The Excruciating Pain of Kidney Stones: 2 Most Common Types and How to Prevent Them

human urinary system kidney anatomy 3d illustration

Kidney stones are a common kidney disease, characterized by back pain and hematuria, and the pain they cause is so excruciating that it’s “impossible to forget for life.” Once a patient has kidney stones, he or she will have a high chance of having another one, so it is important to prevent them through diet.

Kidney stones are not painful when they first appear, so many people do not know that they have stones in their bodies.

They are usually diagnosed only when the kidney stone becomes lodged in the ureter, causing severe back pain and hematuria.

According to Dr. John Cijiang He, lifetime professor and chief of Nephrology at Mount Sinai Health System, the pain of kidney stones is something that’s “impossible to forget for life.”

Common causes of kidney stones include:

• Medical history: A past history of kidney stones or diseases that can cause kidney stones, such as gout, diabetes, obesity, gastrointestinal malabsorption, distal renal tubular acidosis, hyperparathyroidism, or certain genetic diseases;
• Family history: A history of kidney stones or urinary tract stones in the family;
• Medications: Intake of calcium and vitamin C supplements, diuretics, aspirin or anti-gout medications over a long period of time;
• Dietary habits: Inadequate water intake, high-sodium diet (penchant for foods with heavy flavors), high-animal protein diet or high-purine diet;
• Lifestyle: Holding in urine, low urination, or working in a high temperature environment where it is easy to sweat.

Generally speaking, if a kidney stone is less than 0.6 centimeters in diameter, drinking a lot of water can make the stone pass on its own.

However, if the size of a kidney stone is too large, extracorporeal shock wave lithotripsy can be performed to break the large stone into smaller pieces to facilitate its discharge.

What Measures Can Kidney Stone Patients Take?

There are five types of kidney stones: calcium oxalate stones, calcium phosphate stones, uric acid stones, infected stones, and cystine stones. Among them, calcium oxalate stones are the most common, while infected stones are relatively rare.

According to Dr. He, calcium oxalate stones and uric acid stones are the two most common types of kidney stones.

Calcium Oxalate Stones

As the name suggests, calcium oxalate stones are caused by too much oxalic acid intake. So it is important to eat minimal oxalic acid-rich foods, such as spinach, beets, nuts (including peanuts), and chocolate.

In addition, black tea is also a beverage containing oxalic acid, so we should not drink a lot of tea instead of water every day. According to a report published in the New England Journal of Medicine in 2015, a man in the United States drank about 4,000ml of black tea every day and didn’t like drinking water at all. As a result, a large number of calcium oxalate stones were found in his kidney sections. The doctor believed that the excessive oxalic acid was caused by his body’s inability to excrete the excessive amount of oxalic acid after drinking black tea for a long time.

Dr. He suggested that calcium oxalate stone patients might want to consume foods high in citric acid, such as lemons and oranges. If the concentration of citric acid in the urine increases, it can bind closely with the calcium in the urine, thus inhibiting the formation of calcium oxalate stones. And calcium citrate is more soluble and easier to excrete than oxalic acid. In addition, potassium ions can also inhibit calcium oxalate stones, so these patients can also eat foods high in potassium, such as bananas.

Uric Acid Stones

The formation of uric acid stones depends on the acidity of the urine. If the urine is highly acidic, the body is prone to form stones. Consuming a lot of alcohol and meat can also make the urine more acidic, so gout patients, who love drinking alcohol and eating meat, are also prone to uric acid stones.

These patients should reduce the amount of high-purine foods in their diet, such as animal offal and skins, and avoid drinking beer or alcoholic beverages containing wheat, in order to reduce the formation of uric acid. At the same time, they should eat a lot of vegetables to make their urine less acidic.

2 Methods to Prevent Kidney Stones

According to Dr. He, once someone has had kidney stones, he or she has a high chance (almost 50 percent) of having another stone. However, if he or she pays attention to his or her diet, the individual will have an 80 percent to 90 percent chance of preventing stones.

To prevent kidney stones through diet, there are two key points:

1. Drinking a lot of water, because when urine is diluted, stones are less likely to form
2. Eating a low-salt (low-sodium) diet, because when sodium ions are discharged through urine, calcium ions are also discharged and this will increase the calcium concentration in urine.

This in turn causes calcium and oxalic acid or phosphoric acid to combine, forming calcium oxalate or calcium phosphate stones. Therefore, in addition to reducing the use of condiments, we also need to reduce the consumption of canned and processed foods, as well as the intake of soup and pickled foods.

In addition, a study conducted at Harvard University pointed out that drinking carbonated beverages could result in kidney stones. Although this study is still controversial, Dr. He believes that we should not drink an excessive amount of carbonated beverages, especially those with added fructose, such as Coke, as they can also cause diabetes and other problems.

The popular vitamin C supplements should also be taken in moderation. The metabolism of vitamin C in the body produces oxalic acid. An excessive supplementation of high doses of vitamin C (such as oral tablets) will increase the concentration of oxalic acid in the urine.

Misconceptions About Kidney Stone Prevention Diet

People generally think that to prevent kidney stones, we should avoid eating calcium-containing foods, such as milk and tofu. In fact, there is no need to restrict calcium-containing foods.

Studies have shown that people who consume a lot of calcium are less likely to get kidney stones than the  average person, because calcium binds to oxalic acid in the intestines and is excreted, reducing the chance of calcium oxalate stones.

On the contrary, many studies have found that a low-calcium diet increases the chance of kidney stones.

This is because when the digestive tract does not provide enough calcium to bind with oxalic acid, the oxalic acid concentration in the body rises, increasing the risk of kidney stones.

There are also some online rumors that the combination of spinach, tofu, soy milk, and/or tea will increase the risk of kidney stones. It is believed that the combination of oxalic acid contained in both spinach and tea, and calcium in soy products, will form calcium oxalate stones. In fact, oxalic acid and calcium combine in the gastrointestinal tract and are mostly excreted. It’s only when you eat a lot of sodium (salt), the amount of calcium ions in your urine will increase.