Just the other day, I ran into this mostly great blog post by one of my favorites, Stephan Guyenet, that discussed a 2012 study supposedly comparing a Paleolithic diet with a conventional coronary care diet. In this case, I have to disagree with both the study author’s and Stephan Guyenet’s interpretation of the study.
The study randomized participants – heart disease patients with diabetes – to receive dietary instruction of either (Paleo diet):
They were advised to increase their intake of lean meat, fish, fruits and vegetables and to avoid all kinds of dairy products, cereals (including rice), beans, sugar, bakery products, soft drinks and beer. The following items were accepted in limited amounts for the Palaeolithic group: eggs (one or fewer per day), nuts (preferentially walnuts), potatoes (two or fewer medium-sized per day), rapeseed or olive oil (one or fewer tablespoons per day).
or in the case of the “consensus diet”, they were given the usual dietary instruction by the coronary care unit. For those unfamiliar with this diet, this is pretty representative and summarized by:
a diet rich in whole grains, lean proteins, especially fish, plenty of fresh fruits, vegetables, nuts and seeds, olive oil and a moderate amount of wine.
The ugly: Is the paleo diet really Paleolithic?
Let’s be clear right from the start. Just as you can never “step into the same river twice”, we cannot duplicate either the diet or environment of the cave man. If you think you are eating Paleolithic, try this excellent TED talk by Christina Warinner on for size – you may be in for a surprise. Here are my notes from that video:
3:18-Humans have no known anatomical, physiological or genetic adaptations to meat consumption.
- We cannot manufacture vit C or any of the other carnivorous adaptations.
- Lineages from Europe & Africa have a genetic adaptation to milk, not meat.
4:20-The Meat Myth
- The brain, bone marrow, organs were favored, not the muscle meat
- Wild game was leaner w more omega-3
- Only as you move further north was there more adaptation to meat.
5:10-Origin of the meat myth
- Bone w 80% mineral will preserve better -> inherent bias in archaeological record.
- Nitrogen stable isotope analysis: N15 vs N14, more N15 means higher up on food chain – this is where meat myth originates, but it’s flawed. There’s lotsa variation by area. In very arid areas, east Africans and Mayans fertilized their crops, this analysis is confounded by nitrogen in fertilizer. In cold climates, animals eat lichen and bark which also leads to strange values.
8:36-Paleolithic people DID eat grains and legumes
- We have evidence of mortar & pestles from 30,000 yrs
- Finding grains/legumes in dental calculus from Neanderthal
9:54-14:00-Foods portrayed as being “Paleolithic” are not. They are all a product of farming and agriculture. – we have zero ability to actually eat a truly Paleolithic diet. Examples:
- Bananas are all clones, they can no longer make seeds
- Paleolithic lettuce was fibrous, bitter and toxic (latex)
- Paleolithic tomatoes had toxins – members of deadly nightshade family
- There were no oils, not even olive
- The foods we eat come from around the world, out of season
- Wild avocado has a few mm of fruit
- Sugar content has been GMOd
- Egg were smaller, seasonal
- Brocolli, kohlrabi, cabbage, cauliflower, br spouts, kale didn’t exist; they are all cultivars of wild broc that looks nothing like what we eat. … broc is the flower of the plant
- Wild carrot contains natural pesticides and are bitter
14:13 – There is no one Paleolithic diet
- Oaxac, Mexico, 5000 BCE – in Dec: rabbit, deer, turtle, birds, fruit, legumes, nut, squash
- but by April: very little edible food, would have had to move
- diets varied greatly by region
- plant foods would have been small, woody/fibrous, low sugar content, toxins/phytochemicals
- people would have high mobility due to seasonal availability, ate marrow, organs
17:10 – Lessons from real Paleolithic diets
- There’s no one ‘correct’ diet. Essential nutrients mean we need to consume diversity. This is lacking in processed foods (mostly corn, soy, wheat)
- We evolved to eat fresh food, in season, ripe. Preservatives work by inhibiting the growth of bacteria. Any method that inhibits bacteria that persists during digestion will thus affect your “good” bacteria; and is not your friend.
- We evolved to eat whole foods. One 34 oz soda has as much sugar as 8 feet of sugar cane.
In the interests of total honesty, lest we grant Christina Warinner the status of highest paleo authority, I have to dispute her first point. We do have an adaptation to eating meat: we have a genetic cholesterol disposal mechanism, whereby people with this mechanism in place can shuttle excess cholesterol right down and out the good ol’ drain, if you understand my euphemism. Rabbits, for example, do not have this. So rabbits (in lab experiments) are only a good model only for humans that are genetically unable to dispose of cholesterol, such as in familial hypercholestemia. This is one example of many genetic adaptations that we DO have for eating meat.
But, no matter, that point is actually irrelevant to the thrust and overall message of her talk. Which is to say the idea that we can actually consume a Paleolithic diet is ludicrous.
But wait, there’s more!
Remember I said we can’t “step into the same river twice”? Just as we cannot duplicate the diet, we also cannot duplicate the environment. The Paleolithic folks were infested with parasites. This helped them keep cholesterol levels under control and helped prevent iron overload.
Paleo Advisory: If you are going to eat tons of meat, you should have plenty of leeches on hand or how about a just a schistosomiasis infection? (Just kidding!)
Not only that, the Paleolithic microbiome is no longer available. The genetic material within the boundaries of our outer skin is 90% not human and these microorganism have coevolved with us at a rate many, many multiples that of our evolution. Sorry folks, we cannot go back in time.
In addition, if you look at the dietary items mentioned by Warinner as being consumed back in the day, surprise, surprise, you will see legumes!
