In my personal timings, assuming I do not stuff myself with food and observe digestion of food eaten one kind at a time, this is my observation:

raw ripe fruit: 20 minutes
raw meat such as beef or tuna: 60 minutes

If I stuff myself with too much raw meat, it can take 4 hours.

Lesson for myself is not to stuff myself with too much food in one sitting.  It seems my digestive capacity only goes for so much food eaten at one sitting.

It is worse when I stuff myself with cooked meat, I get so so so sleepy.

T. Colin Campbell, whose name appears second on Diet, Life-style and Mortality in China: A Study of the Characteristics of 65 Chinese Counties is certainly the most well known figure associated with this study.  He is the one who's been interviewed concerning it and has been promoting it.  I think that we can agree that in doing so he has greatly distorted the findings of that large and comprehensive epidemiolgical paper.  I think that it is fair to criticize Campbell and his interpretations of the study, particularly that work of propaganda/fiction that he published as "The China Study" but I have come across no one who has impugned the data from or execution of the original study (other than the normal limitations of epidemiological research, of course, and that some of the questions were poorly worded).  The fact that he has been misusing and perverting the data to his own end does not mean that the original data is flawed.

I think that this is analogous to Wrangham.  We can accept the data of the python study without having to accept any of Wrangham's far-fetched conclusions.  It would be a career-killer for Stephen Secor, who has studied and published more about the digestion of pythons than anyone else, to publish research that could be so easily falsifiable by anyone else who is willing to do the experiment.  I do not claim that Wrangham set the conditions and that some junior scientist did the work.  As reported by Science and Health journalist Rachael Gorman, http://www.rachaelgorman.com/article_full.php?article_stamp=1202161241, Wrangham sought out Secor because he already had experience studying the evolutionary design of the digestive system.  Yes, the research found what Wrangham wanted it to find and he uses it to prop up his theories, but I don't think that that indicates the data to be erroneous any more than I think that the data actually supports his theory.  As I've said before, I find it very hard to believe that the snake data in isolation tells us anything meaningful about the human digestive tract.  I also don't think that this study tells us anything about the quality of the nutrition that the snake is absorbing.  It just tells us that the snake can absorb cooked food more quickly and with less energy than it can raw food.



I do not think that this study proves your point any more than the Oste one does.  The Morgan Kern study is a comparison of raw meat along with 3 samples cooked in different ways.  One sample was boiled until an internal temperature of 84C was reached.  The second was autoclaved at 15 pounds of pressure for 7 minutes, giving a temperature of 84C.  The last was autoclaved at 15lbs of pressure for 1 hour.  The authors did not measure the temperature of this sample, but admit that it probably exceeded 85C.  84C is equivilent to 183F and is far beyond well done.  At no time did the authors of this study examine lightly cooked meat.

The reference to a sample cooked from 66-77C is not from this study but is mentioned as the author discusses all previous studies done in this area of research.  This number came from the work of Jarawussa in '29.  Jarawussa's study found absolutely zero difference in biological value when comparing the raw substance with the cooked.  I say substance instead of meat because Jarawussa used a mixture of "100 gm. of meat, treated in one of the ways given above, with 40gm. of potatoes, 20 gm. of cabbage and 10 gm. of carrots."  Even if the Jarawussa study had only looked at meat and had come to a conclusion that the raw meat showed a difference in biological value it still wouldn't tell us anything about cooking meats to Rare (46-51C).  66C (151F) is considered medium rare by the USDA, but any chef in a kitchen will tell you that their numbers are wacky and that 66C is more Medium to Medium-Well.


If by "the above facts re protein digestibility being reduced" you are referring to the Oste, Morgan and Jarawussa studies and not something else that I've overlooked then I hope that I have demonstrated that they do not tell us anything about what happens between, say, 40C and 60C.  The question about whether enzyme rich foods actually benefit us or if the enzymes are all broken down into basic amino acids in the stomach seems to be still up in the air.  It is still possible that the enzymes are deactivated at 40C but that there is no change in protein digestibility until 58C, to pick a random number.

The issue of the AGE's is more complicated and one where I will have to spend much more time reading through the references that you have provided before I feel that I'll be able to comment intelligently.

On phytonutrients and plants it seems that if too many cause harm and too few give no benefit then cooking which, depending on the method chosen and how it is executed, reduces but generally does not eliminate these compounds and which, according to Oste, makes the plants more digestible might be the preferred way to prepare and consume them.

Yes, I think that Masterjohn supports my contention perfectly, as it uses the data from the original monolith, Diet, Life-style and Mortality in China: A Study of the Characteristics of 65 Chinese Counties to disprove the distortions and lies that Campbell puts forth in his commercial book The China Study.

On the Secor/Wrangham python study I think that we'll have to just agree to disagree.  As I see it, I think that the study gives us a limited amount of information about python digestion times and the energy required and you think that it gives us no information at all.  Either way, I think that we can agree that the results are practically irrelevant to humans.

