19 replies to this topic

[purerealm]

http://www.telegraph...molecule108.xml



Mystery of the meat-eaters' molecule

Last Updated: 12:01am BST 08/07/2008

Our inability to produce a chemical present in every other primate may be linked to a series of chronic diseases. Roger Highfield explains more

What does it mean to be human? For most people, it all comes down to that extraordinary object between our ears, and how it blesses us with language, laughter and logic. But not for Ajit Varki, a doctor-cum-scientist who works in California.

Not so rare: a molecule absorbed by eating red meat has been linked to inflammation and auto-immune illnesses
Not so rare: a molecule absorbed by eating red meat has been linked to inflammation and auto-immune illnesses

For him, being human is also about a single chemical that separates us from our closest relatives, and which could be linked to many of our most debilitating illnesses.

The story began in 1984, when Prof Varki was working at the University of California, San Diego. When treating a woman with bone-marrow failure, he injected her with horse serum. The treatment carried the risk of a side effect called "serum sickness", in which the patient's immune system launches an attack on a molecule present in the serum called Neu5Gc.

Sure enough, her skin erupted with an itchy red rash. Investigating further, Prof Varki found that Neu5Gc was foreign to humans, even though we carry a very similar version of the same molecule - which may be one reason why animal-to-human organ and tissue transplants do not work well.

But in recent years, he has come to believe that the implications of this molecular difference are much wider. He has built up a range of evidence that potentially links Neu5Gc, a so-called sialic acid, to chronic disease.
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This is because the animal version is absorbed by humans as a result of eating red meat and milk products, and there is evidence that the body views it as an invader.

Eating these foods could trigger inflammation and, over the long term, heart disease, certain cancers and auto-immune illnesses. Prof Varki stresses, however, that "we have not proven any link to disease, just suggested that it is something to explore".

This sialic acid plays a number of roles: it helps us recognise cells and helps cells stick together (this stickiness is also exploited by microbes, which latch on to the sugary molecule to invade our cells). It also helps regulate our immune response, which may influence the progression of diseases and even play a part in human evolution.

The first evidence that this particular molecule is of unique importance to humans came a decade ago. Prof Varki's team, along with Prof Elaine Muchmore, also of the University of California, studied blood from chimps, bonobos, gorillas, orangutans and humans.

They found that we are the only primates whose bodies do not produce Neu5Gc - although further research established that our Neanderthal cousins were missing this version of the sugar acid, too.

Instead, human (and Neanderthal) cells bristle with a sugar called Neu5Ac. The two molecules are identical, apart from one little detail: the ape molecule has a single extra oxygen atom. Because of the many different jobs this sugar does throughout the body, this one atom was the first example found of a fundamental genetic and biochemical difference between humans and our closest relatives.

Profs Muchmore and Varki then found out why this oxygen atom is missing: our molecule is the precursor of the animal version. Unlike chimpanzees and other great apes, humans lack a particular version of an enzyme that converts Neu5Ac (or, to give it its full name, N-acetylneuraminic acid) into Neu5Gc. This tiny change could potentially explain some of the more unusual differences between humans and apes.

Chimpanzees do not seem to suffer from heart disease, cancers, rheumatoid arthritis or bronchial asthma - common conditions in humans. Nor do they get sick from the human malaria parasite, which uses sialic acid to latch on to our blood cells.

In recent studies, Prof Varki's team has found tantalising evidence that this mysterious molecule could be exerting a wider effect on our health, through the substances we eat.

After testing a range of foods, they found the highest levels of Neu5Gc in red meat: up to 11,600 micrograms could be absorbed from the recommended daily serving of beef, 5,100 from pork and 4,900 from lamb. The level in goat's cheese was 5,500, but fell to around 700 in milk and salmon. Cod, tuna, turkey and duck were in the twenties.

Given that food is broken down in the stomach, did eating animal tissue present the same dangers of provoking an immune attack as transplanting it? Following that great scientific tradition of self-experimentation, Profs Varki, Muchmore and Pascal Gagneux ate pure Neu5Gc to see what would happen.

Not only did the foreign sugar show up in the body soon after eating, but tests also revealed that many people carry antibodies that react to Neu5Gc - a protective immune response, but one which could trigger damaging inflammation.

