30BaD FADs: Frequently Added Discussions
What are oxalates and oxalic acid?
How can oxalates harm us?
What foods are high in oxalates?
Oxalates are naturally occurring compounds found in almost all plants, and in animals and humans. Oxalate is also a biproduct of human metabolism just like uric acid. The human diet will always contain some oxalate. However diets focusing on high oxalate foods like animal product, grains, starchy foods, and cruciferous vegetables like kale and spinach can cause short term problems such as digestive issues and breathing difficulties, and long term health problems such as kidney and cardiovascular damage. Sensitive indivuals such as those with preexisting lung, kidney or thyroid problems may have to avoid medium oxalate foods as well.
Some of our members here at 30BaD have problems when eating cruciferous veggies like broccoli, kale, spinach, and cauliflower, and root vegetables like carrots, tubers and potatoes, and starchy vegetables like beets as well as other starchy foods like some nuts and seeds, most legumes and beans, whole grains and bread, and processed foods.
Immediate symptoms of high oxalate consumption include burning mouth and throat during consumption, digestive upsets including sour stomach, stomach pains, diarrhea, blood in stools, constipation, bloating, gas in its various forms including burping, belching, flatulence, and flatus, breathing and asthma symptoms, mucus production, skin eruptions such as acne, eczema, and canker sores, dandruff, arthritis flare ups, kidney stones and kidney problems, urinary pain and or problems, blood in urine, foul smelling urine, irritation of the genitalia, body odor, and slowed digestion which makes it difficult to eat enough calories during the day.
Long term symptoms and diseases related to high oxalate consumption include kidney stones and kidney disease, urinary problems, breathing and asthma problems, digestive system irritation and or IBS (Irritable Bowel Syndrome), prevention of calcium absorption and assimilation with risk of osteopenia (bone softening), osteoporosis, and jaw, oral, and dental problems, iron deficiency anemia, and other systemic problems such as calcification of tissues and arteries also known as hardening of the arteries and or arteriosclerosis which can lead to heart problems and cerebrovascular accidents and strokes. Systemic circulation of calcium oxalate crystals can also cause them to be deposited in the visceral organs, bones, cartilage, and synovial fluid of joints resulting in pain, swelling, and arthritis.
Although many of the foods listed here are not against guidelines, we do request members who are sensitive to these foods to avoid eating them.
This blogpost will explain one aspect of why these foods cause sensitivities, and that is because they are high to moderately high in oxalate. A few problems regarding high oxalate consumption will be addressed here, although these problems and the list of high oxalate foods are not all inclusive.
Oxalates are naturally occurring organic acids found in plants, animals and humans. Oxalate is normally produced in plants, primarily in their leaves, nuts, fruit, and bark. In humans, however, oxalate seems to have no substantially beneficial role and act as a metabolic end-product, much like uric acid. Oxalate is the salt form of oxalic acid, and is a natural end product of metabolism. (1) (2)
Dietary oxalate is an organic molecule found in many vegetables, fruits, and nuts. Some foods high in oxalate are broccoli, cauliflower, cabbage, brussels sprouts, kale, bok choy (greens), collard greens and spinach. (3)
Eating a diet high in oxalates can cause problems in the body such as kidney stones and pain. Oxalate can also cause other pain related health problems like fibromyalgia, vulval pain, chronic pelvis pain and some other unexplained pains as well. (4)
Side Effects of Consumption
Eating foods high in oxalate may cause the following symptoms: breathing difficulty, burning in the mouth, burning in the throat, coma, diarrhea, eye pain, kidney stones, nausea, red-colored urine, seizures, stomach pain, vomiting, and weakness, esophagitis, slurred or unintelligible speech, laryngeal edema, pain and edema in the tongue. (5)
Oxalic acid poisoning may involve the following symptoms: abdominal pain, burns and blisters if acid contact is made, collapse, convulsions, kidney problems, low blood pressure, mouth pain, shock, throat pain, tremors, vomiting, and weak pulse. (6)
If extremely high doses of oxalate are consumed, death can result. (7)
Links With Some Conditions
According to researcher Susan Owens of the Low Oxalate Diet,there may be a link between excess oxalate in the body and the following conditions: (8)
Clive Solomons, Ph.D., former director of research at the University of Colorado Health Sciences Center, has explored the connection between excess oxalate, pain, and weakened connective tissue in his research, which is aptly called The Pain Project.
