole family also follows the diet.^
8. Consider online grocery shopping - Research suggests ordering certain ingredients online may help reduce the time spent in the grocery store(s).^ Doing the research ahead of time on which items you plan to buy at a grocery store and which you’ll purchase online could help reduce overwhelm when you start the SCD.
9. Ease into the diet - It may be helpful to make one new SCD friendly meal a week until you have a list of a few enjoyable breakfasts, lunches, dinners, & snacks to get you started. 
10. Consider cost - Keep in mind that you may be spending more money on groceries while following the SCD, so you may need to adjust your finances accordingly. However, depending on the frequency of which you used to dine outside the home, the finances may even out, since you’ll be cooking all your meals at home while on the SCD which is often less expensive than dining out.
11. Consider your plan for dining at social events - You may want to consider ahead of time what your plan is for sleepovers, dinner parties, BBQs, holidays, or dining out with friends as you will not be able to follow the SCD in most of these settings unless you bring your own food. 

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SCD legal and illegal foods and drinks

This is not an exhaustive list of SCD legal and illegal foods and should not be used as a guide for implementing this diet.

SCD “legal” foods:

• Protein - Fresh poultry, fresh seafood, fresh fish, fresh red meat, eggs
• Vegetables - All vegetables, except for starchy vegetables (see below), are allowed
• Fruits - All fruits are allowed
• Dairy - Homemade yogurt fermented for at least 24 hours & cheeses aged for 30+ days
• Nuts - All nuts are allowed
• Legumes - Peanuts, dried navy beans, dried lima beans, dried black beans, dried lentils, dried split peas
• Sweeteners - Honey 
• Drinks - Coffee

SCD "illegal" foods:

• Protein - Processed meats are not allowed
• Vegetables - Starchy vegetables such as potatoes, sweet potatoes, turnips, and parsnips are not allowed
• Fruits - No restrictions
• Dairy - All dairy except those listed above are not allowed
• Nuts - No restrictions
• Seeds - Chia and flax seeds are not allowed
• Grains - Gluten/wheat, corn, oats, rice, and all other grains are not allowed
• Processed foods - None are allowed 
• Drinks - Oral nutrition supplements (Ensure, Pediasure, Kate Farms, etc) are not allowed

Potential benefits of following the Specific Carbohydrate Diet

There are some potential benefits that may arise from following the specific carbohydrate diet including:

• Reduced symptoms - Research suggests the SCD may help reduce symptoms in certain patients with mild-to-moderate Crohn’s disease.^
• Increased consumption of whole foods - May encourage an increase in whole foods consumed in the diet since it encourages you to make all of your meals and snacks from scratch.^
• Improved cooking skills - Given the diet requires you to make everything you eat, it may encourage you to get more creative in the kitchen and improve your culinary skills. 
• Improved diet quality for other family members - The diet may encourage other family members to eat more whole foods if they follow the diet as well.^

Potential risks, challenges, and considerations of the SCD 

Individuals with IBD may choose to follow a diet for many reasons but it’s important to consider the potential risks and challenges with the SCD, and not just the potential benefits. Here are some things to keep in mind:

• Restrictive diets can have side effects - It’s natural for individuals experiencing symptoms to want to follow a diet as an attempt to manage symptoms but keep in mind that diets have potential side effects, just like medications. Some of the potential side effects of restrictive diets like the SCD include higher reported levels of post traumatic stress symptoms, higher anxiety and depression levels, more nutrient deficiencies, higher rates of malnutrition, greater fear of gastrointestinal symptoms, and reduced interest in food.^{    }
• Financial cost - Most parents of kids following the SCD reported increased grocery costs.^ This can be an added financial stressor to families and therefore, following the SCD may not be the appropriate choice for everyone. 
• Time commitment - It takes time to plan and prepare meals. On the Specific Carbohydrate Diet, consider the time it takes to not only prepare and cook meals and snacks, but also the added time grocery shopping. While grocery shopping, you’ll likely need to read nutrition labels more closely, shop more frequently, and purchase fresh produce and special ingredients.^ One study found that it took an average of 10.8 hours to prepare SCD food for the week.^ 
• Nutritional adequacy - Given the restriction of multiple foods, there’s a risk for nutrient deficiencies,^ especially for those following this diet without the support of an IBD focused dietitian.^ In two small studies, children who followed the SCD while working with a registered dietitian were able to meet their nutritional needs on the diet.^{ }
• Weight loss/malnutrition - the SCD may lead to increased risk for weight loss for certain individuals.^{ }If you lose weight, or your child fails to grow or gain weight, reach out to your IBD team immediately as malnutrition is associated with worse disease outcomes.^
• Cultural aspects of diet - A drawback of most diets, including the SCD, is the foods included in the diet may not include traditional cultural food staples. For instance, the specific carbohydrate diet does not allow rice, which is a staple food of many cultures. This can make it challenging to follow these diets, and obtain pleasure in eating.
• May encourage increased morality associated with food - Food morality is defined as the placement of morality when eating certain foods. For instance, one may deem certain foods as “good” or “clean” and others as “bad”. The “legal” and “illegal” food lists for the SCD may encourage this morality associated with foods and lead to feelings of guilt or shame after eating “illegal” foods, or other disordered eating behaviors. If you know you already have morality associated with foods, and/or have feelings of guilt or shame after eating certain foods, this diet may not be right for you. 

Long term outlook on the SCD

There are no high quality studies to date that have evaluated the long-term safety and efficacy of the Specific Carbohydrate Diet.

If you follow a restrictive diet for an extended period of time, you may be at an increased risk for nutrient deficiencies.^ Certain nutrient deficiencies like calcium and vitamin D may contribute to an increased risk for bone breakdown and osteoporosis which is more prevalent in people with IBD compared to the general population.^

Measuring your progress on the SCD

If you and your health care team decide to try this diet for induction of remission (nutrition guidelines do not recommend the SCD for the induction of remission at this time), it should be for a specified period of time, such as 3-12 months, and inflammatory markers should be checked regularly to monitor for any improvements.

Although reducing your symptoms and achieving symptom remission is helpful in improving your quality of life, symptom improvement is not always correlated with a reduction in intestinal inflammation, particularly in people with Crohn’s disease.^

Regularly checking your inflammatory markers such as fecal calprotectin and C-reactive protein, or checking for disease activity using colonoscopy or MRI can give you more objective data which can help you make informed decisions about your treatment. 

When to stop the Specific Carbohydrate Diet:

If you’re following the SCD, there are several reasons you may want to stop the diet including^{    }

• Lack of symptom improvement or increased symptoms
• Increased weight loss
• Increased lethargy
• Increased hunger
• Limited support with the diet
• The diet is too restrictive

You may also consider discontinuing the diet if you experience any of the following disordered eating patterns:

• Feel an increased morality associated with food
• Experience guilt or shame after eating certain foods
• Feeling preoccupied with food
• Binge eating
• Skipping meals or fasting

Summary / our view:

We agree with the current nutrition guidelines for inflammatory bowel disease which do not recommend the use of the Specific Carbohydrate Diet for induction or maintenance of remission in individuals with Crohn’s disease or ulcerative colitis.^{ }

The highest quality study conducted to date compared the Mediterranean diet to the Specific Carbohydrate Diet and found that there were no significant differences between the diets in reducing symptoms or inflammatory markers.^

Given the similar results, fewer diet restrictions, and the health benefits associated with the Mediterranean diet, researchers recommend trying the Mediterranean diet over the SCD for patients with mild-to-moderate Crohn’s disease.^

To date, no high quality studies have been published that look at the effectiveness of the SCD in people with ulcerative colitis or microscopic colitis.

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