Wednesday, January 23, 2013

Dogs Eating Carbs

Five years ago, I had an interesting conversation with a veterinarian friend about dog food.  We were talking about diabetes in one of the dogs she was treating, and I remarked "that's what happens when you feed a carnivore carbohydrate".  She gave me a funny look.  At the time, I was seeing the world through the low-carb lens, and I remember thinking how bizarre it was that she didn't yield to my impeccable logic.  As they say, live and learn.

The journal Nature published a fascinating paper on the evolution of the domestic dog today (1).  Researchers compared the genome of wolves and domestic dogs to see what genetic changes accompanied domestication.


Humans first domesticated dogs at least 10,000 years ago, so they went through the agricultural revolution alongside us (2, 3).  In other words, when we ate grains and legumes, they ate grains and legumes, at least to some extent.  I've described in previous posts how humans acquired genetic adaptations to recent dietary changes (4, 5).

It is therefore fitting that the Nature article is titled "The Genomic Signature of Dog Domestication Reveals Adaptation to a Starch-rich Diet".  Along with a variety of genetic changes that may impact brain development and function, they identified changes in three genes that play a key role in starch digestion and absorption.  One of these genes, AMY2B, encodes pancreatic amylase, an enzyme that digests starch into glucose in the small intestine.  Wolves only have two copies of AMY2B (one on each copy of chromosome 6), while domestic dogs carry 4-30 copies, suggesting that domestication has improved dogs' ability to digest starch.

This is fascinating because a similar genetic change occurred in humans.  Dogs only produce amylase in the pancreas, while primates such as humans express it in the saliva in addition to the pancreas.  Salivary amylase is encoded by the AMY1 gene.  Chimpanzees, which eat a low-starch diet*, only have two copies of AMY1, while humans carry 2-15 copies (average ~6) (6).  In other words, both humans and dogs responded to increased starch consumption with similar genetic adaptions.  This is an example of a phenomenon called "convergent evolution".

It appears that my veterinarian friend was right to doubt my impeccable logic-- she knew from experience that dogs tolerate a certain amount of carbohydrate in the diet quite well.  Now she has genetic evidence to back her up.  Wolves may be largely carnivores, but domestic dogs tend to be omnivores-- yet another example of rapid genetic adaptation to diet.


* The diet of chimpanzees and bonobos is low in starch but not low in carbohydrate-- fruit is their main staple.

54 comments:

Tuck said...

So why do dogs get diabetes when fed a carb-rich diet?

Maybe it's the seed oils?

I'll wager that if you don't feed them any carbs but more seed oils, they won't get diabetes...

I'm running the reverse experiment with my dog: virtually no seed oils, some carbs. So far he's doing fine, and he's a breed that supposedly prone to over-eating. (According to his breeder, the best breeder in the country.)

It's funny that when the dog's on what's basically a paleo diet for dogs, he can walk away from food, even though he's a breed that's prone to obesity and over-eating.

Tuck said...

BTW, just for a comparison: our friends fed their dog an "industrial" diet of regular dog food. The dog died of heart disease at three years old.

Matt Lentzner said...

Pretty interesting. I think people forget that cooking allowed man to eat two things - meat and starch. Most starchy food is inedible when raw.

Ray Medina said...

I agree with you that dogs can eat carbs. What I take issue with is dogs eating gluten grains.

I covered my unfortunate experience with my dog Gorky who developed diabetes in this blog post: http://syontix.com/insulin-resistance-diabetes-and-endotoxemia-2/

Now, I imagine his endotoxemia was also caused by vegetable oils in his crap-in-a-bag diet. I haven't made that mistake again.

My second Siberian lived to the ripe old age of 15 years, 9 months and one day and she was a big girl at 65 pounds.

My current dog who weighs over 50 pounds, although diagnosed with congestive heart failure in April, is still going strong on only one diuretic medication. She is at least 15 and half years old, although she may be older as she was a rescue.

Neither of these two latter dogs (Sasha and Tahoe) were exposed to gluten grains under my watch. Both, however, ate/eat plenty of white rice, tubers and meat.

Besides arthritis and the congestive heart failure in my current dog, neither developed diabetes or Crohn's disease or cancer.

