Dr. William Davis on AGEs

[PaleoPhil]

Tyler, you should like this...Dr. William Davis of HeartScanBlog acknowledged the potential importance of AGEs (some emphases are mine):

Advanced Glycation End-products, or AGEs, have the potential to change our entire conversation about diet.

....

2) Choose and prepare foods with lower AGE content. Food content of AGEs is a major determinant of blood AGE levels. Fats and meats are the primary dietary source of AGEs, particularly if cooked at high temperature (broiling, frying). While this does not mean that meats and fats need to be avoided, it can mean that limiting serving size of meats and fats, while being selective in how they are prepared, are important. This can mean cutting your meats in thinner slices or smaller pieces to permit faster cooking, eating rare when possible (not poultry, of course), avoiding cooking with sauces that contain sugar (which enhances AGE formation). Is this an argument in favor of sashimi?

Minimizing exposure to AGEs, endogenous or exogenous, has the potential to slow the aging process, or at least to lessen the likelihood of many of the phenomena of aging.

AGEing gracefully
Wednesday, May 05, 2010
http://heartscanblog.blogspot.com/2010/05/ageing-gracefully.html

[TylerDurden]

Well, it's nice to find a doctor who admits that AGEs are harmful. There's so much more research being done that pro-cooking people like Taubes are increasingly looking more and more unscientific as time goes by.

As for the 2 above claims in the article, 1 of them implies that lowering carbs would work. I would beg to differ. From what I've heard re reports of raw-food-gatherings in the US, the (usually raw carb-eating)Instinctos generally look healthier/younger than the Primal Dieters with their high intakes of raw meats. Granted, the raw dairy component of Primal Dieters wouldn't help things either, but it seems that the raw and palaeo aspects of a diet are more important than the carb-factor. And I haven't noticed the Inuit having long average lifespans, even on traditional diets.

Also, there is another argument against cooked, low-carb diets:- there are additional toxins such as heterocyclic amines formed only in cooked meats, not cooked plant foods, last I checked, so the issue of AGEs isn't important. Nitrosamines seem to be a problem re smoked or processed meats, primarily.

[alphagruis]

Also, there is another argument against cooked, low-carb diets:- there are additional toxins such as heterocyclic amines formed only in cooked meats, not cooked plant foods, last I checked, so the issue of AGEs isn't important. Nitrosamines seem to be a problem re smoked or processed meats, primarily.

Yes absolutely and may I add that ingestion of cooked low-carb diets also strongly increases the ingestion of damaged amino acids (  damaged by heat induced racemization, deamidation, oxidation etc) that cannot be used by the organisms neither to build his own proteins nor to convert them into the minimum amount of glucose (needed and not available from carbs) nor even to use them more directly as fuel and eliminate them by oxidation since these damaged amino acids can't a priori enter into the relevant enzymatic pathways.

The fate of this unusual high amount of damaged amino acids is simply unknown and most likely they behave as highly toxic molecules too.

AGEs are by far only a small part of the toxic substances formed upon heating food.    

[Paleo Donk]

But we still don't know what percentage of these damaged amino acids are actually damaged enough so that the body excretes them. I've seen one study that compared two diets, one with a high amount of malliard products and the other with a more moderate amount and the more moderate amount only had significantly less fecal nitrogen excretion (which was a very small amount iirc) and about the same urinary nitrogen excretion. Here's the relevant results. BD = brown diet - higher malliard products

Compared with consumption of the WD, consumption of the BD resulted in 47% higher fecal nitrogen fecal excretion (P = 0.002), 12% lower apparent nitrogen absorption (P = 0.000), and a 6% lower nitrogen digestibility (P = 0.000). The apparent nitrogen retention and the utilization of ingested nitrogen did not differ significantly between the diets, although values after the BD tended to decrease. Serum biochemical variables related to nitrogen metabolism did not differ significantly.

http://www.ajcn.org/cgi/content/full/83/5/1082

Obviously this is two different cooked diets so the results may be much different for raw. Perhaps the body spends more energy and thus is damaged more utilizing these damaged amino acids but they are still used in roughly the same proportions?

