In recent years, an increasing number of people have been diagnosed with stones, and reports linking "eating tofu to kidney stones" have become common. Are these "little stones" in the body really caused by diet? To find out, a reporter interviewed Cai Donglian, Chief Physician of the Department of Nutrition at Changhai Hospital, affiliated with the Second Military Medical University.
Data shows that China has become one of the countries with the highest incidence of kidney stones, with the rate exceeding 10% in some southern regions. Cai Donglian explained that there are many reasons for stone formation in the human body. Besides living in hot climates, getting too little exercise, and suffering from certain diseases, poor eating habits are also a significant cause. In summary, there are several main dietary habits that can make one prone to stones.
Drinking too little water or poor-quality water is the easiest way to trigger stones. Common kidney stones are related to long-term insufficient water intake. 70% of the human body is water, and its metabolism and detoxification require large amounts of water. Too little water intake increases blood concentration and the burden on the kidneys, leading to concentrated urine, which can easily cause stones. It is recommended that adults drink at least 8 glasses of water a day. Cai Donglian noted that drinking water in some areas is hard water, with high levels of crystals and calcium, which can increase urinary calcium in the body and lead to stone formation.
Consuming too many high-protein foods. For example, people who frequently eat too much meat or even treat meat as a staple food. After protein is digested and metabolized in the body, it increases the acidity of urine. To balance the pH of the urine, the body releases alkaline calcium, which can then form stones with uric acid in the urinary system. Adults need 60-80 grams of protein per day, and people who often overeat are likely to exceed this limit. They can eat more fruits and vegetables and correspondingly reduce meat intake.
Eating too salty is risky. When high salt content in the body is excreted in urine, it also increases the amount of calcium excreted, raising urinary calcium levels. This makes it easier for calcium to bind with oxalate in the urine to form stones. When cooking, use steaming or boiling instead of frying, add salt only after the dish is served, and eat less high-salt foods like pickles and sauces.
Eating too many foods high in purines. Such as animal offal and seafood. The metabolic product of purine is uric acid, and high levels of uric acid can lead to uric acid stones. When eating purine-rich foods, it is best not to drink alcohol. Instead, drink more water to increase purine metabolism and excretion.
A diet high in fat. Fat can hinder uric acid metabolism, leading to an increase in uric acid concentration in the blood. When water intake is insufficient, this can easily lead to stone formation. After eating fatty foods, it is even more important to drink more water to avoid stones.
In addition, Cai Donglian also listed several common misconceptions in daily life about "eating your way to stones."
Misconception 1: Eating spinach and tofu soup causes kidney stones. Vegetables like spinach contain large amounts of oxalate, and tofu is rich in calcium. People believe that eating them together produces common calcium oxalate stones. Cai Donglian stated that while spinach and tofu together do form calcium oxalate, it is not absorbable by the human body and does not enter the urinary system. Instead, it is excreted through feces along with other undigested food residue and does not cause stones. By the same logic, the oxalate in milk tea will not cause stones either.
Misconception 2: Eating calcium-rich foods causes kidney stones. Many people are afraid of getting stones and avoid eating tofu or drinking milk. Cai Donglian explained that the average person or even a stone patient does not need to deliberately avoid calcium-rich foods. The components that form stones only precipitate under specific urinary pH conditions. On the contrary, sufficient calcium binds with oxalate in the intestines to form calcium oxalate, which is not easily absorbed, thus preventing stone formation. It is recommended that adults drink 300 ml of milk daily to meet their calcium needs for the day without worrying about excessive calcium causing stones.
Misconception 3: Eating too many foods high in vitamin C causes kidney stones. Vitamin C is metabolized in the body into oxalate, and some people worry that eating too many vitamin C-rich foods will increase oxalate concentration in the urine. Research has confirmed that a large intake of vitamin C in the diet is not related to the formation of calcium oxalate stones. Cai Donglian stated that unless one consumes massive amounts through supplements, the amount of vitamin C obtained from the diet is not enough to be a cause of stones.
Misconception 4: Drinking beer can prevent kidney stones. This saying comes from the diuretic effect of alcohol and water in beer. Research shows that while the diuretic effect of alcohol can help with urination in the short term, drinking too much causes faster water loss through frequent urination, which can more easily lead to stone formation.