George Henderson said...

My dog won't eat safe starches unless they are thoroughly mixed with meat. She will snack on the occasional toast crust though.
She will eat prunes and raisins and I have heard of another dog eating berries off bushes.
Dogs are not adapted to eat allium plants although these have long been part of human diets.
Dogs may be adapted to starch because an ancestor ate it and they have retained amylase genes.

European and Asian wolves were voracious man-eaters, in fairly recent historical times, but New World wolves were not.

My experience with feeding my dog paleo:
http://hopefulgeranium.blogspot.co.nz/2012/12/what-would-bluebelle-eat-feeding-paleo.html

Kelly said...

There is quite a range cited for the number of the AMYx genes: dogs have between 4 and 30, humans between 2 and 15. That means some humans have no more copies of the gene for amylase than a chimpanzee. And some dogs have not much more than a wolf, although most have more than some humans. That begs the question, what exactly does the distributionn look like? It seems clear that some dogs (and humans) have less genetic potential to digest starch efficiently than others.

A second question is, how does one determine how many of these potential genetic adaptations are actually expressed? In other words, has anyone measured the amount of amylase actually produced by domesticated dogs?

Jane said...

I was deeply shocked a few months ago to discover there are VEGAN dogs, and moreover that they are often healthier than dogs living on commercial meat-based dogfood. I was trained as a zoologist and this just couldn't be true. But it is.

Here's what a vegan website says.

'A dog’s protein requirements are greater than ours. To ensure that your dog gets enough, make sure that approximately a third to a half of their meal consists of a high-quality protein source (such as well-cooked legumes – pintos, chick peas, soy beans, lentils, and split peas are all good). Other high-protein foods include tempeh, tofu, TVP, hummus, sprouted lentils/garbanzo beans (ground/blended).

'Unless your dog requires a grain-free diet for health reasons, well-cooked whole grains are good sources of both protein and carbohydrates, as well as other nutrients such as B vitamins. We’ve found that whole grains in moderation work really well for our dogs, including brown rice, quinoa, millet, polenta (corn grits) or blended fresh corn kernels, oats, barley, and buckwheat.

'Seitan (wheat-meat) is a high-protein vegetarian ‘meat’ made from gluten flour. Dogs absolutely love it, and (just like with humans) seitan can be a great help when ‘veganizing’ a formerly carnivorous dog. ...'
http://gentleworld.org/good-nutrition-for-healthy-vegan-dogs/

Dex Banner said...

Carbohydrates have had a bad rap over the past couple of decades, with women around the world shunning the bread basket and even avoiding fruit

Ed said...

+1 Kelly -- I too am interested in the distribution, and the actual impact of those genes on starch compatibility. I suppose you'd determine your (or your dog's) compatibility through self-experimentation... I'm somewhat persuaded by Jaminet's reasoning regarding the justification and volume of recommended carbohydrate, but even that is still a range.

Kevin Ash said...

Re: Vegan dogs

My dog is vegan and does exceptionally well. She has no problem out-running me on 30 mile runs in the mountains.

I know the following is anecdotal, but as a member of the vegan community, I am familiar with others who have vegan dogs. Of all the people I'm familiar with who have vegan, their dogs lived exceptionally long lives (most are still living). I dated a woman a few years ago who had two 18-year old dogs who were vegan since they were one. They were fed entirely human food, FWIW.

Somewhere I read that industrial dog food researchers for senior formulas said that the best way to extend dogs' lives is to feed them less protein - esp animal protein. Makes sense with the vegan diet.

PaleoCure said...

My dog loves to eat the blue berries that fall from the palms here in Tampa Bay, FL. I think they are nutritious. That said, I do NOT feed my dog any food with Genetically modified grains like wheat and he eats a mix of real Paleo foods that are in my diet, Darwins raw dog food, and Earthborn Holistics grain free.

He is now nearly 13 and is doing way better than he was when he was getting a high carb diet at age 7. Down 5 lbs and looking/acting like a puppy.

Gerard Pinzone said...

Dogs are omnivores, not carnivores. Cats are carnivores. http://www.petmd.com/cat/nutrition/evr_ct_cat_nutritional_needs_different

PaleoCure said...

