Oxalic Acid and Your Health

Oxalic acid is a strong acid that is about 3,000 times stronger than acetic acid, a chemical name for ordinary vinegar. It’s a chemical substance that has chemical formula of C2O2(OH)2. 

According to the Nutrient Data Laboratory of USDA, oxalic acid (g/100g) content of selected vegetables are: amaranth (1.09), asparagus (.13), beans, snap (.36), beet leaves (.61), broccoli (.19), brussels sprouts (.36), cabbage (.10), carrot (.50), cassava (1.26), cauliflower (.15), celery (.19), chicory (.21), chives (1.48), collards (.45), coriander (.01), corn, sweet (.01), cucumbers (.02), eggplant (.19), endive (.11), garlic (.36), kale (.02), lettuce (.33), okra (.05), onion (.05), parsley (1.70), parsnip (.04), pea (.05), pepper (.04), potato (.05), purslane (1.31), radish (.48), rutabaga (.03), spinach (.97), squash (.02), sweet potato (.24), tomato (.05), turnip (.21), turnip greens (.05), and watercress (.31).

In general, oxalic acid is a naturally occurring component in plants, and is especially found relatively high concentrations are found in dark-green leafy vegetables such as spinach and beetroot. Tea, chocolate as well as cocoa products have more oxalic acid with much higher concentrations than in even star fruit.

Tomatoes have very little oxalic acid as compared to spinach. Other foods like potatoes and white bread are found to have contained much more oxalic acid than tomatoes. 

A low oxalate diet should provide less than 50 mg oxalate per day. Certainly, a diet which includes cocoa, coffee, tea and spinach will cause more accumulation of oxalic acid in our body as compared to eating the same weight of star fruit.

Oxalic acid which is present in lower level in plant-based foods does not act as a neurotoxin just like mercury. It certainly does not link directly to create Fenton reactions in the body which usually results in significant clinical symptoms, or to be more exact relatively low amounts of oxalate in foods are unlikely to harm our health. 

A variety of green leafy vegetables and nuts are packed with relatively much higher amounts of oxalate in comparison to most fruits. However, it’s certainly that one shouldn’t avoid eating vegetables just because of the present of oxalic acid. This is because vegetables are excellent sources of carotenes, vitamin K, lutein, potassium and magnesium, folic acid as well as vitamin C which offer essential nutrition for healthy eyes. 

The actual toxicity of rhubarb is in its leaves which are the part that you normally eat. Since the levels of oxalic acid are so high in rhubarb leaves, they can pose a threat to our health. Eating eleven pounds of rhubarb leaves is a lethal dose to cause one feeling very sick. Concentrations of oxalic acid are pretty high in chard, beet greens and spinach to cause the interference of the calcium absorption these plants contain. Due to the interference of oxalic acid, you’ve to eat more than 16 cups of raw or more than 8 cups of cooked spinach to get the similar amount of calcium available in one cup of yogurt even though one half cup cooked spinach contains 115 mg calcium.

As far as calcium is concerned, one should make an attempt to meet a daily calcium intake. For females, it is suggested to take a total daily calcium intake of 1,000 to 1,200 mg per day from a variety of sources (also include 500 to 700 mg of supplements such as calcium citrate in two divided doses taken along with meals), while for males, it is suggested for them to aim for 500mg per day from a variety of sources unless they’re lacking calcium intake from meals. Males are encouraged not to be in higher calcium intake as it has been linked to an increased risk of prostate cancer. 

The toxicity risk of oxalic acid obtaining from foods is not immediate, but over the time, it contributes to the development of oxalate crystals. Specifically, there is no direct poisonous risk from ingestion of fruits and vegetables as compared to the consumption of drugs and antibiotics. The problem arises from the “stones” that tend to act as an oxidative –stress inhibitor that disrupt the oxidation of calcium oxalate into water and carbon dioxide. That means oxalate crystals that were developed in the body can’t be thoroughly metabolised and thereby causing irritating and discomfort feeling. 

As it appears, eating appropriate amount of fruits and vegetables doesn’t introduce much more oxalic acid into the body to cause immediate toxicity. We have long been exposed to small amounts of oxalic acid for years; so basically, lower amounts of oxalic acid are unlikely to do harm to our body. This is different from the oxalate poisoning from sodium oxalate seen in most industrial chemicals which has been observed to cause much more clinical problems than eating fruits and vegetables in normal portions. The chemical property of pesticides such as antimycin A and mercury compounds are found to produce oxidatively damaged cell membranes and mitochondria ending in immediate poisoning and clinical conditions while one ingests foods contaminated with ingredients of pesticides. 

Final remark:

The degree of how higher amounts of oxalate diets can cause a potential health threat to one’s health depends much on one’s existing health condition and eating pattern. Caution is particularly exercised for those who are prone to oxalates, particularly those with rheumatoid arthritis, kidney stones, gout, kidney disorders or some particular forms of chronic vulvar pain (or called vulvodynia) which may require a careful attention regarding their oxalic acid intake. For a normal healthy person, the exposure to a potential health risk of oxalic acid is slight unless they have been consuming unusually large amounts of oxalate diets on a long-term regular basis.