I'm pretty sure there is no study in humans on this with raw food, though I think there are some on animals that compare raw vs cooked.

[alphagruis]

Paleo Donk,

Your link mainly shows (and confirms) that protein digestibility is impaired upon heating due to the presence of Maillard products and probably many other induced chemical changes. This is one effect of cooking (technically impaired enzymatic hydrolysis of polypeptides)  and another effect, I had in mind, is the fraction of damaged amino acids that are indeed absorbed from that part of the food proteins that the organism nevertheless manages to digest i. e that are hydrolysed or cut into their amino acid pieces in the digestive system. In other words I mean those damaged amino acids that inevitably get into the blood stream when one eats cooked food.

This damage is not simply due to the formation of Maillard products. It may be due to many other effects for instance to racemization i.e conversion of left handed to right handed forms due to heat (same chemical formula but distinct atomic arrangements in space that differ as the right hand differs from left one). This altered form cannot enter a priori in usual enzymatic pathways as the right hand cannot fit into the left hand glove.

It is well known in biochemistry that usual determination of the amino acid composition of protein damages the amino acids because it precisely involves hydrolysis by heating to 100-120 °C at low or high pH for several hours. Biochemists very well know that a substantial fraction of the amino acids are damaged in this way, a phenomenon that must be carefully taken into account to get meaningful results. (See for instance the chapter on the determination of primary structure of protein in Biochemistry by D. and J. Voet, John Wiley and Sons 1995)

Most affected by heat is tryptophane (almost completely destroyed by heating in acid for 10 to 100 h). High percentages of others such as serine or thyrosine or aspartic acid are racemized, aspargine and glutamine loose their amine group etc. Quite similar things obviously must happen during usual cooking at temperatures around boiling water or higher[/b]

All this has been known for many decades and should have logically led at least some life scientists to seriously question an ubiquitous practice such as cooking many decades ago.    

 
  

[Raw Kyle]

He didn't say avoid carbs, he said avoid cooking meat and fat with sauces that contain sugar.

[MrBBQ]

It's acknowledged that endogenous AGEs are more sinister than exogenous (although exogenous are still a major consideration), which are the result of PUFA interactions.

It's also acknowledged that cooking in water does not form the same load of AGEs. Furthermore, addition of antioxidant spices (e.g. in marinades) reduces AGE formation (especially useful when BBQing). It's the same with rendering fats like ghee - traditionally, curry or betel leaves were added to minimise oxidation products (as well as heating the butter in an earthenware pot).

Are AGEs water-soluble, like in the case of bone broth (which is simmered in water over longer periods with the fat skimmed afterwards and debris filtered through a cheese cloth)?

Bone/collagen broth is touted for its minerals and anti-inflammatory amino acids proline, glycine and hydroxyproline, which would probably not be straightforward to consume raw - I can't imagine chewing on feet or knuckles...Having said that, I believe it's the collagen-style amino acids that make cuts tougher, so eating the tough cuts might be a better source of these amino acids. Maybe excess proline, glycine and hydroxyproline are not required in very good health, but for people finding little progress in tooth/bone healing like me, it's a means to an end - AGEs or not. I'm persisting with the fresh raw bone meal, but it's time consuming to produce in ideal quantity.

Is free glutamic acid produced in cooking, which is particularly problematic for some people?

Black tea, green tea, white tea and specifically yerba mate prevent or block the activity of AGEs - maybe it's good to have a cup along with an exceptional cooked meal.

[Paleo Donk]

Alpha, the only real point I was attempting to make was that even though these amino acids succumb to all sorts of the nasties from heat, there still are populations that do well on a diet that consists of nearly every single amino acid being heated. An outsider that read what you just wrote that knew nothing about diets would probably believe a cooked zero-carb diet to be one of the worst diets possible, yet many are thriving on such a diet.

