Plant Paleo Part 2: Grains, Legumes, Fiber, and Antinutrients
In Part 1 of this series, I suggested that:
(1) a single set of Paleolithic-inspired dietary rules is not only futile, but entirely misses the point of the actual Paleolithic example, which shows us vast diet diversity amongst human groups; and that (2) the Paleo paradigm includes a wide array of whole-food diets consisting of various macronutrient ratios and plant-to-animal ratios.
This article will show that a dietary approach with plenty of whole fiber-containing foods, including grains and legumes, is consistent with both the evolutionary clues and the scientific evidence.
Paleolithic Consumption of Grains & Legumes
The common Paleo narrative tells us that humans did not eat grains or legumes prior to 10,000 years ago when we suddenly started farming and cultivating them during the agricultural revolution. This, according to the narrative, marked the end of Paleo Eden and the beginning of Neolithic Toil & Suffering.
Yet, modern archaeological evidence suggests some grain consumption by pre-humans as far back as 4 million years ago and by various prehistoric human groups as far back as 105,000 years ago. Sure, there are no smoking guns: no Lentil Food Trucks buried in Middle Eastern caves, no home videos of hunter-gatherers eating barley cakes as they adventurously emigrated out of humanity’s East African cradle.
However, taken all together, recent findings do suggest grains and legumes played some part in the stone-age diet.
Mozambique ~105,000 years ago
In 2007, Julio Mercader, a Canadian archaeologist, discovered the earliest known evidence of potential human grain consumption while exploring a cave in Mozambique. Dozens of tools were found that point to humans using and processing grains about 105,000 years ago.
A large assemblage of starch granules has been retrieved from the surfaces of Middle Stone Age stone tools from Mozambique, showing that early Homo sapiens relied on grass seeds starting at least 105,000 years ago, including those of sorghum grasses.
Those wild sorghum grasses, by the way, were the ancestors of what is now the main cereal crop in sub-Saharan Africa. Today, Africans mill it, make it into porridge, bake it, and even use it to brew beer. It’s important, to say the least, and the Mozambican discoveries suggest they have a long, long history with the plant.
The Neanderthals of Spain – 40-50,000 years ago
Up until very recently, Neanderthals have been portrayed as our stronger, larger brained, carnivorous, extinct, taxonomical siblings. Assumptions about their diet were based on faunal assemblage analyses and stable isotope studies, but these methods tend to overestimate animal-based food consumption and underestimate the amount of plant-based food in the diet.
In just the last 4 years or so, several studies have been published showing starch grains on the dental remains of neanderthals. At the Spy I & II sites in Belgium and the Shanidar III site in Iraq, starch granules from legumes, dates, and wild barley were found in the roughly 40,000-year old dental plaque of Neanderthals.
Now, based on this new evidence, archaeologists believe that Neanderthals ate a wide array of plant foods including tubers and grass seeds, in both warm and cold climates. A shadow of doubt is being cast on the theory that dietary deficiencies caused their extinction.
At the 50,000-year old El Salt site in Alicante, Spain, more evidence has been discovered. Here they found not only evidence of grain consumption…but they were cooking it, too. Evaluation of fecal matter at the site helped to verify that the Neanderthals were in fact ingesting their porridge.
Think about this for a moment. Neanderthals were cooking barley 40,000 to 50,000 years ago.
This certainly suggests that humans could have done the same. Humans were reproducing with Neanderthals around that time; it’s not so hard to speculate about them sharing meals and/or technology, too, considering they were sharing DNA.
Italy, Russia, Czech Republic ~30,000 years ago
In a study published in 2010, archaeologists reported tools like grindstones and pestle grinders were found at sites in Italy, Russia, and Czech Republic—all dating back to about 28,000 years ago. These tools were covered with traces of grain, mostly from starchy cattails and ferns.
