Scientists discovered that people with chronic kidney disease have different gut bacteria than healthy people, and what they eat makes a big difference. When kidney disease patients ate more fiber and less protein, their gut bacteria became healthier and produced fewer harmful substances. The study looked at 135 people with kidney disease and compared them to healthy people. Those eating high-protein, low-fiber diets had more harmful bacteria and higher levels of toxic compounds in their blood. This research suggests that changing your diet might help protect your kidneys by improving your gut health.

The Quick Take

  • What they studied: How different eating patterns affect the bacteria living in your gut and whether this impacts kidney disease patients differently than healthy people
  • Who participated: 135 people with chronic kidney disease who weren’t on dialysis yet, plus 19 healthy people for comparison. Researchers looked at what they ate over three days and tested their gut bacteria and blood.
  • Key finding: People with kidney disease who ate more fiber and less protein had healthier gut bacteria and lower levels of harmful compounds in their blood compared to those eating high-protein, low-fiber diets
  • What it means for you: If you have kidney disease, eating more fiber-rich foods and moderating protein intake may help your gut bacteria stay healthier, which could reduce inflammation and harmful substances in your body. However, talk to your doctor before making major diet changes, as protein needs vary by kidney disease stage.

The Research Details

This was a cross-sectional study, which means researchers took a snapshot in time of 135 people with kidney disease and 19 healthy people. They asked everyone to write down everything they ate for three days, then analyzed the nutrients in their meals. Researchers collected stool samples to identify and count the different types of bacteria living in each person’s gut using a genetic test called 16S ribosomal RNA sequencing. They also took blood samples to measure harmful compounds and inflammatory markers.

The researchers divided the kidney disease patients into two groups based on their eating patterns: those eating low-protein and high-fiber diets versus those eating high-protein and low-fiber diets. They then compared how the gut bacteria differed between these groups and between the kidney disease patients and healthy controls.

This approach is important because it shows real-world eating patterns and their connection to gut health in kidney disease patients. By looking at actual food intake rather than controlled diets, the findings reflect what really happens in people’s lives. The genetic testing of gut bacteria is precise and can identify specific bacterial types that produce helpful or harmful substances.

This study has some strengths: it used precise genetic testing to identify bacteria, measured multiple health markers, and compared kidney disease patients to healthy controls. However, because it’s a snapshot in time rather than following people over months or years, we can’t prove that diet changes caused the bacterial changes. The sample size is moderate (135 kidney disease patients), which is reasonable but not huge. The study was published in Scientific Reports, a well-respected journal, which suggests it passed peer review.

What the Results Show

Kidney disease patients had noticeably different gut bacteria compared to healthy people. The most important difference was that kidney disease patients had fewer bacteria that produce short-chain fatty acids (SCFAs), which are helpful compounds that protect the gut and reduce inflammation.

When researchers compared kidney disease patients eating different diets, they found clear differences. Those eating low-protein, high-fiber diets had more of the good bacteria that produce SCFAs, including types called Lachnospiraceae NK4A136 and Eubacterium ruminantium. In contrast, those eating high-protein, low-fiber diets had more harmful bacteria like Klebsiella, which produce toxic compounds.

The blood tests showed that people eating high-protein, low-fiber diets had significantly higher levels of TMAO (a harmful compound linked to heart and kidney problems) and inflammatory markers like IL-18 and MCP-1. These inflammatory markers suggest more inflammation in the body, which can worsen kidney disease.

The study also showed that the harmful bacteria in high-protein diets produce substances that get absorbed into the bloodstream and cause inflammation throughout the body. This creates a chain reaction: high-protein diet → wrong bacteria grow → toxic compounds produced → inflammation increases → kidney damage worsens. The low-protein, high-fiber diet appears to break this harmful chain.

Previous research suggested that gut bacteria play a role in kidney disease, but this study provides specific evidence about which bacteria are helpful or harmful and how diet directly influences them. The findings align with other research showing that high-fiber diets generally improve gut health and reduce inflammation. This study adds new information by showing these effects are particularly important for kidney disease patients.

This study took only a snapshot of people’s diets (three days) rather than tracking them over time, so we don’t know if these eating patterns are typical for each person. The study couldn’t prove that changing diet would actually change the bacteria—it only shows they’re connected. The healthy control group was much smaller (19 people) than the kidney disease group (135 people), which could affect comparisons. Additionally, the study didn’t account for medications people were taking, which could affect gut bacteria. Finally, this was one study in one population, so results may not apply to everyone with kidney disease.

The Bottom Line

If you have chronic kidney disease, consider eating more fiber-rich foods like vegetables, fruits, and whole grains while moderating protein intake. This may help your gut bacteria stay healthier and reduce harmful inflammation. However, protein needs vary depending on your kidney disease stage, so work with your nephrologist or kidney dietitian before making changes. This research suggests benefits, but it’s not yet strong enough to be a definitive treatment recommendation.

This research is most relevant for people with chronic kidney disease who aren’t on dialysis yet. It may also interest people with early kidney disease or those at risk for kidney problems. Healthy people don’t need to change their diets based on this study. If you have kidney disease, discuss these findings with your kidney specialist before making dietary changes.

Changes to gut bacteria typically take 2-4 weeks to show up after diet changes, but it may take 8-12 weeks to see improvements in blood markers like TMAO and inflammatory compounds. Benefits to kidney function would likely take months to become apparent, if they occur at all.

Want to Apply This Research?

  • Log daily fiber intake (target: 25-30 grams) and protein intake (as recommended by your doctor) for 12 weeks. Track any changes in energy levels, digestion, or lab markers at your doctor’s visits.
  • Add one high-fiber food to each meal (example: beans, vegetables, or whole grains) while keeping protein portions at your doctor-recommended size. Use the app to plan meals that balance these nutrients.
  • Check in weekly with your logged meals to ensure you’re hitting fiber and protein targets. Schedule quarterly reviews of your lab work with your doctor to see if TMAO, inflammatory markers, or kidney function numbers improve.

This research suggests a potential connection between diet and gut health in kidney disease patients, but it does not prove that changing your diet will improve your kidney function. Chronic kidney disease is a serious condition requiring medical supervision. Before making any significant dietary changes, especially regarding protein intake, consult with your nephrologist or kidney dietitian, as protein needs vary based on your kidney disease stage and other health factors. This article is for educational purposes and should not replace professional medical advice.