This blog is about the intersection between evolutionary biology and food. But also about practical applications, sustainable agriculture, and general tasty things.
In autoimmune disorders the immune system attacks the body's own tissues. We recommend that these tissues be removed because clearly they are causing an immune reaction.
Um...what? It seems funny, but that seems to be the reaction of some scientists to Neu5Gc, a sugar that apes, but not humans, synthesize naturally. However, we do ingest it in food, particularly meat and dairy products.
Some humans have an inflammatory immune reaction to it. Does that mean it's bad to eat? Numerous papers on Neu5Gc that I've read seem to suggest so in their discussion sections.
I was reminded of that when reading this Atlantic article on chimp fertility studies:
Gagneux’s lab space was adjacent to that of his collaborator Ajit Varki, who had helped uncover the functioning of the sugars, known as sialic acids, on cell surfaces. The sialic acids on the surfaces of human and chimp sperm have become the focus of Gagneux’s work, too. Humans, as Varki discovered, have lost the ability to make one sialic acid, Neu5Gc, and Gagneux suspected that Neu5Gc played a role in fertilization. He hypothesized that Neu5Gc helped female chimpanzees, in a process called “cryptic female choice,” get the benefit of the most-compatible, highest-quality sperm. The sugar acted like the fuzzy part of Velcro and attached to barbs formed by sugar-binding proteins on the surface of the cells in the uterus or fallopian tubes. Neu5Gc, as Gagneux imagined it, might “sweet-talk” the female reproductive system.
Gagneux’s Neu5Gc ideas had a critical implication for human fertility. Although we have lost the ability to synthesize Neu5Gc, we ingest the sugar when we eat meat and dairy products, and it, in turn, can then be incorporated into our cells. Does Neu5Gc coat the surface of human sperm? Is it found more readily on the sperm of men who eat lots of animal products? Does the extremely foreign Neu5Gc then trigger in women an immune response that selects against the survival of the sperm? “It could be that men who eat loads of meat pass a threshold and become infertile,” suggested Gagneux. [emphasis mine]
This just cries out for better general education of scientists. Does her hypothesis make sense? Inuit and Nenet cultures eat almost all-meat. Shouldn't they have died out by then?
Maybe instead of pegging this sugar as the bad guy, we should wonder why we are reacting to it in the first place? Unfortunately all the populations that they have studied for a reaction have been western. Most people do seem to have a reaction to Neu5Gc, but this paper has a tantalizing graph:
See the humans clustered around the chimps? Who are they? Why the difference?
If cow’s milk gangliosides are the source of Neu5Gc in breastmilk, then how do the infants develop antibodies to these relatively rare antigens? Babies receive all of their antibodies from their mother until their immune systems start to develop at about six months of age. The answer is hinted at by the observation of a mother whose exclusively breastfed infant developed sensitivity to breast milk after the mother ate dairy products. The mother reported that she shifted from a long term vegan diet to a meat diet to improve her nutrition during her pregnancy. It is also likely that she produced IgE antibodies to Neu5Gc, which were then transferred to her baby across the placenta during gestation.
I would also suspect that increased gut permeability due to the constant irritation from foods like gluten, poor gut microflora populations, and general inflammation play a role.
Aunt Maude still sending you links on that study that purported to show how terrible meaty diets are? Here are some great links for a takedown:
For about a year Robb Wolf has hosted the excellent and extremely informative Paleolithic Solution Podcast. Despite publicly admitting to only having six listeners, the truth is that the podcast has been a phenemenon in the paleo diet community. Robb Wolf is a research biochemist turned trainer and paleo diet proponent, so he brings some formidable expertise to the paleo diet table. He knows his science, but his experience coaching others in paleo food and fitness is equally valuable. Finally he has a book that brings it all together, presenting paleo as a scientific solution that anyone can follow: The Paleo Solution: The Original Human Diet.
