Oxalates are produced in small amounts as a waste product of human metabolism but occur in very large amounts in some plants. Oxalates occur as a combination of oxalic acid with a mineral such as calcium and can cause pain, kidney stones and other issues over time. Some of the most popular and healthy foods are high in oxalates so we should understand how to deal with them.

Oxalates and plants

In humans oxalic acid is produced as a result of the breakdown of amino acids and is excreted in the urine. Oxalic acids has various uses in plants.

Plants make and use oxalic acid in a different way. Oxalic acid is formed as part of photosynthesis to regulate minerals but also as a defence mechanism against predators. Oxalic acid forms to protect from predation like animals, insects, and fungi. Animals that eat too much of it die unpleasantly unless they have well-developed oxalic acid detoxifying systems.

Humans on the other hand produce 10-30mg per day but don’t have much of it in bigger amounts. However we can invest through certain compounds such a spinach several hundreds of miolligrams . You could even ingest a thousands of milligrams of oxalates from a green smoothie! In sensitive people, even small amounts of oxalates cause burning in the eyes, ears and much more. People who eat large quantities of raw vegetables may be particularly susceptible. Approximately 75% of all kidney stones are composed primarily of calcium oxalate.

Symptoms of a high oxalate diet

Symptoms can vary as oxalate crystals can be deposited into almost any part of the body. Joint, tissues, cells !

The most common condition associated to oxalates is kidney stones, but the symptoms can vary a lot. Here are only some

  • Oxalate poisoning can happen when your chronic (daily) consumption of oxalates is so high that your body fails to clear it. 
  • Muscle pain. When oxalates bind to calcium in your blood, tiny, sharp oxalic acid crystals form and can be deposited anywhere in the body and cause muscle pain or weakness.
  • Burning in the mouth, eyes, ears, nose. In extreme cases it causes ausea, vomiting, or diarrhea. 
  • Blocking of thyroid production. Kale and other cruciferous vegetables like broccoli, cabbage, cauliflower, etc. can block production of thyroid hormones and inhibit iodine into the thyroid gland, which slows the production of thyroid hormones. Thyroid hormones such as T3 and T4 play an incredibly important roll in regulating your metabolism. If thyroid production slows down, your metabolism slows down, and your fat burning ability slows way down. Goitrogens are no joke. Reducing the amount of uncooked cruciferous vegetables (i.e. kale) you eat will reduce the amount of goitrogens you let in your body. 
  • Joint problems like gout, rheumatoid arthritis-like joint pains, stiffness, soreness, swelling etc. Oxalates’ ability to accumulate in joint spaces, to harm connective tissues, and to trigger inflammation has implications for joint tissues. Inflammation due to oxalate accumulation may: 1) induce pain, or 2) tightness that doesn’t respond to stretching exercises, and 3) lead to joint degeneration.
  • Osteoporosis, weak or broken bones, cracked teeth. Calcium is an oxalate magnet. As a chemically reactive metal, the calcium you need for strong bones and teeth combines readily with oxalic acid to form calcium oxalate. Oxalates can then accumulate in bones and teeth, displacing normal tissues and causing weakness, demineralization, and cysts.
  • Mineral deficiencies. Oxalates bind with minerals and not only with calcium. They can cause deficiency in iron, zinc, copper although the exact impact is not researced in depth at the time of writing.
Foods high in Oxalate

Unfortunately high sources of oxalate are some very popular and keto friendly foods. From highest to lowest, – buckwheat, black pepper, parsley, poppy seed, rhubarb, amaranth, spinach, chard, beets, chocolate, most nuts, most berries, and beans. Others include kale, radishes, cauliflower, broccoli, parsley, black pepper.

Nine types of raw and cooked vegetables were analyzed for oxalate using an enzymatic method. There was a high proportion of water-soluble oxalate in most of the tested raw vegetables. Your beloved spinach and kale green smoothies may be causing more harm than good! You could be easily take 1000mg in one take.

There are also sources which are low in oxalate, although there is a lot of variance. In general cabbage and lettuce are low in oxalates.


How to deal with oxalates

With some green vegetables in focus in this article, it’s also important to acknowledge steamed veggies provides a wealth of vitamins to support good health and performance.Green veggies like kale have a high concentrations of antioxidant vitamins A, C, and K. Just one cup of chopped steam kale contains 885 mcg of vitamin A. It also helps protect against infection from pathogenic organisms. The vitamin C found in kale facilitates tissue repair, boosts the immune system, and provides antioxidant protection against pathogens and toxins. Kale is also incredibly rich in vitamin K and suppr a wide variety of bodily functions, including normal blood clotting, antioxidant activity, and bone health.Because veggies like kale contain an abundance of health and performance optimizing vitamins, you should keep them in your diet but only if you take action against its built-in problems.

