This blog is about the intersection between evolutionary biology and food. But also about practical applications, sustainable agriculture, and general tasty things.
A new free-full text paper by Ian Spreadbury has been making the rounds lately. "Comparison with ancestral diets suggests dense acellular carbohydrates promote an inflammatory microbiota, and may be the primary dietary cause of leptin resistance and obesity" is interesting because it is written through a distinctly Ancestral Health lens to provide a new framework for thinking about possible causes of Western disease.
For some time, many people in the Ancestral Health movement have blamed carbohydrates for various diseases of civilization, but over time, this idea has lost its hold and many writers in the movement now reject it. We perhaps have our own paradox- the "Kitavan paradox," which was probably the source for much of this questioning, particularly since so many paleo diet books in the past cited the Kitavan study and then told readers to restrict carbohydrates. This paper looks for reasons why
Despite food abundance and a clear overlap of macronutrients and glycemic index with Western diets, Kitavans are reported to possess leptin levels, fasting insulin, and blood glucose levels dramatically lower than those in Western populations deemed healthy, and appear to have a virtual absence of overweight, diabetes, and atherosclerotic disease.
What if it were something about grains per-se rather than carbohydrates? The paper describes how endotoxemia in the gut, particularly Lipopolysaccharide (LPS), can lead to systematic inflammation related to many elements of metabolic syndrome like leptin resistance. Endotoxins are part of the cell-wall in gram-negative bacteria such as E.Coli and Salmonella and they provoke an inflammatory response in many contexts. The idea here is that Western diets perhaps might increase endotoxemia by promoting growth of pathogenic bacteria and adding fuel to the fire by increasing intestinal permeability, allowing endotoxins to ply their inflammation across the entire body. He also mentions the fact that science is showing that this process occurs in the mouth as well, where modern diets promote "leaky teeth" aka gingivitis, which has convincing ties to metabolic syndrome (which pilot studies show a paleo diet might treat).
Unfortunately, we then develop another paradox because most of the studies on LPS in humans show that absorption is promoted by a high-fat diet. And as the paper notes, foraging peoples with higher fat diets do not seem impaired.
Spreadbury lays out a hypothesis that carbohydrates can be divided into two groups. Cellular carbohydrates, which are:
Tubers, fruits, or functional plant parts such as leaves and stems store their carbohydrates in organelles as part of fiber-walled living cells. These are thought to remain largely intact during cooking, which instead mostly breaks cell-to-cell adhesion. This cellular storage appears to mandate a maximum density of around 23% non-fibrous carbohydrate by mass, the bulk of the cellular weight being made up of water.
Then there are the acellular carbohydrates:
The acellular carbohydrates of flour,94 sugar and processed plant-starch products are considerably more dense. Grains themselves are also highly dense, dry stores of starch designed for rapid macroscopic enzymic mobilization during germination.95 Whereas foods with living cells will have their low carbohydrate density “locked in” until their cell walls are breached by digestive processes, the chyme produced after consumption of acellular flour and sugar-based foods is thus suggested to have a higher carbohydrate concentration than almost anything the microbiota of the upper GI tract from mouth to small bowel would have encountered during our coevolution.
And here we have another problem. Because archeologists continue to find earlier and earlier evidence of what was once considered advanced food processing, from pottery to grind stones. The foods that are characterized as "acellular"...well, how long have they been in the human diet? The paper mentions some of these finds, but says they were likely a small part of ancient diets, but that is far from a sure thing. We also have an ethnographical gap here in this chart:
Because you can see modern processed foods there, but nothing on indigenous "processed" foods. No chicha or poi or any of the variety of ground/fermented/pounded foods that many of these cultures consume. This is partially because there is very little data on these foods, which is unfortunate.
My prediction is that better accounting of indigenous diets will show that they consume more of the acellular carbohydrates than initially predicted by some. We also need ethnographical data that records everything consumed, even things that seem incidental like teas.
But I think we need to look further into the types of these consumed and other compounds they contain. Same for fatty foods.
An interesting thing here (thanks Stabby the Raccoon) is that studies show that orange juice, a accellular carbohydrate, reduces endotoxin load. Orange juice is one of those things you probably thought was healthy and then you realized it had sugar and it was "bad" and now people are rediscovering it again. But I think the sugar here is incidental, what is probably more interesting is the ability of antioxidants to suppress endotoxins. Wine and olive oil may have similar properties.
I was browsing The Human Food Project's website and came across a letter written by anthropologist Jeff Leach on low-carb diets:
In a series of elegant studies, Cani and colleagues ( 2-4) have shown that holding calories constant and varying macro levels of fat can induce low-grade metabolic endotoxemia which can lead to complications associated with cardiovascular health. As fat intake, so do serum levels of LPS and associated biomarkers. However, in high-fat diets with prebiotic oligosaccharides added (derived from chicory roots), serum levels of LPS drop, as do the metabolic markers of inflammation.