So, bottom line? There is no way a person can hope to duplicate the Paleolithic experience. It would even be impossible for a man in, say, Kansas to duplicate the just the diet, unless he was extremely wealthy and can afford to have someone daily fly in fresh produce and game, seasonal for Kansas, from some remote habitat untouched by modern agriculture. So let’s not fool ourselves into thinking it’s more suitable for us than it is by calling it “Paleolithic” and let’s call it what it is – “paleo”, a very different diet depending on who is setting the parameters, that is currently in vogue now, but which seems to have a lot going for it.
The actual study – What did they eat?
I made a screen shot from the journal article and colored in interventions that would be helpful (green) or harmful (orange) to heart disease patients with diabetes. My ratings of these items are based both on self-experimentation and reading of the journal literature:
The first difference I notice is in salt, sweets and calories: the consensus diet averages 1800 daily calories, the paleo only 1350. Huge difference. So why would the paleo dieters be satisfied with less? My guess is the replacement of cereals, dairy, sauces, pastry, jam, sugary beverages with whole fruits and vegetables. Also, the consensus group used more salt. That would be lesson number 1. All that sweet, starchy, salty stuff shoots straight to your appetite and less towards your actual food needs.
A big significant difference (p< 0.005) was in sat fat intake. Apparently the advice given to the paleo group for “lean meat” was more effective than that for the consensus group for “not more than 7% of total calories”.
Another significant difference was the protein content, the paleo diet being higher. Protein stimulates insulin production even more than does glucose, so that would contribute to better glycemic control.
Although not quite reaching significance, how did they get the paleos to eat more fish? Both diets were supposed to emphasize fish. An unanswered question is, why did the paleo counseling work better?
But finally, here’s where we get to the reason I had to write this. Look at the glycemic load in the consensus group. This is THE most significant difference between the two diets, and by that I mean statistical difference. So, really, instead of attributing the observed benefit to the diet being “Palaeolithic”, the journal title should have more honestly been (red correction mine): A Palaeolithic lower glycemic load diet improves glucose tolerance more than a Mediterranean-like diet in individuals with ischaemic heart disease and mild diabetes. But, golly, gee whiz!, that’s already been demonstrated, over and over again, since starting back in 1981. But, obviously, that title would not have served Lindeberg’s needs as a proponent of the paleo diet.
Additionally, I hope I’ve demonstrated that the intervention group instructions must have steered the paleo group towards food choices very different than standard paleo as practiced out there in the real world or as enjoyed by our ancestors of the Paleolithic era.
So, getting back to my opening sentence, in the post where Guyenet reviews the study, he sadly repeats the same misdirected attribution of what was causing the benefit. But here’s also what I want you to know. That blog piece by Guyenet was written in Feb 2012.
But that’s not the end of the story! In the interim, he did manage to get it a lot more right and come around to this way of thinking. Here‘s a great lecture from less than 2 weeks ago where (tada!) he describes how our western diet promotes proliferation of LPS type microorganisms, which in term promote obesity, inflammation and insulin resistance. Here’s a slide from that lecture:
BTW, the lecture isn’t perfect, in the middle there is again some mis-attribution of benefit.
But wait, there’s more to explain!
Q: Why would the replacement of cereals, dairy, sauces, pastry, jam, sugary beverages with whole fruits and vegetables be better at supporting the friendly microbes? If you look at the numbers from the experiment, fiber as a percent of total calories is about the same in both diets.
A: If you’ve been reading my last few blog posts, you already know the answer. The 1999 JÄRVI study showed that by the time our food industry has finished processing carbohydrate foods, their ability to support these friendly gut bacteria has somehow been destroyed. This particular experiment might lend credence to the thought that more sugar in the diet also favors unfriendly bacteria. I find it simply amazing how such a small thing (gut bacteria) can make such a huge difference (diabetes)!
So, after all the hullabaloo has been said and re-said, what’s great about paleo? Why does it deserve our attention?
- the emphasis on whole foods, minimally processed;
- the admonition to stay out of the center isles of your grocery store;
- fresh local foods in season;
- avoiding drinks other than water, tea, etc;
- avoiding dairy – mostly because the casein in “A1” cows breaks down to BCM-7 which isn’t friendly.
But there’s still a lot that paleo gets wrong. Where does it fail?
- The emphasis on fat and meat, in those versions of paleo that are low carb. This is a whole ‘nother can of worms, which I may get into someday soon. Right now, suffice it to say, IMO (and that opinion is very considered), your best bet is to not overdo your protein intake and keep your fat to about 25% (or lower if your glucose disposal is able to handle more carbs).
- The failure to emphasize the necessity for balance between omega-3 and omega-6.
- The cross-the-board restriction on legumes. They are both Paleolithic, as well as, not a problem.
- The cross-the-board restriction on grains. There are a few very low GI grains that are gluten-free and safe.
So, there you have it for paleo – the good, the bad and the ugly.
So, how does the minimally processed, low GI diet achieve all these great results? Think about it. In the 1999 JÄRVI study, same macronutrients, same foods, just ground or not ground, yet they observed a hugely significant, positive, effect on all kinds of disease markers in just 24 days!
Back in 1999, I don’t think many investigators were studying the interactions between diet, microbiome and chronic disease, but the study does hint that this was starting to be recognized. The study authors said,
Like dietary ﬁber, resistant starch will be fermented by the colonic microﬂora. … increased colonic fermentation (is) associated with improved glucose tolerance.
Over the last 50 – 75 years, the study of what has been going on in our guts has become an exploding field of interest with the number of journal articles more than doubling every year since 2010. I’m guessing that at least some of the source of the epidemic of chronic disease will be proven to be here, in how the food industry has modified what we eat so as to no longer support our friendly micro-fellow travelers.