People who have participated in the Pain Project have reported recovery or improvement from a variety of painful conditions including: (9)
Breathing and Asthma Problems
Digestive System Irritation
The digestive system is made up of the digestive tract—a series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food. Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, large intestine—also called the colon—rectum, and anus. (10)
Oxalates irritate the lining of the digestive system when consumed. This could cause nausea, stomach pain, abdominal pain, diarrhea, and weakness. (4) (5)
During chewing and swallowing, eating foods high in oxalates can burn the mouth and throat, and cause pain in the throat and mouth.There may be swelling and pain in the tounge. In some cases, esophagitis may develop with laryngeal edema which might result in slurred speech. (4) (5) (11)
Long term problems with high oxalate consumption can cause conditions such as IBS (irriatable bowel syndrome). Irritable bowel syndrome is a problem that affects the large intestine. It can cause abdominal cramping, bloating and a change in bowel habits. Some people with the disorder have constipation. Some have diarrhea. Some go back and forth between constipation and diarrhea.
Eating foods high in oxalates may produce urine that is irritating. In females, this can contribute to symptoms of vulvodynia which is chronic pain and discomfort of the vulva. Symptoms include burning, stinging, rawness, itching, aching, soreness, throbbing and swelling. (12)
Because oxalate is expelled through the urine, irritation, itching, and burning of the genitals can happen in both males and females.
Hyperoxaluria is a condition where too much oxalate is present in the urine. Since oxalate and calcium are continuously excreted by the kidney into the urine, it can combine with calcium causing formations of calcium-oxalate crystals and grow into a kidney stone.
A high intake of oxalate-rich foods (eg, chocolate, nuts, spinach) and a diet rich in animal protein can result in hyperoxaluria. Low dietary calcium intake can also result in hyperoxaluria via decreased intestinal binding of oxalate and the resulting increased absorption. (1)
Kidney Stone Formation and Damage
The body uses food for energy and tissue repair. After the body uses what it needs, waste products in the bloodstream are carried to the kidneys and excreted as urine. Certain foods create wastes that may form crystals in the urinary tract. In some people, the crystals grow into stones. Calcium oxalate stones are the most common.
Some of the oxalate in urine is made by the body. By eating certain foods with high levels of oxalate that can increase the amount of oxalate in the urine where it combines with calcium to form calcium oxalate stones.
Avoiding these foods may help reduce the amount of oxalate in the urine. Eating foods containing calcium also reduces oxalate in the urine. Calcium binds oxalate in the digestive tract so it is not excreted into the urine. (10)
Osteoporosis and Dental Problems and Loss
Calcium is one of the most important minerals for the the human body. Calcium helps form and maintain healthy teeth and bones, clotting blood, sending and receiving nerve signals, muscle movement and relaxation, releasing hormones and other chemicals, and keeping a normal heartbeat. (14)
Lack of calcium in the diet and or inability to absorb calcium can lead to low bone density which is a risk for osteoporosis. Osteoporsos is when bones get weak and brittle. When this happens, all bones of the body can be affected including the jaw bone resulting in loose teeth and or loss of teeth. (15)
Oxalate inhibits calcium assimilation. In the digestive system, calcium binds with oxalate to prevent it from entering the blood stream. This means that there is less calcium available for absorption and assimilation by the body for bone building and other healthy body functions. (13)
Impairs Iron Absorption Promoting Anemia
There are two forms of dietary iron: heme and nonheme. Heme iron is found in animal foods that originally contained hemoglobin. Iron in plant foods is called nonheme iron. Most dietary iron is nonheme iron. (13)
Iron deficiency develops gradually and usually begins with a negative iron balance, when iron intake does not meet the daily need for dietary iron. Iron deficiency anemia is an advanced stage of iron depletion. It occurs when storage sites of iron are deficient and blood levels of iron cannot meet daily needs. Blood hemoglobin levels are below normal with iron deficiency anemia.
Signs of iron deficiency anemia include: feeling tired and weak, decreased work and school performance, slow cognitive and social development during childhood, difficulty maintaining body temperature, decreased immune function, which increases susceptibility to infection, and glossitis (an inflamed tongue).
Iron deficiency anemia can be associated with low dietary intake of iron, inadequate absorption of iron, or excessive blood loss
Oxalates impair the absorption of nonheme iron. (16)
Long term, a diet high in oxalate foods such as grains and bread, processed food, legumes and beans, tubers and potatoes, most nuts and seeds, and cruciferous veggies like kale and spinach can promote kidney disease and failure, calcification of body tissues, iron deficiency anemia, calcification and hardening of arteries which can long term lead to heart problems and cerebrovascular accidents and strokes. (18)
The kidneys, when working normally, are very efficient at eliminating excess oxalate that is produced by the liver or absorbed from the intestinal tract. In patients with good kidney function, blood concentrations of oxalate are kept normal or near the normal range, and it is only in the urine and the kidney tissue that high concentrations of oxalate occur. It is the high concentration of oxalate in the urine (hyperoxaluria) that causes stones to form, and over time causes damage to kidney tissue.
