Cooking increases the digestibility of animal foods

[Hanna]

An interesting study: http://www.pnas.org/content/early/2011/10/31/1112128108

Using mice as a model, we show that cooking substantially increases the energy gained from meat, leading to elevations in body mass that are not attributable to differences in food intake or activity levels. The positive energetic effects of cooking were found to be superior to the effects of pounding in both meat and starch-rich tubers, a conclusion further supported by food preferences in fasted animals.

In Wrangham´s book a study about eggs is cited. When the eggs were cooked, the proportion of protein digested averaged 91 percent to 94 percent, On the other hand, the digestibility of raw eggs was a meager 65 percent. 35 percent of the ingested protein left the small intestine undigested.

Some sections of Wrangham´s book seem to be worth reading. However, I´m looking forward to your rantings and especially Tyler´s rantings ;-).

[Projectile Vomit]

I'm interested in seeing the reaction to this also. I just downloaded the original article from PNAS and will read it later this afternoon. If anything strikes me, I'll report back.

[CitrusHigh]

Absorptive capacity does not translate to utilization. Cooked food will be absorbed, but poorly utilized, that is the difference.

[HIT_it_RAW]

Absorptive capacity does not translate to utilization. Cooked food will be absorbed, but poorly utilized, that is the difference.

Also I think with raw food the body can easier take what it needs and let the rest pass?

[TylerDurden]

I have to admit I am appalled that no one has yet mentioned that Richard Wrangham is one of the main scientists involved in that very study cited above. Richard Wrangham has  a vested interest in pretending that cooking makes food more digestible, so it is dishonest to pretend this study has any value whatsoever. Furthermore, Richard Wrangham has previously openly admitted to being a vegetarian and a feminist, which political leanings would explain why he is so against the notion of  meat, and raw meat at that, helping to produce bigger human brains.

Besides, there are far more objective studies proving the exact opposite, that cooking meats make them LESS digestible, not more:-

"From Bach Knudsen et al. [1988], protein utilization and digestibility are decreased by cooking in some varieties of sorghum. In contrast, protein digestibility of pearl millet and corn (maize) decreases only very little (not significantly) after cooking [Ejeta et al. 1987].

From Oste [1991], heating (above 100°C, or 212°F) decreases meat protein digestibility. Frying chickpeas, oven-heating winged beans, or roasting cereals at 200-280°C (392-536°F) reduces protein digestibility.

Seidler [1987] studied the effects of heating on the digestibility of the protein in hake, a type of fish. Fish meat heated for 10 minutes at 130°C (266°F), showed a 1.5% decrease in protein digestibility. Similar heating of hake meat in the presence of potato starch, soy oil, and salt caused a 6% decrease in amino acid content." taken from:-

http://www.beyondveg.com/tu-j-l/raw-cooked/raw-cooked-2a.shtml

In case people read the whole of the above website and get the wrong ideas, here is an anti-BYV link:-

http://www.rawpaleodiet.com/articles/anti-raw-bias-on-beyondveg-com-website-debunked/

Oste RE (1996) "Digestibility of processed food protein." Adv Exp Med Biol, vol. 289, pp. 371-388. Review.

Seidler T (1987) "Effects of additives and thermal treatment on the content of nitrogen compounds and the nutritive value of hake meat." Die Nahrung, vol. 31, no. 10, pp. 959-970.

Bach Knudsen KE, et al. (1988) "Effect of cooking, pH and polyphenol level on carbohydrate composition and nutritional quality of a sorghum (Sorghum bicolor (L.) Moench) food, ugali." Br J Nutr, vol. 59, no. 1 (Jan.), pp. 31-47.

The raw egg study is just one study, so may well be faulty. Plus, it overlooks something:- a fertilised raw egg(such as found in the wild) has much lower avidin(antinutrient) levels than unfertilised raw eggs, such as found in the supermarket, so the former would be far more digestible.

[Hanna]

I just downloaded the original article from PNAS and will read it later this afternoon. If anything strikes me, I'll report back.

