The Specific Carbohydrate Diet (SCD) is a form of elimination diet that removes many common carb sources — including all grains, dairy products, most starches and many types of sugars — in order to help heal the digestive system. According to the creators of the SCD diet, based on feedback received over the past several decades, at least 75 percent of those who adhere rigidly to this diet gain significant improvements in their health. (1)
Although an SCD lifestyle can feel restrictive and calls for cutting out many foods that people eating “western diets” enjoy, it can offer serious benefits to people with compromised digestive systems, including those with inflammatory bowel disease, Crohn’s disease, ulcerative colitis, irritable bowel syndrome and SIBO.
Even if you don’t have a diagnosable digestive disorder but suffer from ongoing symptoms like constipation or painful stomach bloating, you can find relief by choosing the types of carbohydrates you include in your diet wisely. How so? Eliminating most troublesome carbs, while only keeping specific types in the diet that are the easiest to digest and metabolize properly (such as vegetables), helps lower fermentation in the gut, gas accumulation and gut permeability.
The SCD diet targets both the underlying problems within the gastrointestinal tract that can lead to serious disorders and common symptoms related to bacterial overgrowth, inflammation and blocked nutrient absorption. By removing “complex carbohydrates” from the diet — including lactose, sucrose (sugar) and many synthetic ingredients — digestive processes improve, toxins are reduced and overall health gets better as inflammation subsides.
What Is the SCD Diet?
Who should practice an SCD diet? Anyone who has trouble digesting certain carbohydrates can benefit from this plan (for reasons you’ll learn more about later), but SCD diets are mostly recommended for people with uncomfortable GI disorders, including:
- irritable bowel syndrome (IBS)
- inflammatory bowel disease
- ulcerative colitis
- Crohn’s disease
- food allergies like celiac disease or lactose intolerance
- cystic fibrosis
In addition, it can also be beneficial for anyone with food sensitivities and intolerance to things like FODMAPs, which cause problems such as constipation, diarrhea, bloating, gas, fatigue, etc. People taking medications that interfere with how they digest certain carbohydrates can also find relief. It’s even been suggested that a SCD diet can help with learning disabilities like autism.
Who came up with the SCD diet and popularized it? A biochemist named Dr. Elaine Gottschall wrote the book “Breaking the Vicious Cycle: Intestinal Health Through Diet,” which described her now-famous protocol her following an SCD diet to lower inflammatory responses that stem from the GI tract.
In “Breaking the Vicious Cycle” Gottshall explains how a faulty digestive system can cause permeability of the gut — often called leaky gut syndrome — which allows for particles to pass through the gut lining and enter the bloodstream, kicking off a cascade of negative reactions from the immune system.
You might have heard of the GAPS diet plan and protocol in the past (created by Dr. Natasha Campbell), which has the same goal of eliminating certain types of carbs and triggering foods from someone’s diet that are known to worsen gut permeability and inflammation.
An SCD diet and the GAPS diet have a lot in common. Food elimination during the GAPS diet is done in stages, and the GAPS diet food list includes many of the same ones used an SCD diet, such as most vegetables, fish, healthy fats and oils, grass-fed meat, and sprouted nuts, seeds and legumes. The macrobiotic diet also shares some similarities, though only uses plant-based foods.
1. Helps Treat Digestive Disorders
The SCD diet has been shown to help treat difficult disorders, such as Crohn’s disease and ulcerative colitis. Crohn’s disease is characterized by chronic intestinal inflammation in the absence of a recognized etiology, but studies like the one published in the Journal of Pediatric Gastroenterology and Nutrition show that dietary changes play an important role in management. Elimination of specific complex carbohydrates is often very successful at helping relieve many patients’ sometimes debilitating symptoms. (2)
One study involving children with Crohn’s disease found significant clinical and mucosal improvements in those who used an SCD diet for 12 and 52 weeks. (3) Other research has found SCD diets to be highly beneficial for people with ulcerative colitis after adherence for three to six months, resulting in both symptomatic and clinical improvement and complete remission in certain patients. (4)
In addition, research done in 2016 by the Department of Pediatrics at Seattle Children’s Hospital and the University of Washington found SCD diets offer hope to those with inflammatory bowel disease who don’t find relief with normal treatments alone. They found that an integrated dietary program incorporating the specific carbohydrate diet as well as adjunctive therapies helped improve clinical and laboratory parameters in patients with Crohn’s disease and ulcerative colitis. (5)
2. Lowers Digestive Symptoms Like Gas, Diarrhea and Bloating
The overgrowth of bacteria into the small intestine causes a cycle of increased gas and acid production through fermentation. This can lead to toxic waste accumulation, discomfort, trouble digesting foods and even problems absorbing nutrients properly. Symptoms range from person to person but can include constipation, gas, bloated stomach, diarrhea and changes in appetite.