I also think that perhaps some dogs are more succeptible to carbohydrate difficulties. There are dogs that seem to be compulsive eaters and other dogs who are not. I am not convinced that dogs are all adapted to eat a high carbohydrate diet. It is highly unlikely based on my observation of dogs.

Wendy Schwartz, Go Paleo!
http://www.gopaleo.com

RachaelHD said...

My dog has eaten blueberries when we came across them on camping trips, though it's hard to know if that was interest or just extreme hunger. She is a pretty good blueberry dog (like a truffle dog) and leads us right too them.

Heath said...

I feed my dog fruit, dairy and other animal products. Never seen a healthier and more svelte animal. He was raised mostly carnivorous and was equally as healthy. I still maintain that most things can live on most things, provided that there are enough calories.

Alex said...

It is unbelievably weird to me that people would impose human, religious/philosophical restrictions on their pets. That's like me converting to Islam and insisting our two female kitties wear burqas.

Heath said...

My only concern with vegan diets is the retinol/carotene issue. But dogs can handle that conversion a lot better than humans, for some reason.

Stephen Boulet said...

Our vet always raves about our dogs' health when they come in for a checkup. We use a grain free feed (Origin). They look ripped to me, and are energetic. I don't know if I can conclude anything else from that other than this diet is good for my dogs. It does seem that mainstream dog foods aren't optimal for dog health though.

Stylooke said...

If anything, dogs get diabetes because they can cut up starch into glucose, else it would just pass the GI tract and possibly cause some intestinal distress, but not diabetes.

Amylase does not prove dogs should eat carbs, it hints that there might be other adaptations too, but in itself it does not prove anything.

Can dogs digest starch? Absolutely. Will removing starch from their diet cure their diabetes? Most likely.

Mike said...

I feed my black lab as much meat as possible. She can tolerate a little bit of CHO, but too much and her coat losses its sheen and she fattens up. My point would be that just because they can use something as food, does not make it optimal.

I was watching a program recently on how dogs evolved from wolves. Interesting, it appears to have happened quite quickly and with some interesting physiological adaptations. In the transition, dogs became smaller and in relative terms their jaws and brains became smaller. I wonder if the introduction of human foods (starches, grains) had anything to do with it?

Paul N said...

Sounds like a similar situation as for people - if dogs eat a lot of processed garbage food - especially containing gluten - their health will suffer.

At my local pet store I have noticed how "gluten free", "grain free" and "raw meat" are increasingly prominent labels.

The starch question is interesting, especially the lack of salivary amylase, as is the one about the adaptation being to cooked starches.

I wonder how the vegan dogs are doing for B12? I think it is added to commercial dog foods (along with a bunch of other nutrients) but a dog fed on plant "whole foods" would be at risk.

Paul N said...

"yet another example of rapid genetic adaptation to diet. "

While technically this statement is true, I don't think it tells the whole story.

I say this as it is not a just case of dog populations adapting to diet by the normal process of evolutionary/reproductive advantage and natural selection, but it is also a case of selective breeding.

In other words humans have -greatly - influenced the sexual selection of the dogs, for our different purposes. If the dogs were merely exposed to the different foods - even cooked starches/legumes - without human influence on breeding - the adaptation would not have been nearly so rapid - or diverse.

Dan said...

So some dogs have adaptations for digesting starch. Do all dogs display these adaptations, and of those that do eat starch is a starch-rich diet optimal?

Chris Masterjohn's talk at the AHS was discussing the human starch adaptations -- clearly we have also developed some genetic adaptations towards eating starch, but the fact that we have some adaptations does not imply that it's the best thing to eat. But on the other hand, maybe it's better to eat some starch than no starch at all.

Chris Wilson said...

Interesting stuff! My thoughts on dog evolution were shaped heavily by the Coppinger's book:
http://www.amazon.com/Dogs-Understanding-Canine-Behavior-Evolution/dp/0226115631

Dr. Coppinger taught biology at Hampshire college and is big-time into working dogs. Not everyone agrees with his assessment, but he makes a convincing case that the familiar domestic dog basically arose at the same time as early human settlements- it was a selection on a population of wild canids that had behavioral and anatomical traits conducive to living in proximity with this new resource, largely human processed foods. It makes sense that multiple starch adaptations would have had to be selected to facilitate this in the long run...


