Transcript: The Leaky Gut Theory of Why Animal Products Cause Inflammation
The anti-inflammatory effect of plant-based diets is more than just about the power of plants, but the avoidance of animal foods. We’ve known for 15 years that a single meal high in animal fat— sausage and egg McMuffins were used in the original landmark study— can cause a elevation in inflammation within our bodies that peaks at about four hours.
Remember the whole endothelial dysfunction story? Where you can hook people up to a device that can measure the natural dilation of their arteries and blood flow through ultrasound.
So as you can see here, within hours of eating animal fat, our arteries get paralyzed, we nearly cut their ability to open normally in half. And that's not just happening in our arm, the lining of our whole vascular tree gets inflamed, stiffened, crippled. And just as it starts to calm down five or six hours later, we may whack it with another load of meat, eggs, or dairy for lunch such that most of our lives we’re stuck in this chronic low-grade inflammation danger zone, which may set us up for inflammatory diseases such as heart disease, diabetes, and certain cancers one meal at a time.
It does the same thing to our lungs, again, within hours. Inflammation in our airways. A single meal with animal fat causing internal damage not just decades down the road but right then and there, that day.
What exactly is causing the inflammation, though? Well, what is inflammation? It’s an immune response to a perceived threat. What’s the body attacking though? At first—like in arthritis—scientists thought it might be the animal proteins triggering inflammation, which the body might see as like an invader, whereas the reason plant foods don’t trigger inflammation was thought to be because the body doesn’t consider plants a threat.
But you can get that same jolt of inflammation just eating whipped cream, and there isn’t a lot of protein in whipped cream, so attention turned to the fat, the saturated animal fat: butterfat, or lard, tallow, chicken fat, etc., but that still doesn’t answer the original question. What is the body attacking? Our immune system doesn’t attack just fat. So they dug deeper, analyzing people’s blood before and after the meal and found something extraordinary. After a meal of animal products, people suffer from endotoxemia, their bloodstream becomes awash with bacterial toxins, known as endotoxins.
OK, well that certainly explains the inflammation. We evolved to be acutely sensitive to bacterial invasion and with this much endotoxin flooding into our system after a meal, our immune system must feel it's under assault.
OK, but where is it coming from? Well, the researchers knew endotoxin comes from bacteria, and they figured, hey, where is there bacteria? In our gut. So maybe saturated fat causes our gut lining to become leaky and allow our own bacteria to slip into our blood stream and cause the inflammation. And indeed that’s what they found--in mice; you feed them lard and their guts get leaky. And so for years, the prevailing theory has been that “saturated fats increase the permeability of intestinal lining and contribute to the breakdown of the intestinal barrier.” But is that true in people?
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Serena.
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