Oxalate - needle like crystals that plants make to reduce insects from eating them.
And it works - they hurt the gut and bladder - so it is good to know what is causing the pain. High oxalate and low oxalate food lists are included. Goal - prevent Kidney Stones.
The defense against insects in many common plants involves needle like calcium oxalate crystals (raphides) and there is often a protease enzyme present or other defense proteins. Konno, Inoue, and Nakamura, 2014 tested whether plants may be using a combination of defense mechanisms that increased effectiveness.
The purified calcium oxalate crystals from kiwi fruit and painted that on the surface of other produce either alone or with cysteine protease. The combination worked as an insecticide better than either the oxalate crystals or cysteine protease worked on their own. The addition of a small amount of the oxalate crystals increased toxicity of cysteine protease 16-32 times. The team suggest the plants are using the needle-like crystals as actual tiny needles to puncture an insect in order to improve entry of the defense proteins such as protease or chitinase. Calcium oxalate also has an amorphous form and testing that found that it did not work with the protease as an insecticide.
We are not insects, but an excess load of oxalate rich foods can feel like your digestive tract or bladder is full of tiny needles - painfully prickly. Painful to eat shortly after eating, and painful to urinate later. Lose/Lose situation. Avoiding oxalate rich sources is the solution - and possibly structured water.
I wonder if structured water helps the calcium oxalate to take the amorphous shape rather than the needle-like shape.
I seem able to drink a small amount of coffee when I make it the structured water way, while otherwise it tends to cause gut pain.
The quantum field effects of fluid help stabilize proteins. I have always like gelatin desserts because it seems a little like magic to have wiggly water that can hold a shape.
Having adequate calcium in the diet and vitamin C also helps to digest the oxalate. Plenty of water helps move it through.
Oxalate is an accumulative problem too. Does a meal have kale and buckwheat and black beans and pineapple? Or chocolate and dried blueberries, buckwheat, brown rice and almond flour and almond milk in a gluten free brownie? The additive load can lead to the needle-like pain, where having only one oxalate rich source at a meal or snack might not be uncomfortable.
Oxalate rich foods include varied plant foods, but beans, nuts, seeds and whole grains tend to have more.
Oxalate rich foods include kiwi, pineapple, cactus pears, rhubarb, taro and yucca/cassava root, beets, okra, buckwheat, cornmeal, soy flour, wheatberries, rice bran (brown rice), pumpkin and sunflower seeds, spinach, Swiss chard, soybeans, tofu has more than tempeh, miso, and sweet potato/yam. Variety can matter, curly kale has more than flatter Lacinto kale.
Black beans and many other beans, including soy are oxalate rich with a few exceptions listed below. Black chickpeas are lower oxalate and a good delphinidin source (black beans are also so I had way increased my use of black beans - and they can hurt in excess).
The skin on almonds, hazelnuts, cashews, and pistachios, walnuts and pecans to a lesser extent. Since almonds are suddenly being used in almond milk, crackers, flour, and many products - some people may be getting a big load of oxalates from those seemingly different foods.
What to do: Blanched almonds are the answer here - boil for about 2-3 minutes, drain, and the peels should slip off easily. Let the nuts redry for a crunchier texture or I like to refrigerate in a container and keep them softer. They take on a slightly cheese-like texture when boiled a little longer. Too short of a heating time and the peels won’t slip off easily. When the nuts are still damp, sometimes I toss them with powdered salt and rosemary and leave them in the fridge for a chewy snack instead of sharp crunchy mouthfeel.
When health is worse, the mucous membranes can repair slower and food that is sharper edged can cause abraded tissue and pain, (like almonds or potato chips or other really crisp snack foods or crackers). Combining almonds with soft and moist fruit like pears or bananas was more comfortable, or cracker and avocado, chips and dip. Adding the moistness helps the mouth soften the dry foods.
What to do: Cooking beans with a vigorous boil for ten minutes at the beginning of the cook-time may help breakdown the oxalates. Throwing out the pre-soak water can help too. Taro root or cassava/yucca root also need to be thoroughly cooked in plenty of water and throw out the cooking water.
Other oxalate rich foods include kiwi, pineapple, cactus pears, rhubarb, taro and yucca/cassava root, beets, okra, buckwheat, cornmeal, soy flour, wheatberries, rice bran (brown rice), pumpkin and sunflower seeds, spinach, Swiss chard, soybeans, tofu has more than tempeh, miso, and sweet potato/yam. Variety can matter, curly kale has more than flatter Lacinto kale.
This article about oxalate has a kidney stone focus, (WebMD), and lists oxalate content of a variety of foods. Not all of them bother me the same - portion control counts. Chocolate is an oxalate food and almonds and tofu - which are you likely to overeat if you are an overeater at times? Probably not the tofu - it doesn’t bother me as long as I buy non-GMO or organic. Fresh blueberries are okay for me, but using dried blueberries in baked goods was a problem - overeating blueberry chocolate chip bars might have been part of that.
This four-page (pdf) is a table of foods with oxalate content showing high, “Spinach (cooked) ½ cup 755 mg” and low oxalate foods and a few combination foods. Animal products and dairy are not oxalate sources except for the combined plant/dairy product chocolate milk.
