Gut-Kidney Connection

Our knowledge and understanding of the body, including the gut and its microbiome, has grown in recent years. We now know that the bacteria, called microbiota, in the gut impact kidney disease progression – as well as other aspects of our health, such as digestive conditions, mental health, and cardiovascular disease. This microbiome (grouping of microbiota) is an organ itself. As a result, we now know that we can’t think of the body as separate organs, as they are all intertwined together, and nutrition recommendations should be preventative and holistic.

What is the microbiome?

Every individual has a unique microbiome made up of many types of microbes or microbiota that are specific to their DNA and life experiences. For example, what we are exposed to in-utero, during delivery, where we live, and what we eat can all change the microbiota that we have.

There are both good and bad microbiota in the gut. The good microbiota helps to keep us healthy and keep the bad bacteria down. Microbiota work with the immune system, help to digest food, and make certain vitamins in the body. They can also help protect against pathogens from eating or drinking contaminated foods or fluids. However, if the numbers of bad microbiota increase, this can lead to health problems.

This type of science can be confusing, so let’s break it down with an example. The gut is like a house. Each of us has a different house, just like each of us has a different microbiome. How we fill the house (or our microbiome) with furniture is going to be different. This furniture inside the house is like our microbiota. Some furniture may be well-kept and clean, which is the good microbiota, and other furniture may be stained and collecting dust; think of that as the bad microbiota. Either way, this furniture makes our house function. As long as the bad furniture does not overtake the good furniture (this is called dysbiosis), we can enjoy our house in harmony (or symbiosis) and health.

The role of the microbiome

Alterations in the gut microbiome have been linked to the development of diseases such as obesity, cancer, diabetes, inflammatory bowel disease, cardiovascular disease, and kidney disease. When there is a disruption of the normal gut microbiota, it may lead to intestinal dysbiosis, intestinal barrier dysfunction, and bacterial translocation. With kidney disease, excessive uremic toxins are produced because of gut microbiota changes. This can lead to the progression of kidney disease.

This area of gut health and kidney disease is relatively new, and there are limited studies looking at the progression of gut health in PKD specifically. However, there are important ways that the gut plays a role in our health beyond digestion, including disease prevention, and these can impact PKD.

Inflammation control

The bacteria-like microbes produce by-products as they live, and these by-products can impact inflammation in our body if they move across the gut barrier. This is known as the “gut-kidney axis” which suggests that a decline in kidney function impacts the gut, which then impacts the kidney function.

Uremic toxins

Urea is an amino acid that the kidneys typically get rid of through the urine. With kidney disease, urea may build up in the blood. With too much urea, we can feel tired, have difficulty concentrating, have unexplained weight loss, and poor taste in our mouth. Too much urea can lead to kidney disease progression – as well as changes in the gut microbiome – as high levels of the bad bacteria lead to increased uremic toxins. If there are not enough good bacteria to manage the bad bacteria and the increase in uremic toxins, we can feel unwell.

Foods to include for gut health with PKD

Nutrition is one strategy to support gut health with kidney disease. Aim to increase prebiotic foods to assist with gut health. Prebiotics are non-digestible carbohydrates that act as food for probiotics, healthy or good bacteria, that are in the microbiome. The foods that are highest in prebiotics include: fresh fruits and vegetables, and whole grains. Additionally, intestinal changes in pH can support the growth of different types of bacteria, and lead to metabolic acidosis. Including more sources of fruit and vegetables in the diet can help reduce the acid load on the body, thereby preserving kidney function.

Some of the top sources to include with PKD are:

Limit packaged and processed foods. These are higher in salt, which can increase blood pressure and impact the microbiome. Limit foods with preservatives or additives such as potassium and phosphorus for overall health. Remember to read food labels and aim to choose foods with 5% daily value of sodium or less per serving. Cook at home, choose products with nutrient content claims such as “no added salt” or “low in sodium,” and read ingredient lists to limit additives and preservatives.

What about probiotic supplements? Probiotics are healthy bacteria that, when eaten in the right amounts, have a health benefit. While there is great literature for the support of probiotics and some health conditions, there is no concrete recommendation that probiotics should be used with kidney disease and specifically PKD. Remember that everyone’s gut microbiome is different, so specific strains may be more helpful than others depending on your make-up. A renal dietitian can help you to determine if a probiotic supplement would be beneficial for you.

Your gut health is important for kidney health!

Your gut microbiome is very individual but also quite important for kidney disease. Managing your gut health should be included in your nutrition plan. You can do this by including foods that nourish the body, reduce uremic toxins, and reduce inflammation to improve the microbiome. Renal dietitians are available to help support you with your PKD nutrition and put together personalized plans. Ask your healthcare team for a referral. It is important to speak with your healthcare team before making any nutrition changes.

Written by: Emily Campbell, RD CDE MScFN is a Registered Dietitian and Certified Diabetes Educator with a Master’s Degree in Foods and Nutrition. Emily specializes in renal nutrition, helping those with kidney disease overcome the confusing world of nutrition to promote health. Emily can be found at kidneynutrition.ca.