So it is also possible that prebiotics in indigenous diets also have a protective effect. So we shouldn't look so much perhaps at dividing carbohydrates into two categories, but tracing each type of carbohydrate to the type of bacterial environment it promotes.
Now n=1 time here, but I had gingivitis before I started eating better and it went away. And all the sudden it came back. And it was incredibly frustrating. Frustrating to the point that I even thought the problem might have been caused by the cavity-ridden guy I had started dating when my gums got bad again for giving me his lame mouth bacteria. I started supplementing a few things, notably K2, D3, and switched back to the flax oil that I had been using when my gums were better. The problem resolved and has not come back and my gums even survived the breakup with bad-teeth guy despite the fact I was eating mainly ice cream. So I don't know if for me, it was more about nutrients I needed to get rather than too much simple sugar.
A problem with reconstructing diets from the past is that people often forget to fathom the amount of information and cultural diversity that has been lost. Lost to cultural change, to habitat change, or simply to nature's rising oceans or lava flows.
Often you only have pale glimpses of what was lost in the form of archeological remains or the writings of passing travelers who probably did not realize that they were witnessing things that few can even imagine today.
When most people today think of the arctic or an ice age, they think of people clad in skins subsisting on wooly mammoth. But the truth is that arctic peoples of the past and of today rely on a huge variety of plants as well. I have written about the excellent book called Plants That We Eat, which describes the amazing and diverse plant foods of the Inuit. Most of their plant foods were leaves and berries, but they also collect tiny roots from the stores of mice, which provide a small amount of starch.
Turns out that further-south Arctic cultures in the past probably exploited starches more extensively. In Siberia they called the starchy bulbs of flower "sarana", but as this interesting paper shows, the word probably applies to several types of flower bulbs, mainly in the Lilly (Liliaceae) family.
Like John D. Speth's excellent book, the paper relies extensively on sources written in German, many of which have not yet been translated to English. I was already aware of the use of lily bulbs among the Native Americans of North America, but was not aware that Siberians ate them as well.
Apparently, sarana was eaten by many Siberian tribes: Shor, Tofalar, Tuva, Altai, Buryat, Selkup, Itelmen, Aleut, Evenki, Ket, and Khanti are mentioned in the paper. Of course, all these different peoples had very different lifestyles. Some like the Buryat and Evenki are nomadic pastoralists and others like the Itelmen and Aleut are closer to hunter-gatherers. Use of sarana varied in different regions. It was a staple in some and more of a treat in others.
The accounts of travelers in the area mention that sarana was:
It was mainly gathered by women, who made special tools to dig it out. When it was too cold to dig it out, they could also find large high-quality stores in vole (or other rodent) nests, making sure to leave something in return so that the voles would survive the winter and be able to harvest again next year. Georg Wilhelm Steller, who witnessed this in the 1700s, noted that it resembled a form of trade.
Sarana bulbs could also be steamed and served with berries. According to Krasheninnikov this was the best and foremost dish in Kamchatka. In his view, it was “both sweet and sour at the same time” and it filled the stomach well. “It can be consumed every day, which makes one almost forget the lack of bread”,
says Krasheninnikov (1819: II: 314)... The taste of cooked sarana has been compared to sweet or baked chestnut. Adolph Erman found the taste of sarana delicious. He describes sarana bulbs as excellent food (Erman 1848: III: 161). According to Karl von Ditmar, who calls it “pagan food”, the taste is similar to potato… Bread did not belong to the traditional diet of northern Eurasia. Ditmar correctly observed that the local people did not even miss bread. Bread was (and still is) in comparison extremely important in the European diets and was only partly replaced by potatoes in the 19th century. The lack of bread, potatoes and other familiar food seems to have bothered many of the travellers in Siberia. They were not capable of enjoying the local diet except for some dishes. The boiled bulbs of sarana and other plants were seen as more or less exotic, “pagan”, disgusting, strange or, in rare cases, surprisingly tasty. In general the travellers held a distanced attitude towards local food, which made them unable to correctly estimate the significance of sarana for the Kamchatkan diet.
In many areas of Siberia, game is pretty low in fat. If you've ever tried to eat mainly fish and lean game, it's very much understandable why sarana was so worth the trouble.
It's also understandable why such traditions have died out, as there are many flower bulbs that are quite poisonous and gathering them was probably a skill passed down through the generations.
Unfortunately, many traditions like these died out before people could really study them, which is a real shame. I've met arctic people who believe that wheat bread is a "traditional" food. But the remnants cast skepticism on the idea that arctic or ice age diets were just a bunch of big game.
Earlier on Twitter I circulated an interesting recent paper a commenter pointed me to- Hypogonadism and erectile dysfunction associated with soy product consumption. The paper documents the case of a 19 year old who had type 1 diabetes, but no other health problems. After starting a vegan diet he experienced alarming erectile dysfunction and general loss of libido. Upon examination, low testosterone levels were found. When asked about his habits, he revealed that he had recently switched to a vegan diet: "This diet included a large amount of soy products equalling 360 mg of isoflavones per day. The diet consisted of soy milk, soy cookies (soy crisps), tofu, soy sauce, soy nuts, and soybeans (edamame)." He quit the vegan diet, but it took almost a year for his testosterone levels to normalize (and the normal line should be higher for a young man).