The samples originate from a variety of geographical and environmental contexts, ranging from northeastern Europe to the central Mediterranean, and dated to the Mid-Upper Paleolithic. The three sites suggest that vegetal food processing, and possibly the production of flour, was a common practice, widespread across Europe from at least ~30,000 y ago. It is likely that high energy content plant foods were available and were used as components of the food economy of these mobile hunter–gatherers.
Archaeologists believe the grains were ground up into flours and used for baking flat breads. In order to extract the full nutritive value from these grains, they would have had to have been lightly processed and cooked.
Does this sound like a lot to expect from our Sapiens relatives of 30,000 years ago? Well, paleoanthropologist Bruce Hardy suspects flour-making dates even further back. He says,
“This is not isolated to a small group of people. It’s a regular part of subsistence for humans.“
But would there have been enough wild vegetation to really make it worth our ancestors’ while economically?
Unlike Neolithic humans, who domesticated and cultivated grains such as wheat and barley, these hunter–gatherers relied on wild vegetation. However, many of the plants found by Longo and her team were widely distributed, offering a reliable, even nutritious source of food, she says. For example, once ground and cooked, the cattail grains contain nearly as much energy as domesticated cereals, the researchers calculate.
Israel – 23,000 years ago
Ohalo II, in Israel, is perhaps the most famous archaeological site with regard to grains. It’s located on the southwestern shore of the Sea of Galilee, and it provides rather definitive proof that humans have been processing and consuming grains for at least 20,000 years.
Loren Cordain, author of The Paleo Diet™ says:
To my mind, the Ohalo II data still represents the best earliest evidence for grain consumption by hominins.
This Upper Paleolithic site remained buried in silt until 1989. After it was unearthed, archaeologists found 24 different species of wild grass seeds. Only two of the 24 species of grass were found on the grinding stones, though—wild barley and wheat. Unlike the other wild grasses, wheat and barley must be pounded or ground up to obtain maximum nutrition from them.
Not only did people at the site apparently mill grain, but a simple hearth oven suggests that they may even have baked dough made from the flour.
“Grain starches from [this] ‘Ice Age food processor’ confirm that people were using species that later became cultivated crops,” says paleoecologist Mark Bush of the Florida Institute of Technology in Melbourne. The finding is “clearly a breakthrough” in establishing a time frame for wild grain processing…
Incidentally, no starch from tubers or roots were found embedded in the stone, which suggests the site was used exclusively for grain processing and preparation.
UPDATE 07/25/2015: The Origin of Cultivation and Proto-Weeds, Long Before Neolithic Farming — http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0131422
This study suggests, based on evidence at the Ohalo II site, the cultivation of plants began 11 millennia prior to the agricultural revolution. This pushes small-scale farming back to around 25,000 years ago—or two-and-a-half times further back than the current mainstream Paleo narrative.
Fiber & the Gut Microbiome
Based on the last several years of gut microbiome research, clearly, one could devote a lifetime to studying it and the role various dietary fibers and other prebiotics play in microbial health—and human health, by extension. This section is obviously not an exhaustive analysis of the relationship between us and our gut bugs, but it does presuppose the importance of this relationship.
With that said…
Prebiotics in Mother’s Milk
I doubt many would argue against awarding the Perfect Human Food trophy to breast milk—well, perfect for newborns and infants anyway. It is universally regarded as the ideal food for our children who are growing rapidly, both physically and mentally, during the earliest stages of life after birth.
After lactose (a specific sugar) and lipids (all the fats), oligosaccharides (short chains of sugars) are the third most abundant component of human milk. There are actually over 200 different types of known human milk oligosaccharides (HMOs).
Infants digest a minor portion of HMOs present in the breast milk, while a fraction passes undigested through the intestine. Different researchers have confirmed that HMOs are resistant to enzymatic hydrolysis from intestinal brush border membrane and pancreatic juices. We hypothesize that, given the high concentration of oligosaccharides in human milk, these polymers must have an important role in the well-being of the baby, particularly when considering the evolutionary forces that have shaped the contents of human milk—to ensure the least energy burden on the mother and the greatest survival benefit for the infant.