I've even see some people claim that digestion has improved with the more well-done the meat is. Steffanson did his year long meat trial with well done meats, I think and faired well. Obviously there are many explanations for this and its all relative to millenia of cooked diets but the fact is that the body must be decently good at processing theses disturbed proteins.

It would be interesting to see how much overall nitrogen excretion would differ between completely raw and cooked diet. If it were about the same, then would this imply that the body does eventually utilize every single amino acid in the same manner as a raw diet? I'm thinking the body simply has to work extra hard to deal with these disturbance but eventually fixes the problem and makes the amino acid 'usable'.

I see raw foods as more of a way of prolonging body function in old age. If it really were vastly superior we would have already seen a dramatic shift in areas where money is involved like professional sports - namely weightlifting, bodybuilding, etc.. but we don't. The body does tremendously well the first few decades on pretty much any diet, even those where nearly 100% of the amino acids have heat applied to them, it just seems to wear out faster.

[TylerDurden]

He didn't say avoid carbs, he said avoid cooking meat and fat with sauces that contain sugar.

In the article, he does mention lowering carbs. It's the 1st main point made; the other re AGEs is the 2nd main point.

[alphagruis]

I essentially agree with you, Paleo Donk and my post was certainly not intended to "demonize" cooking but just try to understand the facts and data at hand.

It is quite true that most of us do very well for several decades on a cooked diet. It was clearly my case up to my 45th birthday or so. Obviously we are fairly well equipped to get rid of the poisons generated in cooked food...  but only for a while.

This is IMO not so surprising because all the poisons I mentioned also form to a small extent at room temperature in particular at the surface of a food such as meat or fish left to age. So there certainly exist mechanisms in living organisms to get rid or even perhaps make use of them. What happens is most likely that on cooked diets these detoxination mechanisms "designed" by evolution to deal with only the small amount of such toxins as present in raw food become progressively overwhelmed and the detoxination that still takes place is less and less effective as time goes by. Until some point is reached where the organism becomes sufficiently poisoned to exhibit chronic sickness after a period that depends obviously on genetics and overall way of life (specific content of diet, physical activity,  presence of other sources of chronic poisoning such as dental fillings or working with certain chemicals etc)

It is important to note also that if for instance as one might expect to be typical 30% of the tryptophane in cooked meat is racemized or oxidized, there remains 70% of this amino acid that is intact and can be readily used by the organism as with raw meat. And cooking generally only converts part of a nutriment into a useless or poison form. The organism does not need to use for its own purposes the damaged amino acids or nutriments, just get rid of them in some way or another, for instances excreting them in urine or sweat. Indeed it would be certainly interesting to compare the overall nitrogen excretion in cooked and raw diets.
One observation that is also interesting in this respect is that (after a few years of practice) substantially less food (for instance protein) must be ingested in raw as compared to cooked form to meet the needs of our organism. This is clearly in line with the above reasoning.  

    

[TylerDurden]

re MrBBQ's notions:- All those AGE-reducing etc. ideas first of all are only very minimally effective. For example, a recent study on marinating with beer/wine led to a slight  reduction of only 2 or 3 of the 17 or so  harmful  heterocylic amines in cooked foods. But adding beer and wine is unhealthy in itself, given that they also contain toxins.

And while endogenous AGEs are harmful they cannot generally be removed from the body as they are part of the body's natural processes, so are unavoidable on any diet. Exogenous AGEs on the other hand can only be generally avoided by going on a raw, palaeolithic diet.

As for claims re professional sports by PaleoDonk, that doesn't work. For 1 thing, raw food was widely practised in bodybuilding in the first half of the twentieth century. The trouble is that the widespread use of artificial drugs by athletes of all kinds has been more effective than mere food(indeed I wonder if any professional athletes nowadays practise without the use of drugs). Of course, the downside of using drugs and artificial gimmicks such as deliberately dehydrating oneself  just days before a bodybuilding contest etc. has meant that many bodybuilders and athletes have died well before their time or suffered great ill-health in their last days - their unhealthy diets just helped make things even worse.