Prof Varki's colleague - and wife - Prof Nissi Varki then found that small amounts of Neu5Gc were present in normal human tissue, probably as a result of long-term consumption. And as well as food, many biotherapeutic products made in animal cells and/or using animal materials were also contaminated with Neu5Gc.

This raised the fascinating possibility that anti-Neu5Gc antibodies are involved in auto-immunity. Auto-immune diseases, such as type-1 or juvenile diabetes and some types of arthritis, occur when the body mistakenly attacks healthy tissue.

Because the animal version of the sugar is so similar to the human one, the latter could be caught in the friendly fire directed by the immune system. Chronic inflammation is also linked with cancer; intriguingly, the team found that Neu5Gc was concentrated in tumours, particularly those that spread throughout the body. This could aid detection of such diseases, by getting scientists to look for the animal acid rather than the tumours themselves.

Some of this might sound familiar: several previous studies have linked ingestion of red meat to cancer and heart disease, and possibly to some other disorders involving inflammation, such as arthritis and lupus. But these focused mostly on the role of saturated fats, and on products that arise from cooking.

Prof Varki, however, believes that his little molecular difference could also be to blame: Neu5Gc elicits an immune reaction that might contribute to a whole spectrum of human-specific diseases. Although they have not proven this yet, the evidence is sufficiently compelling for his team to start work on ways to eliminate Neu5Gc from the body.

But the question remains: why are humans unique among primates in not producing Neu5Gc?

By studying the mutations in the enzyme that makes this molecular difference between apes and humans, Prof Varki, along with Prof Naoyuki Takahata of the Graduate University for Advanced Studies in Kanagawa, Japan, estimates that the genetic change first appeared up to three million years ago, which coincides with the emergence of Homo erectus, the first of our ancestors to venture out of Africa.

At the time, life was nasty, brutish and short: any subtle but chronic effects of this foreign sugar would not be felt until old age, and Homo erectus did not survive that long.

If the mutation that kept us producing Neu5Ac rather than Neu5Gc helped shrug off a particular disease, it would have spread rapidly through the population. It is ironic that what may have protected our ancestors then could be responsible for much of the pain of their long-lived descendants.

[kismet]

Never heard about that "sialic acid" but it sounds interesting. However, I'll comment on your strange misconception about veganism and nootropics.
Does honey contain any? Oh, fish and poultry being in the low 20s, makes all those non vegan foods a great alternative. You should probably rethink what vegan means.
Besides I did not see any connection to nootropics, but it's interesting nonetheless.

Edited by kismet, 09 July 2008 - 07:54 PM.

[hamishm00]

Never heard about that "sialic acid" but it sounds interesting. However, I'll comment on your strange misconception about veganism and nootropics.
Does honey contain any? Oh, fish and poultry being in the low 20s, makes all those non vegan foods a great alternative. You should probably rethink what vegan means.
Besides I did not see any connection to nootropics, but it's interesting nonetheless.

What about some sort of supplement that is a Neu5Gc scavenger in the digestive system? any ideas?

[treonsverdery]

I'm a freegan http://en.wikipedia.org/wiki/Freegan vegetarian

that means if i eat on purpose its vegetarian, if I dumpster dive I eat meat unless I'm sure it was donated; meat donations to dumpster divers use meat that would have otherwise have had an opportunity to look around n have a pleasant time.

I will eat donated meat that is past its presentation date

Edited by treonsverdery, 10 July 2008 - 07:32 PM.

[niner]

Never heard about that "sialic acid" but it sounds interesting. However, I'll comment on your strange misconception about veganism and nootropics.
Does honey contain any? Oh, fish and poultry being in the low 20s, makes all those non vegan foods a great alternative. You should probably rethink what vegan means.
Besides I did not see any connection to nootropics, but it's interesting nonetheless.

I took "low twenties" to mean the low twenty thousands. It wasn't very clear writing, but that's a lot more consistent with all the other concentrations they gave.

[niner]

This is an interesting article. My first question was: What does the epidemiology say regarding veganism and the various diseases considered here? Do vegans have substantially lower levels of immune-related or inflammatory problems compared to carnivores? It may well be the case that there is something in meat that isn't good for us. However, there are certainly things in meat that ARE good for us, so the epidemiology is going to be complicated.

