What Is the Specific Carbohydrate Diet?

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The specific carbohydrate diet, or SCD, is a strict grain-free, lactose-free and sucrose-free diet that was designed for people with Crohn's disease, ulcerative colitis, celiac disease, inflammatory bowel disease (IBD), and irritable bowel syndrome (IBS). However, there is little scientific research on its effectiveness.

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

Background

The specific carbohydrate diet was developed by Sidney Valentine Haas, MD, in 1951. Biochemist Elaine Gottschall helped to popularize the diet after using it to help 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 (first published in 1994).

Dr. Haas' theory was that carbohydrates, being forms of sugar, could promote and fuel the growth of bacteria and yeast in the intestines, causing an imbalance and eventual overgrowth of bacteria and yeast. He believed bacterial overgrowth could impair enzymes on the intestinal cell surface from functioning and prevent the proper digestion and absorption of carbohydrates. This would cause the carbohydrates to remain undigested in the intestines and provide even more fuel for bacteria and yeast.

Toxins and acids could then be formed by the bacteria and yeast and injure the lining of the small intestine. Excessive mucus could be produced as a defense mechanism against the irritation caused by toxins, acids, and undigested carbohydrates.

According to Dr. Haas, a number of illnesses could then develop from this altered digestive balance:

  • Crohn's disease
  • Ulcerative colitis
  • Celiac disease
  • Inflammatory bowel disease (IBD)
  • Irritable bowel syndrome (IBS)
  • Chronic diarrhea
  • Spastic colon

Dr. Haas designed the specific carbohydrate diet to correct the imbalance by restricting the carbohydrates available to intestinal bacteria and yeast. Only carbohydrates that he believed to be well absorbed are consumed on the diet so that intestinal bacteria have nothing to feed on. This, he proposed, would help correct the bacterial overgrowth and related mucus and toxin production.

Digestion and absorption of nutrients could then improve, leading to improved nutritional status. Immune system function could then improve.

Proponents of the diet claim that improvement is possible for many people with diverticulitis, irritable bowel syndrome and celiac disease after one year. So far, scientific support for the benefits of the specific carbohydrate diet is limited.

How It Works

The specific carbohydrate diet (SCD) is not exactly a low-carb diet. Instead, it limits many, but not quite all, carbohydrates. While it begins with a large number of restrictions, some of these are eventually eased if the person on the diet can tolerate the foods.

What to Eat

Compliant Foods

  • Fresh and frozen vegetables and legumes

  • Fresh, raw, or dried fruits

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

  • Natural cheeses, homemade yogurt, dry curd cottage cheese

Non-Compliant Foods

  • Canned vegetables

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

  • All grains, including flour

  • Starchy vegetables

  • 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: potatoes, sweet potatoes, yams, parsnips, chickpeas, bean sprouts, soybeans, mung beans, fava beans, and seaweed. Fruits should be fresh, 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.

Meat, Poultry, Fish, and Eggs

These are included in the specific carbohydrate diet as long as they are not processed. So fresh and frozen cuts of meat and fish are OK, but breaded or canned fish and smoked or canned meat are not.

Dairy Products

The specific carbohydrate diet excludes milk or dried milk solids, buttermilk or acidophilus milk, commercially prepared yogurt and sour cream. It also includes many cheeses, including ricotta, mozzarella, cottage cheese, cream cheese, feta, processed cheeses, and cheese spreads. Other natural cheeses are permitted, along with homemade yogurt that has been fermented for at least 24 hours.

Grains

All grains are off-limits on this diet, including those that do not contain gluten. That means people on this diet cannot consume anything made from corn, wheat, wheat germ, barley, oats, rye, rice, buckwheat, spelt, or amaranth. Flours made from legumes are also excluded.

Sugars, Starches, and Sweeteners

People following the specific carbohydrate diet also cannot consume cornstarch, arrowroot or other starches; 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. Honey is allowed.

Recommended Timing

The book Breaking the Vicious Cycle suggests an introductory period of one to five days (depending on 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.

Resources and Tips

Gottschall's book contains more detail on all the foods that are allowed and disallowed, 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.

Pros and Cons

Pros

  • Limited scientific evidence of success

Cons

  • Extremely restricted

  • Complicated and difficult to follow

  • Can cause unwanted weight loss

Pros

Potentially Effective

There are many anecdotal reports of this diet helping people with IBD, Crohn's disease, and ulcerative colitis. Research published in peer-reviewed journals is scant, although some small studies have shown that the diet can work. Adults with these conditions may find it empowering to try to address their symptoms through diet. They should still be monitored carefully by a medical professional.

Cons

Restrictive

This diet eliminates large food groups and 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 if so many are off-limits.

Difficult

The diet is based on a need to eliminate 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 it is challenging to adhere to without constantly referring to the list of "legal" and "illegal" foods (as they are called in Gottschall's book). Even when you know which foods are allowed, it is very challenging to stick to such a limited list of them.

Low-Calorie

Some people with these types of health conditions already struggle to maintain or gain weight. The specific carbohydrate diet's restrictions could mean a person following it consumes too few calories and loses weight.

How It Compares

Some other diets aim to treat diseases of the digestive system (or ease their symptoms). Compared to the USDA guidelines, the specific carbohydrate diet is very limited.

USDA Recommendations

The USDA suggests eating plenty of whole grains and dairy products. Since the specific carbohydrate diet eliminates so many of these foods, it does not meet USDA recommendations. It also may be difficult to get the recommended number of daily calories (roughly 2000, although this number can vary) while following the specific carbohydrate diet. To see how many calories you need each day, try this Weight Loss Calorie Goal Calculator.

Similar Diets

While the role of diet in digestive disease is not well understood, these eating plans all seek to help patients who are dealing with these conditions.

Specific Carbohydrate Diet

  • Who it's for: People with gastrointestinal disorders including IBS, IBD, Crohn's disease, ulcerative colitis, and celiac disease
  • Safety: This diet is very restrictive, so it should be used with caution.
  • Practicality: No specialty foods or supplements are required (except for homemade yogurt). But it can be hard to identify which foods are allowed and which aren't, and to make sure you always have access to them.

Low-FODMAP Diet

  • Who it's for: People with IBS and IBD
  • Safety: The low-FODMAP diet is less restrictive than the specific carbohydrate diet, so it may be safer to follow. It should still be supervised by a medical professional.
  • Practicality: People on this diet have more food options, but they are still sometimes hard to remember or identify. (FODMAP stands for "fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.")

Gluten-Free Diet

  • Who it's for: People with celiac disease and gluten sensitivity
  • Safety: This diet is generally safe because it only restricts the gluten protein (found in certain grains). There are many other sources of the nutrients found in these grains.
  • Practicality: Today, many gluten-free foods are readily available at supermarkets and restaurants.

Microbiome Diet

  • Who it's for: People who want to improve their gut health in order to lose weight
  • Safety: Like the other diets, this one restricts quite a few foods and entire food groups, especially in its first phase. So there is a risk of missing out on important nutrients.
  • Practicality: It may be easier to follow this diet because it is phased. After the first 21 days, some foods and food groups are reintroduced. However, the diet also recommends favoring organic foods and all-natural household products, and suggests taking a large number of supplements.

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 health care 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.

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