So why does human milk contain all of these HMOs, both in quantity and variety, when the infants only digest a minor portion? Well, among other things, these HMOs are also prebiotics—food for the infant’s gut bacteria. It turns out that a beneficial bacteria for newborns, Bifidobacterium infantis, thrives on these oligosaccharides.
Our mothers not only fed us well, but they provided nourishment for our nascent gut bacteria colonies, too.
The Fiber Hypothesis
Back in the 1970’s a new dietary theory emerged known as The Fiber Hypothesis. Scientists were beginning to notice a correlation between consuming high amounts of fiber and positive health outcomes, but one of the fathers of the hypothesis was disappointed by the reductionist interpretation of his ideas:
More than 30 y ago, Trowell surmised that a diet rich in whole grains protected against coronary heart disease (CHD). Trowell believed that the protective effect of grains was in the whole grain and was disappointed that his hypothesis was interpreted as a “fiber hypothesis” rather than as a “high-fiber food hypothesis.”
Paleolithic Fiber Intake
In the summer of 2005, Dr. Boyd S. Eaton—grandfather of Paleo and author of The Paleolithic Prescription— delivered the opening lecture at the annual meeting of The Nutrition Society. His lecture was called, The ancestral human diet: what was it and should it be a paradigm for contemporary nutrition?
Calculation of ancestral dietary fibre intake, based on a 50: 50 animal–vegetable subsistence ratio (as opposed to the 1985 estimate of 35: 65), suggests an average total fibre intake of >100 g/d.
Today’s Adequate Intake of dietary fiber for adults may seem paltry by comparison at about 14 g per 1,000 calories per day—that’s roughly 25 to 38 g/day for women and men, respectively. This potentially low bar represents a level that 97% of Americans do not achieve. The average for Americans is just 15 g/day.
Fiber Intake of the Hadza
In a recent 2-part episode of The ABC’s Catalyst, called Gut Reaction, they took a look at the interaction between the food we eat and the bacteria that live inside the human gut. Among several others, the program featured Dr. Jeff Leach (Ph.D. in anthropology), who is also the founder of the Human Food Project. He is perhaps now most well known for having undergone a fecal transplant donated by a Hadzabe.
An average person in the west—man or woman—is consuming less than 20 grams of fiber a day. And, to put that into an evolutionary perspective, 6-month to 1-year old Hadza kids are eating 50 to 200 grams of fiber a day. Every day. And they do this throughout life. —Dr. Jeff Leach, Gut Reaction Pt.1
[Note: I highly recommend watching Gut Reaction. It covers many of the recent areas of study that I’ve been following in the news and literature, including resistant starch. The program contains a good balance of plain language and science speak to be both entertaining and informative for the average layperson. Not only can you watch the entire program online, but several ancillary interviews are also included at the link above.]
While researchers are making great strides in all areas of microbial research, Leach perhaps puts it best when it comes to summing it up in an actionable step for the public at large (from Gut Reaction, Pt. 1):
What’s lacking in our Western diet is dietary fiber. So, if people can consume a larger quantity and diversity of plants—between 25 and 30 species of plants per week—by default, you’re going to be eating a lot larger quantity. And we know that diversity and quantity will promote an increased diversity of bacteria in the gut. At the end of the day, probiotics are fine, but the thing that will most benefit you is to eat a larger quantity and diversity of dietary fiber, which means eating more whole plants.
It is quite easy to spin a narrative about a diet, a food, or a food component. And therefore, as you can imagine, narratives like these are an especially useful tool for those who sell diets, supplements, so called superfoods, processed foods, and such.
It is their marketing teams’ bread and butter.
On the one hand, the information they use to weave their tales can be factual. But on the other hand, those facts can also be so far removed from a real-world context that they aren’t truly useful or miss the forest for the trees.
