蔬食益生 2018-07-01 01:46:09

本视频由Michael Greger医生于 2018 年 6 月 1 日发布,来自 — 能救命的营养学。



Michael Greger 医生是畅销书《How Not to Die》作者,中文译本:繁体版书名为《食疗圣经》。简体版书名为《救命》,于今年5月底出版。


本视频与 “氧化胆固醇导致阿尔茨海默病” 是姊妹篇。


How to Reduce Cholesterol Oxidation



Chicken, fish, and egg powder in processed foods present greater risk from cholesterol oxidation byproducts, but there are things you can do to reduce exposure.



“A significant body of evidence indicates that oxidized cholesterol may be one of the main triggers of Alzheimer’s disease.” But, that’s not all.



Cholesterol oxidation products “are associated with the initiation and progression of multiple major chronic diseases,” including heart disease, diabetes, and kidney failure.



And, they’re produced when animal products are heated. All forms of cooking can do it, since you can get “maximum cholesterol oxidation” at only about 300 degrees Fahrenheit.



But, is there some type of cooking that’s worse than others?



Well, if you look at foal meat, which is like baby horse meat, higher levels of oxidation in general were found in microwaved meat.



And, indeed, microwaving chicken or beef appears to produce about twice as much cholesterol oxidation than frying.



Whereas, if you look at bacon, raw bacon wasn’t found to have any oxidized cholesterol.  It has cholesterol, like all animal products, but it’s not oxidized until you cook it.



Grilling seems to be the safest the first time around, but then, when you put it back in the fridge and reheat it later using the same method, the oxidized cholesterol levels all shoot up.



It’s not just heat, though. Although levels in raw meats are usually low, “concentrations tend to increase dramatically after exposure to pro-oxidation agents, such as light.”



What are you supposed to do, crawl inside the pig and eat the bacon from the inside?



No, you could wrap the meat in red plastic wrap. Clear plastic wrap doesn’t seem to work, but the red blocks some of the light waves and can “delay cholesterol oxidation.”



This was for “horse meat slices.” The problem is worse with “sliced meat products,” because more of the meat is exposed to air and light. Same problem with ground meat; it’s just so much more exposed.



Unless you keep meat in some kind of vacuum pack, even in a dark refrigerator, the oxygen exposure alone can shoot up oxidation levels. Or, in the freezer.



Yeah, cooking raw fish can boost levels from 8 to 18, but after a few months, frozen fish - even raw - starts out about ten times higher and just goes up from there.



And, in terms of which meat is the worst, microwaved or fried, chicken was twice as bad as beef.



The reason, it seems, has to do with the “polyunsaturated fat content of the muscle,” which goes fish, then poultry, then pork, then beef, then lamb.



So, white meat is more susceptible to cholesterol oxidation.



Yes, red meat has more saturated fat, but fish and chicken tend to build up more oxidized cholesterol.



So, “chicken and roasted salmon have been shown to generate greater amounts of cholesterol oxidation products than other types of meat.”



Surprisingly, though, “the highest increase of oxidized cholesterol in salmon was found through steaming, mainly just because it’s exposed to heat longer. Cholesterol oxidation “increased after each cooking procedure, but steaming increased the total amount by more than 1000%.”



There are two ways chicken meat may pull ahead, though.



One is if you feed the chickens rancid fat in the first place. And, unfortunately, all sorts of substandard stuff ends up at the rendering plants to be turned into animal feed.



And also irradiation. When chicken meat is irradiated to improve its food safety from an infectious disease standpoint, it may diminish food safety from a chronic disease standpoint. But, hey, it’s better than dying from salmonella.



In terms of dairy, in my last video, I talked about the potential dangers of ghee, which made me wonder about UHT milk, which stands for ultra-high temperature processing, to make little half-and-half no-refrigeration-needed coffee creamers. That does seem to boost oxidized cholesterol levels by about 50% — worse than just regular pasteurization, though, interestingly, if you can find goat milk half-and-half, that would be safer.



Same problem with eggs.



Egg powder in processed foods is good for shelf life, but may not be so good for human life.



So, that’s like packaged food with eggs in it, like pasta, many baked goods, mayonnaise. So, even people who stay away from egg eggs, may still be unwittingly exposed through processed foods, if they don’t read the label.



If it’s all about oxidation, why not just add “synthetic or natural antioxidants” to the animal products themselves?



They’ve certainly tried; like, what about adding lemon balm tea to hamburger patties?



It didn’t work, but that’s likely because they couldn’t add enough without affecting the taste.



What about adding cherries



They’re redthey would blend right in. And, it worked! Two different types of tart cherries significantly reduced the cholesterol oxidation, but meat with a cherry on top seems a little out of place.



How about just good old garlic and onions?



Here’s the amount of oxidized cholesterol in a plain pork chop, significantly reduced by adding onion or garlic. 


Though, interestingly, in chicken, cholesterol oxidation was helped by sage, but not garlic. In fact, garlic may even accelerate fat oxidation.



So, “there are several measures that can be taken to reduce cholesterol oxidation in foods:


Reducing the total cholesterol content in food by not cooking food with cholesterol-containing fat”, like butter or lard;


Maybe we can “feed animals antioxidants before, or add them afterwards;



Use as low a temperature to cook as possible;



Use some kind of opaque vacuum packing or something.



But, if you take a step back, only foods that start out with cholesterol can end up with oxidized cholesterol.



So, the primary method, in terms of reducing cholesterol oxidation in foods, may be to “reduce the total cholesterol content of the food” — not just by avoiding adding extra with butter, but instead, centering one’s diet around whole plant foods, which don’t have any cholesterol to get oxidized in the first place.

(翻译:Huiling Liu, 字幕制作及编辑:老玉米 Karen Chou)


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胆固醇那么容易氧化,所以 Michael Greger 医生开玩笑说:“那到底要怎么办,爬进猪的身体里,从里面吃培根?”

Michael Greger 医生给出了解决方案“以全食物植物饮食为主,其本身不含任何胆固醇,也就不用考虑胆固醇氧化的问题了。” 





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