Diet taboos for kidney stones

There is no unified list of taboos for kidney stones. The core principle is to first identify the components of your stones (80% are calcium oxalate, and the remainder are mostly urate, calcium phosphate, cystine stones, etc.), avoid high-risk foods in a targeted manner, and ensure that your daily water intake is 2000-3000ml. Blindly avoiding all foods will increase the risk of stone recurrence due to nutritional imbalance.

I used to sit in the outpatient clinic with a teacher in the Department of Urology for half a year, and eight out of ten patients who came for review had fallen into the trap of "one size fits all". What impressed me the most was a 32-year-old programmer. A 0.4cm calcium oxalate stone was found during a physical examination. He searched the taboo list on the Internet and dared not touch spinach, celery, oranges, or even tofu. He ate polished rice and white noodles with boiled chicken breasts every day. After three months of reexamination, not only did the stone grow to 0.6cm, but it was also found that his blood uric acid was high. He caught a cold during the change of season, and his immunity was greatly reduced.

In fact, many of the taboos posted on the Internet are for the most common calcium oxalate stones, but even with calcium oxalate stones, high oxalate foods are not completely off limits. For example, spinach, which everyone avoids, can remove 70% of the oxalic acid by blanching it in boiling water for one minute. It is not burdensome to eat half a bowl at a time. On the contrary, the dietary fiber and potassium in it can help the body regulate metabolism. If you really don't touch it at all, the body lacks citric acid that inhibits the formation of stones, and it is easier for oxalic acid and calcium to clump together in the kidneys. Oh, by the way, there is still controversy about whether soy products can be eaten: the old version of clinical guidelines would recommend limiting the consumption of soy products, but multiple urology studies in the past three years have shown that processed soy products such as brine, tofu made with gypsum, and dried tofu contain oxalic acid. Most of it is lost during processing, and it also contains a lot of citric acid. Eating about 100g a day can actually reduce the risk of recurrence. Only unprocessed whole soybeans and homemade coarsely ground soy milk need to be controlled in intake. There is no need to hide from tofu when you see it.

If you are found to have urate stones, the contraindications and calcium oxalate stones are completely different. Such patients do not need to worry too much about the oxalic acid content, but should focus on high-purine foods. Don’t believe it. There was a 28-year-old young man who ate barbecue and drank cold beer for a week in the summer. He was rolling in pain in the middle of the night and rushed to the emergency room. It was found that the uric acid stone was blocked in the ureter. Previously, he followed the online list and avoided spinach for half a year, so he was busy. For this type of patients, they really need to avoid animal offal, shelled seafood, and rich broth, and they should stop drinking beer as much as possible. Otherwise, after a meal of crayfish, the blood uric acid will soar by several hundred, and new crystals will immediately grow in the kidneys.

There is another misunderstanding that has been circulating for more than ten years: Can’t you take calcium supplements if you have stones? It really screwed a lot of people up. Clinicians now recommend that everyone consume calcium-containing foods normally. For example, drinking 300ml of milk every day is absolutely fine. The calcium in the food will combine with oxalic acid in the intestines and be excreted with the feces, which can actually reduce the oxalic acid content in the blood. ； If you deliberately starve without taking calcium supplements, all the oxalic acid in the intestines will be absorbed into the blood and run to the kidneys, and stones will grow faster. Of course, you should be cautious when taking extra calcium supplements. It is best to ask your doctor for advice first, and do not buy random supplements on your own.

To be honest, some daily habits are more noteworthy than memorizing a complex list of taboos. Don't make strong tea, drink strong coffee every day, and drink Coke as water. There used to be a 16-year-old high school student who almost didn't drink water in the summer and relied on iced Coke to quench his thirst. A physical examination revealed a 2cm large stone. In the end, he had a minimally invasive surgery, which was blamed by his boss. People who cook with less salt and eat heavy takeaways will have several times higher calcium content in their urine than people who eat light meals, and the recurrence rate of stones will also increase accordingly.

I now like to tell the patients who come for follow-up consultations that if you don’t get stones, you should become an ascetic and not dare to eat anything. Take the time to go to the hospital for a stone composition analysis, adjust your diet, drink more warm water when you have nothing to do, don't wait until you are thirsty to pour water, walk two steps more after get off work and don't sit every day, the probability of recurrence can be reduced by more than 60%, and you won't have to worry about the list of taboos every day.