As time passes, kidney function may be reduced by 50% or more. When that occurs, and the kidney can no longer eliminate excess oxalate efficiently and blood levels of oxalate begin to rise. When blood oxalate concentrations reach a critical level, the amount of oxalate in the blood is high enough to form complexes with calcium leading to calcium oxalate deposits in multiple body tissues (called oxalosis).
Oxalosis can involve many different organs. Most common in patients with primary hyperoxaluria with associated kidney failure are deposits in small blood vessels which can cause painful skin ulcers that do not heal, deposits in bone marrow causing anemia, deposits in bone tissue causing failure to grow in children and fractures in adults and children, and calcium oxalate deposits in the heart causing abnormalities of heart rhythm or poor heart function.Oxalosis will become progressively more severe as long as the blood oxalate concentration remains high, and can lead to death. For this reason, prompt recognition of the problem and prompt treatment are essential. Kidney dialysis can remove oxalate from the blood, but in most patients with primary hyperoxaluria dialysis cannot keep pace with the very large amount of oxalate produced. Definitive treatment of kidney failure and oxalosis in patients with primary hyperoxaluria is transplantation. (2)
Arthritis and Calcium Oxalate Crystals
Just as calcium and oxalate can combine in the urine and kidney and form crystals and stones, so too can these crystals circulate in the blood.
Systemic circulation of calcium oxalate crystals can also cause them to be deposited in the visceral organs, bones, cartilage, and synovial fluid of joints resulting in pain, swelling, and arthritis. (19)
This can results in arthritis also known as acute monarthritis, polyarthritis, and or chronic arthritis. These crystals can also cause soft tissue swelling in areas around the joints but also in places like the hands. (20)
Symptoms of gout and or psuedogout may occur with calcium oxalate crystals. Ironically, high levels of ascorbic acid (vitamin C) are recommended to alleviate symptoms. (21)
Oxalate Content of Some Sample Foods
This list is not all inclusive, rather a sampling of problem foods that may cause some of our members more problems.
High Oxalate Foods
These foods may have 10 or more mg of oxalate per serving and or cause extreme reactions in sensitive individuals and or kidney patients.
Problem Fruits in sensitive individuals
Other high oxalate foods and products include tea, cocoa and chocolate products, many fruit juices, beer, coffee, soy products, many grains and grain products such as amaranth, buckwheat, oats and oatmeal, wheat, as well as the offshoots of these products such as pasta, cakes, cookies, and pies. Many if not most cooked foods are high oxalate foods in part because we use high oxalate foods in our dishes and recipes.
Moderate Oxalate Foods (2-10 mg per serving)
For people who are not sensitive to oxalates, these foods can be eaten sparingly, but preferably not as a main calorie source. However, if one experiences burping and belching, gas, bloating, and or skin eruptions like acne, eczema, or canker sores, eat sparingly or not at all.
Some problems with some of the vegetables on this list such as broccoli, cabbage, and cauliflower, is that they are high in cellulose. Our bodies cannot digest cellulose very well and or extract nutrients from these vegetables thus rendering them somewhat of an empty calorie food. Many of them are low calorie and it is difficult for humans to eat enough of them to satisfy caloric and nutritional requirements.
Even though the oxalate content per serving of these foods may initially look low, because they are low calorie, we have to eat many servings of them verses other fruits and nuts with similar oxalate counts. This will result in an overall oxalate consumption count being higher if these are not eaten sparingly. It might be recommended to just use things like peeled cucumber, broccoli and cauliflower to spice up or crunch up a salad, but not as the salad itself.
Nuts and Seeds
While some nuts and seeds may be moderate to high in oxalate content per serving, many people still tolerate them well in part because we eat them sparingly because of high fat content, and that the oxalate to calorie ratio is quite low verses the oxalate to calorie ratio of some other low calorie per serving items like cabbage. Everyone should do their own personal analyses of how they react to various nuts and seeds.
(22) (23) (24)
Many starchy foods such as grains and bread, tubers, beans, starchy vegetables, and processed foods are high in oxalates. Most fruit juices are high in oxalate in part because the oxalate gets concentrated when fiber and other nutrients are removed. For example, it might take 5-10 or more oranges to make a serving of orange juice. To ensure one is getting enough calories from juices, an exponential amount of fruit has to be used thus increasing oxalate content and consumption. To learn more about other problems caused by starchy foods, read here:
The best choice of green vegetable are tender lettuce greens which are low oxalate foods.
For more assistance in choosing ideal fruits and lettuce greens, consult this list:
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