Many fruits and vegetables are healthy. But a vegetarian diet can also cause problems. Oxalates, for example, which are mainly found in plant products, can cause kidney stones or promote bone loss.
We asked the Bielefeld nutrition expert and personal trainer Sinja Niedringhaus what exactly oxalates are, how they work in the body and which foods contain a particularly large amount of oxalates.
What are oxalates?
Oxalates are the salts of oxalic acid. They are formed as a metabolic product in the human body and are primarily formed when various proteins, vitamin C or fructose are broken down. Oxalates can therefore also be ingested through food. Normally, the oxalates are harmless to humans. But as always, the dose makes the poison – and if we consume too much oxalic acid, it can cause various health problems.
«Oxalates are so-called antinutrients,» explains Sinja Niedringhaus. «They limit the utilization of certain nutrients in the body and are harmful above a certain amount.» One problem is that the oxalates bind calcium and then calcium oxalate stones – also known as kidney stones – form. «Anyone who already suffers from kidney disease should therefore avoid foods rich in oxalate.» The nutrition expert also recommends that vegans take supplements with minerals such as calcium.
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How much oxalate is unhealthy?
The amount of oxalate that causes problems varies from person to person. In addition to weight and general physical fitness, your own metabolism also plays a significant role. Experts recommend that we no more than 50 milligrams of oxalate per day take to us. However, only a dose of four to five grams of oxalate is acutely life-threatening.
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Which foods are high in oxalate?
“Oxalates are mainly found in fruit and vegetables. However, only a few types of vegetables such as spinach or rhubarb have a high oxalate content,” says Sinja Niedringhaus. In contrast, oxalate is hardly found in meat, fish and most dairy products. Here is an overview of foods that are particularly high in oxalate:
- cashew nuts
- peanuts
- hazelnuts
- cocoa
- chard
- Parsely
- rhubarb
- Beetroot
- sorrel
- Black tea
- spinach
- wheat bran
«If you don’t want to do without these foods, you should pay attention to the way they are prepared. Because by cooking or soaking, the oxalate content can be reduced,” recommends the nutrition expert.
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Which foods are low in oxalate?
Of course, if you want to be on the safe side, you can also remove foods that are particularly high in oxalate from your shopping list. After all, there are plenty of alternatives, as this list shows.
- Lamb’s lettuce
- Chicken
- yogurt
- potatoes
- lamb meat
- milk
- paprika
- Quark
- radish
- beef
- Rye bread
- pork meat
- asparagus
- tomatoes
But be careful: Eating too much meat can also cause kidney problems. In addition to healthy meals, we should also make sure to drink enough water. It may already be 2.5 liters. The water helps the oxalic acid to be eliminated more quickly, reducing the risk of kidney stones and other health problems.
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«Anyone who eats a varied diet usually doesn’t have to worry about their oxalate levels,» says Sinja Niedringhaus. «If you still have concerns, you should consult a doctor and get certainty.»