Proteinuria dietary taboos

Avoid uncontrolled intake of high-protein foods, strictly control high-salt dietary intake, and stay away from nephrotoxic foods/supplements with unknown ingredients. This is the best conclusion I have come up with after 7 years of follow-up in the Department of Nephrology, communicating with more than 200 patients with proteinuria, and going through countless pitfalls in adjusting their diets with clinical nutritionists.

Don’t believe it. When I was first diagnosed with 2+ protein in my urine, I thought the same as many people: if protein leaks in my urine, do I need to eat more to make up for it? At that time, I had two boiled eggs for breakfast every day, half a pound of soy sauce beef for lunch, and a glass of milk before going to bed. Occasionally, my family would give me stewed sea cucumber as a supplement. However, after three months of reexamination, my 24-hour urine protein jumped from 1.2g to 3.8g, and my creatinine also increased by 12 units. I was scolded by the doctor. I have to be objective here. In fact, there is no completely unified standard for protein intake in the academic community: the old clinical view once advocated "replenishing as much as you miss", and even recommended that patients with nephrotic syndrome consume 1.2-1.5g of protein per kilogram of body weight every day. ； However, the current mainstream KDIGO chronic kidney disease guidelines recommend that for patients with proteinuria who are not in the nephrotic syndrome range and have normal renal function, a daily protein intake of 0.8-1.0g/kg of body weight is sufficient. If renal insufficiency has already occurred (eGFR is small) (60), it should be reduced to 0.6-0.8g, and priority should be given to high-quality proteins from fish, poultry, eggs, milk, and soybeans, and to reduce the intake of non-high-quality proteins such as pig skin, tendons, and bird's nests—after all, the latter produce more waste through metabolism, which will increase the burden on the kidneys. Of course, there are also small sample studies in recent years that suggest that for young proteinuria patients who have exercise habits and high muscle mass, as long as their kidney function is stable, appropriately relaxing the dosage to 1.0-1.2g will not aggravate kidney damage. Individuals can actually slowly explore their tolerance without hard standards.

By the way, let me clarify a rumor that has been circulating for decades: patients with proteinuria can eat soy products. In the past, everyone always thought that soybeans were plant proteins and would damage the kidneys. Now it has long been confirmed that soybean protein is a high-quality protein, and its amino acid pattern is highly matched to the needs of the human body. As long as the total intake is controlled, it is perfectly fine to eat a tofu and drink a cup of soy milk. On the contrary, it is healthier than eating a lot of processed red meat.

After talking about the easiest pitfalls of protein supplementation, let’s talk about the high-salt problem that many people don’t take seriously. One weekend last year, I couldn't help but get greedy. I ordered a very spicy braised duck dish and drank it with an ice coke. It was so salty that I drank three bottles of mineral water in one night. As a result, I went for a routine urine test the next day. The urine protein that had been negative for almost half a year was directly detected as weak positive. I was so scared that I had to eat a light diet for two weeks before switching back. High-salt diet raises blood pressure on the one hand, and more importantly, it will aggravate the hyperfiltration state of the glomerulus. The already damaged glomerular filtration barrier will leak more protein, and will directly reduce the effect of commonly used urinary protein-lowering drugs such as Preliminary/Satan. When we talk about salt control, we don’t just mean not eating pickles. Soy sauce, bean paste, hot pot base, processed meat products, and even many invisible salts in takeout must be taken into account. It is best to control the total salt amount within 3g per day, which is about the amount of a beer bottle cap with the rubber gasket removed. Don’t think “I eat it bland without adding salt”. Many times, food that you think tastes just right has already exceeded the salt limit.

Finally, I would like to remind everyone not to blindly use folk remedies and supplements with unknown ingredients. A patient I know heard from relatives in his hometown that there is a "miraculous medicine for treating proteinuria" passed down from his ancestors. He ground the herbs into powder and developed symptoms of nausea and fatigue within half a month after taking it. When he went to the hospital, he was diagnosed with acute kidney injury. The protein in his urine jumped directly from 1+ to 4+. He spent more than half a month in the hospital before he recovered. There are also ketogenic diets, high-protein weight loss methods, and functional drinks that add a lot of taurine and caffeine, which are very popular in recent years. They are all hidden dangers for patients with proteinuria. In the first half of last year, I followed the trend and tried ketogenic weight loss for half a month. I ate meat every day and did not eat staple food. The result was 2+ in the urine protein test. It took more than two months to return to the normal level. I really lost it because I ate too much to improve my memory.

To be honest, dietary taboos are not that rigid. It does not mean that eating a bite of pickles will worsen your condition. Occasionally, you will be craving for something you like. As long as the overall long-term diet structure meets the requirements, you don't need to have too much psychological burden. Everyone's kidney tolerance is different. You may not be able to eat what others can eat. Pay more attention to it, review your urine routine every time you eat new food, and slowly find out your own body threshold. It is much more useful than trying to follow other people's recipes.