Our bodies simply have to work better when we get the right amounts of the right molecules, and avoid the wrong ones. That's what I want to get from my diet. Maybe what this article is really telling us is that instead of eating animals, we should eat other people. That would really solve a lot of problems, as J. Swift pointed out.

[Fredrik]

Maybe what this article is really telling us is that instead of eating animals, we should eat other people. That would really solve a lot of problems, as J. Swift pointed out.

Haha. If not a modest, a fair and decent proposition. We could make make processed meat out of aborted tissue. Hey, why throw it away and waste good protein. If someone objects, let´s just use my favorite omnivore argument, "But why, I LIKE meat".

[Brafarality]

Maybe what this article is really telling us is that instead of eating animals, we should eat other people. That would really solve a lot of problems, as J. Swift pointed out.

Haha. If not a modest, a fair and decent proposition. We could make make processed meat out of aborted tissue. Hey, why throw it away and waste good protein. If someone objects, let´s just use my favorite omnivore argument, "But why, I LIKE meat".

That's the worst thing I've ever heard. How marvelous.

[purerealm]

This is an interesting article. My first question was: What does the epidemiology say regarding veganism and the various diseases considered here? Do vegans have substantially lower levels of immune-related or inflammatory problems compared to carnivores? It may well be the case that there is something in meat that isn't good for us. However, there are certainly things in meat that ARE good for us, so the epidemiology is going to be complicated.

Our bodies simply have to work better when we get the right amounts of the right molecules, and avoid the wrong ones. That's what I want to get from my diet. Maybe what this article is really telling us is that instead of eating animals, we should eat other people. That would really solve a lot of problems, as J. Swift pointed out.

i'm reading this book called the vegan diet: chronic disease prevention and it's talking about how people were a lot healthier before the industrial revolution and the american diet of meat , dairy, and smaller amts of vegetables compared to mostly vegetables and a small amount of meat. it's pretty interesting so far and i think i'm going to give it a shot, hopefully i'll see vast energy improvements

[lunarsolarpower]

Haha. If not a modest, a fair and decent proposition. We could make make processed meat out of aborted tissue. Hey, why throw it away and waste good protein. If someone objects, let´s just use my favorite omnivore argument, "But why, I LIKE meat".

That's the worst thing I've ever heard. How marvelous.

That reminds me of one of my prank business ideas. Producing a line of vegetable protein human hands for culinary enjoyment. However I think a properly seasoned "Fetusburger" would prove to be an even better seller. Imagine the target market though

[Brafarality]

Haha. If not a modest, a fair and decent proposition. We could make make processed meat out of aborted tissue. Hey, why throw it away and waste good protein. If someone objects, let´s just use my favorite omnivore argument, "But why, I LIKE meat".

That's the worst thing I've ever heard. How marvelous.

That reminds me of one of my prank business ideas. Producing a line of vegetable protein human hands for culinary enjoyment. However I think a properly seasoned "Fetusburger" would prove to be an even better seller. Imagine the target market though

Sounds like the beginning stages of the menu for a macabre, mad scientist's laboratory-styled, vegan takeout joint in NYC:
like Jekyll & Hyde or Dr. Dreadful for the organic set...
All packaged and tricked out for splendidly twisted vegans and horror film fans...with a few genuinely disturbed patrons thrown in for good measure!

Me like!

[Fredrik]

Haha. If not a modest, a fair and decent proposition. We could make make processed meat out of aborted tissue. Hey, why throw it away and waste good protein. If someone objects, let´s just use my favorite omnivore argument, "But why, I LIKE meat".

That's the worst thing I've ever heard. How marvelous.

That reminds me of one of my prank business ideas. Producing a line of vegetable protein human hands for culinary enjoyment. However I think a properly seasoned "Fetusburger" would prove to be an even better seller. Imagine the target market though

"Fetusburger". That just cracked me up! Sounds satisfying, a robust and filling 190 grams fetusburger with extra dressing to go. I´ve only slept five hours and on top of that I´m real hungry though. Could be that.

