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The Health Dangers of Oxalates

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Have you heard of oxalates? Oxalates (also called oxalic acid) are ingredients commonly found in plants and leafy greens. But just like many other acids, eating too much of them can be harmful. Find out more about the possible health dangers of oxalates below.

Most of us realize that we need to eat more greens and vegetables on a regular basis. Greens have some of the highest nutrient content of any food on the planet. But leafy greens also have a hidden component that not everyone knows about. This sneaky ingredient is oxalate (also called oxalic acid). How can this ingredient harm you?

What is Oxalate?

Oxalate is an organic compound found in most plants. You will find oxalates in seeds, nuts, fruit, vegetables, and nearly all plant matter. You can also produce oxalate in your body and synthesize it from vitamin C, which is necessary for certain processes in the body.

Oxalates are used for forming iron oxalate and calcium oxalate. Oxalates are used to expand and harden cells in plants, but in humans, most of the effects are negative. Your body can remove most oxalates through stool and urine, but if you are sensitive to oxalates, you are at higher risk for developing problems such as kidney stones or even renal failure.

The Problem with Oxalates

Oxalates can cause numerous problems in the body. Some of the most common side effects include: Reduced Mineral Absorption Oxalate binds to minerals in the gut and may prevent the body from absorbing nutrients. Although most leafy greens carry loads of vitamins, oxalates can prevent you from absorbing all of those beneficial nutrients.

Oxalate Can Reduce Mineral Absorption

One of the main health concerns about oxalate is that it can bind to minerals in the gut and prevent the body from absorbing them. A study from 1989 published in the American Journal of Clinical Nutrition found that the oxalates in spinach prevent much of the absorption of the nutrients in spinach. The fiber in spinach also prevents some nutrient absorption.

However, oxalates do not prevent the absorption of all vitamins. Part of the reason why leafy greens are so high in nutrients may be to counteract some of the oxalate blocking that reduces nutrient intake. Or, the oxalate content may be a part of the plant's defense system against getting eaten by cattle and other grazing animals.

Oxalates May Damage Kidneys

The combination of calcium and oxalates may be dangerous form some people prone to developing kidney stones. Part of the role of oxalates is to bind with calcium to form strong crystals, which may cause kidney stones in someone who is dehydrated or prone to develop stones through genetics. In fact, 80 percent of kidney stones are caused by calcium oxalate. If you have a lot of oxalate in your urine, a doctor may prescribe a low-oxalate diet to help reduce the risk of developing kidney stones.

Oxalate Foods are Healthy

Although oxalates can cause problems, usually the foods they are found in are quite healthy. Foods high in oxalates are often necessary as part of a balanced diet. Unless you have problems with kidney stones, there is no reason to fear oxalates, but being mindful of which foods are particularly high in oxalates can help you avoid eating these plants exclusively. A balance of low-oxalate and high-oxalate foods are typically part of a healthy diet. A food is considered high in oxalates if it has between 100 and 900 mg of oxalate per serving.

Eating foods on the lower end of the scale the majority of the time will ensure you get to use the nutrients you are eating.

Foods High in Oxalates


  • Turnip greens
  • Kale
  • Cocoa
  • Spinach
  • Beets
  • Swiss chard
  • Endive
  • Rhubarb
  • Sweet potatoes
  • Okra
  • Peanuts


Are Oxalates Ever Good?

It turns out, oxalates are not all bad or always bad. Some oxalate is used by bacteria in the gut as fuel for bacterial processes which can boost digestion and benefit the immune system. One bacteria uses oxalate as an energy source, meaning that you are absorbing much less than what the package states.

However, if you have lower levels of this bacteria, you will naturally absorb more oxalate and be at higher risk for developing kidney stones. It is impossible to determine if you have low or high levels of this bacteria, which makes determining whether to avoid oxalates trickier. However, research has found that individuals with inflammatory bowel disease and other gut disorders are also more likely to develop kidney stones.

So it could be possible that individuals with gut disorders are low in the bacteria that eat oxalates. In general, if you have taken a lot of antibiotics, have suffered from kidney stones in the past, or have family members who have kidney stones often you may want to consider avoiding oxalates in the diet.

The Low Oxalate Diet

If you do decide to go low-oxalate, it is generally advised to eat less than 50 mg of oxalate daily, if possible. You can also reduce the oxalate content of food in the following ways:


  • Boiling foods
  • Drinking water
  • Eating calcium


Foods Low in Oxalates 
  • Bok choy
  • Fish
  • Cheese
  • Broccoli
  • Yogurt

Do You Need to Avoid Oxalates?

Determining whether it is necessary to avoid oxalates is complicated. The answer is not the same for everyone. In general, if you eat mostly leafy greens or other foods high in oxalates, you may want to cut back for safety and to boost the nutrients you can absorb from all foods. If you have bowel problems or gut disorders a low-oxalate diet can also be helpful.

If you have had kidney stones in the past or a family member who has kidney stones often, cutting back on oxalates can act as a protective measure. However, if none of these situations apply to you, as long as you do not just eat oxalate-rich foods, you shouldn't have to worry about too much of them in your diet. Eat a varied diet, drink plenty of water, and exercise regularly and you will stay healthy.





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