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SCD Autism Summary

“... in many autistic children, bacterial and fungal overgrowths are etiologically significant in the cascade of events that result in autism or one of the other autism spectrum disorders.”-- Jaquelyn McCandless, Children with Starving Brains

“...the use of chelation agents that encourage pathogen overgrowth creates an even greater incentive to get the gut as healthy as possible prior to initiating the chelating process... preventing any known sources of inflammation will help the child’s health improve and make chelation both more effective and shorter in duration.” --Jaquelyn McCandless, Children with Starving Brains

“A sensible and harmless form of warfare on the aberrant population of intestinal microbes is to manipulate their energy (food) supply through diet...By depriving intestinal microbes of their energy source, their numbers gradually decrease along with the products they produce.”--Elaine Gottschall, Breaking the Vicious Cycle

Autism and GI Problems (written by Jody Goddard)

Recent research shows that more than 50% of children with autism have GI symptoms, food allergies, and maldigestion or malabsorption issues (Horvath). It’s obvious from talking to parents that GI problems are a major concern in children with autism. Listservs dealing with autism have discussions on GI issues all the time. Antifungal use, both prescription and alternative remedies, is a common topic. Parents have tried “anti-yeast” diets, prescription drugs and natural remedies, but nothing seems to be “the answer” to the chronic microbial problems their children face. Many parents wish to pursue chelation for their children, but are unable to do so because of their inability to get their children’s gut pathogens under control.

Altered intestinal permeability was found in 43% of autistic patients, but not found in any of the controls (Harvard University). Intestinal permeability, commonly called “leaky gut”, means that there are larger than normal spaces present between the cells of the gut wall. When these large spaces exist in the small intestine, it allows undigested food and other toxins to enter the blood stream. When incompletely broken down foods enter the body, the immune system mounts an attack against the “foreigner” resulting in food allergies and sensitivities. The release of antibodies triggers inflammatory reactions when the foods are eaten again. The chronic inflammation lowers IgA levels. Sufficient levels of IgA are needed to protect the intestinal tract from clostridia and yeast. The decreasing IgA levels allow for even further microbe proliferation in the intestinal tract. Vitamin and mineral deficiencies are also found due to the leaky gut problem.

An example of the problems created by the vitamin deficiencies that occur within a leaky gut is vitamin B12 deficiency. B12 absorption is inhibited early in this process as microbes enter the small intestine because B12 is absorbed in the ileum (last section of the small intestine). Vitamin B12 is essential for metabolism of fats and carbohydrates and the synthesis of proteins. Vitamin B12 is involved in the manufacture of the myelin sheath, a fatty layer which insulates nerves in the brain. It is also essential for the formation of neurotransmitters. A compound known as intrinsic factor, which is secreted by the cells lining the stomach, is necessary for the absorption of vitamin B12. (The New Encyclopedia of Vitamins, Minerals, Supplements, & Herbs)Another important function of B12 is repairing damaged, flattened microvilli. With sufficient B12 and folic acid in the bloodstream, the intestinal cells and microvilli can rejuvenate every 3-4 days.

In a healthy intestinal tract the small intestine and stomach are not inhabited by bacteria. When the flora balance in the colon is lost, the microbes can migrate into the small intestine and stomach, which hampers digestion. The microbes compete for nutrients and their waste products overrun the intestinal tract. One of the toxins produced by yeast is actually an enzyme that allows the yeast to bore into the intestinal wall. The yeast also produce other toxins such as organic acids, which can also damage the intestinal wall.

Bacterial growth in the small intestine destroys enzymes on the intestinal cell surface, which prevents carbohydrate digestion and absorption. The last stage of carbohydrate digestion takes place at the minute projections called microvilli. Complex carbohydrates that have been broken down by the enzymes embedded in the microvilli can be absorbed properly and enter the blood stream. But when the microvilli are damaged, the last stage of digestion cannot take place. At this point only monosaccharides can be absorbed because of their single molecule structure.

*All diagrams from Breaking the Vicious Cycle

In the small intestine, the body should absorb the nutrients needed from what is eaten. But in the case of malabsorption, the undigested carbohydrates left in the small intestine cause the body to draw water into the intestinal tract. This pushes the undigested carbohydrates into the colon where the microbes can feast on it. This allows for even more proliferation of the unwanted microbes and continued increase in malabsorption problems.

Low intestinal carbohydrate digestive enzyme activity was found in 43% of patients with autism. (Horvath) Recent studies point out that ongoing carbohydrate malabsorption keeps the digestive system constantly weakened, leading to systemic disorders. Suspected carbohydrate malabsorption should be treated to ward off further damage to the body’s digestive system. (GSDL)

Most intestinal microbes require carbohydrates for energy. The Specific Carbohydrate Diet limits the availability of carbohydrates. By depriving these microbes of their food source, they gradually decrease in number. As the number of microbes decreases so do the toxic by-products they create.

The Specific Carbohydrate Diet (SCD) is intended to stop the vicious cycle of malabsorption and microbe overgrowth by removing the source of energy from the microbes. The SCD allows simple monosaccharides that do not need to be broken down in order to be absorbed.