[david ellis]

http://www.telegraph...molecule108.xml

To quote the doctor - "Eating these foods could trigger inflammation and, over the long term, heart disease, certain cancers and auto-immune illnesses. Prof Varki stresses, however, that "we have not proven any link to disease, just suggested that it is something to explore"."

[krillin]

I'm reminded of an episode of South Park.

http://en.wikipedia..../Krazy_Kripples

Meanwhile, Christopher Reeve campaigns for stem cell research for the handicapped. By cracking open fetuses and sucking out their juices, he soon regains mobility, and even super powers like the character he portrayed, Superman.

[Zoroaster]

This is an interesting article. My first question was: What does the epidemiology say regarding veganism and the various diseases considered here? Do vegans have substantially lower levels of immune-related or inflammatory problems compared to carnivores? It may well be the case that there is something in meat that isn't good for us. However, there are certainly things in meat that ARE good for us, so the epidemiology is going to be complicated.

Our bodies simply have to work better when we get the right amounts of the right molecules, and avoid the wrong ones. That's what I want to get from my diet. Maybe what this article is really telling us is that instead of eating animals, we should eat other people. That would really solve a lot of problems, as J. Swift pointed out.

Now I did think this article was intriguing and its certainly a subject that warrents more research, but its not something we can be drawing conclusions from. Interesting or not theories like this are born and killed every day. We'll have to see what pans out in his upcoming studies. Either way this isn't really "Scientific evidence" as the title suggests. This is just a theory that if verified could explain why there is some benefit to a vegan diet. But even then it doesn't prove that a vegan diet is best as there are many other dietary factors that affect your health.

Luckily we have plenty of data from large prospective studies that basically look at the combined effects of all of these variables and measure risk of death from various causes. These studies consistently show that vegetarians who eat fish, eggs and milk have the best outcomes, followed by normal vegetarians (who don't eat fish), followed by vegans, followed by normal meat-eaters. Here's one extremely large and well-controlled study to get you started:

http://www.ajcn.org/.../full/70/3/516S

Its a meta-analysis using data from 76,172 individuals followed over an average of 10.6 years. They found a significantly decreased risk for ischemic heart disease with the magnitude of the percentage decrease roughly in-line with the order of diets I listed above. They found no significant difference in death rates for any other condition tested.

Now some studies have shown lower rates of certain kinds of cancer, and some have shown lower rates of other kinds of CVD, but the vegans nearly always fare worse than the vegetarians, who nearly always fare worse than vegetarians who eat fish.

This subject has been very thoroughly studied so we don't really have to guess as to whether or not vegans have the best health outcomes. They don't. Just do a quick search of medical journals and the answer will become pretty clear. When all things are considered, red meat does increase your risk for many diseases. Moderate egg consumption and milk consumption do not. Fish consumption decreases your risk for many diseases. With the amount of data we already have available, those basic facts aren't likely to change. Of course all this is for normal, healthy people. There are some conditions and diseases for which a vegan diet might be best and its pretty well established that diary can exacerbate some conditions once they're acquired.

And of course I'm not trying to say that there aren't good reasons to be a vegan. I personally find their arguments about the efficiency of eating lower on the food chain pretty compelling. There are also animal rights reasons that are valid. But if you're looking for the "healthiest" diet, from the data that's available now (and there's a lot of it) you can't really justify a vegan diet over a vegetarian diet that includes fish.

Edited by Zoroaster, 12 July 2008 - 09:56 PM.

[Zoroaster]

i'm reading this book called the vegan diet: chronic disease prevention and it's talking about how people were a lot healthier before the industrial revolution and the american diet of meat , dairy, and smaller amts of vegetables compared to mostly vegetables and a small amount of meat. it's pretty interesting so far and i think i'm going to give it a shot, hopefully i'll see vast energy improvements

One thing to consider is that before the industrial revolution the average lifespan was in the low 60's. The biggest risk factor of all for most chronic diseases is age. So rates of heart disease, cancer, stroke, etc were drastically lower back then because of a combination of spotty detection methods and the fact that people often died of TB, smallpox, and bacterial infections before they had a chance to get cancer.

