Dietary taboos for kidney patients

Eating high-salt foods without restraint, excessive or insufficient protein intake, not controlling the intake of high-potassium and high-phosphorus foods even after renal function is damaged, and indiscriminately taking "kidney-tonifying" folk prescriptions/health products. All other taboos must be individually adjusted based on your renal function stage, urine protein level, and underlying disease conditions. Do not just copy the list of taboos from patients.

I didn’t just say this casually. Last week, I met Aunt Zhang, a 52-year-old woman with CKD stage 3 membranous nephropathy, who had gone through a detour. I heard from fellow patients in the same ward that patients with kidney disease should never touch soy products, so I quit tofu and soy milk for three months. This time, the albumin was 2g lower than last time, and her legs were so swollen that she couldn’t wear the original cotton shoes. When I asked her carefully, she didn’t even dare to eat more eggs. She only drank white porridge with vegetables every day. The protein intake was not enough, and the edema worsened.

Let’s talk about the salt control that everyone is most familiar with first. Among the patients I’ve seen, many go to two extremes when it comes to salt control. Either he didn’t dare to add any salt and boiled everything he ate. Within half a month, he felt weak all over, felt nauseous and fainted. After being diagnosed with hyponatremia, he had to be hospitalized for sodium supplementation. ； Either he couldn't control his mouth and secretly ate pickles, bacon, or processed snacks. His blood pressure soared to 160 and he couldn't lower it, and his urine protein also increased. Current mainstream guidelines recommend that patients with CKD stage 1-2 should limit their daily salt intake to less than 5g, which is about the amount of a beer bottle cap. Patients with stage 3 and later or those with high blood pressure or edema should reduce their salt intake to 3g. However, some clinicians believe that patients who often work outdoors and sweat a lot should not be so stuck. It is okay to eat more occasionally. Otherwise, hyponatremia will occur, and the body will become weak and unable to stand, which will be more than worth the gain.

The pitfalls of soy products like Aunt Zhang's are actually the most widely spread misunderstanding among kidney friends. Here are two different opinions in the industry. In the early years, nephrology diagnosis and treatment did recommend that patients completely avoid soy products, believing that plant protein metabolism wastes a lot and will increase the burden on the kidneys. However, evidence-based medicine in recent years has made it clear that the protein of soybeans (soybeans, black beans, green beans) is high-quality protein, and the amino acid ratio is very consistent with the needs of the human body. It is not essentially different from eggs, milk, and lean meat. The saturated fat content is even lower than that of red meat, making it more suitable for kidney patients with hyperlipidemia. Nowadays, many young doctors will clearly tell patients that as long as the total protein amount is controlled to the standard, tofu and soy milk are completely OK to eat. Only some old doctors who are accustomed to using old experience will advise to avoid it. You don’t have to worry about who to listen to. As long as your attending doctor does not clearly say that you can’t eat it, it is perfectly fine to eat some soy products to change the taste. The specific amount is actually easy to calculate. For patients with CKD stage 3 or above without dialysis, the daily protein intake should be controlled at 0.6-0.8g per kilogram of body weight. For example, a 60-kg person should eat 1 egg, 1 box of 250ml pure milk, 1 tael of lean pork, and A piece of northern tofu of about 100g has a total protein content that is just within the safety line and will not put a burden on the kidneys at all. If you have started regular dialysis, your protein intake will have to be increased. Instead, you need to eat more high-quality protein, otherwise you will not be able to survive even dialysis due to malnutrition.

Let’s talk about the high-potassium and high-phosphorus foods that many people are afraid of. In fact, not everyone should avoid them. If you are a CKD stage 1-2 patient with good kidney function and normal urination and potassium excretion, it is no problem to eat some bananas, oranges, fungi, and nuts on a daily basis, and there is no need to deliberately limit food. ； But if you have reached CKD stage 3b or later, or have been on dialysis, and your daily urine output is less than 1000ml, you need to be a little more careful. This does not mean that you cannot touch one bite. Cut and soak high-potassium vegetables for half an hour, blanch them and then fry them, which can remove more than 30% of the potassium. It is perfectly fine to eat a few bites occasionally to satisfy your cravings. By the way, I would like to mention low-sodium salt here. Ordinary people eat it healthily, but people with poor kidney function should not touch it. It contains a lot of potassium chloride, which cannot be excreted and stays in the body. If the blood potassium is higher than 6, it can induce cardiac arrest. Last year, I received an old man from the emergency department who had hyperkalemia after eating low-sodium salt for half a month. When he was delivered, his heart rate dropped to 40, and he almost couldn't be saved.

The last taboo to mention is really fatal - random supplements. Many kidney lovers always think that "what you eat will replenish you" and they eat stewed pork kidneys every now and then. In fact, the purine and cholesterol content of pork kidneys are very high, which not only fails to replenish the kidneys, but will increase uric acid and blood lipids, increasing the burden on the kidneys. There are also many people who are looking for "kidney-tonifying folk prescriptions" everywhere, including local recipes, health products with unknown ingredients, and Chinese herbal medicines claimed to be able to "radically cure kidney disease." There used to be a 28-year-old young man who originally had mild IgA nephropathy and only 0.5g of protein in his urine. I heard from relatives that the folk prescriptions of an old Chinese doctor were very effective. After taking it for half a year, he directly developed uremia. Now he needs dialysis three times a week. It's a pity. In particular, Chinese medicinal materials such as Guanmutong and Fangchi containing aristolochic acid have been confirmed to be nephrotoxic, so do not touch them.

In fact, every time I talk to patients about diet, I don’t like to make a full-page fasting list. The diet for kidney disease should be flexible. If you really want to eat a bite of watermelon in summer, as long as your kidney function is normal and your urine output is normal, what’s wrong with eating one or two pieces? It's better than holding back your mood and causing your blood pressure to rise. Last time, there was a young man who was undergoing regular dialysis. He heard others tell him not to eat oranges, but he didn’t eat them for half a year. His blood potassium was as low as 3.0 during the retest, so he had to take oral potassium supplements. Do you think this is a torment?

If you are really unsure about what to eat, during your next check-up, just casually mention a few things you have eaten in the past week to the nephrologist and ask him or her to help you check. This is much more reliable than searching online for a long time and listening to random rumors from patients.