 In my last video about avocados, I described the anti-inflammatory effects and cholesterol and triglyceride lowering effects. But what about that video I did years ago about the chromosome-damaging effects in a Petri dish? That all goes back to 1975 when a pesticide naturally produced by the avocado tree was discovered. I thought to explain why lactating livestock suffered mammary gland damage nibbling on the leaves. The toxin was named person, also found to be damaging to the heart, which is why you should never feed avocado to your pet birds. But hey, if it attacks mammary cells in animals, might it attack breast cancer cells in humans? It did seem to have the same kind of cell cytoskeleton clumping effect in vitro that chemotherapy can have, demonstrating potent cell growth stopping and killing effects of the novel plant toxin among various lines of human breast cancer cells. So they're thinking about how it might one day be used as chemo itself. But here I am thinking, holy guacamole, Batman! Please tell me it doesn't have toxic effects on normal cells, too. In 2010, we got an answer. An evaluation of the genotoxicity, the toxicity to our chromosomes of avocado extracts on human white blood cells in a petri dish. Normally, less than 10% of our dividing cells have any chromosome abnormalities, but drip some avocado fruit extracts on them and up to half come out defective in some way. They conclude that there's something in avocado fruit that can potentially induce significant genomic instability and some genetic damage in human white blood cells in a petri dish. If the same effect occurs in actual people, it could, for example, result in transforming cells into cancer. That's a big if, though. These were blood cells. You don't inject guac into the vein. For anything to get into our bloodstream, it first has to survive our stomach acid, get absorbed through our intestines, and then sneak past our liver's detoxification enzyme. And indeed, a person may be affected, changed by acidic conditions. And so, given all the differences between what happens in a petri dish and a person, it's essential to carry out further studies before making a final remark about its toxicity. Okay, but what do you do before these studies come out? I was concerned enough. I provisionally moved it from a stuff-your-face green light food to a moderate-year intake yellow light food until we knew more to err on the side of caution. Even if a person was utterly destroyed by stomach acid, what about oral cancer? At high enough concentrations, avocado extract can harm the growth of the kinds of cells that line our mouths. Yeah, but this is in a petri dish, where the avocado is coming in direct contact with the cells. But that's kind of what happens in your mouth when you eat it. But it harms oral cancer cells even more. Here's a bunch of oral cancer cells. Those red dots are the mitochondria, the power plants of the cells fueling cancer growth extinguished by the avocado extract. But since it does this more to cancerous than normal cells, they end up concluding avocados may end up preventing cancer. What about the esophagus, which lies between the mouth and the stomach? They similarly found that an avocado fruit extract appeared to inhibit cancer cell growth more than normal cell growth when it came to colon cancer cells, or esophageal cancer cells. But rather than comparing the effects to normal colon and esophagus cells, they compared to a type of blood cell, which again has limited relevance in a petri dish study of something you eat. This study was pretty exciting, though. It looked at p-cressol, which is a uremic toxin, may also be toxic to the liver, has been found associated with autism, and it comes from eating high-protein diets, whereas if you eat more plant-based diet, the only source of prebiotics like fiber and resistance starch, your levels go down. See, fermentation of carbohydrates in the colon, like fiber, is considered beneficial, whereas fermentation of protein, which is called putrefaction, is considered detrimental. So you switch people to a high-protein diet, and within days the excess protein putrefying in their gut leads to an increase in ammonia, as well as p-cressol. In fact, a doubling of levels within a week. But might phytonutrient-rich plant foods like apples, cranberries, grapes, or avocados protect the cells lining our colon from the deleterious effects of p-cressol, in terms of cell viability, mitochondrial function, and epithelial integrity, meaning protection against gut leakiness? Here's that data on barrier function integrity, damaged by p-cressol, but rescued by all the cranberry, avocado, grape, and apple extracts, though mitochondrial function was only approved by the cranberries and avocados, and they're also the only ones that appeared to prevent the deleterious effect of p-cressol on colon cell viability. But bottom line, avocados appearing to have beneficial effects on colon lining cells, so that's a good sign. Okay, but enough of these in vitro studies already. Yes, an avocado extract can inhibit cancer cell growth in a petri dish, but unless you're doing some unspeakable things to that avocado, like guacamole-width benefits, there's no way that the avocado is going to come in direct contact with your prostate cells, so what does this study mean? That's why I was so excited to see this study, the first to actually look for a link between avocado consumption, actual human beings eating avocados, and prostate cancer. So do avocado eaters have more cancer risk, or less cancer risk? We'll find out right now. Men who ate the most avocado, more than about a third of an avocado a day, reduced their risk of prostate cancer, in fact less than half the odds. So with the data on improved artery function, lower cholesterol, and if anything in association with decreased cancer risk, I'd suggest moving it back into the green zone.