With the above in mind here are some suggestions.

Dosage is important

Keep the amount oxalates per day to around 100mg.  Avoid having big amounts of high oxalate foods in one meal.

Boiling / Steaming

Boiling markedly reduced soluble oxalate content by 30-80% and was more effective than steaming (50%). The losses of insoluble oxalate during cooking varied greatly, ranging from 0 to 70%. Because soluble sources of oxalate appear to be better absorbed than insoluble sources, employing cooking methods that significantly reduce soluble oxalate may be an effective strategy for decreasing oxaluria in individuals predisposed to the development of kidney stones.

Boiling your vegetables will cause the oxalate to “leach” out of them. Leaching is the extraction of certain materials from a carrier (in this case, your vegetable) into a liquid (the boiling water). A study of this process found that boiling fresh New Zealand grown spinach reduced the amount of soluble oxalate by more than 60%. (Plants carry both soluble and insoluble oxalate; it’s generally harder to reduce insoluble oxalate.) To leach your leafy greens, you can boil them in water for about 6-10 minutes, depending on the type of green. Once you have boiled and drained your greens, be sure to season them to taste with some spices, like garlic or mustard.

In general there is a big variance reported in how much oxalate is reduced by boiling/steaming, so don’t over-consume them.

Eat Veggies with Fat for Optimal Absorption of Vitamins

Many vitamins and micronutrients are fat-soluble, meaning they are not well absorbed without the presence of adequate fat. One study showed that people who consume salads with fat-free salad dressing absorbed far less of the helpful phytonutrients and vitamins from spinach, lettuce, tomatoes, and carrots than those who consumed their salads with salad dressing containing fat.

Calcium Loading

Because oxalic acid binds vital minerals in the gut, long-term consumption of foods high in oxalic acid can lead to nutrient deficiencies. When calcium supplements are taken with foods high in oxalic acid, the oxalic acid actually precipitates in the gut and drastically reduces the levels of oxalate absorbed by the body. Some cases show as much as a 97% decrease in oxalate levels.Additionally, a 1997 study showed that “mineral water containing calcium and magnesium deserves to be considered as a possible therapeutic or prophylactic agent in calcium oxalate kidney stone disease”. The best way to calcium load is not to take pills or drink water, but to toss your calcium carbonate and magnesium oxide supplements in the blender with your kale. Let the harmful oxalic acid precipitate out in the blender, so your body can filter it out when you drink it. If you allow free oxalic acid into your body without minerals at the exact same time, it will absorb into your body, then, depending on your genetics, infections, history, and your oxalate load, it can form crystals in your muscle tissue and/or kidneys.

Lightly steaming cruciferous vegetables for up to 30 minutes (far less helps) also significantly reduces the amount of goitrogens. In the same way lightly cooking vegetables also helps break down the cellular structures to increase the digestibility and nutrient absorption of nutrients in the vegetables. Nutrient absorption is also important in terms of the amount of energy your body is actually getting from the food you eat.

Use with Citric Acid

Always add lemon juice and/or apple cider vineger (ACV)

Oxalate dumping

Oxalate dumping is the process of removing of oxalates from the body through urine,stool, sweat or any other way the body can find. This is a healthy process but can mean there are side-effects which you need to be aware of

  • Gently reduce by 10% weekly.  
  • Symptoms of oxalate dumping can include a yeast flare, painful bowel movements, rashes or hives, grainy stools, pain with urination and irritability or moodiness.  
  • Alongside a good specific probiotic, I also use a binding agent such as activated charcoal, a good B6, calcium and magnesium citrate to bind to oxalates in the gut and a good quality high dose fish oil to reduce oxalates.
  • Sulfate helps get oxalates out of the cells so alongside magnesium sulfate (as a supplement) try taking salt baths.

Key Takeaways

  • Oxalic acid is something you should minimize no matter where it comes from. Limit to 100mg per day.
  • Avoid nuts and seeds.
  • Never add raw kale, spinach, or chard to salads or smoothies. Steam them first, drain them , add some fat, lemon/vinegar and some cheese.

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