Researchers looked at dozens of studies about how different diets affect kidney health. They found that eating less protein, less salt, and following Mediterranean or DASH diets can help protect your kidneys and slow down kidney disease. While these diets didn’t directly help people live longer in the studies reviewed, they did reduce protein leaking into urine and helped keep kidneys working better. This research suggests that what you eat is really important for managing kidney problems and preventing them from getting worse.

The Quick Take

  • What they studied: How different eating patterns and food choices affect kidney health and kidney disease
  • Who participated: This review looked at 28 different research studies that included thousands of people with kidney disease and people without kidney disease
  • Key finding: Eating less protein, eating less salt, and following Mediterranean or DASH diets all helped protect kidneys and slow kidney disease progression
  • What it means for you: If you have kidney problems or want to prevent them, changing what you eat—especially reducing salt and protein—may help your kidneys stay healthier. Talk to your doctor before making big diet changes, especially if you already have kidney disease.

The Research Details

This is called an ‘umbrella review,’ which means researchers looked at many other research studies instead of doing their own experiment. They searched four big medical databases for studies that had already reviewed and combined results from multiple kidney and diet studies. Two researchers independently checked each study to make sure it was good quality and pulled out the important information. They looked at studies about different diets: low-protein diets, very low-protein diets with special supplements, Mediterranean diet, DASH diet, and diets with less salt. The researchers were very careful to avoid counting the same information twice when studies overlapped.

This approach is important because it gathers all the best evidence in one place instead of looking at single studies. When many studies point to the same answer, we can be more confident that the answer is true. This helps doctors and patients make better decisions about diet and kidney health.

This review was registered before it started (which is good practice), was published in a respected nutrition journal, and used strict methods to pick and evaluate studies. However, because it reviews other people’s work rather than doing original research, the quality depends on how good those original studies were. The review looked at many studies together, which makes the findings stronger than any single study.

What the Results Show

Low-protein diets helped reduce protein leaking into urine in people with kidney disease. Very low-protein diets were even more powerful—they helped prevent kidney disease from reaching the most serious stage (end-stage renal disease). When people on very low-protein diets also took special supplements called ketoanalogues, they saw even better results: less protein in urine, lower waste products in blood, and better kidney function measurements. Lower salt intake was very effective at reducing the amount of salt and protein in urine and helped prevent serious kidney problems from developing. Both the Mediterranean diet (lots of vegetables, fish, olive oil) and the DASH diet (designed to lower blood pressure) reduced the risk of getting kidney disease in people who didn’t have it yet. The DASH diet also helped slow down kidney function decline in people who already had kidney disease.

The research showed that the type of protein you eat matters—not all proteins affect kidneys the same way. Plant-based proteins appeared to be gentler on kidneys than animal proteins. The studies also confirmed that managing blood pressure through diet is connected to kidney health, since both Mediterranean and DASH diets help with both.

These findings support what doctors have suspected for years: diet is one of the most important things people with kidney disease can control. This review brings together scattered evidence and shows that multiple different eating approaches work, giving patients and doctors more options to choose from based on what fits their lifestyle.

The review couldn’t prove that these diets directly help people live longer because most studies didn’t track that. The studies reviewed had different quality levels, and some were small. Most studies were done in developed countries, so results might not apply everywhere. The review also couldn’t determine the perfect amount of protein or salt for each person, since needs vary.

The Bottom Line

If you have kidney disease, talk to your doctor or a kidney specialist about eating less protein and less salt—the evidence strongly supports this (high confidence). Following a Mediterranean or DASH diet is also a good choice if you want to prevent kidney disease or slow it down (moderate to high confidence). If you have advanced kidney disease, ask about ketoanalogue supplements with a low-protein diet (moderate confidence). These changes take time—expect to see improvements in kidney function tests over weeks to months, not days.

People with kidney disease should definitely pay attention to this research and work with their doctors on diet changes. People with high blood pressure or diabetes should care because these conditions damage kidneys. Anyone with a family history of kidney disease might want to follow these eating patterns to prevent problems. People with normal kidney function don’t need to restrict protein, but following Mediterranean or DASH diets is healthy anyway.

Changes in kidney function tests (like creatinine and eGFR) typically show up within 4-12 weeks of diet changes. Protein in urine may decrease faster, sometimes within 2-4 weeks. The protective effects of preventing kidney disease take longer—months to years of following the diet.

Want to Apply This Research?

  • Track daily sodium intake (aim for less than 2,300mg per day, or lower if your doctor recommends) and protein intake. Log meals and note any changes in energy levels or how you feel.
  • Start by reducing salt in cooking and avoiding processed foods, which have hidden salt. Gradually shift toward more plant-based proteins like beans and lentils instead of red meat. Add more vegetables, fruits, and whole grains to meals.
  • Check in monthly with kidney function test results from your doctor (creatinine, eGFR, and protein in urine). Use the app to track diet consistency and correlate it with test results over 3-6 months to see your personal response.

This review summarizes research about diet and kidney health but is not medical advice. Kidney disease is serious and requires professional medical care. Before making any diet changes, especially if you have kidney disease, diabetes, or high blood pressure, talk to your doctor or a registered dietitian who specializes in kidney health. They can recommend the right diet for your specific situation. This information is for educational purposes and should not replace personalized medical advice from your healthcare provider.