Whether you are new to the wellness world or have been around a while, you’ve probably heard a lot of talk around probiotics and gut health. As a functional medicine expert, probiotics are one the few supplements that I believe are beneficial for most people - regardless of your specific health case. However, it can get pretty confusing choosing which one to take from the endless variety on the market. And when you throw in terms like “soil-based” and “spore-based” it can leave you stuck in decision paralysis. So instead of adding to the confusion, it’s my job to demystify the differences between the various types of probiotics so you can make the best choice when it comes to your health.

What are probiotics and why are they important?

Your gut microbiome contains trillions of different microorganisms - bacteria, yeast, and fungi - that influence almost every aspect of your health from your weight to your immunity. In order to maintain a healthy microbiome, you want to ensure that your gut has a diverse range of different beneficial bacterial strains.

While these beneficial microorganisms are naturally present in our guts, there are many external factors that can disrupt the delicate balance of your microbiome (also known as bacterial dysbiosis) including stress, antibiotics, and poor dietary choices. Probiotics are supplements that contain strains of these beneficial microorganisms that work to either maintain a healthy balance of bacteria or replenish good bacteria to fight against any opportunistic overgrowths.

Types of probiotics

Unfortunately, choosing a probiotic is not as simple as going to your local vitamin shop. There are seemingly endless options for probiotic supplements depending on what you are looking for. In fact, there are actually a few different types of probiotics that each offer their own unique benefits. Here’s a breakdown of the types you’ll see most often. You may have even heard these terms tossed around before in various health and wellness podcasts, videos, and articles.

1. Traditional probiotics

Traditional probiotic supplements are formulated with live microorganisms - typically bacteria - that are often derived from fermented foods or specific strains that have been extensively studied for their positive impact on gut health. Some of the most common strains used in probiotic supplements include:

• Lactobacillus acidophilus (1)
• Bifidobacterium bifidum (2)
• Lactobacillus casei (3)

2. Soil-based probiotics

Soil-based probiotics contain microorganisms naturally found in soil, with many researchers believing that reintroducing these soil-based microbes into the human gut can contribute to a healthy and resilient microbiome by mimicking the ancestral exposure humans had to diverse soil microbes. Since they can also withstand harsh environmental conditions inside and outside of your gut, they are often chosen for their adaptability and don't typically require refrigeration. Common strains of soil-based probiotics include:

• Bacillus subtilis (4)
• Bacillus coagulans (5)
• Bacillus licheniformis (6)

3. Spore-based

Unlike the live bacteria found in traditional probiotics, spore-based probiotics are bacterial spores – dormant, protective forms that allow them to withstand the harsh environmental conditions of your gut. These spores serve as a resilient shield, protecting the probiotic bacteria from heat, light, and the acidic environment of the stomach. Once in your gut, these spores activate, transforming into live, beneficial bacteria, making them a great option for people looking for more targeted, stable probiotic supplementation. 

It’s important to note that while there is some overlap between spore-based and soil-based probiotics, as some spore-based probiotics can have soil origins, that doesn’t mean that all spore-based probiotics are derived from bacteria found in soil. Some of the most well researched strains of spore-forming probiotics include:

• Bacillus clausii (7)
• Bacillus coagulans
• Bacillus subtilis