What Is the Specific Carbohydrate Diet?

Specific carb diet

Verywell / Debbie Burkhoff

At Verywell, we believe there is no one-size-fits-all approach to a healthy lifestyle. Successful eating plans need to be individualized and take the whole person into consideration. Prior to starting a new diet plan, consult with your healthcare provider or a registered dietitian, especially if you have an underlying health condition.

The Specific Carbohydrate Diet, or SCD, is a strict grain-free, lactose-free, and sucrose-free diet designed for people with irritable bowel disease (IBD), irritable bowel syndrome (IBS), and other gastrointestinal conditions. It was first developed by Sidney Valentine Haas, MD, who outlined the protocol in his book, "Management of Celiac Disease," in 1951.

The diet became popularized in the 1990s by the biochemist Elaine Gottschall, who claimed the plan helped her daughter recover from ulcerative colitis. Gottschall continued research on the diet and later wrote a book, "Breaking the Vicious Cycle: Intestinal Health Through Diet" (originally published in 1994).

The basis of the diet, according to Dr. Haas, is that carbohydrates, being forms of sugar, promote and fuel the growth of bacteria and yeast in the intestines, causing an imbalance and eventual overgrowth. He believed bacterial and yeast overgrowth could impair the function of enzymes on the intestinal cell surface, which would prevent the proper digestion and absorption of carbohydrates.

Toxins and acids would then be formed by the bacterial and yeast overgrowth and cause damage to the lining of the small intestine. As a defense mechanism, the body would produce excessive mucus to combat the irritation. This digestive imbalance would mean that carbohydrates remain undigested in the small intestine and provide even more food for bacteria and yeast.

Dr. Haas developed the Specific Carbohydrate Diet plan to correct digestional imbalances by restricting the carbohydrates available to intestinal bacteria and yeast. The diet includes only the specific carbohydrates that he believed can be well-absorbed by the small intestine so that the bacteria have nothing to feed on. This, he proposed, could correct bacterial overgrowth and any related production of mucus and toxins.

Dr. Haas believed that the eating plan could benefit people with related gastrointestinal disorders including IBD, IBS, Crohn's disease, ulcerative colitis, diverticulitis, celiac disease, chronic diarrhea, and spastic colon. He proposed that following the SCD plan could improve the digestion and absorption of nutrients to repair immune function and improve nutritional status. Proponents of the diet claim that improvement is possible within one year. However, scientific support for the diet is still limited.

What Experts Say

"This plan restricts certain carbohydrates, claiming this will reduce symptoms in those with GI disorders. There is little research to support this. However, experts agree the diet is likely not harmful, so long as it’s under professional guidance to ensure nutrient needs are met."
Chrissy Carroll, RD, MPH

What Can You Eat?

The Specific Carbohydrate Diet is not exactly a typical low-carb diet. It limits many, but not quite all, carbohydrates. While it begins with a large number of restrictions, some of these are eventually eased over time for those who are able to tolerate some of the non-compliant foods.

However, all grains are off-limits on this plan, including those that do not contain gluten. Fruits and low-starch vegetables are strongly encouraged and should be consumed as close to their natural state as possible. But fruits can also be dried or canned in their own juices. Some fruit juice, such as apple cider and fresh-squeezed orange juice, is also acceptable. Most nuts are allowed, but seeds are not.

Lean protein sources, including meat, fish, and eggs, are allowed on the SCD plan, as long as they are not processed. Some milk-derived dairy products are excluded with the exception of several types of approved cheeses. Many sugars and artificial sweeteners are also banned.

What You Need to Know

This diet is very restrictive, so it should be used with caution and only under the guidance of a medical professional. No specialty foods or supplements are required with the exception of homemade yogurt. But it can be hard to identify which foods are allowed and which aren't, and some people may not always have access to them.

Gottschall's book, "Breaking the Vicious Cycle," suggests an introductory period of one to five days (depending on the severity of symptoms) that includes just a few basic foods. After one month, three months, and six months on the diet, some previously forbidden foods can be added back in small amounts.

"Breaking the Vicious Cycle," also contains more detail on all the foods that are compliant and non-compliant, as well as recipes. In particular, there is a recipe for homemade SCD yogurt that is thought to be important to the success of the diet, since it introduces "good" bacteria into the gut.

What to Eat
  • Fresh and frozen vegetables and some legumes

  • Fresh, raw, or dried fruits

  • Fresh or frozen meats, poultry, fish, and eggs

  • Natural cheeses, homemade yogurt, dry curd cottage cheese

What Not to Eat
  • Canned vegetables

  • Canned fruits, unless they are packed in their own juices

  • All grains, including flour

  • Starchy vegetables, including some specified legumes

  • Processed meats

  • Most dairy products

  • Sugars and sweeteners

Fruits, Vegetables, and Legumes

Most are allowed, as long as they are fresh or frozen, with the exception of those high in starch. That means potatoes, sweet potatoes, yams, parsnips, chickpeas, bean sprouts, soybeans, mung beans, fava beans, and seaweed are off-limits.

Meat, Poultry, Fish, and Eggs

Fresh and frozen cuts of meat and fish are permitted, but breaded or canned fish and smoked or canned meats are not.

Dairy Products

The SCD plan excludes milk or dried milk solids, buttermilk or acidophilus milk, commercially prepared yogurt, and sour cream. But it also includes many kinds of cheese, including ricotta, mozzarella, cottage cheese, cream cheese, feta, processed cheeses, and cheese spreads. Other natural cheeses are permitted, along with homemade yogurt that's been fermented for at least 24 hours.