[purerealm]

i'm reading this book called the vegan diet: chronic disease prevention and it's talking about how people were a lot healthier before the industrial revolution and the american diet of meat , dairy, and smaller amts of vegetables compared to mostly vegetables and a small amount of meat. it's pretty interesting so far and i think i'm going to give it a shot, hopefully i'll see vast energy improvements

One thing to consider is that before the industrial revolution the average lifespan was in the low 60's. The biggest risk factor of all for most chronic diseases is age. So rates of heart disease, cancer, stroke, etc were drastically lower back then because of a combination of spotty detection methods and the fact that people often died of TB, smallpox, and bacterial infections before they had a chance to get cancer.

good point, my interest in this topic is indeed spurred by significant fatigue though, do you know any good diets for that?

[Zoroaster]

good point, my interest in this topic is indeed spurred by significant fatigue though, do you know any good diets for that?

If you have had a drastic and significant change in your energy levels recently then the first thing to do would be to go to a doctor and get some tests run. You want to make sure your thyroid is functioning properly and that you don't have a condition like sleep apnea affecting your energy levels.

Once all that is ruled out I would recommend that you make sure you're exercising regularly. Frequent moderate exercise can positively impact your energy levels more significantly than any dietary changes you're likely to make. Personally I think a combination of aerobic and anaerobic exercises works best but some people get good results from aerobic exercise alone.

Another important step would be making sure you're sleeping well. Everyone's requirements are different but you want to be getting 6-9 hours of sleep per night. Stress during the day can also impact your energy levels so if you feel that may be an issue for you then it wouldn't hurt to try implementing some stress reduction techniques or regular meditation.

Of course at the same time it wouldn't hurt to make sure your diet is in order. I don't know that there's any one diet that specifically targets energy aside from a normal healthy diet. That means eating plenty of fruits and vegetables, moderate carbohydrates, lots of whole grains, low red meat intake, a good amount of protein (preferably from vegetables like legumes or soy), low saturated and trans fat but moderate in "good fats", and very few processed foods. If you're not already doing so I would recommend taking a good multivitamin as well.

Of course if you're hanging out on these boards you've probably already doing some of the above but if you're missing any one of those elements it can make a big difference.

[Gerald W. Gaston]

Never heard about that "sialic acid" but it sounds interesting. However, I'll comment on your strange misconception about veganism and nootropics.Does honey contain any? Oh, fish and poultry being in the low 20s, makes all those non vegan foods a great alternative. You should probably rethink what vegan means.Besides I did not see any connection to nootropics, but it's interesting nonetheless.

I took "low twenties" to mean the low twenty thousands. It wasn't very clear writing, but that's a lot more consistent with all the other concentrations they gave.

Actually the article says "in the twenties" and more like 27 per this chart (from 2003), which shows that they did not mean in the "twenty thousands":

http://www.pnas.org/...1556Table2.html

Humanuptake and incorporation of an immunogenic nonhuman dietary sialic acid

Table2. Sia and Neu5Gc content of common food items

Food	Neu5Gc,% of total Sia	TotalSia, μg/g	Neu5Gc, μg/g	Neu5Gcintake if eaten at daily recommended servings, total μ g
Cod	0.1	40	0.04	27
Salmon	3	49	1.47	810
Tuna	0.1	32	0.032	27
Chicken	0.1	76	0.076	27
Turkey	0.1	46	0.046	27
Duck	0.1	20	0.02	27
Milk(cow, 2%)	3	258	7.74	711
Milk(cow, raw)	3	262	7.86	711
Butter	3	40	1.2	45
Cheese(cow)	4	160	6.4	600
Lamb	18	101	18.2	4,860
Pork	19	134	25.5	5,130
Cheese(goat)	42	95	39.9	5,544
Beef	43	70	30.1	11,610
Beef,lean portion	36	62	22.3	9,720
Beeffat	38	82	31.2	10,260

TotalSia content and percent of Neu5Gc in each food item was quantified asdescribed in Materialsand Methods. Recommended daily servings of each item arebased on guidelines set by the U.S. Department of Agriculture (1).

1.U.S. Department of Agriculture (2000) Nutritionand Your Health: Dietary Guidelines for Americans (U.S.Department of Agriculture, Washington, DC), Home Garden Bulletin 323,5th Ed.

edit:chart text size

Edited by frankbuzin, 16 December 2009 - 08:02 AM.

[tunt01]

ty for posting this frank. appreciate it.