Diarrhea is a common symptom of digestive disorders, since undigested carbohydrates and those left remaining in the gut contribute to water and nutrients being pulled into the colon, which speeds up how fast waste and fluids are removed. Inflammation is also a contributing factor to diarrhea and other symptoms. (6)
3. Improves Nutrient Absorption
The harmful byproducts caused during fermentation affect enzymes produced in the digestive tract that are needed to metabolize food and absorb their available nutrients. Important digestive enzymes located on the surface of the small intestines can become damaged or reduced by growing bacteria and their toxic waste, blocking normal vitamin and mineral absorption. The mucosal layer of the small intestine is also negatively impacted by toxic byproducts, so it starts producing even more of a protective mucus coating, which further inhibits normal digestive processes. (7)
Patients, especially children with bowel diseases, risk deficiencies, weight loss and diarrhea that can be harmful. Research done in 2016 published in the World Journal of Gastroenterology found that children with inflammatory bowel diseases were able to gain healthy weight and grow in terms of height while still on strict SCD diets that improved their overall symptoms. (8)
4. Lowers Inflammation
Important parts of the mucosal layer within the GI tract are tiny microvilli, which form the gut’s natural barrier that separates the particles found inside the gut from the outside (the bloodstream).
The longer that nutrient absorption is inhibited — such as decreased absorption of folic acid and vitamin B12, which help build the mucosal layer — and the more fermentation that occurs, the worse damage becomes to the microvilli and gut barrier. This allows for more gut permeability and particles to enter the bloodstream where they shouldn’t be, signaling to the immune system that something is wrong. By reversing this process, research suggests bodywide inflammation can be better controlled. (9)
5. Might Help Protect the Brain
Beyond just the GI tract, the brain is also impacted by inflammation and bacterial fermentation. GI dysfunction is commonly seen in individuals with autism spectrum disorder (ASD), and the role of the microbiota in ASD is still being researched. There’s some evidence that the shifted microbiota in those with autism can be a result of “westernization” and can affect gut-brain interactions in a way that alters normal cognitive development. (10)
Some evidence shows that lactic acid produced during bacterial fermentation within the gut can affect brain function and behaviors.
For people new to the SCD diet or similar protocols like the GAPS diet, this way of eating can seem hard and restrictive at first. The SCD diet eliminates many grain-based, dairy-based and packaged foods that are popular in a typical American diet, not to mention added sugars, many starches and many types of beverages too.
Foods are either eliminated or included based on their chemical composition. Specifically, carbohydrates that are classified as monosaccharides, which have a single molecule structure, are allowed, but complex carbohydrates called disaccharides and polysaccharides are not allowed.
The reason for this is because of how complex carbs are broken down in the digestive tract. They often feed harmful bacteria in the intestines and cause increased fermentation because they’re tough for many people to fully metabolize. Double sugar molecules (disaccharides) include lactose, sucrose, maltose and isomaltose, while sugar molecule chains (polysaccharides) include grains, starches and starchy veggies.