Yes, please. Did the mice who received cooked food become overweight or did the mice who received raw food become underweight? Did they start at normal weight? Was there a big difference in weight between the groups?

[jessica]

are mice carnivores? what is their natural diet?
we aren't mice, they have different digestive systems as well as dietary needs

[Hanna]

I have to admit I am appalled that no one has yet mentioned that Richard Wrangham is one of the main scientists

Oh yes, the devil in person!

Plus, it overlooks something:- a fertilised raw egg(such as found in the wild) has much lower avidin(antinutrient) levels than unfertilised raw eggs, such as found in the supermarket, so the former would be far more digestible.

Yes, I suspect that the avidin in raw eggs possibly reduced the digestibility of the eggs. Anyway, I usually just eat the yolk. However, I also don´t like raw meat very often except fish, seafood, liver, brain, bone marrow and sometimes meat which has aged for a long time, such as air-dried "prosciutto crudo".

what is there natural diet?

At least rats do eat meat in nature, even the meat of mammals. Mice are omnivores, just as we are. You can catch mice with raw meat in a mousetrap. In Germany there is a saying: „You will catch mice with bacon.“

[TylerDurden]

Oh yes, the devil in person!

  Not at all. Richard Wrangham is too stupid and ignorant  to be genuinely evil.

[HIT_it_RAW]

  Not at all. Richard Wrangham is too stupid and ignorant  to be genuinely evil.

Heh heh. Maybe we ought to start collecting these remarks from you. I really like them!   

[cherimoya_kid]

  Not at all. Richard Wrangham is too stupid and ignorant  to be genuinely evil.

That's my hypothesis as well.

[Projectile Vomit]

I did get to read through the study in question earlier this afternoon. Not very impressive.

One issue that I saw is that the experimental treatments were only allowed to continue for 4 days. I recall from when I switched to eating raw meat it took a couple weeks for me to really feel good on the diet, so it might be that the beneficial impacts of eating raw just didn't have time to materialize. (Mice fed diets of both cooked tubers and meat and raw tubers and meat all lost weight during the trial, suggesting that, for whatever reason, none of the treatment diets appeared to suit them well.)

Another issue is that the mice, between 4-day trials with the raw meat and raw tubers, were fed a highly processed and most likely cooked mouse chow. So their normal state was something cooked or at least highly processed, so the raw food (either tubers or meat) would naturally have taken some getting used to, particularly since they've probably been eating the chow for their entire lives, and their parents eaten it for their entire lives, and their parents too, etc. So a quick 4-day trial eating raw doesn't strike me as adequate for drawing any conclusions whatever, regardless of the results.

A methodological approach that would have impressed me more would be to raise independent groups of rodents on the diets tested (including a control group that was fed normal mouse chow), and then raise the next generation of mice on the same diets as their parents. I'd test both the parent generation (who started the novel diet mid-life) and the first generation to see how well they assimilate their respective foods. And heck, mice have quick generation times so why not test the 2nd and 3rd generations too?

Now if the researchers had done something like this and demonstrated that cooked food (meat and/or tuber) was more easily assimilated, then I would accept the results as a win for the cooked foodists. But with the experimental methods used, I don't think you can draw any meaningful conclusions from the study.

It's a shame that researchers who want to study raw food diets don't talk to raw foodists before designing their studies...

[TylerDurden]

Interesting comments, Eric. I have often suggested, in the past, that certain changes occur after transitioning to a RVAF diet. These changes usually happen rather slowly. One thing I noticed, for example, was that I found, after some months on RVAF diets, that if I ate raw pastry, such as croissants, I would be forced to wash it down with water, whereas in pre-RVAF diet days I would not need to do so - suggesting that I was producing far less mucus in my throat. Also, I suspect that RVAFers don't need to produce as much stomach-acid to digest their raw foods, so that the body gradually reduces the output thereof, over months.

[HIT_it_RAW]

Also, I suspect that RVAFers don't need to produce as much stomach-acid to digest their raw foods, so that the body gradually reduces the output thereof, over months.

not to mention digestive enzymes..

[Hanna]

I read that the amount of avidin in eggs is VERY small, so this is probably not the reason for the reduced digestibility of raw eggs.