Low oxalate choices include:
Flax seeds 1 tablespoon, 0 mg
Alfalfa sprouts ½ cup 0 mg
Bok choy (raw) 1 cup 1 mg
Broccoli ½ cup 1 mg
Brussel sprouts ½ cup 2 mg
Cabbage ½ cup 1 mg
Cauliflower (cooked) ½ cup, 1 mg
Celery (raw) 1 stalk, 3 mg
Corn ½ cup, 1 mg
Cucumber ¼, 1 mg
Endive ½ cup, 0 mg
Green Pepper 1 ring, 1 mg
Kale (chopped) 1 cup, 2 mg (which type though? look for the flatter Lacinto)
Lettuce 1 cup, 0 mg
Mung beans ½ cup, 3 mg
Mushrooms 1, 0 mg
Onions 1 small, 0 mg
Peas ½ cup, 1 mg
Radish 10, 0 mg
Rapini (chopped) 1 cup, 4 mg
Squash ½ cup, 1 mg
Water chestnuts 4, 0 mg
Zucchini ½ cup, 1 mg, (pdf)
Low oxalate fruits include: apples, apricots, bananas, cantaloupe, blackberries, blueberries (1/2 cup fresh), strawberries, cherries, grapes, lemons, limes, mango, Honeydew melon, watermelon, nectarines, peaches, papayas, pears, plums, orange or pineapple juice. Drying or canning pineapple increases the oxalate content and dried figs also have more oxalate content than fresh. (pdf)
Lower oxalate legumes include:
Black Eyed Peas, 3mg per 1/2 cup.
Lentils, 8mg oxalate per 1/2 cup. Moong beans/Moong dal/Mung beans were said to have zero in the (pdf). Moong/Mung beans are also a functional food. A medicinal extract is made with moong dal. “The mung bean has been documented to ameliorate hyperglycemia, hyperlipemia, and hypertension, and prevent cancer and melanogenesis, as well as possess hepatoprotective and immunomodulatory activities.” (Hou, et al., 2019) And they taste great with little other seasoning, a unique flavor. Why buy an extract when you can eat the beans was my thought.
Lima Beans, 8mg oxalate per 1/2 cup.
Green Peas, 1mg oxalate per 1/2 cup
Split Peas, 5mg oxalate per 1/2 cup. (dried green peas that have the outer coating removed and they dry in two halves. Split peas are used to make pea soup.)
Red Beans, 14mg oxalate per 1/2 cup
Kidney Beans, 15mg oxalate per 1/2 cup
Broad (or Fava) Beans, 10mg per 1/2 cup.
Butter Beans, 8mg per 1/2 cup. (Lima beans that are fully mature - very large, soft and starchy - The Kidney Dietitian listed them twice because they are so good and so different than the immature lima beans.)
Oxalate crystals may be causing other symptoms before kidney stones would be a diagnosis.
Why wait for a kidney stones diagnosis? They can cause excruciating pain at times. Kidney stones may be the eventual risk, but an excess of oxalate can also be a daily painful problem with a few weird symptoms that may be misidentified and treated as something else. “Indigestion - take a Tums.” “Painful urination - bladder infection?” More calcium from a Tums might help but not much. A wrong diagnosis leaves you still in pain if you are still eating too much of the foods that are causing the daily or fluctuating symptoms. Your favorites, your daily routine, is a good place to start looking when low-level discomfort becomes noticeable. Food sensitivities tend to occur with our most routine choices.
Oxalate pain for me was a prickly needle-like pain upon urination and also gut pain for a while after eating or a few sips of coffee. It hurt, a lot. Also, in the morning I occasionally have nausea and vomiting, and it seems to occur after I had too many oxalate foods the night before. Late night eating does seem to be harder on the gut no matter what the food, but example oxalate food: too many pistachios.
Rotation Diets can help reduce allergy or other food sensitivity risks and increase intake of trace minerals and other nutrients from the wider range of foods.
A rotation diet where the same foods are not eaten everyday year around can help reduce allergy or sensitivity risks. Many people eat wheat not just once a day, but several times every day.
Wheat = bread, buns, pizza crust, pasta, dumplings, crackers, cereal, tabouli salad, cake, doughnuts, cookies, pie, chicken nuggets, burritos, and more.
A way to assess for picky eating is to ask how many different base whole foods are used on a daily or weekly basis. Wheat would count as one food. Eating less than 15 foods on a routine basis is considered ~ picky eating. The tabouli salad would add tomatoes, parsley, onion, olive oil and lemon juice, and the wheat = 6 foods.
Who might need to keep oxalate food sources in mind besides kidney stone patients?
Vegans and maybe vegetarians too. When I cut out all animal products due to a suspected albumin autoimmune reaction (and it worked), I was effectively cutting out almost all protein foods that are oxalate free. When Klaus Schwab wants us to “Own nothing and be happy,” if the plan includes putting us all on a meat free diet, then low oxalate protein foods need to be considered. No one is going to be very happy if urinating feels like tiny needles.
Beans, nuts, seeds and grains are all oxalate sources - vegans need to be aware of oxalate risks and/or assure adequate calcium, vitamin C and water intake - possibly structured water intake - see this post.
Disclaimer: Opinions are my own and the information is provided for educational purposes within the guidelines of Fair Use. While I am a Registered Dietitian this information is not intended to provide individual health guidance. Please see a functional health professional for individual health care purposes.
(Hou, et al., 2019) Hou D, Yousaf L, Xue Y, Hu J, Wu J, Hu X, Feng N, Shen Q. Mung Bean (Vigna radiata L.): Bioactive Polyphenols, Polysaccharides, Peptides, and Health Benefits. Nutrients. 2019 May 31;11(6):1238. doi: 10.3390/nu11061238. PMID: 31159173; PMCID: PMC6627095. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6627095/
(Konno, Inoue, Nakamura, 2014) Konno, K., Inoue, T.A., Nakamura, M., Synergistic defensive function of raphides and protease, 2014, https://www.naro.affrc.go.jp/archive/nias/eng/research/h26/nias2014e-08.htm
Oxalate in Foods, St. Joseph’s Healthcare - Hamilton, (pdf)
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