Have you heard the term leaky gut but don’t know what it’s about? Have you consulted Dr. Google only to find out it doesn’t exist, or that if you eat gluten you definitely have it?

Unfortunately, there’s a lot of myths and misconceptions circulating the interwebz. And even worse, those things somehow manage to be in the first couple of pages of web results. In other words, most people have seen those things, and don’t bother looking to confirm or deny them before repeating them.

So let’s put the myths to rest and discuss what we know about “leaky gut”, and answer the question, “Does leaky gut exist?”

What is leaky gut?

To begin with, leaky gut is just a terrible way of saying intestinal permeability. By permeable, we mean that it lets things through, like a leaky bucket let’s out water.

But it’s important to mention it’s not just general permeability. Your intestine is supposed to be permeable to some things. If it wasn’t, how would we get nutrients from our gut into our blood?

What most people refer to when talking about leaky gut is the intestine being more permeable to things it’s not supposed to let in, like endotoxin. Endotoxin is something normally in the gut, but if it “leaks” into the bloodstream it causes inflammation in the body.

Having endotoxin in the blood has a name: Endotoxemia. So what is endotoxin? It sounds like a new super-dank strain of weed from Snoop, but it’s not. It’s actually just a toxin present in bacterial cell walls that causes inflammation when it gets into our blood.

When bacteria die, they release millions of endotoxin molecules in our gut. But a healthy, properly functioning gut is mostly impermeable to endotoxin. So it stays in the gut, and hitches a ride out the back door.

It’s normal to have endotoxin in your gut, though there are limits to what is normal or healthy. But having endotoxin in your blood is bad…real bad. In essence, that’s what people refer to when they’re talking about leaky gut.

Leaky gut: Where’s most of the endotoxin?

Where is the bacteria hanging around?

There are a lot of bacteria floating around in our gut. The most recent estimate has the total number of bacteria in our gut as 38 trillion. And they’re not evenly distributed throughout the gut.

Different areas of the gut have varying levels of bacterial numbers due to different environmental conditions. This includes:

• pH
• Oxygen levels
• Presence of bile
• Presence of enzymes
• Which end of the hallway they’re hanging in

When we look at the gut, the lowest amount of bacteria is found in the stomach, numbering in the thousands to tens of thousands. This makes sense, one of the primary functions of stomach acid is to kill and suppress bacteria.

The small intestine has a similar amount of bacteria, thousands to tens of thousands. But it varies across different segments(duodenum, jejunum, ileum). This is primarily due to the presence of antibacterial bile, digestive enzymes, and antimicrobial peptides.

The largest number of bacteria are, by far, found in the colon. There, you can expect to see hundreds of billions of bacteria. This makes sense, no digestive enzymes, very little bile, and it’s close to an exit. It’s essentially oceanfront property for bacteria.

This actually reminds us, we did leave another part out. Though not normally thought of as the gut, the mouth is part of the gastrointestinal tract and regulates the amount of bacteria going through it. The mouth can hold upwards of 6 billion bacteria, the second highest amount. Makes sense as well…no acid, low enzymes, near the entrance.

Is leaky gut real?

The types of bacteria differ between segments as well. Some prefer low pH, some require oxygen, and some are resistant to bile. Ultimately, the gut is a very heterogenous system with different segments that are not really all that alike.

Well, aside from the shared goal of breaking down and absorbing your food. Oh yeah, and keeping bacteria and their toxins out of your blood. But the presence of different types of bacteria in different parts of the gut can help us determine where they’re coming from if they get into the blood.

It’s kind of common sense that bacteria in the mouth can get into the blood. People with poor oral health often have bleeding gums, and more bacteria in their mouth than people with good oral hygiene.

Flushing food out of your mouth by flossing and brushing after every meal leaves less for the microbes hanging there to snack on between meals. Less food means less reproduction.

They’ve found the DNA of oral bacteria in the brains of stroke and Alzheimer’s patients, so we know it’s coming from there. And in psoriasis, they’ve found bacterial DNA consistent with being from the intestine, though they don’t exactly leave a forwarding address so you can never be 100% sure.

The lung is another potential source of endotoxin and bacterial DNA, so we have to consider that as well. However, the primary bacterial DNA found in people with psoriasis is E. coli, which isn’t normally found in the lung.

Even based on the strictest criteria for determining if something is evidence-based, it’s pretty clear that bacteria make it from the gut into the blood. So yeah, leaky gut exists.

But is it a common problem or a problem for you? That’s not as straightforward of an answer. We’ll dig into that next time…