Sugars, Starches, and Sweeteners

Cornstarch, arrowroot, or other starches are banned from the diet, as is chocolate or carob; bouillon cubes or instant soup bases; all products made with refined sugar, agar-agar, carrageenan, agave, Splenda, stevia, or pectin; ketchup; ice cream; molasses; corn or maple syrup; baking powder; or medication containing sugar. However, honey is allowed.

Those who follow the SCD protocol cannot consume anything made from corn, wheat, wheat germ, barley, oats, rye, rice, buckwheat, spelt, or amaranth. Flours made from legumes are also excluded.

Pros and Cons

Pros
  • May improve symptoms, but evidence is lacking

Cons
  • Extremely restricted

  • Complicated and difficult to follow

  • Can cause unwanted weight loss

  • Not nutritionally complete

Pros

May Improve Symptoms

There are many anecdotal reports of this diet helping people with IBD, Crohn's disease, ulcerative colitis, and other conditions. Adults with gastrointestinal disorders may wish to try to address their symptoms through diet, but they should still be monitored carefully by a medical professional. Still, the diet lacks rigorous scientific evidence to support its claims.

Cons

Restrictive

The SCD plan eliminates entire food groups including whole grains and many legumes as well as dozens of individual foods. That means a big risk of missing out on important nutrients. It can also be difficult to determine what foods work for you and what foods don't since so many are off-limits.

Difficult to Follow

The protocol is based on eliminating specific carbohydrates—sugars that are often not listed on ingredient labels. And of course, whole foods like fresh vegetables do not come with ingredient lists. So the diet can be challenging to adhere to without constantly referring to the list of "legal" and "illegal" foods (as they are called in Gottschall's book). Even if you know which foods are allowed, it is still very challenging to stick to such a limited list of them for the long term.

Because so many foods are off-limits, this eating plan does not provide sound nutrition and may not supply enough calories for some people. In addition, there is little scientific research on the effectiveness of this plan.

Is the Specific Carbohydrate Diet a Healthy Choice for You?

While the role of diet in digestive disease is not yet well-understood, there are similar diets that aim to help treat symptoms associated with gastrointestinal disorders. The low-FODMAP diet, which is geared toward people with IBS and IBD, is less restrictive than the SCD, so it may be safer to follow. It should still be supervised by a medical professional, however.

The gluten-free diet was developed for those with celiac disease and gluten sensitivity. This eating pattern is generally safe because it only restricts the gluten protein (found in certain grains). The microbiome diet appeals to those seeking to improve their gut health and lose weight. Like the other diets, this one restricts entire food groups, especially in its first phase, so there is a risk of missing out on key nutrients.

When compared to federal guidelines for a healthy, balanced diet, the Specific Carbohydrate Diet is very limited, particularly when it comes to the consumption of grains, which are not allowed on the plan. The U.S. Department of Agriculture (USDA) recommends consuming a variety of nutrient-dense whole foods including fruits and vegetables, whole grains, lean protein, legumes, low-fat dairy products, and healthy fats to maintain optimal health. The SCD falls short of meeting these recommendations.

It's also important to note that the Specific Carbohydrate Diet is not a weight loss plan. However, due to its restrictive nature, some people may have a hard time getting enough calories each day to maintain a healthy weight. On average, a target of 2,000 calories a day is typically recommended for adults, though this number can vary based on an individual's age, sex, weight, height, and level of physical activity. This calculator can provide an estimate for your daily calorie needs to help you stay nourished and healthy.

The USDA suggests eating plenty of whole grains, legumes, and dairy products. The Specific Carbohydrate Diet eliminates many of these foods, which means that it does not meet the current recommendations set by nutrition experts.

Health Benefits

Most evidence on the effectiveness of the Specific Carbohydrate Diet is anecdotal. However, there are a few small studies published in peer-reviewed journals that have shown the diet can work. For instance, a study published in 2016 in World Journal of Gastroenterology found that SCD helped children aged 6–17 with pediatric Crohn's disease manage their symptoms.

In addition, a 2016 review of the existing literature published in the journal Nutrition echoed the findings and determined that SCD could be integrated into the treatment of both pediatric Crohn's disease and ulcerative colitis. However, both reports indicate that further research is still needed to determine both the safety and efficacy of this eating plan for the treatment of inflammatory bowel disease in the general population.

Health Risks

While there are no common health risks associated with the SCD plan, as with some other low-carb diets, restricting or eliminating all grains can result in nutrient deficiencies.

A small study published in 2017 tracked the nutrient intakes of subjects who followed the SCD protocol for 12 weeks. Results showed that 100% of subjects did not meet the recommended daily allowance (RDA) for vitamin D and 75% were deficient in calcium. However, the subjects did meet the RDA for multiple B vitamins as well as vitamins A, C, and E, and 42% met their RDA for magnesium.

In addition, Some people with gastrointestinal disorders may already struggle to maintain or gain weight. The restrictions on this plan could mean a person following it consumes too few calories and loses weight, which could put them at risk for being underweight.

A Word From Verywell

Due to a lack of supporting research, it's too soon to recommend the Specific Carbohydrate Diet for the treatment of any health condition. If you're considering this diet, talk with your healthcare provider first. 

Self-treating a condition and avoiding or delaying standard care may have serious consequences. Your doctor may be receptive to the idea of the diet as long as you consult with a nutritionist and continue to have your health monitored carefully.

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.

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Article Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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