“The diet is often used in children and adults with mild to moderate Crohn’s disease,” says Laura Manning, MPH, RDN, a clinical nutrition coordinator at Mount Sinai Hospital in New York City. “It has been shown to induce remission in 70 percent of pediatric [patients] and 69 percent of adults who used the diet successfully.” CDED was originally developed to exclude certain foods from the Western diet, which is thought to alter the gut microbiome — the trillions of bacteria, fungi, parasites, and viruses found in the gut. A disrupted gut microbiome may impair the body’s immune response and may cause increased inflammation, according to an article in the October 2019 issue of Nutrients. “The typical Westernized diet has been suggested to lead to dysbiosis [imbalance of bacteria in the gut] or damage to the protective gut barrier,” says Brittany Roman-Green, a registered dietitian and a member of the Crohn’s & Colitis Foundation’s National Scientific Advisory Committee. “The reasoning behind the diet format was to combine the benefits of exclusive enteral nutrition with anti-inflammatory foods to help provide an ideal fuel source for beneficial bacteria and optimize the patient’s microbiome,” says Dr. Manning. “When the patient’s microbiome shifts to having more beneficial bacteria, it can lower inflammation in the gut.”
A Diet That Works in 3 Phases
During CDED, many foods are removed from the diet and slowly reintroduced. The diet follows three phases broken into six-week increments, and they each include partial enteral nutrition (liquid formula). During phase 1, foods are limited to fish, lean meats, rice, potatoes, tomatoes, onion, garlic, ginger, olive oil, and canola oil. Limited quantities of cucumbers, carrots, spinach, lettuce, bananas, apples, avocados, strawberries, melon, and citrus juices are allowed. In phase 2, participants eat foods from phase 1, and added foods like tuna, limited amounts of whole-grain bread, oatmeal, yams, and red peppers. Certain vegetables, beans, peas, turnips, and parsnips are reintroduced after week 10. Phase 3 begins the maintenance phase of the diet. In addition to foods from phase 2, other foods are introduced, such as more seafood, eggs, cocoa, coffee, grains, some dairy, and alcohol. Foods that trigger symptoms may differ from person to person. If symptoms flare up during the maintenance phase, you can return to phase 1 to regain control over your symptoms. “A patient’s quality of life around food was strongly considered in the development of the diet,” Manning explains. “If [patients] are able to achieve similar results with the addition of solid food, then it is a higher likelihood that patients will remain on the diet for the duration and beyond.”
Who Benefits From This Diet?
The CDED can be used for both adults and children with active Crohn’s disease. For children especially, who often can’t take medications like steroids or maintain a liquid-only diet like EEN, CDED can help reduce inflammation in the digestive tract so they can continue to absorb nutrients for normal growth and development. In a study published in June 2019 Gastroenterology that compared the CDED with a liquid-only diet in children with mild to moderate Crohn’s disease, researchers found that while both diets were effective at reducing Crohn’s disease symptoms by week 6, the children were better able to tolerate the CDED with supplemental nutrition and experienced a sustained reduction in symptoms. Researchers also found that the composition of gut microbes changed through the study. In particular, they found the protective microbes assembled during the beginning of the study were effective against inflammation, but this protection diminished as more food was introduced into the diet, which changed the environment for the gut bacteria.
What the Research Says
Ongoing clinical trials continue to study the effectiveness of the CDED in different groups with more severe symptoms of the disease. In a 24-week study published in the November 2021 issue of the Lancet Gastroenterology & Hepatology, one group of adults (18–55 years old) followed the CDED along with a fortified nutritional drink while the second group followed the CDED only. Researchers found the CDED with or without the addition of the nutrition drink was effective at reducing symptoms. Because of the restrictive nature of the diet, Roman-Green encourages anyone considering the CDED to work with a registered dietitian and their gastroenterologist. As with all medical treatments, exclusion diets have potential side effects, including disordered eating patterns. “The CDED diet is highly structured but allows for some flexibility in choices, so you can continue to enjoy eating while being proactive in your care process,” says Manning. “It is important to know that when you do embark on a diet therapy, you give yourself grace occasionally if it is not exact.”
