 Seven years ago, I introduced the endotoxin theory literature, which sought to explain how a single meal of sausage and egg McMuffins could cripple artery function within hours of consumption. Maybe because such a meal causes inflammation by inducing a low-grade endotoxemia, endotoxins in the bloodstream, within hours of consumption. Endotoxins are structural components of gram-negative bacteria e. coli, and certain foods have such high bacterial loads like ground meat. The thought was that it was the endotoxins in the food that was triggering the inflammation. Critics of the theory argued that because we have so many bacteria already living in our colon, so many endotoxins just sitting down there in our large intestine. A few more endotoxins in our food wouldn't matter much in terms of causing systematic inflammation. After all, we have like two pounds of pure bacteria down there where the sun don't shine, so there could be like a whole ounce of endotoxin. And the lethal dose of intravenously injected endotoxin could be just like a few millions of a gram. So we could have like a million lethal doses down there, but the apparent paradox is explained by compartmentalization. It's location, location, location. Poop is harmless in your colon, but shouldn't be injected into your bloodstream, or eaten for that matter, particularly with fat, as that can promote the absorption of endotoxins up in the small intestine, even well-cooked poop. You can boil endotoxins for two hours straight, with no detriment in their ability to induce inflammation. You could easily kill off any bacteria if you boiled your poop soup long enough, but you can't kill off the endotoxins they make, just like you can't cook the crap out of the meat, right? The consumption of meat contaminated with feces doesn't just cause food poisoning, right? I mean, it can, you know, spill out during the evisceration process when the digestive tract is ruptured. Even when slaughterhouse workers trim off the visible fecal contamination, the trimming itself can, ironically, sometimes lead to an increase in certain fecal bacteria thought to be caused by cross-contamination from one cargis to the next. Then, even when properly stored in the fridge, endotoxins start accumulating along with the bacterial growth. What about other foods? The highest levels of endotoxins were found in meat and dairy, and the lowest levels in fresh fruits and vegetables. But that was testing whole fruits and vegetables. Most spoilage organisms can't penetrate the plant's surface barrier and spoil the inner tissues. I mean, that's why, you know, fruits and veggies can just sit out there all day in the sun, out in the fields, right? But once you cut them open, though, and bacteria can gain access to the inner tissues, within a matter of days, your veggies can start to spoil. So what does that mean for all those convenient pre-chopped veggies these days? While endotoxins were not detectable, the majority of unprocessed fish was once you damaged the protective outer layer of vegetables, you diminished the resistance to microbial growth. So while freshly chopped carrots and onions start out with undetectable levels day after day, even kept chilled in the fridge, you start to get the growth of bacteria, and along with them endotoxin buildup. Not as much as meat, but not insignificant. Enough to make a difference, though? You don't know until you put it to the test. What would happen if you switched people between a diet expected to have a lower endotoxin load to foods containing more endotoxins, like going from intact meat like steaks and whole fruits and vegetables to more like ground beef and pre-chopped veggies and more ready-made meals? After just one week on the lower endotoxin diet, people's white blood cell count, which is an indicator of total body inflammation, dropped 12%, but then bumped 14% up after just four days on the higher endotoxin diet. And they actually lost a pound and a half on the lower endotoxin diet and slimmed their waist a bit, but they weren't really eating otherwise identical diets. It looked like they were eating more meat and cheese overall on the higher endotoxin diet and maybe getting more food additives in the ready-made meals. So how do we know endotoxins had anything to do with it? That's where the onion study comes in. A new study was designed based on two meals that differed in their content of bacterial products, but which were otherwise nutritionally identical. So they compared freshly-chopped onion to pre-chopped onion that had been refrigerated for a few days. I mean, it wasn't spoiled. It was still before the kind of best before date. So would it make any difference? Within three hours of consumption, the fresh onion meal caused significant reductions in several markers of inflammation. That's what fruits and vegetables do. They reduce inflammation. But these effects were not observed after eating the pre-chopped onions. For example, here's one inflammatory marker. Three hours after eating fresh chopped onions, a significant drop in inflammatory status. But three hours after eating the exact same amount of pre-chopped onions, no significant change. So it's not like the pre-chopped onions caused more inflammation, like in the meat, eggs, and dairy studies, but they did appear to extinguish some of the anti-inflammatory effects of the onion. In conclusion, the modern trend towards eating the pre-chopped vegetables rather than whole intact foods is likely to be associated with an increased oral endotoxin exposure. I mean, it's definitely still better to eat pre-chopped vegetables than no vegetables, but chopping your own might be the healthiest.