One of the most popular arguments against the consumption of grains and legumes is that these foods contain antinutrients (like phytic acid, lectins, and saponins). The phytic acid in grains and legumes, for example, is characterized by its ability to bind to minerals such as calcium, zinc, magnesium, and iron, preventing their absorption by the human body.
This can potentially lead to real problems for individuals who are barely scraping by on the nutrition front or whose diets are largely dominated by grains and legumes with little else of nutritional value (like animal- and plant-based whole foods). This issue is resolved by eating a nutrient-dense diet, along with the grains, legumes, potatoes, nuts, and any other foods with anti-nutrient properties.
But why bother?
Well, for example, phytic acid is considered by many to be a health-promoting phytonutrient (phyto=plant). It is a natural antioxidant, which is especially effective in preventing iron from forming free radicals. Phytic acid may have anti-cancer effects, and the researchers behind this study even go so far as to suggest that we consider it an essential nutrient or vitamin.
All these facts of normal physiological presence of [phytic acid] in our body the level of which fluctuates with intake, association of an [phytic acid]-rich diet with low incidence of several diseases and vice versa, and finally reversal of some of these conditions, at least in part, by [phytic acid] supplementation strongly argue in favour of its inclusion as an essential nutrient or perhaps a vitamin.
Beans, including fava, black, soy and lentils, are the cornerstone of most centenarian diets. Meat—mostly pork—is eaten on average only five times per month. Serving sizes are 3-4 oz., about the size of a deck of cards.
If beans are filled with dangerous toxins, these centenarians appear to have missed the memo or possess some sort of bean immunity. But they’re not the only ones benefiting from legume consumption. In fact, it is quite challenging to find any published articles implicating beans, lentils, or peas in poor health outcomes.
Based on the present ancestral clues and scientific evidence, I find it very difficult to believe the (currently) standard Paleo™ narrative about legumes. I find it far more likely that what Paleo™ considers to be phytochemical toxins are instead protective and/or hormetically beneficial in the proper dose.
But the underlying thrust contradicts assumptions about the need to protect oneself from hardship. Certain kinds of difficulty, it turns out, may be required for health. That’s because health doesn’t result solely from the instructions your genome contains, but from your relationship with the wider world. Resilience isn’t completely inherent to your body; it’s cultivated by outside stimuli. And some of those stimuli just happen to be mildly noxious, slightly stressful chemicals in plants.
For more on hunter-gatherer consumption of antinutrients, see this article posted on the Free the Animal blog. Here is an article about the Paleo status of legumes, written by Stephan Guyanet. And another by Chris Kresser.
It is apparent from the archaeological evidence that at the very least our ancient ancestors had a good deal of experience with grains and legumes prior to eventually cultivating them. And, frankly, this makes me feel a lot better about the sapiens in our species’ label (homo sapiens translates to wise man). I mean there’s plenty of crazy to go around, but can you imagine picking random plants from the forest to start your garden?
Me either. And that’s not what happened 10,000 years ago. Rather, our ancestors began cultivating plants they were familiar with and that they presumably already valued.
Notably, all of the examples of prehistoric grain and legume consumption in this article—which range from 4 million years ago to 23,000 years ago—were discovered and published after 2002, which would be after the publication of Loren Cordain’s The Paleo Diet™: Lose Weight and Get Healthy by Eating the Foods You Were Designed to Eat.
Does this evidence conclusively point to regular consumption of these foods in large amounts? Unknown. But, I do strongly suspect further discoveries will continue to point to our ancestors’ familiarity with and consumption of grains and legumes.
Much less controversial is our species’ proclivity for fiber consumption. While it certainly appears to be the case that humans can survive on low-fiber diets, it’s unlikely that this is ideal for most of us.
Are current levels of under 20 grams/day optimal? Likely not.
The Hadza, like many other modern hunter-gatherer groups, provide a convincing example that shows, at the very least, high-fiber consumption is not detrimental to health. Their natural dietary pattern is aligned with widely accepted recommendations to eat a diet that is high in fiber and whole foods.