Toxic said...

Lol! Would be fun to try...

nathan sauve said...

My dog eats his own shit sometimes.

Gabriella Kadar said...

Nathan is on the right track. Dogs are coprophagic. When are the researchers going to 'discover' that dogs eat shit. Even until today, in parts of the world where people defecate in the open, dogs eat it.

Dogs are nature's recycling machine. This is why dogs and pigs are 'unclean'.

I must admit I had a good chuckle reading about research on Ebola virus. Humans in the area wouldn't allow the researchers to take blood in order to test for antibodies to Ebola. So researchers went for the dogs. Reason being that dogs may be exposed to the same pathogen via the reservoir specie, whatever it is. I thought, good choice, wrong idea. Dogs eat shit, bloody diarrhoea and everything else.

Dogs just plain old eat shit. Donkey shit, human shit, raccoon shit, any shit.

So let's stop sanitizing dogs. Maybe they do well with the 'probiotics'.

George Henderson said...

Agree with Nathan. My dog ate sheep poo regularly and I tried to stop her (hydatids) but I realize now she knew what she was doing.

@ Jane, I wouldn't believe everything I read on vegan websites. But really, what they're feeding the dog isn't far different from commercial dry dog food. Vets swear by it, it kills dogs.
Our vet said "make sure you feed her dry food. You can expect your dog to develop cancer". Not kidding.

The grain-fed dog was much hungrier than the paleo dog. The paleo-fed dog will sometimes go for a couple of days without asking to be fed. The dry-food dog expected to be fed twice a day.

Gabriella Kadar said...

So basically dogs ended up chumming with humans because they ate human shit. Cleaned up the campgrounds. Not starches.

Maybe scientists should watch dogs and not just study their enzymes.

nathan sauve said...

George, that's so true about eating organic wild-dropped feces too, I'd blocked it out of my mind until you brought it up.

I live on an island in the middle of nowhere and deer outnumber humans, eating entire gardens and sleeping/shitting in the backyard every night. Often when I let my puppy out I'd watch in horror and amusement as she spent the entire time going from pile to pile, gobbling merrily away.

In hindsight I'm pretty sure the highlight of her year was feasting on migrating swan/goose shit for one gluttonous week every fall.

Miki said...

Chimpanzees eat mainly fruit but most of their calories come from fat via fiber fermentation by bacteria. Carbs compose only 30% or so of the caloric value of their diet. See calculations and references here http://www.paleostyle.com/?p=2001

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Jane said...

@Kevin Ash
Yes, your account of vegan dogs corresponds with what I have read. I didn't believe it at first but once I had read enough I had to. These dogs can be extremely healthy, and are long-lived and good natured.

@George
'Jane, I wouldn't believe everything I read on vegan websites.'
What is it in the link I gave that I should not have believed? Did you read it? Or did you avoid it for fear of contamination?

Evelyn aka CarbSane said...

@Miki

"Chimpanzees eat mainly fruit but most of their calories come from fat via fiber fermentation by bacteria. Carbs compose only 30% or so of the caloric value of their diet. See calculations and references here "

SCFA's are not "fats"
http://carbsanity.blogspot.com/2011/02/when-is-fat-fat.html

Chimps may indeed convert SCFA to LCFA through de novo lipogenesis somewhere intermediate to ruminants (almost all) and humans (almost none), but this is not the same as ingesting LCFA.

nada said...

Being able to digest starch better than a wolf doesn't mean much- they did not do a comparison study finding out exactly how much nutritional content wolves vs. dogs derive from starches. Just because dogs have been shown to be able to digest starch better than wolves doesn't mean they do it WELL, just better. If wolves having only two genes for amylase digest starch very very poorly, it doesn't mean that dogs are great at digesting starch just because they have more genes for it. Better than wolves, but not necessarily great overall. Not to mention that the article mentioned some dogs in the study only had four copies of the gene for amylase... That's hardly any better than wolves.

Bally Balldez said...

Wolves an ancestral dog for both omnivores. One of the things a wolf eats after it kills its prey are its intestinal contents.

