Will Eating Tomatoes Really Cause Kidney Stones?

Kidney stones are known medically as urolithiasis and are hard deposits of minerals and salts that occur in the urinary tract. As the name suggests, kidney stones are solid pieces that resemble stones and although they rarely cause permanent damage, they often cause a lot of pain as they pass through the urinary tract. Bigger stones require kidney stone treatments such as extracorporeal shock wave lithotripsy (which uses shock waves to break the stone) or even surgery but smaller stones can be treated with a specific and personalized diet for kidney stones. You may have heard that tomatoes cause kidney stones but is there any truth to it?

Types Of Kidney Stones

To understand how tomatoes can affect kidney stones, it is important to differentiate between the various types of kidney stones. There are 4 types of kidney stones.

Calcium Kidney Stones

This is the most common type of kidney stone. It occurs when calcium combines with oxalate to form a stone.

Uric Acid Kidney Stones

This type of stone occurs when your urine is highly acidic.

Struvite Kidney Stones

This type of stone occurs when your urine has a high alkaline value. If you've recently suffered from a bacterial infection in your urinary system, you are at a higher risk of getting a struvite stone as the bacteria make urine alkaline.

Cystine Kidney Stones

Cystine stones are caused by the excess of cystine in the urine. These stones run in families and are very rare.

Why Tomatoes Are Bad For Kidney Stones

Calcium kidney stones are the most common type of stone and they are a combination of calcium and oxalates or oxalic acid. Oxalic acids are present in plant tissue so when we consume these vegetables, the oxalic acids pass through the kidneys before they are excreted from our system. If your consumption of foods high in oxalic acid is high, your kidneys might not be able to excrete all the oxalic acids and these acids may combine with the calcium in your system to form a kidney stone. Tomatoes have a relatively high



oxalic acid content which is why your doctor will tell you to reduce your intake of tomatoes if you have a calcium kidney stone. You should also avoid packaged tomato juice as preserved juice has a higher level of oxalates as compared to fresh juice. Avoid ketchup and other condiments that are made from tomatoes. You would also have to avoid other high oxalate foods such as spinach, beet, and soy products. Chocolates, potato chips and French fries are also very high in oxalates which is why almost every kidney stone diet plan will not contain these foods. There is evidence that links colas with kidney stone formation, so it would be wise to avoid them altogether if you have a stone or if your doctor tells you that you are at a high risk for a kidney stone.

Do Tomato Seeds Cause Kidney Stones?

Earlier it was believed that tomatoes seeds as well as seeds from other fruit such as the guava would get lodged in the kidneys and then a kidney stone would form around it. This is not possible as the kidneys are not connected to your stomach or your digestive system. When you eat a tomato, it travels through your stomach and digestive system and the nutrients from it are absorbed into your system. The fluids from the tomato are absorbed by the cells that line your intestinal tract and this water then enters your bloodstream. After that, your blood is filtered through your kidneys and the excess water moves to your bladder where it can be excreted in the form of urine. This is why it is just not possible for a tomato seed to get stuck in your kidneys.

Kidney stones are not a life-threatening health condition but that does not mean that you should ignore this problem. If you experience a sharp or dull pain in your abdomen or lower back (near your kidneys), if you experience a sudden increase in urination frequency, or if you notice any other kidney stone symptoms, contact your doctor immediately. If you have a small stone, it is likely that your doctor will suggest a kidney stone diet along with an increase in fluids so that you pass your kidney stone naturally.