CHAPTER 8
The Low Oxalate Diet (LOD)
WHAT ARE OXALATES?
Oxalates are organic acids that come from three main sources: diet, fungi/yeast, and the body’s own metabolism. Oxalates are particularly high in soy products, spinach, beets, chocolate, peanuts, wheat bran, tea, cashews, pecans, almonds, and berries. Plants make oxalates to protect themselves against infection or from being consumed.
WHY ARE OXALATES A PROBLEM?
Normally, oxalates are metabolized by bacteria in the intestine or bound by fecal calcium and eliminated via the stool. In the presence of insufficient calcium, imbalanced intestinal flora, or altered intestinal permeability (known as “leaky gut”), oxalates can be absorbed from the gut into the bloodstream.
When oxalates are high in the blood, they can combine with calcium and form crystals that deposit in tissues and cause severe pain. Crystals may deposit in bones, joints, blood vessels, lungs, and brain. They may also form kidney stones. The crystals may cause tissue damage and are also thought to lead to inflammation in the tissues.
Excessive oxalates have a number of negative effects on the body. These include:
Formation of kidney stones
Pain
Inflammation
Oxidative stress
Depletion of glutathione, a potent, sulfur rich, antioxidant that is already deficient in a number of children with autism
Negative effects on the function of mitochondria, the energy machinery in cells
Interference with biotin, an important B vitamin
Interference with sulfation, a process that is important for detoxification
Oxalates may be a particular problem for individuals with autism. According to data reported by Dr. William Shaw at Great Plains Laboratory, oxalates in the urine are much higher in children with autism than in neurotypical children.
Research has shown that a subset of individuals with autism have differences in the pathways that make glutathione, which is critical in sulfation and detoxification. Excessive oxalates affect glutathione production and interfere with sulfation. Therefore, it is possible that oxalates may have even more of a negative effect in individuals with autism. Individuals with hypomethylation problems may also experience sulfation deficits.
WHAT INCREASES OXALATES OR OXALATE ABSORPTION?
Factors that can increase oxalates include:
Diets high in high oxalate foods
Insufficient sulfate and impaired sulfation, which are needed to rid oxalates
Excessive intestinal yeast (especially Aspergillus)
Genetic disorders called hyperoxalurias
Factors that can increase oxalate absorption include:
Insufficient calcium in diet
Insufficient sulfur in diet
Excessive fat intake in diet if fatty acids are poorly absorbed due to deficiency of bile salts. These free fatty acids can bind calcium, leaving less calcium available to bind to oxalates.
Altered intestinal permeability (also known as “leaky gut”)
Vitamin A deficiency
Deficiencies of magnesium and zinc
WHAT KIND OF SYMPTOMS CAN OXALATES CAUSE?
Oxalates can cause a variety of types of pain including:
Urinary pain, including pain with urination or pain from passage of kidney stones
Genital pain (especially vulvar pain)
Headaches
Joint or muscle pain
Gastrointestinal pain
Eye pain
WHEN SHOULD THIS DIET BE CONSIDERED?
We recommend that a trial elimination of oxalates be considered in a child with the following symptoms that have not responded to traditional medical diagnosis and treatment:
Extreme pain with urination
Eye-poking behaviors not explained by visual loss or other clear ophthalmologic reason
Self-injurious behavior (SIB), especially in a nonverbal child, in whom the cause of SIB is not clear
Kidney stones (Calcium oxalate stones are the most common type of kidney stone.)
Worsening of symptoms or behavior when on the Specific Carbohydrate Diet (since nut flours are high in oxalates)
WHAT IS A LOW OXALATE DIET AND HOW IS IT DONE?
The initial step is to remove foods that are high in oxalates. Then, if necessary, medium oxalate foods can also be removed. Oxalates should be removed gradually from the diet, as some children will have worsened pain or discomfort if they are removed too rapidly.
WHICH FOODS ARE AVOIDED?
Oxalates are high in almost all seeds and nuts. Foods especially high in oxalates include soy, spinach, beets, chocolate, peanuts, wheat bran, tea, cashews, pecans, almonds, and berries. See the table for detailed information. The table includes very high and high oxalate foods; foods highest in oxalates are indicated by an asterisk.
Most flour substitutes for gluten are high oxalate, but rice flour, coconut flour, and pumpkin seed flours are not. Most milk substitutes are high in oxalates, such as brown rice milk, almond milk, and potato milk. Coconut and goat milk are acceptable substitutes.