As for the Goldberg study on AGE formulation I contend that, like the other studies mentioned thus far, it does not actually tell us anything about meat that is cooked only to bleau or to rare.  To start, it does not give us a true control by not telling us how many AGE's are in raw beef.  It may be similar to the raw breast milk, but there is no law saying that it needs to be.  Second, while they state that they boiled the meat for 1 hour they do not tell us what the final internal temperature of the meat is.  We cannot duplicate the experiment ourselves, cooking meat for an hour and then measuring the temperature, because they do not tell us the mass of the beef, a factor that could have a significant impact on the final internal temperature.  Speaking just from limited experience, I have never had a pot roast (the closest thing to true boiled beef that I've ever consumed) that has not been cooked to well done.  The sample probably never made it all the way to 100C, but how close, who knows?

Just as there is no enzyme damage at 38C but there is at 40C it remains possible, based on the data presented so far, that there is no significant AGE formation or reduction in digestibility in food heated to (to pull hypothetical numbers out of a hat) 58C but that they do show up at 60C and start increasing rapidly after that.

The data on the fats I find a little more confusing.  Did they actually cook them at all, or are they just measuring them as purchased from the supermarket?  If the latter then the butter numbers probably tell us something quite interesting about pasteurization.  I'm also curious about the olive oil.  I wonder what type they used.  If they did not heat them at all then I would expect there to certainly be a difference between cold-pressed extra virgin and the heat extracted, second press Pure olive oil garbage.  If they did not heat the fats in any way themselves and they did use good quality fats (both assumptions that we can't confirm from this paper) then it actually tells us nothing about AV's claim that the best food raw is the worst cooked.   The AGE's might be endogenous to the fats themselves.

I don't understand what you mean when you say that destroying phytonutrients by cooking plant matter is deemed good by zero-carbers.  Since zero-carbers don't consume plant matter why would they have an opinion on whether or not cooking it is a good thing?  As for whether the creation of toxins is worse than the destruction of anti-nutrients I think that this would be dependent upon both the quantity of the substances created and destroyed and the relative effects that these substances have on the body.  Without knowing the levels of the various substances and their effects I don't think that we can say with certainty which method of ingestion is ultimately better.

The stated purpose of the "article was to determine the AGE content of commonly consumed foods and to evaluate the effects of various methods of food preparation on AGE production."  From the start this clearly leaves them the ability to present data on both heated and non-heated foods.  In table 1 they clearly provide the details on when some of the substances have been cooked and what method was used, e.g. beef broiledx 15 min, Egg yolk boiled, chicken breast broiledx15 min, tofu raw.  While they do specify some of the foods as raw the majority of the foods on the table are not given any qualifier or information identifying what heating was done to them.  This is the case with the olive oil and the butter.  It is also the case with the human breast milk.  No more information is given on the status of whether the breast milk was heated than is given about whether the olive oil was heated, yet you come to the conclusion that the milk was raw while the olive oil was not.  Is there information somewhere else that does describe a difference?  I went and looked for the tables 2.6 that they keep on their website but was unwilling to pay the $25 that they charge for 24 hrs access.  I never claimed that there would be little difference between raw beef and boiled beef, but as we are not given (in table 1, at least) the value for raw beef we have no way of saying, other than making an unfounded assumption or finding outside information, that the values for raw beef are anywhere near the same range as those for raw milk (assuming that the milk actually is raw).

I have been unable to find data for the AGE content of raw beef, but this study

http://cjasn.asnjournals.org/cgi/content/full/1/6/1293

gives data for raw and cooked skinless chicken breast.  While they don't use the same units of measurement they find that a raw breast has 692 AGE kilounits raw and 1011 AGE kilounits boiled, 5245 AGE kilounits broiled.  While it is an increase from raw to boiled it is only a 46% increase.  If we can extrapolate the percentages back to the values of Goldberg article and assume that the percentages for chicken are similar to those for beef (a big if, I know, but it seems reasonable to me as an approximation until better data is found) then the beef which has a value of 22 kU/g when boiled would have a measurement of about 15 kU/g when raw, far higher than the data given for the (possibly) raw milk.  I find it a safer comparison to just extrapolate the numbers from chicken to chicken.  To get from the broiled data in the chicken study (5245) to the broiled data in the Goldberg study (58) we divide by 90.  Using this same factor on the raw chicken data we get a hypothetical 11 kU/g of AGE's Goldbergs scale.  This is far, far higher than the data for the carbohydrate containing foods.  It's even higher then is present in the tuna that has been roasted for 40 minutes at 177C (6 kU/g).  Raw chicken has almost twice as many AGE's per gram than heavily overcooked tuna.

I do not question their conclusions that heat-increase is the most relevant factor in the increase of AGE's but as this study does not mention lightly cooked meats then we still know nothing about the relative levels of AGE content for rare meats or at what point the increase starts in earnest.


If the type of damage that causes the decrease in digestibility is a very similar chemical reaction to that which destroys the enzymes then you are correct that we should expect to see it appearing at about the same temperature.  However, if it is a different type of reaction then it is very reasonable to expect the amount of heat that is needed as a catalyst to be different.  As I know nothing about the type of reaction that takes place I prefer to not make any assumptions for which I have no supporting data.