Kidney Disease Changes Gut Flora

End stage renal disease may change makeup of gut bacteria that play a role in fighting off disease

(RxWiki News) As many as 1,000 different species of bacteria live in your gut. These bacteria play a large role in fending off disease. Now, research suggests kidney disease can change the makeup of these bacteria.

Patients with kidney failure may have less helpful bacteria in their gut than those without kidney failure. This finding may explain why kidney failure patients experience certain complications.

"Eat more low-potassium fiber if you have kidney disease."

These changes to the makeup of the gut environment may contribute to uremia (a common condition in patients with kidney failure), inflammation and nutritional problems, said Nostratola D. Vaziri, MD, of the University of California Irvine, and colleagues.

Uremia is a condition in which urea and other nitrogen waste products - which are usually filtered out of the body through urine - build up in the blood. Uremia can lead to fatigue, confusion, decreased alertness and decreased urine production.

Eating more high-fiber foods and better control of uremia - which can be done through more frequent dialysis - may be beneficial to patients with kidney failure, said Dr. Vaziri. In other words, a better diet and more frequent dialysis may improve the makeup of gut bacteria and the well-being of patients.

For their study, Dr. Vaziri and colleagues took DNA samples of microbes taken from stool samples of kidney failure patients and healthy individuals. They found differences in the abundance of about 190 types of gut bacteria in patients with kidney disease. Then they confirmed their results in a study on rats with and without kidney disease.

According to Dr. Vaziri, nitrogen-rich waste products like urea and uric acid are usually passed out of the body through the kidneys. In patients with kidney failure, these products build up in the body fluids, eventually dumping into the gastrointestinal tract. When these products find their way to the gut, certain bacterial species use them to thrive - which may explain the bacterial changes in the gut of kidney failure patients.

The dumping of the nitrogen-rich waste products into the gut is worsened by the fact that kidney failure patients cannot eat certain high-fiber foods that could be helpful. Fruits and vegetables are high in fibers that favorable gut bacteria feed on.

However, they also contain high levels of potassium - a substance normally filtered out of the body by the kidneys. In people with kidney failure, potassium levels can get high, which boosts the risk of cardiac arrest.

One answer to these problems may be to provide kidney failure patients with longer, more frequent dialysis treatments, said Dr. Vaziri. More dialysis would mean that more potassium is removed, allowing more potassium to be included in a patient's diet.

Another answer could be to offer patients packaged fiber foods that do not include potassium.

The study was small, with 24 kidney failure patients and 12 healthy participants. However, it adds to a growing body of evidence that gut bacteria play a role in a variety of diseases, including diabetes, colon cancer and obesity.

The research was published September 19 in Kidney International, a journal of the International Society of Nephrology.

Review Date: 
October 11, 2012