The Specific Carbohydrate Diet (SCD) is a restrictive eating plan designed to manage symptoms of digestive disorders, such as Crohn’s disease and ulcerative colitis. It involves eliminating specific carbohydrates that are believed to be difficult to digest, potentially reducing harmful gut bacteria and inflammation.
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.
The SCD emphasizes simple carbohydrates that are easily absorbed, including certain fruits, honey, and specific vegetables. It restricts the consumption of complex carbohydrates such as grains, cereals, certain starchy vegetables, and most sugars. The diet encourages the consumption of lean meats, poultry, fish, eggs, and non-processed fats like olive oil, avocados, and nuts. Fermented foods are encouraged, as they contain beneficial probiotics that can help support gut health, especially home-made yogurt with specific strains of bacteria. Fiber-rich foods like vegetables and fruits are permitted, but only those low in complex carbohydrates. The diet emphasizes nutrient-dense, whole foods, avoiding processed and artificial ingredients.
History and Development
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. In her book, Gottschall described how the diet improved her daughter’s IBD symptoms. In her book, Gottschall suggests that diet might also be helpful for diverticulitis, celiac disease, cystic fibrosis, and other chronic diseases.
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.
Read also: The Hoxsey Diet
The specific carbohydrate diet eliminates hard-to-digest carbs. You only eat carbohydrates that are easy for your digestive system to break down and absorb. This keeps the harmful bacteria from growing, which may help you feel better and reduce inflammation. This diet is also low in processed foods, food additives, and preservatives. Some of these foods, additives, and ingredients have been linked to gut inflammation. Avoiding these additives may be another reason people feel better on this diet.
Who Might Benefit from the SCD?
Individuals with mild to moderate Crohn’s disease who want to use a structured diet to potentially improve their symptoms may benefit from following the SCD.
However, the following individuals 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 their diet as expansive as possible, this may not be the right choice.
The SCD may be inappropriate for patients with stricturing Crohn’s disease (as there may be a risk for obstructions).
SCD "Legal" and "Illegal" Foods
This is not an all-inclusive list of the allowed and restricted foods, nor does it define all the rules of the diet. This list should NOT be used as a guide to following the diet.
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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
- Dairy: All dairy except those listed above are not allowed
- 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
Challenges and Considerations
- Dietary Restrictions: The diet is restrictive, which can be challenging. Dietary restrictions are one of the barriers that prevent patients from sticking to the diet.
- Perceived Lack of Variety and Taste Fatigue: These are barriers that prevent patients from sticking to the diet.
- Psychosocial Impacts: Psychosocial impacts are one of the barriers that prevent patients from sticking to the diet.
- Financial Burden: Financial burden is one of the barriers that prevent patients from sticking to the diet.
- Time Commitment: Time commitment is one of the barriers that prevent patients from sticking to the diet. A study of 50 people on the diet found the average person spent nearly 11 hours a week preparing food.
- Inconsistent Clinical Responses: Inconsistent clinical responses are one of the barriers that prevent patients from sticking to the diet.
- Nutrient Deficiencies: People on the Specific Carbohydrate Diet may not get enough of certain nutrients, including folate, thiamine, vitamin B6, calcium, and vitamin D. A study looking at nine children using the diet to treat IBD found that they didn’t get enough vitamin D and calcium.
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:
- 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.
- 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.
- 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.
- 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.
- 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.
- 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?
- Get family support: Research suggests that it’s easier to stick to the SCD if your whole family also follows the diet.
- 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.
- 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.
- 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.
- 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.
Reasons for Starting and Stopping the SCD
Reasons people start the Specific Carbohydrate Diet:
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:
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
Research on the SCD
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.
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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.
- 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.
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
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.