Paleo Phil said...

"Wolves eating berries!" http://www.youtube.com/watch?v=TmuYTb6ynbg

Wolves and wild dogs are both scientifically classified as facultative carnivores, which differs from obligate carnivores and carnivore by itself does not mean "eats only meat." Nature is rarely as simple as most people assume.

Helen said...

@ George Henderson -

Raisins are toxic to dogs. So are onions and garlic. Just FYI - hope folks are being careful.

Jane said...

Many years ago I spent some time working on a mink farm in Sweden, and I learned something about feeding captive carnivores. In Sweden, mink were fed on whole fish, and were large and healthy. In Britain, they were fed on fish scraps from the fishmonger, and were not. They needed the whole fish.

Perhaps the best diet for dogs is whole freshly killed rabbits. We know that works. But who has access to those? Tinned dogfood has all kinds of dreadful things in it like sick cows and rotting carcasses. The evidence I have seen suggests a vegan diet is better.

Craig said...

Carbsane, go on an equacaloric potato diet and measure your ketones after a few days. You should find PURPLE on the ketone strips!

I have been eating nothing but sweet potatoes and white potatoes with a fatty meal about once or twice a week. Resistant starch and butyrate is very ketogenic in me at least.

Evelyn aka CarbSane said...

Craig, how do you propose butyrate is converted to ketones?

Go Meat! said...

Hi Stephan,

I am looking to feed my dog an ancestral diet/real foods diet. What percent carbohydrates do you think dogs can tolerate in their diet? What percent carbohydrates do you think is optimal? And should the sources of carbohydrates be starchy tubers and rice, soaked grains and legumes, or a combination of both?

Craig said...

Carbsane,

Supposedly it is because butyrate can't be stored so it must be burned. I can't tell you how it is ketogenic. I just know is that it happens in me and in animals even when eating high carb. http://www.jbc.org/content/135/1/183.full.pdf

Jane said...

I suppose butyrate is made into beta-hydroxybutyrate? In the liver? Via acetyl-CoA?

I think it's very interesting. Potatoes are ketogenic!!

Bob Bejaan said...

I have fed my cat a vegan diet for 6 years now and he is thriving on it. Before when I fed him tinned cat food from the store he would scratch my sofa and get grouchy if I didn't get him outside.

Now on his new diet (mostly quinoa, legumes and brown rice) he is much happier and better behaved.

And for what it's worth Snuggles just loves his saucer of soy milk in the morning

~*Connie*~ said...

cats are obligate carnivores and your take on their diet would be interesting..

http://www.catinfo.org

Jane said...

@Bob Bejaan
Please could you give us something that would help us determine whether you are for real? Apparently cats are more difficult to keep on a vegan diet than dogs, and I would be amazed if your cat really was healthy on a vegan diet without extra taurine, for instance.

Bob Bejaan said...

Connie, cats are not obligate carnivores, that is a myth promoted by the meat industry so it can sell its leftover scraps as pet food (most pet food manufacturers are owned by meat processing companies).

Yes cats can eat meat and even survive on it (much like humans). But many cats that are fed a meat-based diet will develop illnesses in old age, and few rarely even live beyond 15 years.

Vegan cats are much healthier and happier, and often live well into their 40s and 50s with no sign of heart disease or diabetes.

The taurine myth is another ridiculous red herring peddled by the meat industry. Cats in the wild obtain most of their taurine from berries and nuts, and the stomach contents of their rodent prey (for those that do occasionally eat other animals).

Think about this Connie (if that is your real name): why would God make cats obligate carnivores, and then pass a commandment "thou shalt not kill" that his creations could not obey?

Doesn't make sense.

nathan sauve said...

Checkmate.

Fausto Levantesi said...

http://news.sciencemag.org/sciencenow/2013/01/dog-domestication-tied-to-starch.html#comment-777292437

Jim said...
This comment has been removed by the author.
Jim said...

I'll just keep feeding raw meat, bone & offal (zero carbs) to my ridiculously healthy 6 year old dog.

Jane said...

@Bob Bejaan
You have not passed the test.

Terry Vaughan said...

I do not understand your use of impeccable !!