[alphagruis]

The idea that a chemical whatever it might be added to cooked food might substantially reduce its toxicity is just ridiculous. Besides AGEs there are many many other toxins generated and there is simply no way to neutralize the effect of a sizable amount of them.

As to professional sports I also agree with TD. Notice that athletes are usually young people ( typically in their twenties) so that their diet, whatever it is or has been, has often not yet poisened them enough to clearly affect their activity.     

[MrBBQ]

By no means am I advocating exogenous AGE consumption - just some potential interest in the research literature (and tradition) on the activity of polyphenols and anti-oxidants. I certainly never mentioned beer/wine as the source of anti-oxidants (did I?) - more like the traditional spices...curry, cinnamon, turmeric - even sage, marjoram, tarragon, and rosemary. Maybe these herbs/spices are effective when rendering tallow (for the pemmican makers - especially for longer-term storage), even though I raw-render my fat (big difference in taste texture).

The other point I wanted to make is increase of PUFA (half life of 2 years) consumption correlates with increased endogenous AGE and ALE formation.

Interesting point about handedness and racemisation though - I've never heard that term before.

So the other point is that AGE formation occurs less in the presence of moisture (e.g. in broth) - maybe that combined with anti-oxidant herbs/spices represents a valuable compromise for some people. I refer again to my point about how to extract useful nutrients from the cartilaginous tissues, which is a valid enquiry.

Face it, some people (e.g. my parents, associates and good contemporaries) cannot face an all-raw lifestyle (sacrificing longevity/everyday health for small pleasures), so these strategies would be useful to at least attenuate/mitigate some of the effects.

Most of you on here simply dismiss my commentary though, so I'll crawl back under my stone, hehe...My intent is essentially good! ;-))

[Josh]

Can I ask what raw-rendering of fat is? and how long it lasts out of the fridge?

Cheers.

[MrBBQ]

Good question...it's fat that I mince then melt bain marie-stylee (carefully with stirring and a thermometer) at ~40-45 degrees C.

You can observe the procedure in this journal post: http://www.rawpaleoforum.com/journals/anthropomorphistic-intent/msg35102/#msg35102

I find it to be more easily digested when it's raw-rendered out like this, plus there is minimal waste judging by what I've hot-rendered out of the raw scratchings (which I just pass onto my parents as a healthier cooking fat than refined vegetable oil or olive oil in a clear bottle).

Also, I've been considering using the hot-rendered tallow to homemake a very high quality soap, if my parents don't want it. I'm knitting myself a long parka-style cardigan for the winter though, so that's occupying more of my time.

Maybe the raw-rendered fat is good as a topical skin moisturiser as well...

[Josh]

Thanks.

[MrBBQ]

Oh, I always consume it quickly and it's generally kept in the fridge before I melt it on a radiator at work or something...

[PaleoPhil]

If you raw-render fat, make sure you eat "the raw scratchings" too, as Lex posted info on how some fatty acids don't get rendered out of them if the temp is too low.

[MrBBQ]

Thanks for the insight PaleoPhil, which is most appreciated. I noticed that my skin gets much oilier with the raw-rendered fat, so the digestion is probably better. I reckon I'll try to mix back in some of the scratchings and see how my digestion fares, because I'm not sure yet if it's the bulk of the fats and maldigestion that's causing constipation when minimising carbs - or maybe I just wasn't eating enough calories to keep my metabolism running.

I'm still pretty much in the dark about how I should really eat (nothing seems to work for me yet). Too much fruit harms my teeth and too little carbs seems to screw my metabolic rate up. Maybe raw-rendered fat plus separate raw scratchings will be an interim solution for me.

Also, I've begun with the Super K on odd days, which seems to give me blood in my bogies and bloodshot eyes, so I don't think that man-made version is acceptable for me - or maybe one cap per week is already enough.