I came to paleo from the anthropological side of things. I was won over by the health of ancestral bones and of tribes that continue to eat an ancestral diet. Paleo made sense to me because it was the diet we evolved to eat and the diet that brought us to our physical prime as a species. Robb writes a little about this, but mostly his book is dedicated to the biochemical basis of paleo. He shows why paleolithic eating, living, and moving make the biology of our bodies work properly and how neolithic agents can muck things up. Cancer, heart disease, osteoporosis, infertility, IBS, colitis, and PCOS are just a few of the diseases of civilization addressed in the book.
His approach is multifaceted— from experience he knows that it's not just food that matters. He devotes chapters to exercise and lifestyle. For me, the lifestyle chapter was the most important, because it drove home the point that it's not just gluten that can mess you up. Poor sleep, constant stress, and overtraining are just as bad.
That's saying a lot, since one of the take-home points in the book is that gluten is sooooooooooooooooooooooooooooo evil.
A comprehensive solution to modern health problems
He makes a convincing case for not including gluten even in paleo "cheats." At his seminar he said to "cheat" with a gluten-free beer or a corn tortilla and not to wreck your immune system with bread. Because that's exactly what wheat does. Lectins in wheat are generally considered by researchers to be the most dangerous because of how they can disrupt the gut lining. In good digestion the gut cells have healthy microvilli (the brush thingys) rich in enzymes that help break things down in order to usher usable proteins into the bloodstream.
Yay, this steak is so nicely broken down, your microvili are very happy
Lectins in gluten assault the microvilli, potentially leading to poorer absorption of nutrients and increased gut permeability, which can allow poorly broken down proteins into the bloodstream. This can activate the immune system, leading to autoimmunity and inflammation.
W/ Gluten Ur microvilli R sad
Sound complicated? The Achilles heel of Robb's book is that it might not appeal to people who are intimidated by science. If you like watching NOVA and enjoyed biology class, this book is for you.
If the very thought of omega-3 fatty acids gives you a massive headache...maybe you need some fish oil and frankly you can skip the science-y chapters, because they make up only half of the book. The other half is practical implementation: how to get nutrients, when to supplement, how to exercise, and how to plan meals. One of the take home messages is that almost everyone has the ability to do paleo. If you can make scrambled eggs and saute chicken breast, you can do paleo. Paleo doesn't have to be complicated, it can involve foods you already eat and love! Furthermore, Robb tells you how to customize the diet based on your goals:
Another unique aspect of this book is Robb's writing style, which is hilarious like his podcast. You can tell he's been preaching this to a diverse group of people, some of whose stories he has included as case studies. Some of these seem miraculous, but as someone who was cured of autoimmune problems through paleo it doesn't surprise me.
For the more seasoned paleo dieter, the information on cortisol is particularly important. I didn't really know much about this stuff until his seminar when I realized that some of the stress issues I was experiencing were probably caused by this very interesting hormone. You can be eating perfectly, but still wreck yourself by staying up late, working a gazillion hours a week, and drinking excessive amounts of coffee (or all of the above). It seems like common sense, but many paleos are type-As who want to use the diet as a tool to support their super-human crazy overworked lifestyles. Seems to work for some, but for most of us burn-out is inevitable. Robb Wolf says to sleep for 8-9 hours a night in a very very dark room— like a bat cave. Apprently ALL your cells are sensitive to that stupid streetlight outside your window, so just an eye mask won't cut it.
If you live in NYC come get this book at our super-cool rooftop party on the 18th! If you can't make it, please do pick up a copy on Amazon via this link. It supports me and boy would it be awesome to see this in the top 10 list there!
*My major complainst about the book and what will likely give other design nerds an aneurysm are the fonts and typesetting. Robb, please never ever use Papyrus again. Or the paleo!design!nerds (all 20 of us) on Twitter will make fun of you.
If you read the media accounts you might think that this study is about Aktins or low-carb diets. But it's not. Because the people studied, as far as we know, weren't on such diets. Some of them just happened to eat lower carb and higher in meat, and the statisticians/idiots associated this with mortality. But were these people low carbers? For all we know they ate hot dogs from Safeway and their carb sources included twinkies and slurpies.
Here is a hint researchers: if you want to study a diet, have people actually do it. Don't try to evaluate a diet based on generalized data. Unfortunately these researchers are insulated by the fact that their data is behind a paywall.