Which Type of Diet Is Right for You?
The Anti-Inflammatory Diet (IBD-AID)
Developed by researchers at the University of Massachusetts Medical School in Worcester, the IBD-AID diet aims to restore the bacterial balance in the gut and reduce IBD symptoms. The diet includes probiotic and prebiotic foods while restricting certain carbohydrates. Probiotic foods:
Plain yogurtMisoKimchiAged cheesesPickles
Prebiotic foods:
Steel-cut oatsGarlic, onionsBananasAsparagusBeans: kidney, lima, chickpeas, green peas
The diet also requires avoiding pro-inflammatory carbohydrates, anything with lactose, wheat, refined sugar, and corn. Like CDED, the diet is restrictive, and more evidence is needed to determine if it’s effective.
The Low-FODMAP Diet
FODMAP, which stands for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols” refers to the short-chain carbohydrates and polyols that are poorly absorbed in the digestive tract. The low-FODMAP diet eliminates foods that are high in FODMAPs and requires eating foods that are low in FODMAPs. The good news is there is a wide range of foods to choose from, which makes the diet easy to follow. High-FODMAP foods:
ApplesDried fruitAsaparagusWheatHoneyCow’s milkOnions and garlic
Low-FODMAP foods:
Lean meatsPotatoesTomatoesPeppersCarrotsBananasCitrus fruitsCucumbersOrangesHard cheesesEggsOatsStrawberries
While more research is needed on the effects of the low-FODMAP diet in Crohn’s patients, a study published in October 2019 in Gastroenterology found that when people with IBD, including Crohn’s disease, stuck to a low-FODMAP diet, they experienced a significant reduction in several gut symptoms after just four weeks. The diet had no effect on disease severity, but the research adds to the growing body of evidence that a low-FODMAP diet may provide people with GI symptoms some relief.
The Specific Carbohydrate Diet
Developed in the 1920s by Dr. Sidney Haas, a pediatrician, this diet eliminates refined and processed foods in order to reduce the growth of harmful bacteria in the gut. While there are a few preliminary studies that show a positive effect, experts don’t recommend this diet because it’s more restrictive. In a study published in May 2021 in Gastroenterology, results showed the specific carbohydrate diet wasn’t any better than the Mediterranean diet at achieving remission or improving inflammation in Crohn’s patients with mild to moderate symptoms. Allowed foods:
Fruits and most vegetablesFresh meat and fishDairy limited to hard cheeses and homemade yogurtMost nutsMost oils, teas, coffee, and juices with no additives or sugarsHoney as a sweetenerCertain legumes: beans and lentils
Foods to avoid:
All grains and starchesSugars, maple syrup, sucrose, fructoseStarchy vegetables: potatoes, yams, parsnipsDairy products: cow’s milk, ice cream, sour cream, store-bought yogurtSome legumes: chickpeas, bean sprouts
In addition to being highly restrictive, the diet can lead to deficiencies in certain vitamins and minerals, so supplements like vitamin B6, calcium, and vitamin D may be needed.
Mediterranean Diet
Considered more of an eating approach than a diet, the Mediterranean diet is loaded with vegetables and healthy fats like olive oil and omega-3 fatty acids from fish. The diet has been cited as having a number of health benefits, including lowering the risk of heart disease, reducing cancer risk, and improving blood sugar to keep type 2 diabetes in check. A study published in a 2020 issue of Gut found that individuals who adhered to a Mediterranean diet had a 60 percent reduced risk of Crohn’s disease. While the study was observational, and more research is needed, the results do offer hope. Foods allowed:
Healthy fats like olive oilAll vegetablesFruitsNuts and seedsWhole grainsLegumesFishLow amount of red meatModerate amount of dairy foodsModerate amount of red wine
Foods to avoid:
Processed foods that are high in sugar, refined carbohydrates, and unhealthy fats (cookies, white bread, white rice)