It is interesting to note that the oxalate content of some foods varies based on the form it is in. For example, some are higher in oxalates when eaten steamed, but lower when eaten raw or boiled. Tomato paste, sauce, and purée (canned) are high in oxalates but fresh tomatoes are medium. Lemon peel is high in oxalates but lemons and lemon juice are low. Lime peel is high in oxalates but lime juice is low. In some lists, zucchini is listed as high in oxalates while on others, it is very low. We would recommend avoiding zucchini initially until it is clear whether your child reacts to it. Other factors that can affect the oxalate content of food include growth season (whether plants are picked early or late in a season), nutrients in the soil, and the length of time the plant is grown.
FOODS HIGH IN OXALATES
LEGUMES, NUTS, AND SEEDS |
GRAINS |
VEGETABLES |
FRUITS |
OTHERS |
Almonds * Black beans * Cashews * Filberts (Hazelnuts) * Macadamia nuts* Navy beans * Peanuts *, peanut butter * Pecans * Pine nuts * Pinto beans * Pistachio nuts Sesame seeds * Soy, soybeans, * and soy milk * Tahini * Walnuts * |
Amaranth Buckwheat * Durum flour * Kamut Millet * Rye * Wheat * |
Beets * Broccoli (steamed) Brussels sprouts (steamed) Carrots * Celery * Chard * Chili peppers Collard greens (steamed) Dandelion greens Okra * Olives (black and green) * Potatoes * Rhubarb * Sorrel Spinach * Sweet potatoes * Tomato paste, purée, or sauce (canned) Yellow dock Zucchini (see previous page for more information) |
Blackberries * Currants Dates Dewberries Gooseberries Kiwi * Lemon peel Lime peel Oranges and orange peel Persimmons Raspberries: black *, red Star fruit * |
Chocolate *, cocoa powder *, chocolate milk V8 Juice Sesame oil * Spices/Herbs: Cinnamon, oregano, black pepper, turmeric* Sweeteners: Date sugar, stevia * |
* Indicates foods that are very high in oxalates.
Source: The Autism Oxalate Project
WHICH FOODS ARE ALLOWED ON A LOW OXALATE DIET?
Foods that are very low in oxalates and allowed on the diet include:
Meats (except cured meats), fish, and dairy products
Fruits: apples, avocados, cherries, citrus, cranberries, melons (cantaloupe, honeydew, watermelon), seedless grapes, peaches, and plums
Vegetables: asparagus, cauliflower, cucumbers, lettuce (iceberg and romaine), mushrooms, onions (yellow and white), radishes, red sweet peppers, squash (acorn and yellow), turnips, and water chestnuts
Beverages: spring and filtered water, chamomile tea, ginger ale, apple juice, and apple cider
Chocolate: white chocolate
Grains: white and wild rice; barley
Herbs and spices: basil, cilantro, mustard, nutmeg, white pepper, saffron, tarragon, vanilla, and salt
Condiments: mustard, mayonnaise, and vinegar
Nuts, peas, and seeds: coconut, black-eyed peas, green peas, yellow split peas, and flaxseeds
Fats and oils: butter and vegetable oils including olive, and safflower
Sweets and sweeteners: sugar (white), maple syrup, corn syrup, and honey
WHAT ELSE MAY HELP?
Good hydration and daily stools are both important to help promote elimination of oxalates. Citrus juices can also be helpful in oxalate elimination. Taking a calcium citrate supplement 20 minutes before meals containing high oxalate foods may be helpful. Calcium binds oxalate in the intestine, which prevents it from being absorbed so that it can be eliminated in the stool. It is important to provide additional minerals such as magnesium and zinc, which can also bind with oxalates to be eliminated in the stool. Probiotics, prebiotics, and biotin support can be helpful by providing sufficient beneficial bacteria that can metabolize oxalates in the intestine. Vitamin B6 may also be helpful by supporting the enzyme that degrades oxalates. The guidance of a health practitioner with experience with the low oxalate diet is recommended for determining appropriate amounts of these supportive nutrients and supplements.
For a summary of the Low Oxalate Diet.
LOW OXALATE DIET (LOD) |
Chapter 8 |
What Are Oxalates? Oxalates are in foods, in fungi and yeast, and made by the body. Plants make oxalates to protect against infection and consumption. Avoid:
Why Is the Diet Needed? Problems occur when there are insufficient good bacteria (microbiota) to metabolize oxalates and prevent the overgrowth of yeast. Inadequate fecal calcium impairs elimination of oxalates. Oxalate crystals can damage the GI tract, cross into the bloodstream, and damage tissues, causing inflammation and pain. Symptoms the Diet May Help:
Diet Includes:
Resources:
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