 The anti-inflammatory effect of plant-based diets is more than just about the power of plants, but also 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 an immediate elevation in inflammation within our bodies that peaks at about four hours. Remember the whole endothelial dysfunction story where you can hook up people 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 from just one meal. And just as things start to calm down five or six hours later, we may whack our arteries with another load of meat eggs or dairy for lunch, such that most of our lives were stuck in this chronic low-grade inflammation danger zone, which may set us up for inflammatory diseases, such as heart disease, diabetes, cancer, kind of one meal at a time. Does the same thing happen in our lungs? Yes, again, after just hours of 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? Well, at first, like an arthritis, scientists thought it might be animal proteins triggering inflammation, which the body might see as 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 the same jolt of inflammation just eating whipped cream. There isn't a lot of protein in whipped cream. So attention turned to the fat, the saturated animal fat, butter fat, or lard, tallow, chicken fat. 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 a wash with bacterial toxins known as endotoxins. OK, well, that certainly explains the inflammation. We've evolved to be acutely sensitive to bacterial invasion, and with this much endotoxin flooding into our system after a meal, our immune system might feel it's under assault. OK, but where are the endotoxins coming from? Well, the researchers knew endotoxins come from bacteria, and they figured, hey, where is their bacteria? In the gut. So maybe animal fat causes our gut lining to become leaky and allow our own bacteria to slip into our bloodstream and cause the inflammation every time we eat. 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 that contributes to the breakdown of the intestinal barrier. But is that true in people? Stay tuned.