Dietary taboos for patients with urinary stones

First, identify the composition of your own stones (more than 90% are calcium oxalate, calcium urate, calcium phosphate, and uric acid stones), and avoid excessive intake of high-risk foods.； Second, ensure adequate drinking water every day to dilute urine to reduce crystal deposition. ； Third, do not blindly supplement high doses of mineral and vitamin health products. All one-size-fits-all “absolute fasting lists” are myths.

I have been working in the field of urinary health science for almost 5 years, and I have seen too many patients throw away all the tofu, spinach, and strong tea at home just after breaking the stone. It is really unnecessary. Take calcium, which everyone is most afraid of, as an example. In the early years, the old concept did say that stone patients should limit calcium, but the 2023 version of the Urological Surgery Guidelines for the Prevention and Treatment of Urinary Stones has long been clear: Calcium in a normal diet (such as drinking a glass of milk every day, eating a piece of brine tofu) will not aggravate stones, but can combine with oxalic acid in the intestines, reduce the amount of oxalic acid absorbed by the body, and actually reduce the risk of stones. Only those who take extra high-dose calcium tablets (such as taking more than 1000 mg of calcium a day) should be cautious, especially when taken on an empty stomach, as the excess calcium will flow into the urine and increase the probability of crystallization. Two years ago, I met an aunt who was over 60 years old. She heard that taking calcium tablets can prevent osteoporosis. She took 2 tablets a day and drank high-calcium milk. As a result, she developed three calcium oxalate stones in six months. After she stopped taking extra calcium tablets, there was no recurrence after 2 years of follow-up.

When it comes to oxalic acid, everyone's first reaction is probably the old rumor that "spinach and tofu cannot be eaten together". Spinach, amaranth, strong tea, chocolate, and nuts with high oxalic acid are indeed high-risk foods for patients with calcium oxalate stones, but there is no need to fast: Blanching spinach for 1 minute can remove more than 70% of the oxalic acid. It is okay to eat less than half a bowl each time. Instead, the habit of making strong tea every day and chewing half a pound of nuts every day needs to be changed. Oh, by the way, spinach with tofu is actually safer than eating spinach alone - the calcium in tofu is just enough to combine with the oxalic acid in spinach and be excreted in the intestines, so it won't cause stones in the kidneys. This has long been clinically proven. Don't be scared by the old saying.

If you are diagnosed with uric acid stones, you don’t need to pay too much attention to dishes with high oxalic acid. The focus should be on foods with high purine. In the summer, the common skewers with cold beer can easily exceed the purine limit by three times in one meal. There is also the Laohuo soup that Guangdong friends love to drink, which has been simmered for more than 3 hours. The purine content is higher than that of meat. In addition, if you eat too much animal offal and shelled seafood, your uric acid will soar. Not only will you be prone to gout, but it will also form uric acid crystals in your urine, which will slowly pile up into stones. Last year, there was a 28-year-old Internet guy who ordered crayfish with cold beer every day while working overtime. He ate it for half a month. He was rolling in pain in the middle of the night and came to the emergency room. It was found that uric acid stones had blocked the ureter. He shed tears in pain and said that he would never dare to do this again.

There are also some invisible pitfalls that are easy to ignore, such as milk tea that many people like to drink, and carbonated drinks with a large amount of fructose syrup added, which will significantly increase the excretion of calcium and oxalic acid in the urine. The most exaggerated example I have seen is the post-00s generation who drank at least 2 cups of milk tea every day and broke stones twice in six months. The oxalic acid concentration in the urine test was more than three times higher than the normal value. After he changed the milk tea to plain water, it has not relapsed for almost a year. In addition, there is a lot of controversy about high-dose vitamin C: the current mainstream consensus is that vitamin C in daily diet (such as eating an orange or a few kiwi fruits every day) will not increase the risk of stones at all. Only supplementing more than 1000 mg of medicinal/health-care vitamin C every day will metabolize in the body to produce more oxalic acid, which will increase the risk of stones. So don’t just buy those high-dose vitamin C effervescent tablets and eat them blindly.

In fact, there is really no need to make dietary taboos a scourge. I have encountered too many patients who dare not eat or touch this after breaking the stone. After half a year, they are malnourished, which is not worth the gain. As long as the last time you passed stones or crushed stones, save a sample for a component analysis that costs tens of dollars to find out what kind of stones you have, and control the amount accordingly. If you are really craving for hot pot or two pieces of chocolate, then drink two more bottles of water to make the urine as clear as cold boiled water, and it will not be so easy to cause accidents. After all, compared with absolute taboos, maintaining a regular drinking habit and having an annual B-ultrasound review are the most effective ways to prevent recurrence.