It's funny because professional soy shill (he works for the Soy Board) and (not coincidentally) animal rights activist Mark Messinahas written many articles that male vegan friends of mine have showed me about how soy doesn't feminize men. He even published a review on it in which he concludes "Thus, men can feel confident that making soy a part of their diet will not compromise their virility or reproductive health." This despite the infancy of the science. For example, look at how long these studies are:
And how much soy? For whom? Are their genetic differences in processing isoflavones? Hmm. I can't say that soy is always an issue for men, but like any plant food, it can have powerful hormonal effects that people should be aware of. On the other side of the spectrum is a man who used phytoestrogens to improve his sperm quality and was able get his wife pregnant.
One thing that struck me about the list of foods from the young man is that they are all the processed dreck that Messina and his Soy Board shills want to sell us. They are hyperpalatable and my experience with them is that they are very easy to overeat. I remember buying a box of Tofutti Cuties and eating them all in a single night...
I am not one of those folks who doesn't ever eat soy. I enjoy miso and soy sauce when I eat Japanese food. Like most traditional soy foods, they are very strong and it's hard to eat too much of them. When I was at ag school in Illinois, I had a class that was a series of seminars. One of them was a visit to the food science lab sponsored by the Soy Board. In that lab the lead scientist talked about how they were removing (or overpowering) the natural bitter flavors in soy to make tastier soy foods! Hmm. That bitter taste is what keeps us from eating too much plant poison. I feel bad for vegans who care more about their health than about soy farmers, because the reality is that you CAN do a vegan diet with reasonable levels of soy or no soy at all.
In other news, my spell checker wants to correct edamame into "damned."
A commenter writes in:
I have been wanting to increase my [carbs] and veggies as its pretty much zero right now, I have never felt better(though the current state is less than perfect) but meat is not cheap and I want to have a more diverse diet. But it seems that every time I eat something plant based I start getting acne, rashes, asthma, dry skin and other minor annoyances again, lately I tried to eat potatoes and I immediately noticed a minor shortness of breath and it didn't take more than a couple of days before my face was glowing red and I started getting dry flaking skin. You say you eat rice - brown rice?
Yes, this is a real problem. Many of us started paleo because of sensitivities and diversifying our diets can be frustrating. I don't think this was a problem for humans in the old days, but modern humans have a different immunological milleu. What causes it? A major hypothesis is that it's caused by too-clean environment in childhood, which we can't exactly undo now.
Before I started messing around with my diet and going veg*n and then paleo, I never had acne. But since I went vegetarian I've had it occasionally and while paleo has lessened it, it still appears occasionally, usually alongside scalp issues and keratosis pilaris. Today was one of these days.
My diet before vegetarianism was absolutely atrocious, but I almost never ate vegetables and it was fairly bland. Unfortunately, now that I have discovered the deliciousness of hot peppers, I realize they are the probable cause of my skin issues. I also have problems with many members of the cabbage family.
If you are having a frustrating problem like this, I highly recommend checking out the failsafe diet (the site used to have a more awesome name: Plant Poisons and Other Nasty Stuff). The best strategy is probably to introduce families of plants into your diet gradually until you figure out what is making you sick. The author of that site notes that once she identified some problem foods and avoided them for awhile, she was eventually able to add some back in. Interestingly, she also discovered she had thyroid disease.
For me, it seems the reaction is quite complex. I can eat hot peppers sometimes, but if I eat them in the last week of my menstrual cycle that's when they really wreck my skin.
As far as starches, poatoes are known to be a problem for many people because they are in the nightshade family and contain solanine and some potent glycoalkaloids. Yams are much better tolerated and another rec would be cassava, which is prized for its hypoallergenic qualities. Brown rice is full of stuff that can be a problem, white rice much less so.
Occasionally people will assert that evolutionary nutrition should involve mostly plants. After all, they read somewhere that the !Kung eat most of their calories from plants. And their nutrition science professor said so. Or some vegan book they read. And it's politically correct, so why not?
Here are some facts
I think plant pushers are either trying to be politically correct or relying on outdated info (or sources that rely on outdated info). For example, Boyd Eaton has revised his views on the subject.
Besides, find me a plant food that even rivals the best meat...it's pretty hard. I love vegetables, think they are important, but meat is the core of the paleolithic diet. You can do it with less meat if you want, but don't claim your diet is more authentic or some bullshit.
What did our ancestor's eat? We don't know exactly, but modern hunter-gatherers do not support the notion of a plant-based diet. What does? If you think you have some good evidence let me know, but since it doesn't seem like it makes a difference health-wise, I don't see a reason to advise people to eat mostly plants.