By following the SCD, malabsorption is replaced with proper absorption. Inflammation is decreased and the immune system can return to normal. Once the immune system is returned to adequate levels, it can begin to keep in the intestines microbes in proper balance.

The SCD allows simple carbohydrates, but prohibits complex carbohydrates. The diet is started by following an introductory diet, which consists of a limited selection of foods. After the introductory diet, the next stage of the diet allows many more foods, but requires that all fruits and vegetables be peeled, seeded and cooked in order to make them more easily digested. Raw fruits, vegetables, nuts and seeds are added to the diet later. To properly follow this diet, it is imperative to read Breaking the Vicious Cycle by Elaine Gottschall. The book details the progression of allowed foods as well as providing many delicious recipes.

The Specific Carbohydrate Diet is the only diet that targets the malabsorption issues that are so prevalent in children with Autism. By removing the foods that cannot be properly broken down, the energy source for the unwanted gut pathogens is eliminated. With their food source taken away, the microbes die off and the proper gut flora balance can be restored. The vicious cycle of malabsorption, inflammation and food allergies seen in children with autism is broken and healthy digestion can begin.

Specific Carbohydrate Diet Food List:


ALLOWED: All fresh or frozen beef, lamb, pork, poultry, fish, and shellfish, eggs, natural cheeses (see appendix of BTVC for full list of allowed cheeses), homemade yogurt (recipe in BTVC) and dry curd cottage cheese.

NOT ALLOWED: Processed meats such as hot dogs, bologna, turkey loaf, spiced ham, breaded fish, canned meat if they contain starches such as whey powder, lactose, sucrose, etc. Processed cheeses and cheeses not listed in appendix.


ALLOWED: Fresh or frozen (with no added sugar or starch). Artichoke (not Jerusalem type), asparagus, beets, dried white navy beans, lentils, split peas, broccoli, brussel sprouts, cabbage, cauliflower, carrots, celery, cucumbers and dill pickles, eggplant, garlic, kale, lettuce of all kinds, lima beans, mushrooms, mustard, olives, onions, parsley, peas, pumpkin, spinach, winter and summer squash, string beans, tomatoes, turnips, watercress.

NOT ALLOWED: No canned vegetables allowed. Grains such as: arrowroot, barley, buckwheat, bulgur, corn, millet, oats, rice, rye, triticale, or wheat. No flour, germ, pasta, starch, or cereal products from these. Potatoes (white or sweet), yams or parsnips. Beans (sprouts, soybeans, mung, fava and garbanzo). Amaranth flour, Jerusalem artichoke flour or powder, quinoa flour, or other grain substitutes such as cottonseed, tapioca, sago, seaweed.


ALLOWED: Fresh raw, cooked, frozen, or dried apples, avocados, apricots, ripe bananas, berries of all kinds, cherries, fresh or unsweetened shredded coconut, loose dates that do not stick together, grapefruit, grapes, kiwi, kumquats, lemons, limes, mangoes, melons, nectarines, oranges, papayas, peaches, pears, pineapples, prunes, dark raisins, rhubarb, and tangerines.

NOT ALLOWED: Canned fruits. Dried fruit that has been glazed with corn syrup or sugar such as many brands of banana chips. Molasses, ketchup (unless homemade), agar-agar, carrageenan, jams, jellies.


ALLOWED: Almonds, pecans, Brazil nuts, filberts, hazelnuts, walnuts, unroasted cashews and chestnuts. Peanut butter and other nut butters without any additives.

NOT ALLOWED: Roasted nuts or peanuts in salted mixtures. Beer nuts, glazed nuts, etc.


ALLOWED: Tomato and vegetable juices. Tropicana 100% orange juice, Welch’s grape juice, pineapple juice, some brands of apple juice, weak tea or coffee, herbal teas (peppermint and spearmint only). Milkshakes made with homemade yogurt, fruits and sweetened to taste with honey. Freshly squeezed vegetable or fruit juices made from the list of allowed foods.

NOT ALLOWED: Cow's milk, goat's milk, soy milk, rice milk, canned coconut milk. Instant coffee or tea, postum, coffee substitutes, soft drinks.



Breaking the Vicious Cycle, by Elaine Gottschall, M.Sc.

Children with Starving Brains, by Jaquelyn McCandless, M.D.

The New Encyclopedia of Vitamins, Minerals, Supplements, & Herbs, by Nicola Reavley

Articles and Websites:

“Altered Immunity & The Leaky Gut Syndrome”, Zoltan P Rona, M.D., M.Sc.

“Lactose Intolerance Breath Test-Application Guide”
Great Smokies Diagnostic Lab

“Gastrointestinal Microflora Studies in Late-Onset Autism”
Finegold, et al
Finegold Abstract

“Preliminary Findings in Gastrointestinal Investigation of Autistic Patients, 2002”
Harvard University and Mass General Hospital
Harvard Abstract

“Gastrointestinal Abnormalities in Children with Autistic Disorder”
Horvath, et al
Horvath Abstract-PubMed

“Abnormal Intestinal Permeability in Children with Autism”
D’Eufemia, et al
D'Eufemia Abstract-PubMed

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