Diet taboos for patients with proteinuria

Do not blindly supplement high protein, strictly control sodium intake, and avoid foods that are clearly nephrotoxic. All other taboos need to be adjusted individually based on your own kidney function, urine protein quantification, and pathological type. There is no unified fasting list that applies to all patients.

Many people have just been diagnosed with positive proteinuria, and their first reaction is to search a bunch of "10 foods that cannot be eaten with kidney disease" on the Internet, and list the taboos one by one. In the end, they end up either suffering from malnutrition or stepping on invisible pitfalls. I met a 28-year-old young man with membranous nephropathy in the outpatient clinic before. His urine protein was just 3.2g/24 hours. He heard from his relatives that if he leaked protein, he needed to make up for it. He had two eggs and a cup of whole milk every morning, a steamed shrimp meal at noon and night, and two spoons of protein powder for snacks. As a result, he came back for a follow-up examination in half a month and found that his urine protein soared to 7.1g. His legs were so swollen that he used to wear 42 shoes, but now 43 shoes are pinching his feet.

Regarding the restriction of protein intake, in fact, the industry has always had different recommendations. Guidelines from the past decade or so generally require all patients with proteinuria to control their daily protein intake to 0.6-0.8g per kilogram of body weight to avoid increasing the filtration burden on the kidneys. ； However, in recent years, more and more clinical data have shown that if the pathology is mild, such as minimal lesions, or patients who are sensitive to hormone therapy and are expected to turn negative in 1-3 months, they can maintain a normal protein intake (1g per kilogram of body weight/day), as long as they do not oversupply, which can actually reduce the risk of malnutrition. Only patients who have declined renal function and whose eGFR is lower than 60ml/min·1.73m² need to strictly implement a low-protein diet and supplement essential amino acids with compound α-keto acid when necessary.

What is easier to get into than protein intake is sodium control. Many people's understanding of sodium control is still at the level of "put less salt in cooking", but they don't know that most people's excess sodium comes from invisible places. I once had an aunt with IGA kidney disease who used a salt-limited spoon for every meal she cooked at home. She was stuck with 3g of salt every day. As a result, she had to eat the soybean from downstairs two or three times a week. Occasionally, her grandson would also eat two leftover potato chips. The last time she checked her urine protein increased from 0.4g to 1.1g. It took me a long time to find out why. The soybean she bought contained nearly 800mg of sodium per 100g. Eating two taels of it accounted for almost half of the day's sodium quota. Of course, not everyone has to be so stuck in sodium. If you often work outdoors and sweat a lot, or are taking diuretics and occasionally develop hyponatremia, it is completely fine to consume less than 5g of salt per day. Only patients with edema and renal hypertension need to strictly control their daily sodium intake within 2000mg (equivalent to 5g of table salt, which is the amount of a beer bottle cap).

There is also a misunderstanding that has been circulating for more than ten years, saying that patients with proteinuria cannot eat soy products. This is really unjust. The current consensus among nephrology departments is that soy protein is a high-quality protein with a high amino acid ratio that matches the needs of the human body. It even has a smaller metabolic burden than red meat such as pork, beef, and mutton. As long as the total protein intake is controlled throughout the day, it is absolutely fine to eat some tofu and drink a cup of soy milk. What you really need to avoid 100% are those folk remedies with unknown ingredients, "ancestral secret recipes for kidney disease," and health products that claim to "turn yin and lower protein." Many unknown Chinese herbal medicines contain aristolochic acid, which can directly cause irreversible renal tubular damage, which is more than ten times more harmful than eating an occasional hot pot meal. If you are a proteinuria patient with high uric acid, you should also avoid ultra-high purine foods such as animal offal, thick broth, and shelled seafood. If your uric acid is always stable within the normal range, you don’t have to feel too much psychological burden if you occasionally eat braised prawns or take a sip of pork rib soup.

I have been working in the Department of Nephrology for almost ten years, and I have seen too many patients who make dietary taboos like strict rules. They dare not touch this or eat that. There is a female patient in her 30s who did not dare to eat a bite of braised pork for two years. She even dared to eat only apples. As a result, she had a fever for two days during the last flu, and her urine protein jumped directly from 0.5g to 4.2g during the review. On the contrary, it is much more harmful than an occasional bite of meat.

In fact, to put it bluntly, the dietary taboos for proteinuria have never been a unified list of taboos. The core is to grasp the general principles, and the rest can be adjusted according to your own body's reaction. If your urine foam obviously increases after eating a certain food, and the urine protein has indeed increased during a recheck, then eat less next time ； If there is no reaction at all after eating, then feel free to eat the normal amount. After all, individual differences are always much more reliable than the universal taboo list on the Internet.