The Specific Carbohydrate Diet (SCD) is a very restrictive, unconventional diet plan that severely limits most carbs.
It is based on the theory that by eliminating most carbs (primarily grains, starches, dairy, and sugars) and allowing only specific carbs that require minimal digestion, it can reduce inflammation and make eating enjoyable for people with gastrointestinal (GI) disorders.
People with various GI disorders, including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), ulcerative colitis (UC), Crohn’s disease, and celiac disease, can have difficulty dealing with food and side effects from medications and food intolerances.
Removing the carbs that are difficult to digest and cause inflammation in the gut is the rationale of the diet, popularized by the late biochemist and author Elaine Gottschall, MSc, in her book, Breaking the Vicious Cycle: Intestinal Health Through Diet. Gottschall modeled the SCD based on the work of Sidney Haas, MD, to treat her then 5-year-old daughter, who had been diagnosed with ulcerative colitis.
Specific Carbohydrate Diet: What You Can Eat
This can be a very challenging diet to follow because there are a limited number of foods allowed. The SCD eliminates many of the foods in a typical American diet, including all simple sugars, grains, starches, most dairy, and more.
Not only is the SCD difficult to follow, it may also be risky for your health. When you eliminate whole food groups like dairy and grains, you significantly reduce the nutritional quality of the diet, which may result in nutritional deficiencies.
Multivitamins and minerals can fill in the gaps, but they fall short when compared to the nutritional goodness of foods. “You can’t get in a pill all the phytochemicals, fiber, and synergy (foods working together) that foods provide. Supplements are designed to supplement the diet, not replace nutritious foods,” says American Dietetic Association spokeswoman Dee Sandquist, MS, RD.
You need to carefully read food labels to select foods allowed on the SCD and be cautious when eating out.
The following foods are allowed in the diet:
- Vegetables (except canned)
- Legumes (except the ones noted below)
- Unprocessed meats, poultry, fish, and eggs
- Natural cheeses (except those listed below)
- Homemade yogurt fermented at least 24 hours
- Most fruits and juices without additives
- Nuts, peanuts in the shell, natural peanut butter
- Oils: olive, coconut, soybean, and corn
- Weak tea and coffee
- Unflavored gelatin
- Mustard and vinegar
Foods and ingredients not allowed on the SCD include:
- Sugars: lactose, sucrose, high-fructose corn syrup, fructose, molasses, maltose, isomaltose, fructooligosaccharides, and any processed sugar
- All canned vegetables
- All grains: anything made from corn, wheat, wheat germ, barley, oats, rye, rice, buckwheat, soy, spelt, and amaranth
- Some legumes: chickpeas, bean sprouts, soybeans, mung beans, fava beans, and garbanzo beans
- Starchy vegetables: potatoes, yam, parsnips, seaweed products, agar, and carrageenan
- Canned and processed meats
- Dairy: milk, milk products, ice cream, whey powder, commercial yogurt, heavy cream, buttermilk, sour cream, and the following cheeses: ricotta, mozzarella, cottage cheese, cream cheese, feta, processed cheeses, and cheese spreads
- Canola oil, commercial mayonnaise, commercial ketchup, margarine, baking powder, and balsamic vinegar
- Candy, chocolate, carob
Specific Carbohydrate Diet: How It Works
Yet unproven by scientific studies, the effectiveness of this diet is promoted by the testimonials from people who claim their symptoms improved and their disease went into remission.
In theory, the benefits of the SCD occur at the cellular level controlling bacteria. The premise is that unrefined carbs alter bacteria in the gut; by removing offending carbs, it changes the metabolism of the bacteria that live in the gut and reduces inflammation.
Further, Gottschall believed the intestines of patients with GI disorders are damaged and missing enzymes to break down complex sugars and starches, which provide more food for bacteria to feed upon.
Specific carbs that are allowed require minimal digestion, are well absorbed, and leave virtually nothing for bacteria to feed on. The diet encourages eating foods that contain "good" bacteria, such as homemade yogurt, on a daily basis to replenish healthy bacteria in the gut.
“Gut bacteria are sensitive to what you eat, but it is a very complicated phenomenon and whether or not the Specific Carb Diet is anti-inflammatory and beneficial remains unknown,” says Joel Mason, MD, associate professor of medicine, nutrition, and gastroenterology at Tufts University in Boston.
It appears to work for some people and not others, says Sandquist.
Specific Carbohydrate Diet: Experts' Views
Despite the fact that there is little scientific evidence for the SCD, it is hard to ignore the anecdotal praises for the plan. "We don’t have perfect treatments for these GI diseases, and we should be open to unconventional therapies that are worthy of consideration [and] proceed cautiously and with careful medical supervision," Mason says.
Anecdotal doesn’t necessarily mean effective. "There can be a placebo effect, or because these diseases are cyclic, there may be improvements not related to the diet," Mason says.
And when you eliminate so many foods, Sandquist says, it makes it hard to pinpoint culprit foods causing problems.
Mason also has other concerns. “It is very difficult to stick to this diet because it is so restrictive," he says. "Strict adherence to it could result in weight loss from too few calories, and certain patients, like those with IBD, who tend to already be underweight can’t risk additional weight loss."
Calories along with protein are essential to help maintain the immune system, stay healthy, and be able to heal, Sandquist says.
Another concern is the nutritional inadequacy of the diet. Eliminating whole food groups from the diet sets up the dieter for potential nutrient deficiencies. “When you don’t eat grains you miss out on B vitamins, fiber, and iron. Eliminating dairy pulls out the best source of calcium and vitamin D along with potassium," Sandquist says.
On the positive side, there can be a psychological benefit for adults who are proactive and empowered by taking charge of their disease with the diet.
However, when it comes to children, it could be an emotional burden and an even greater nutritional concern.
“Children and teens have extraordinary nutritional needs to support growth and to combat their disease. Therefore, the additional restrictions of this diet could be overwhelming emotionally and physically," says Mason, who does not recommend the SCD diet for children.
Specific Carbohydrate Diet: Food for Thought
The SCD has been around for years because for some people with GI diseases, it minimizes symptoms. But the diet, because of its severe restrictions and nutritional inadequacies, needs to be studied further and validated by the medical community.
If you want to try the SCD, consult your doctor first. "If any of my patients wanted to try this plan (which they have not), I would be willing as long as they agreed to being monitored very closely," Mason says.
You may also want to consult a registered dietitian to make sure you're meeting all your nutritional needs while you're on the SCD diet.
Kathleen Zelman, MPH, RD, is director of nutrition for WebMD. Her opinions and conclusions are her own.