[Iguana]

Thanks a lot, Eric!

Hanna, another reason could be that commercial - industrial (even organic) eggs are very bad and totally unsuitable to be eaten raw. 

[Löwenherz]

..Also, I suspect that RVAFers don't need to produce as much stomach-acid to digest their raw foods, so that the body gradually reduces the output thereof, over months.

Oh really? My impression was always that you need higher levels of stomach-acid to digest raw meats (especially red muscle meat) properly.

Löwenherz

[TylerDurden]

Oh really? My impression was always that you need higher levels of stomach-acid to digest raw meats (especially red muscle meat) properly.

Löwenherz

Not my own experience. I had extremely severe stomach-pains in my pre-rawpalaeo days, but none thereafter. Aajonus also claims that he had no problems with raw animal foods, despite him not being able to produce stomach-acid(I think he claimed his vagus nerve was destroyed, which stimulates stomach-acid production, or some such?).

[Löwenherz]

Hanna, another reason could be that commercial - industrial (even organic) eggs are very bad and totally unsuitable to be eaten raw. 

From my own experience I wholeheartly agree with your notion.

I have extreme reactions to grain-fed meats, but eggs are even worse, no matter if organic or not. They effect me mentally extremely negative (but without physcial problems in my gi tract that I get additionally from grain-fed meats). The message was always so bad, so strong and so clear that I decided in 2008 to never ever touch 'normal' eggs again until the end of my current life. Nevertheless I love the taste of raw whole eggs. Unfortunately I can't get any wild eggs. Very rarely I get some eggs from chickens who get only tiny amounts of grains plus lots of raw animal food. Their egg yolk is dark red..

Löwenherz

[Löwenherz]

..Aajonus also claims that he had no problems with raw animal foods, despite him not being able to produce stomach-acid(I think he claimed his vagus nerve was destroyed, which stimulates stomach-acid production, or some such?).

Yes, I remember. Maybe this is also the explanation why he places so much emphasis on butter which most people find much easier to digest than solid animal fats like backfat etc.

Löwenherz

[HIT_it_RAW]

Not my own experience. I had extremely severe stomach-pains in my pre-rawpalaeo days, but none thereafter.

Same here. On non raw I frequently had acid reflux, never on raw. Difference is night and day.

Very rarely I get some eggs from chickens who get only tiny amounts of grains plus lots of raw animal food. Their egg yolk is dark red..

Dark red?! I've really been searching for good quality raw eggs and had a lot of varieties but never with red yolks. Orange from free range chicken but never red.

[Projectile Vomit]

Yeah, most people are used to seeing eggs with yellow yolks but I don't think that's how it's supposed to be.

I've eaten eggs from chickens that I know for a fact were never fed grain and thrived on a diet of largely insects and wild vegetation, and their yolks were vivid orange to orange-red. These eggs tasted incredibly rich and were almost bitter, but they were very good. I've made it known to the group of friends who raise these chickens that if they ever have any eggs to get rid of they can always send them my way.

[Hanna]

I have just read that at least HEAVY heating can significantly reduce the digestibility of dietary protein, with consequences for the gut flora:

"A 47% increase in faecal nitrogen in adolescent
males followed consumption of a heavily heated
diet compared to a mildly heated diet, the differ-
ence being attributed to heat-induced protein-sugar
reactions (Seiquer et al. 2006). AGE/ALE-modi-
fied protein is less readily digested, leading to an
elevated level of protein residues in the colon and a
modified colonic microflora. For example, we have
used validated colonic models to demonstrate that,
compared to untreated protein, glycated protein
modulated the gut microbiota of ulcerative colitis
(UC) patients towards a more detrimental commu-
nity structure, with significant increases in putatively
harmful bacteria (clostridia, bacteroides and sul-
fate reducing bacteria) and decreases in dominant
and putatively beneficial bacteria (eubacteria and
bifidobacteria) (Mills et al. 2008)."

http://journals.uzpi.cz/publicFiles/07583.pdf
http://www.ncbi.nlm.nih.gov/pubmed/16685050