Creating a healthy microbiome in your intestines, mouth, and even on your skin is crucial for preventing disease, but it also has longevity-prolonging effects and helps you live a healthy and happy life. If your gut pals are numerous and diverse, they'll keep you young forever.
This seems easy to do.
You would think that by starving the bad guys to death and feeding your gut buddies plenty of food that they can thrive on, you and your gut buddies could age well together.
Unfortunately, it's not that simple.
Having the right kind of good gut bacteria (your gut friends) is only half the battle; you must also ensure they stay within the intestinal wall. Whether they are good or bad bacteria, their debris can have serious consequences when they pass through the intestinal wall and enter your organs, tissues, lymph, or blood. Any bacteria, lipopolysaccharide, or other invaders lurking in territory that does not belong to them will trigger an immune response, thereby triggering large-scale inflammation, and laying hidden dangers for accelerated aging and disease.
Stomach acids, enzymes, and your gut friends break down the food you eat into its individual molecules:
amino acids (from proteins) fatty acids (from fat) sugar molecules (from sugar and starch)
Mucosal cells eat the digested individual amino acids, fatty acids, and sugar molecules, transport them through the cells, and release them into the portal vein or lymphatic system. Normally, everything but these small molecules should be in the intestines, where they belong.
Robert Frost's poem illustrates the point: "Good fences make good neighbors."
If the mucosal cells are hand in hand, side by side, lined up, and tightly united in the intestinal wall, then your intestinal mucosal layer is a "good fence." In addition to digested amino acids, fatty acids, and sugars, the intestinal mucosa keeps other substances in the intestines. But if your "fence" is broken and full of microscopic holes, other compounds can leak out of the intestinal wall, and your health will suffer. This is what we call "leaky gut", also known as intestinal permeability. This is the underlying cause of most of the common diseases associated with aging. You will soon understand that it is the gradual breakdown of the intestinal barrier that accelerates aging.
This is because once abnormal molecules or bacteria pass through the intestinal wall, the immune system kicks into high gear.
Think of the immune system as the police station in your apartment. Once an intruder is detected, police rush to the scene to release inflammatory hormones called cytokines and call for reinforcements.
That's a good thing when you really need the police. For example, when bad guys damage the intestinal mucosa and cause danger, such as bacterial infection, these "police" can save your life. If you are injured, inflammation helps your wound heal. But if the "police" are called repeatedly for trivial matters, it will be more troublesome and can easily lead to chronic inflammation. Chronic inflammation is a major causative factor in common aging diseases, such as Alzheimer's disease, cancer, diabetes, and autoimmune diseases.
Again, because aging and inflammation in the body are so closely related, my colleagues who study longevity coined the term “inflammatory aging” to describe the phenomenon of aging caused by chronic low-grade inflammation.
Although the word is easy to remember, I've found that inflammation is actually just a symptom and not the true cause of aging. If your gut lacks the right bacterial population and develops a leaky gut, allowing bacteria and other particles to seep from the gut wall to the outside, the result is aging. After I help my patients heal their leaky gut and bring their gut's best friends into a stable balance, their inflammation levels (as measured by the number of cytokines in their blood) drop significantly, and their body's damage is quickly repaired, which is like... An old house was renovated using excellent skeletal materials.
What substance first destroys the intestinal wall and then incites the "police" to launch a sustained inflammatory attack?
One of the culprits is lectins, which break down the tight junctions between the mucosal cells that line the intestinal wall. The best-case scenario is that you don't eat lectins at all, or that the mucosa in your nose, mouth, and esophagus (collectively called mucopolysaccharides) has teamed up to bind them before they enter the mucosa of your intestinal wall. It can prevent lectins from entering the intestines at the source. Lectins like to stick to sugar, and mucopolysaccharides are designed to adsorb lectins. If lectins do invade the mucosal layer of the intestinal wall, the mucosal cells there serve as a second layer of defense. Under good circumstances, mucosal cells produce more mucus, which binds lectins and prevents them from leaking out of the intestinal wall.
For most people, this protective mucosal layer is either in short supply or non-existent. If your diet is high in lectins, the mucus will be depleted by constantly binding the lectins.
Worse, without mucus, the mucus-producing mucosal cells are under direct attack from acids, bacteria, and more lectins, leaving less protective mucus.
Unfortunately, without mucus-trapping lectins, they attach to receptors (cell structures responsible for responding to signals) in the intestinal mucosa, producing a compound called zonulin.
Zonulin breaks the tight junctions in the gut wall, just like the kid in the game "Red Rover" breaks apart the arms of you and your friends.
Imagine what it would be like to have such a large-scale event happen on an intestinal wall as big as a tennis court:
Zonin creates gaps between cells, opening a channel for foreign invaders (including more lectins) to leak out of the intestinal wall and break into your tissues, lymph nodes, and bloodstream.
Once foreign proteins cross this boundary, they will be recognized by sophisticated "barcode scanners" called Toll-like receptors (TLRs for short). Toll-like receptors are located on immune cells, especially T cells. At this time, sirens sounded, a comprehensive warrant was issued, and the "police" rushed to arrest these intruders. Imagine if something like this happened every minute of every day, chronic inflammation would quickly develop.
The problem now is Lipopolysaccharides are not living bacteria, they are just the outer lining of bacterial cell walls. Toll-like receptors in immune cells cannot distinguish between lipopolysaccharides and living bacteria. They mistake lipopolysaccharide for real bacteria and call in the troops to deal with it. So every time lipopolysaccharide escapes through the intestinal wall, the police are on the scene, causing more and more inflammation.
New mouse research proves that this inflammatory response is also a major cause of aging. In 2018, researchers at Yale University School of Medicine linked a certain type of bacteria that invaded mouse organs through the intestines to lupus-like autoimmune diseases. They found that the mice had intestinal wall ruptures and were invaded by bacteria. Immune cells (you can think of them as police officers) also appeared in the body's organs. Notably, the same harmful bacteria were found in samples from human patients with autoimmune diseases through liver biopsies, but not in healthy controls. In other words, a leaky gut allows bacteria to seep through the intestinal wall, causing autoimmune diseases in mice and humans. You might think that leaky gut only affects a very small number of “canaries in the coal mine,” but unfortunately, that’s not the case.
I admit that I was skeptical when people first started talking about leaky gut. If you had asked me about this 15 years ago, I would have probably ignored it and thought it was just a weird idea that people have. But there is no doubt that it is real and common. In my experience treating thousands of patients, I have discovered that leaky gut (and holes in the mouth, nose, and skin) is the root cause of aging and disease.
Dale Bredesen said that abnormal bacteria entering the brain from the nose and sinuses may cause Parkinson's disease, and more research shows that bacteria and other microorganisms may cause atherosclerosis. I and other researchers now believe that all people have varying degrees of intestinal permeability.