As the “Breaking the Vicious Cycle” website puts it, “The simpler the structure of the carbohydrate, the more easily the body digests and absorbs it. Monosaccharides (single molecules of glucose, fructose, or galactose) require no splitting by digestive enzymes in order to be absorbed by the body. These are the sugars we rely on in the diet.” (11)
Once complex carbs and toxic additives are removed from the diet, the balance of bacteria in the gut improves. Another benefit is that people eating an SCD diet can also focus more on getting their calories from nutrient-dense food sources. A specific carbohydrate diet has many things in common with the Paleo diet because it emphasizes unprocessed, whole foods that people have been eating for hundreds of thousands of years.
High-quality grass-fed meats poultry, wild-caught fish, eggs, vegetables, soaked/sprouted nuts, and certain low-sugar fruits and yogurts are the bulk of the SCD diet. On the other hand, “modern foods” — meaning those that only emerged within the past 10,000 years or so — are excluded along with harmful, synthetic ingredients found in may processed foods.
The food groups included in an SCD diet include:
- many types of vegetables (depending on their carbohydrate structure)
- grass-fed, pasture-raised meats and poultry
- wild-caught fish
- cage-free eggs
- homemade probiotic yogurt (fermented at least 24 hour)
- certain low-sugar fruits
- certain soaked/sprouted legumes (some shave been shown to be tolerated after three months on the diet, such as dried beans, lentils and split peas, but first must be soaked for 10–12 hours prior to cooking and the water discarded)
- healthy fats, including coconut oil and olive oil
- simple sugars, including honey and saccharin
- condiments or flavor enhancers like fresh spices, mustard and vinegar
- unsweetened, unprocessed drinks, including weak tea or coffee, water, club soda, dry wine and some liquors
Foods to Avoid
Foods and ingredients not allowed on the SCD diet include:
- many types of sugars: lactose, sucrose, high-fructose corn syrup, fructose, molasses, maltose, isomaltose, fructooligosaccharides and any processed added sugars
- grains and grain-based product, including wheat (all types), corn, barley, oats, rye, rice, buckwheat, soy, spelt, amaranth and products made with grain flours
- Starches and starchy vegetables like potatoes, sweet potatoes, yam and parsnips
- most dairy — milk, most yogurt, cheeses, ice cream, etc.
- processed meats
- canned veggies or fruit with added sugar and ingredients
- most beans and legumes — chickpeas, bean sprouts, soybeans, mung beans, fava beans and garbanzo beans
- refined oils and fats, such as vegetable oils like canola oil, safflower oil and mayonnaise
- many condiments, such as ketchup, mustard with sugar, margarine and balsamic vinegar
- sweets and most packaged snacks — candy, chocolate, cookies, anything with corn syrup, etc.
- seaweed products, algae, agar and carrageenan
- sweetened drinks, beer and juice
You can find a lcomplete ist of all SCD diet foods that are “legal and illegal” on the “Breaking the Vicious Cycle” website. (12)
What are some SCD diet recipe ideas you can try at home or useful tips that can help you along the way when practicing a SCD diet lifestyle? (13)
- Plan to cook more at home, since this makes it easiest to control ingredients. Invest in a few good kitchen gadgets and appliances, especially a yogurt-making kit/maker and perhaps a crockpot to cook meat/veggies easily.
- Get to know the list of excluded ingredients carefully, and check labels when shopping. Sugar can be hiding under many disguised names!
- In place of grain flours, use things like almond or coconut flour to make breads, crusts, cookies, sauces, etc.
- Cooked foods are usually easier to digest, especially things like soups and stews. Make double batches, and freeze them for later.
- Look for wild, pasture-raised, grass-fed meat products online. You can purchase these in bulk and save money, plus use the bones to make healing bone broth afterward.
- For the first three months, avoid all legumes, but you can try introducing them (soaked and sprouted first) after to test your tolerance.
- Consider taking supplements if you eat a very restrictive diet, since eliminating whole food groups raises the risk for potential nutrient deficiencies. Try to eat a variety of foods to get the widest nutrient intake you can.
- Make sure to consume enough calories in general to avoid deficiencies, fatigue, hormonal problems and muscle wasting.
