Diet taboos for kidney patients

There are no universal absolute dietary taboos for kidney disease. All taboos must be dynamically adjusted based on your pathological type, kidney disease stage, and current indicators. There is only one core principle—don’t put additional burden on the already diseased kidneys. Those who say "all kidney patients cannot eat soy products and salt" are all one-sided, so don't believe them blindly.

Let me tell you something I encountered in the outpatient clinic last week. Aunt Zhang, 62, has stage II membranous nephropathy. Her creatinine is completely normal, but her urine protein is always 3+. She heard from neighbors in the community that people with kidney disease need to eat a vegetarian diet to nourish their kidneys. She even stopped eating eggs and milk. She only eats vegetables and white rice every day. After three months, her albumin dropped to 26g/L. Her legs were so swollen that she couldn't even lift her pants. The hormones she used to be effective were compromised due to malnutrition. In fact, the kidney is like a water purifier at home. Half of the filter element is already broken. If you pour sewage and impurities into it every day, it will definitely break down faster. But if you want to protect it and don't even let clean water pass through it, it will gradually become clogged, which is useless.

Let’s first talk about the salt issue that people are most likely to go to extremes. There was a 28-year-old young man with IgA nephropathy. He was afraid of edema, so he didn't even dare to touch low-sodium salts. He ate all his meals without soy sauce. As a result, within a month, he was so weak that he couldn't even go to work. An electrolyte test revealed that he had hyponatremia, which actually affected the blood perfusion of the kidneys. The gain outweighed the gain. There are actually different opinions about salt intake. The old-school view would suggest that as long as you have kidney disease, you should strictly limit salt to less than 3g. However, the latest clinical guidelines are more inclined to personalization: if you are in stage 1-2 of kidney disease and do not have high blood pressure or edema, it is enough to control salt within 5g per day, which is about the amount of a beer bottle cap. There is no need to be hard on yourself. ； If you already have edema, high blood pressure, or your kidney function drops to stage 3 or later, then reduce the salt amount to 3g. But no matter what the situation, salt must not be completely cut off, and low-sodium salt must be eaten with caution. It contains a lot of potassium chloride, which people with poor kidney function cannot excrete, which can easily cause hyperkalemia. In severe cases, it can directly affect the heart. This is a red line that has been repeatedly emphasized in clinical practice.

After talking about salt, let’s talk about the protein issue that everyone is arguing about the most. Ten years ago, many doctors would tell patients that "you should not eat soy products if you have kidney disease." Now this view has long been overturned. Kidney disease guidelines at home and abroad have clearly mentioned that soy protein is a high-quality protein, and its amino acid structure is highly matched to the needs of the human body. It is similar to that of pigs. There is no essential difference between animal proteins such as cattle, sheep, eggs, and milk. As long as you don’t have gout or high uric acid problems, drinking a cup of sugar-free soy milk and eating less than half a bowl of tofu every day is completely fine. It is much more reliable than eating health products with unknown ingredients that are said to “nourish the kidneys.” Of course, it depends on the situation. If you are currently in a period of massive proteinuria and leak more than 3.5g of protein every day, then the protein intake should be controlled at 0.8-1.0g per kilogram of body weight per day. For example, for a 60-kg person, one egg a day, a cup of 200ml milk, one or two lean pork, and a small bowl of tofu are just enough. If you take too much, your glomeruli will be in a state of "high-pressure protein leakage" for a long time, which will harm the kidneys. ； But if you have started regular dialysis, you should eat more protein instead, because a lot of nutrients will be lost during dialysis. Many dialysis patients end up losing either to kidney disease or malnutrition. At this time, if you continue to control protein according to the previous standards, it will drag down the body.

There are also high-potassium and high-phosphorus foods that everyone often asks about. Not everyone needs to avoid them. I have seen many young people who have just been diagnosed with proteinuria + and stopped eating bananas and oranges. It is completely unnecessary. Only when your glomerular filtration rate drops below 30ml/min, or your creatinine has increased, and your blood potassium and phosphorus have exceeded the standard, you need to specifically control: high potassium foods such as winter dates, bananas, and oranges. If you want to eat them, cut them into small pieces and soak them in water for half an hour and then boil them. Most of the potassium can be removed, and it is no problem to satisfy your cravings. ； The main sources of high phosphorus are additives in processed foods, such as ham sausages, instant noodles, prepared dishes, and commercially available milk tea drinks. These phosphorus are all inorganic phosphorus and have a very high absorption rate by the human body. Just try to touch them as little as possible. I’m not being alarmist. Last year, an old man who was on regular dialysis secretly ate half of an iced watermelon in the summer. His blood potassium rose to 7.1mmol/L that night. He was sent directly to the emergency room for intubation to lower the potassium. He almost had a serious accident.

As for issues such as drinking water and whether to eat spicy food, it is more flexible. People with no edema and normal urine output can just drink 1500-2000ml of water every day. Don't hold back your urine or deliberately pour a lot of water to burden the kidneys. ； If you already have obvious edema, oliguria, or are in the dialysis stage, then live within your means. Add 500ml to the previous day's urine output to get the total water intake that day. The water in porridge, soup, and fruits must be included. Some people ask if they can eat spicy food with onion, ginger, garlic. As long as you don’t have sore throat or high uric acid, it’s absolutely fine to eat some seasoning. If you have kidney disease, you have many restrictions. If you make the food bland and in a bad mood, it will not be good for your condition.

I have been in the Department of Nephrology for almost ten years and have seen too many patients who go to extremes. They either eat hot pot and barbecue with cold beer and their creatinine has doubled in half a year.； Either they dare not eat anything, become so thin that only a handful of bones are left, and their immunity is so low that they easily get infected, which in turn accelerates the progression of kidney disease. To be honest, the diet for kidney disease is never a one-size-fits-all standard answer. We often say in clinical practice that the diet plan for kidney disease is more "one person, one diet" than medication. Ask your attending doctor "What should I pay attention to when eating recently" during each review, which is more effective than searching for ten general taboos on the Internet. After all, only if you can eat well and comfortably can you have the energy to fight a protracted battle against this chronic disease.