This blog is part of a series discussing our integrative approach to kidney stone prevention and management. In this blog we will focus on the microbiome and kidney stone formation.

Kidney stone formation (urolithiasis) is a complex disease influenced by multiple factors including diet, genetics, and environment. They are painful, inconvenient, and when left untreated, they may contribute to more serious conditions including obstruction and kidney damage.

Kidneys

Read more about the etiology and prevalence of kidney stones here.

In this series we’re building a case for a more integrative approach to preventing kidney stone formation.

Conventionally, the treatment approach does address kidney stones via a multi-pronged approach that may include medication, dietary and lifestyle, surgical removal, and using ultrasonic waves to break up stone.

However, these guidelines tend to focus too far downstream, on stone composition instead of on the underlying pathology upstream. Instead, we advocate for a more comprehensive approach that focuses on risk factors to prevent formation. Those factors include:

·       Type of stone

·       Socioeconomic factors

·       Environment

·       Diet

·       Hydration and electrolyte balance

·       Microbiome and gut health

·       Genetics

We covered individual dietary components in detail in a previous blog. Today we’ll look at the gut-kidney stone connection and the impact of the microbiome.

Gut Integrity and Kidney Stones: Leaky Gut

A normal and healthy GI tract has a natural barrier. This barrier serves to protect the GI and has three major jobs: 1. ensure proper digestion and absorption of nutrients and 2. ensure elimination of toxins and 3. protect the integrity of the microbiome – the “good” bacteria that lives in our GI tract and works with our body to maintain health.

Leaky gut describes a state when the cells that make up the lining of the GI tract separate enough to allow the contents of the gut to leak out. This is also sometimes called intestinal permeability or IP for short. This is a problem because it reduces absorption of nutrients, causes toxins to build up, alters the balance of the gut microbiome, and results in systemic inflammation.

One of the major contributors to leaky gut is the standard American diet (SAD), which seems to increase risk of kidney stone formation. When we use the term SAD, we are generally referring to a diet that includes:

·       Consumption of sugary beverages and soda (and high carbohydrate consumption in general)

·       Increased intake of processed/refined foods like cereals, crackers, baked goods, etc…

·       Processed, fried, conventionally raised, high-nitrate animal protein

·       Low intake of fiber and fresh produce in general

·       A “beige” diet (low in phytonutrients and antioxidants) from consuming a variety of colorful fruits and vegetables 

·       Inadequate amounts of healthy, anti-inflammatory fats, and high amounts of refined unhealthy fats

We have already established that eating more fresh produce, is protective from kidney stone formation, and we’ve done a deeper dive on specific nutrition impact on kidney stone risk in another blog if you’d like to learn more.

There are several factors that may contribute to development of leaky gut:

·       “Proinflammatory” SAD: too much processed and high-sugar foods, not enough fiber and the wrong inflammatory fats

·       Food sensitivities: consuming food that are cause reactivity

·       Overconsumption of caffeine and alcohol – irritants to gut lining

·       Use of certain medications, including NSIADs, steroids, antibiotics

·       Stress and poor-quality sleep

We address risk factors for intestinal permeability in more detail in a previous blog here, as well as dive into a comprehensive gut restoration strategy here in this 5-part series. 

The Microbiome and Kidney Stones

Balance of the gut bacteria also play an important role in causing or preventing kidney stones. The most studied organism is Oxalobacter formigenes, which has been found to be protective when present in adequate quantities as part of the GI microflora. This bacterium degrades oxalate in the gut decreasing its absorption and excretion in the urine.

When Oxalobacter was discovered, scientists thought they had pinpointed the key to curing kidney stones. They concluded that simply supplementing this missing species should reduce risk of stone formation in susceptible individuals. It would turn out that the connection wasn’t that simple.  

More recent evidence points to a more complex picture in the connection between microbiome diversity and kidney stone pathology. The emerging research shows increased risk in kidney stone formation in certain susceptible individuals also presented with alterations in normal microbiome and metabolome (metabolic byproducts from microflora) – also termed dysbiosis.

In other words, it’s likely that genetic factors might be “turned on” by dysbiosis leading to increased risk of kidney stone formation in certain individuals. The good news is that means they should be “turned off” when the microbiome balance is restored.

Studies that looked at the use of targeted probiotics have failed to show enough significant improvement of risk of urolithiasis. Although there’s been some limited and temporary reduction in oxalate excretion and kidney stone formation with the use of a combination of Lactobacillus, Bifidobacterium, Enterococcus, it’s been shown to be temporary and limited in benefit. This is because dysbiosis cannot be addressed by simply applying a band aid of a probiotic.

We recommend instead a more comprehensive approach to gut restoration and microbiome balance. You can read more about the 5R protocol in our comprehensive 5-part series on gut restoration. 

The Bottom Line

Although initial findings about the impact of the microflora that looked at Oxalobacter in isolation have not demonstrated significance in reducing incidence of kidney stone formation, more recent evidence pointing to an interplay of factors on microbiome diversity is promising. Furthermore, factors that impact kidney stone formation include dietary factors, including food quality, nutrient composition, and dehydration. Along with environmental factors, lifestyle, genetics, and gut integrity and microbiome balance should be addressed through a comprehensive and personalized approach. Practitioners working with individuals to prevent kidney stone formation should formulate a patient care plan that modifies all relevant components in their integrative approach to maximize effectiveness in preventing urolithiasis.