How It Works
The rationale behind an SCD diet is that many digestive disorders stem from “an overgrowth and imbalance of intestinal microbial flora” — in other words, there are too many harmful types of bacteria, yeast and fungus residing within the body, mostly within the gut where the majority of the immune system is located. The human digestive tract is actually considered an amazing type of ecosystem for various bacteria. It’s been shown that most people’s internal microbiome contains over 400 different types of bacterial species!
Our diet has an enormous impact on the balance of microbial organisms that take hold within our digestive systems, considering these organisms actually feed and thrive off of the very food we put into our bodies. So it makes sense that if we change the types of foods we eat, we can alter how harmful bacteria are able to repopulate. Not all bacteria within the gut are bad. In fact, many are beneficial and important for immune functions, hormonal balance and even weight control. The goal of an SCD diet is to allow the good kind to flourish while reducing the bad kind, thereby improving the bacterial ratio.
As Dr. Gottschall puts it, “By altering the nutrition we take in, we can affect the constitution of our intestinal flora, and bring it back into balance, healing our digestive tracts and restoring proper absorption.”
Wondering what carbohydrates in your diet have to do with lowering the presence of certain bacteria within the gut? Many of our “gut bugs” (microbes) are able to survive by essentially consuming certain types of carbohydrates that haven’t been digested properly, which produces waste and toxins through the process of bacterial fermentation in the process. Fermentation produces gases and toxins, such as lactic acid, acetic acid, methane, carbon dioxide and hydrogen, which not only cause you to feel bloated and gassy, but also damage and irritate the gut leading to increased permeability.
The “vicious cycle” that Dr. Gottschall refers to has to do with how microbes migrate to the small intestine and stomach when they become overly populated (the condition called SIBO, which is an acronym for “small intestinal bacterial overgrowth”), where they then leave behind toxic byproducts of their digestion that further cause problems. This can cause bacterial mutations, changes in stomach acidity, nutrient deficiencies and worsened inflammation that affects the entire body, from the brain to the skin. Many dietary plans to treat SIBO are very similar to the SCD diet. (14)
Causes of Bacterial Overgrowth
- antibiotics, medications, vaccinations and oral contraceptive use
- reduced stomach acidity (which can be caused as a side effect of some medications, by aging or from the overuse of antacids)
- a weakened immune system to begin with (caused by things like malnutrition and chronic stress), which increases gut permeability
- a poor diet high in inflammatory foods and low in key nutrients
- environmental and lifestyle factors (low economic status, cigarette smoking, poor sanitation and hygiene)
- infectious microbes
- genetic susceptibility and conditions that affect the gut during the first few years of life, such as not being breast-fed
- Based on feedback received over the past several decades, at least 75 percent of those who adhere rigidly to this diet gain significant improvements in their health.
- SCD diets are mostly recommended for people with uncomfortable GI disorders, including IBS, inflammatory bowel disease, ulcerative colitis, Crohn’s disease, food allergies like celiac disease and lactose intolerance, diverticulitis and cystic fibrosis. In addition, it can also be beneficial for anyone with food sensitivities and intolerance to things like FODMAPs, which cause problems such as constipation, diarrhea, bloating, gas, fatigue, etc. People taking medications that interfere with how they digest certain carbohydrates can also find relief. It’s even been suggested that a SCD diet can help with learning disabilities like autism.
- The SCD diet helps treat digestive disorders; lowers digestive symptoms like gas, diarrhea and bloating; improves nutrient absorption; lowers inflammation; and might help protect the brain.
- The foods included in the SCD diet are many vegetables (depending on carb structure), grass-fed, pasture-raised meats and poultry, wild-caught fish, cage-free eggs, homemade yogurt, low-sugar fruit, certain soaked/sprouted legumes, healthy fats, simple sugars, fresh spices and healthy condiments, and unsweetened, unprocessed drinks.
- Foods not allowed on the SCD diet include many sugars, most grains, starches and starchy vegetables, most dairy, processed meats, canned veggies or fruit with added sugar and ingredients, most beans and legumes, refined oils and fats, unhealthy condiments, sweets and most packaged snacks, seaweed products, algae, agar, carrageenan, and sweetened drinks, beer and juice.