To Go Paleo Or Not? PT 4
Evolution of the human GI tract
In Paleo circles, it’s sometimes said that while the world has changed in innumerable ways in the last 10,000 years, our genes have changed very little. And further, that we really only thrive in a world with similar conditions to the Paleolithic era.
Quite frankly, this is not how evolution or genetic expression works.
If humans and other organisms could thrive only in circumstances similar to the ones their predecessors lived in, life would not have lasted very long.
Examples of the ways we have evolved in the past 10,000 years abound.
For example, over the past 8,000 years or so, about forty per cent of us have developed the capacity to consume dairy for a lifetime. As a species, we’re evolving a mutation whereby we continue to produce the lactase enzyme to break down lactose for far longer periods than our ancestors ever could. True, not everyone can digest lactose well, but more of us can do so than ever before.
And studies have shown that even people who don’t digest lactose well are capable of consuming moderate amounts of dairy, tolerating an average 12 grams of lactose at a time (the amount of lactose in one cup of milk) with few to no symptoms.
Additionally, the emerging science of epigenetics is showing that a “blueprint” alone isn’t enough — genes can be “switched off” or “on” by a variety of physiological and environmental cues.
Our digestive systems have adapted over millennia to process a low-energy, nutrient-poor, and presumably high-fibre diet. Meanwhile, Western diets have become high-energy, low-fibre, and high-fat.
Our genes produce only the enzymes necessary to break down starch, simple sugars, most proteins, and fats. They aren’t well adapted to cope with a steady influx of chicken nuggets, Potato chips, and ice cream.
So how is it that we can still digest our food, albeit imperfectly at times?
Thank the trillions of bacteria that live in our gut. These friendly critters interact with our food in many ways, helping us break down tough plant fibres, releasing bound phytonutrients and anti-oxidants, and helping us to assimilate many important compounds.
Now, we don’t have direct evidence of which bacterial species thrived in Paleolithic intestines, but we can be pretty confident that our ancestors’ microbial communities would not exactly match our own.
That’s because bacteria evolve and adapt at a rate much faster than our slow human genes. And for us, that’s a good thing.
It helps to explain why, even if the ancient human diet didn’t include grains, legumes, dairy, and other relatively modern agricultural products, we still might thrive on such a diet today – at least, with a little help from our bacterial friends.
The magical microbiome
Thanks to the Human Microbiome Project and other massive research projects around the world, we now know that trillions of microorganisms from thousands of different species inhabit the human body.
In fact, the total genetic makeup of these little creatures is at least 100 times greater than our own! (Essentially, we’re only 1% human. Think about that.)
This vast genetic diversity ensures that our GI tracts can adapt rapidly to changes in diet and lifestyle.
A single meal can change the type of bacteria that populate your gut. And as little as several days on a new diet can lead to dramatic changes in the bacterial populations in your GI tract.
The diverse, complex, and dynamic nature of our microbiome helps to explain why some of us seem to do well on one type of diet, while others will feel and perform better with another type of diet — even though, genetically, we’re all 99% the same!
Many of us can break down the more “modern” food compounds that Paleo advocates claim we do not tolerate well — simply because our intestines harbour bacteria that have evolved to do that job.
For instance, some Japanese people host unique bacteria that can help them digest seaweed.
And many people can alleviate symptoms of lactose intolerance by eating yogurt or other probiotic-rich foods that provide lactose-digesting bacteria.
So even if you don’t naturally break down lactose well, it’s possible, through the right combination of foods and/or probiotic supplements, to persuade the bacteria in your gut to do this job on your behalf.
What’s more, the same strategy could also address gluten intolerance. Recent research shows that some bacteria actually produce enzymes that break down gluten — as well as phytic acid — reducing any inflammatory or anti-nutrient effects.
Which, as we know, are two of the main reasons people recommend starting Paleo diets in the first place.
Modern Paleo research
No matter how you slice it, the Paleo proponents’ evolutionary arguments just don’t hold up.
But that doesn’t mean that the diet itself is necessarily bad.
Maybe it’s a good diet for completely different reasons than they say.
To find out if that is so, a number of researchers have been putting Paleo diets to the test with controlled clinical trials. And so far, the results are promising, though incomplete.
Paleo vs. Mediterranean diets
Perhaps the best known of these researchers is Dr. Lindeberg — the one who also studied the Kitavan Islanders. He and his colleagues have conducted two clinical trials testing the efficacy of the Paleo diet.
In the first, they recruited diabetic and pre-diabetic volunteers with heart disease and placed them on one of two diets:
A “Paleolithic” diet focused on lean meat, fish, fruit, vegetables, starchy root vegetables, eggs, and nuts, or
A “Mediterranean” diet focused on whole grains, low-fat dairy, vegetables, fruit, fish, oils, and margarine.