[Josh]

Oh right...well if I was going to eat it quickly I just take it raw but each to his own. I find that if I let good suet get a bit warm it's palatable and if it's a bit aged it's more tasty.

[TylerDurden]

You maka good point re others not having the desire to try all-raw and needing "less worse" ways of cooking. I just don't buy into the notion that they do much good. I mean getting rid of all preservatives/chemicals in foods would help some, but reducing just some of the various types of cooked toxins rather than going raw, still means a buildup of heat-created toxins in the body leading to a difficult old age(and people are living ever longer due to technology such as artificial hips etc.)

It might be an idea for me to eventually do an article on rawpaleodiet.com featuring ways to reduce heat-created toxins in foods to some extent. A few RPDers have very unhelpful spouses/parents etc. who frown heavily  on their raw lifestyle, so they can use such gimmicks to temporarily placate them.

[alphagruis]

The other point I wanted to make is increase of PUFA (half life of 2 years) consumption correlates with increased endogenous AGE and ALE formation.

What do you mean precisely? Link or reference?

[MrBBQ]

@Tyler: I'm glad you agree in that sense - in my opinion, it's important for me to help my parents and grandparents to enjoy happy lives, given my research and their passive interest. I love the spirit of goodsamaritan's www.curemanual.com and I'd like to think I could bring ideal comfort to my extended family. At the moment, I have no family of my own, so I take care of my flesh and blood, who mean a lot to me. Maybe mitigating toxins for those desiring cooked fodder is a worthwhile endeavour, even if they are not projecting a skull and crossbones onto anything without its complementary enzymes and low levels of AGEs/ALEs. There are degrees of everything...I'd like to remind you that we live in a chaotic realm, where nothing is always quite what it seems, black and white etc. May I also assert that humans have been replicating their DNA for many, many generations on cooked food, even though there's a measure of toxicity that's escalating as food production has shifted into the industrial/commercial domain.

@Josh: I've been eating a fairly exclusive raw paleo diet (with very short term side experimentation) since last June, and having still not developed a real taste for everyday fat consumption (in chunky, bulk quantity), as well as maldigestion, I'm inclined to be somewhat pioneering in preparation. Like I said, if I mince the fat beforehand, I find it's better absorbed - rendered from scratchings or not. The raw rendering is a nice way to create a dip for slightly dried meats (in a pemmican stylee) or something to mix with grated frozen heart/liver to create a pseudo-pate. In my opinion, if you struggle to eat something that you know is ideal (that said, I should have the appetite of a wolf for whole organs by now!), you prepare it in a more intelligent way as a means to gradually introduce oneself to the nature of that food - you know, establish a little rapport...For me, chewing chunks of fat that haven't been a bit melted is like chewing on cardboard - that includes cuts from all over the animal, including the creamy marrow. Also, I hate those nasty bone bristles in unmelted marrow.

@alphagruis: Voila! Par example...http://inhumanexperiment.blogspot.com/2009/10/fats-and-ages-pufas-are-even-worse-than.html (Juissance!) This is of course just a blog post commentary on studies, but it makes one wonder about AA oxidation in high meats...Does anyone know how dietary AA is metabolised, given that it's a PUFA?

[MrBBQ]

LOL @ Tyler...Mitigation through placation. Sounds more like perpetuation of an unresolved disrespect for mutual individuality in co-existence to me! ;-)) Probably the reason why my relationships remain casual or short-term...Anarcho-individualism rules!

[MrBBQ]

On the point of people's ignorance, it's doubtful that there will be a major revolution, whereby people adopt a raw lifestyle - mainly because we're a niche (albeit growing) community in a world where profit/capitalism comes before nature. Sad, but true.

Furthermore, I have access to free fat and bones (that would be destroyed otherwise) while the farmer's wife is now frying in rape seed oil as the bad-sat-fat myth continues to perpetuate...A very strange twist of fate for our mod-cons, hi-tech race.

Now I'd just like to know how to raw-process cartilage for the extra glycine, proline and hydroxyproline - that would be a great raw paleo feat.