It's easy enough to stop eating crap and start eating a diet closer to what evolution intended. Other evolutionary disconnects are harder to remedy. As a young woman, I can say one of the hardest is childbearing. Most middle-class young women in developed countries cannot afford to have children during our prime childbearing years. Furthermore, having children often means relying on two incomes and leaving the childcare to someone else outside the family. American children start school young (Swedish children start school at 7, American at 4-5) and our schools generally do a terrible job at providing an evolutionarily-appropriate environment. Think about hunter-gatherer children: lots of play, mixed age groups, and spending time and learning from relatives.
What are the consequences of this evolutionary disconnect? I think we are just starting to see them. One alarming trend is that the age of puberty is falling. Some blame diet, others blame pollution, but it's probably all that and more. Here is an interesting study on how social factors might influence puberty. It suggests that poor mother-child bonds might lead to early puberty. The unfortunate thing about these studies is that it's often hard to tease out social issues like that fact that children whose mothers have to work long hours often live in environments that are poor in many other ways.
The evolutionary disconnect goes so much deeper than just eating inappropriate foods for our species like bread....it goes into how we work, move, and raise our children. The problem here is that the disconnect is so deep that it's hard to remedy it unless you want to run off and become Amish. And that the disconnect is psychological and social as well. How many 24-year-old women want to spend their days taking care of children anyway? How many of us have the extended family to help us?
While I was gone, apparently The China Study received some belated smackdown. I've personally never paid much attention to that book. I took several advanced statistics classes for my degree and an epidemiology class. If I wanted to base my diet on that flawed methodology, I might be more interested. But you can hash and rehash data and it won't change the fact that epidemiology (like my own science, economics) has been responsible for crap conclusions that have not bared out in the real world. I don't think economics or epidemiology are bad and in fact I'm quite interested in them, but they are rough tools that I'm not going to use them to manage my life.
As Kurt Harris said:
This is all just epidemiology, and epidemiology is bogus. Now, I don't mean it has absolutely no value. It is good for hypothesis generation. It is almost worthless for finding the truth. It is especially worthless the way it is used by hacks like Campbell who are simply trying to sell people a book that tells them what they want to hear.
You can run all kind of analytics on that China data and maybe find some interesting hypotheses to test, but then you have to worry about the data itself. I'm not sure rural Chinese people from the 80s have much to tell us about what to eat in America now. As Denise pointed out, there are pathogens present in rural China that aren't exactly common in Brooklyn, NY.
While Denise's post is certainly very interesting, I'm alarmed that she is now working with a vegan epidemiologist, but who also is a fruit-based raw vegan. While there are several academics who have formulated scientific vegan nutrition, no conventional science supports the fruit-base raw vegan diet- it's pure quackery and lately its proponents have unfortunately been trolling paleo blogs.
Evolutionary fitness is not about epidemiology- it's applied evolutionary theory. I'll be reviewing some books in the next month about that science, but needless to say, I think it's a far better groundwork for living as a human.
Mmm fatty fat flavored fatty fat
The earlier graphic was a pyramid, which many mistook for a dietary recommendation graph like the USDA's' idiotic food pyramid. I feel this graphic illustrates the philosophy behind my thoughts better. Plus it adds on a new concept, which is thinking about diet in terms of the human continuum. Just like the babies in The Continuum Concept biologically expect to be held, our bodies biologically expect certain food. When we consume things like soybean oil our bodies just don't function properly, just like babies that are never held as infants. Of course there is variance based on genetics, gut bacteria, etc, but overall animal fat is the nutrient that the human body seems to be evolved to eat.
Animal fat is the nutrient our bodies can handle most perfectly. We absorb it and utilize it in a way that fuels us without dragging us down. Contrast that with a dinner of just some chicken breast and some spinach. It's a meal that's "paleo", but unlike anything our ancient human would have encountered in a thriving environment. It takes energy to digest all that protein and fiber. Add a chicken thigh with a bunch of skin and things are looking a lot better in terms of actually fueling us.