Hopefully, I’m not painting The Paleo Diet™ or other popular Paleo diets as being anti-fiber. However, most adherents would probably be surprised by how low their levels of fiber intake are in practice. Even without elevating whole grains and legumes to staple status—which I avoid with my own diet—small portions of each provide an easy way to healthfully add nutrients, fiber, and seemingly beneficial phytochemicals to one’s diet, even if some of the compounds present in these foods sound undesirable because they are called antinutrients.
The dose makes the poison.
It is apparent that the scientific community does not regard all phytochemicals with antinutrient properties as being necessarily bad for human health. In fact, some even suggest that we change the name of some antinutrients to more clearly represent their role in the diet:
Antinutrients commonly found in plant foods have both adverse effects and health benefits. For example, phytic acid, lectins, phenolic compounds (tannins), saponins and enzyme (amylase and protease) inhibitors have been shown to reduce the availability of nutrients and cause growth inhibition, while phytoestrogens and lignans have been linked with infertility problems. However, phytic acid, lectins, phenolic compounds, amylase inhibitors and saponins have also been shown to reduce the blood glucose and insulin responses to starchy foods and/or the plasma cholesterol and triglycerides. In addition, phytic acid, phenolics, saponins, protease inhibitors, phytoestrogens and lignans have been related to reduced cancer risks. Because antinutrients can also be mitigating agents, they need re-evaluation and perhaps a change in name in the future.
Not only is it OK to be wrong, but being OK with being wrong, helps us become more right over time.
Heck, we may even be wrong about cavemen living in caves. Is it so hard to believe, then, that we are still piecing together the clues and evidence that are helping us to paint the picture of what healthful human diets look like? And, healthful human diets is intentionally plural here.
In science it often happens that scientists say, “You know, that’s a really good argument, my position is mistaken,” and then they actually change their minds, and you never hear that old view from them again. They really do it. It doesn’t happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion. —Carl Sagan
This isn’t to say that mainstream flavors of Paleo™ or The Paleo Diet™ are wrong or unhealthful. Not at all. But, I firmly believe they’re not for everyone—at least not for a lifetime. Some gurus who beat their chests the loudest, claiming they maintain the most orthodox approach, tell us they continue to suffer, or even start suffering, from overweight, obesity, autoimmune diseases, fatigue, brain fog, etc.
If you’re in that boat…should you continue to put up with it for the sake of belief in a narrative or belonging to a tribe?
Just as our ancestors have always done, I would rather look at my present food environment and make the most of it. For me, making the most of it means eating in such a way that adds the most years to my life, but far more importantly, adds the most life to my years.
Nutritionism—or nutrition reductionism—analyzing foods from the perspective of discreet components—has its place. It’s nice not worrying about scurvy, after all. However, the reductionist view of grains and legumes in the Paleo approach may be leading some people astray. Let’s not ignore the new evolutionary clues, the scientific evidence (including epidemiology), nor the value of simple, whole foods.
So what do you think…do grains and legumes have a place in some people’s Paleo diets? Share your thoughts in the comments.
As new research comes in, I will post links to articles and/or studies here. If enough are collected, or if any particularly interesting discoveries are made, I’ll write another article on the topic.
- New Scientist: Ancient leftovers show the real Paleo diet was a veggie feast
- New Scientist: Stone-age People Were Making Porridge 32,000 Years Ago. (Oldest known evidence of humans eating oats.)
- The Quarterly Review of Biology: The Importance of Dietary Carbohydrate in Human Evolution.
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If you’re new to the blog, have a look at what Humans Are Not Broken means. Then, you might want to take a look at The Plant Paleo Diet to see how I eat to support my body transformation. The reasoning behind the diet can be found here and here. And if you’re into podcasts, you’ll probably really enjoy Latest in Paleo, which looks at the latest health news in a uniquely entertaining way.