After 12 weeks, the Mediterranean group lost body fat and saw an improvement in markers of diabetes. Four of the nine participants with diabetic blood sugar levels at the beginning of the study had normal levels by the end. That’s a very good result and must have made the participants happy.
But those in the Paleo group fared even better.
They lost 70 percent more body fat than the Mediterranean group and also normalized their blood sugars. In fact, all ten participants with diabetic blood sugar levels at the beginning of the study reached non-diabetic levels by the end of the study.
By any estimation, that is an astonishing result.
Now, these volunteers were suffering from mild, early cases of diabetes. But a second study of long-term diabetics showed that a Paleo diet didn’t cure them but it did improve their condition significantly.
Other research has found:
The Paleo diet is more satiating per calorie than a Mediterranean diet.
The Paleo diet improves blood pressure, glucose tolerance, and blood lipids.
However, one caveat: Like most low-carb trials, the macronutrients (especially protein) in these studies weren’t matched.
The Paleo group ate a lot more protein, compared to the other diet groups. Plenty of protein helps keep our lean mass dense and strong, stay lean, and feel satisfied by our meals.
So, we’re not just comparing apples to oranges when protein intakes are different; this is more like comparing grains to goat meat. Literally.
The Paleo diet may indeed be the best plan, but it’s hard to know for sure without direct comparisons that match macronutrients and calories.
Conclusion & recommendations
What does the Paleo diet get right?
A. Despite the faulty evolutionary theory it’s based on, in the end, the Paleo diet likely gets more right than it gets wrong.
B. Paleo-style eating emphasizes whole foods, lean proteins, vegetables, fruits, nuts, seeds, and other healthy fats, which is a massive improvement over the average Western diet.
C. Paleo-style eating has been extremely effective for improving several chronic diseases. That alone is a huge plus.
D. Paleo-style eating has made us more aware of how processed and crappy a lot of our 21st century food is.
However, we need more rigorous (and carefully matched) trials before we can reach any definitive conclusions.
What are the challenges?
Despite its obvious benefits over the typical Western diet, the Paleo diet has some flaws.
The evidence for excluding dairy, legumes, and grains isn’t (yet) strong. So as a nutrition coach, I can’t say it’s a one-size-fits-all prescription. Certainly, some people should avoid dairy and gluten, and control legume and grain consumption. But most of us can improve the way we look, feel, and perform without completely eliminating these foods.
The evolutionary arguments don’t hold up. The human body isn’t simply a collection of adaptations to life in the Paleolithic era. Each of us is a dynamic assemblage of inherited traits (and microorganisms) that have been tweaked, transformed, lost, and regained since the beginning of life itself. Such changes have continued over the past 10,000 years — and won’t stop any time soon.
In the broader sense, strictly following a list of “good” and “bad” or “allowed” and “not allowed” foods tends to be problematic for most people. Generally, this approach leads to anxiety and all-or-nothing thinking. Maybe it makes us feel more confident and (falsely) sure of ourselves in the short term. But it’s less effective over the long-term — because ultimately, it decreases our consistency.
This may explain why we are seeing the Paleo diet itself evolve.
It’s evolution, baby
Many Paleo advocates have recently come to appreciate and encourage the addition of moderate amounts of starch (albeit a more limited variety of options than I would prefer), as well as some dark chocolate, red wine and non-grain spirits (such as tequila), and grass-fed dairy.
These additions make life much more pleasant. They make healthy eating more attractive and achievable.
In fact, this new “leniency” may partly explain why the Paleo diet continues to gain traction in mainstream nutrition circles.
Because in the end, moderation, sanity and your personal preferences are more important than any specific food list, anti-nutrient avoidance, or evolutionary theory.
What to do today
Consider the good things about ancestral lifestyles. This includes fresh food, fresh air, lots of movement, good sleep, and a strong social network.
How could you get just a little bit of these in your life today?
Think about how you could move along the spectrum — from processed 21st century life and food — to choices that are a little more in tune with what your ancient body needs and loves.
Learn a little more about your ancestors. Evolution is cool. Dig into your roots: Where did your people come from? What were their ancestral diets?
Keep it simple and sane. Doing a few good things pretty well (like getting a little extra sleep or fresh veggies) is much better than trying to get a lot of things “perfect”.
Stay critical and informed. Avoid dogmatic or cultish thinking. Be skeptical. Look for evidence. Question everything. Primal eating is a super cool idea and may turn out to be more or less right; just keep your late-evolving prefrontal cortex (aka your thinky brain) in the game as you consider all the options.
Help your old body (and your trillions of little buddies) do their jobs. Our bodies are resilient. We didn’t get to be one of the dominant species on the planet by being fussy, delicate flowers.
Nevertheless, think about how you can nourish your body optimally in order to give your body and microbiome the best chance of surviving and thriving.
Eat Clean, Stay Active. Feel Great