Not on the human evolutionary continuum: too much omega-6, too much fructose, too many antinutrients, too few nutrients
Butter and ghee might get to jump the continuum...after all, they are very close to being like lard, tallow, and the other animal fats. But they have their detractors.
Another interesting thing about the analogy is that The Continuum Concept maintains that the consequences of not raising children the way humans evolved to be raised aren't just horrifying things like reactive attachment disorder, but annoying behaviors we very as normal in modern children. It's the same for not eating the way humans evolved to eat. Heart disease and diabetes are the tip of the iceberg. Health problems that probably aren't normal for humans include things we view as nuisances like acne, constipation, cold sores, and a whole host of other "small" things.
From the comments:
Lets see how many diseases you could get from raw meat
Let's look at all the diseases you can get from vegetables:
Liver fluke, salmonella, pathogenic e coli, botulism, campylobacteriosis, listeria, staphylococcus aureus, brucellosis...the list goes on and on.
Actually, vegetables cause most food poisoning outbreaks. Cooked meat and fish also do plenty of damage. Definitely raw meat can be dangerous, but food poisoning is simply a danger of food. Most of the raw meat outbreaks occur when people make mistakes in the kitchen. Very few people want to eat chicken raw, but it's quite common for people to cut raw chicken and then use the same knife on vegetables for their salad. That's way different from intentionally eating raw meat.
Plenty of cultures from the Japanese to the Inuit consume raw meat without all keeling over and dying. For me, the benefits of eating raw meat outweighed the small risks. I only eat whole prime cuts from herbivorous animals, I don't just buy ground beef from the supermarket. Most contamination occurs during processing.
Most of the raw foods I eat aren't exactly shocking. Millions of people eat sushi and raw oysters every day. Be careful, but life is too short for scare mongering. Thanks for the warning :) I do know about food poisoning. I had food poisoning, serious chronic salmonella that sent me to the E.R. I was a vegetarian then.
I would hate for people to think that the paleo diet is about recovering some "paradise lost." Just because peasant agriculture was miserable for most people doesn't mean foraging was a walk in the part. Almost every foraging culture studied has a wide range of remedies for illness and medicine men are revered. Hunter-gatherers suffered from malaria, tuberculosis, parasites, wounds from wild animal bites, and all sorts of horrendous infections.
The preferred medicine against diarrhea was clay, kaolin-like powders or pulverized bone ash while bee larva, certain tree barks and the fruits of two trees were eaten to relieve constipation.
But many detractors of the paleo diet point to studies of more modern hunter-gatherer cultures to draw out evidence they were ill. We have to remember that what is left on that lifestyle is people who were able to survive on the worst lands not coveted by farmers. The Inuit or the San diet might be healthier than most American diets, but neither is really similar to the diet of paleolithic people.
In Innu mythology, Matshishkapeu (literally the "Fart Man") is the most powerful spirit—even more powerful than the Caribou Master, Kanipinikassikueu. He proved himself when the Kanipinikassikueu refused to give the Innu any caribou to eat. Matshishkapeu was so angry that he cursed the Caribou Master with a painful case of constipation.
It's even possible we could do better. For example, both the high and low fiber diets of hunter-gatherers are touted as solutions to digestive problems, but digestive ailments clearly still plagued cultures eating both diets. Personally, I try to eat the vegetables that work for me and I don't worry about counting fiber. I'm pretty such that if I ate the bazillion grams of fiber the San eat, I would feel pretty sick. Maybe that's what anecdotes like this convey: there is lots of learn from hunter-gatherer and ancestral diets, but imitating their fiber consumption with BRAN4LIFE bread is on the same level as imitating snake bite wounds by keeping your own pet PALEOvipers.
Despite all that hunter-gatherers suffered, the paleo diet is about avoiding diseases of civilization, and it seems they did that well. We should eat like them, but still with an eye to the fact that they ate what they could to survive.
Postscript: I think many of the stomach problems attributed to hunter-gatherers were probably post-infectious or in the case of the Inuit, because of a lean time...literally...Vilhjalmur Stefansson found that without ample amount of fat, stomach issues ensued.