I like a lot of Dave Asprey's paleo-ish recommendations, and while his low-carb diet is ideal for those with metabolic issues and brain issues, most low-carb diets lack resistant starch and just don't provide enough fermentable fibers for a healthy microbiome.
As you know, the Paleo world is currently divided into two camps: low carb and
moderate "safe" carbs.
When Loren Cordain wrote the original
Paleo Diet book, he hypothesized that the "Paleo Diet" should be low carb. Jimmy Moore, Art De Vany, Dave Asprey, Ron Rosedale, Robb Wolf, and a few others are in that low carb camp – and sticking with it to the bitter end. And while there is a ton of research showing the great (short term) therapeutic effects of low carb dieting, the long term research on low carb dieting isn't as clear cut.
Chris Kresser, Paul Jaminet, Kurt Harris, Stephan Guyenet, Richard Nikoley (and Marc Sission to a lesser degree) are in the
moderate carb camp for those without metabolic issues — and they both recommend modified low carb diets for those with metabolic issues. They believe there is strong evidence that moderate "safe" carb consumption is vital for a healthy immune function and healthy gut flora.
But, here's where it gets interesting....
Resistant Starch.
Resistant Starch is an undigestible starch found in potatoes and other starchy vegetables — and it is sorely lacking in low carb diets.
Richard Nikoley — who runs the blog
FreeTheAnimal.com — at the advice of one of his own blog commenters decided to start experimenting with Resistant Starch with n=1 experiments and a few tablespoons of raw Bob's Red Mill Unmodified Potato Starch (an excellent source of Resistant Starch). Both Richard and this commenter — and many of his readers — had started becoming disillusioned with low carb Paleo over the past few years and found their blood sugar control slowly getting worse over time and other health issues cropping up — a side effect more and more people are noticing from long-term low carb dieting. So, while Richard had already begun reintroducing starches back into his diet, this one reader encouraged Richard to look at the studies that had been done on Resistant Starch over the past few decades.
What they found was a
treasure trove of research that had been largely ignored by many researchers — cast aside as a worthless undigestible fiber. Resistant Starch
improves insulin sensitivity even in people with metabolic syndrome. It
promotes greater butyrate production than other prebiotics (and better than Asprey's butter eating). The improved butyrate production is likely why Resistant Starch consumption correlates with
reduced colon cancer. And, here's the kicker, eating a few grams of Resistant Starch can
lower postprandial insulin and blood glucose levels.
In other words, the research suggests that if you take 1 Tablespoon of unmodified potato starch, just before eating a ton of carbs, you can actually prevent an insulin spike while improving your blood sugar control over the long term. And nobody knows exactly why. Richard, and many of his readers
were able to confirm through self-experimentation eating 140g of starch
in a single meal and blood sugar only spiking to 110!
A diabetic reader was able to eat CUP AND A HALF of potato salad
and had their blood sugar only "spike" to 125mg/dl.
Turns out Resistant Starch is a main source of food for your gut biome — a natural
prebiotic. It seems that if you don't feed your gut flora fermentable fibers, from carbs, your flora will dwindle and the mucus lining and mucin in your stomach becomes compromised as your remaining gut flora start to gnaw on you for a food source.
Chris Kresser recently hosted Jeff Leach on his podcast, last week. Jeff is the co-founder of the American Gut Project, a non-profit research group that aims to sequence the gut of a wide range of people. In that podcast, they discuss the importance of healthy "safe"carb and fermentable fiber consumption and the potential dangers of low carb dieting with respect to the gut:
Chris Kresser Podcast: Revolution Health Radio wrote:Jeff Leach: One of the big things that the low carb diets do is they really drop out the resistant starch in the diet. And what’s interesting about a lot of butyrate producers, Roseburia and these guys and Eubacterium, they’re cross-feeders. For example, you have certain species of bacteria, groups of bacteria that break down whatever, cellulose and hemicellulose, and produce acetate and propionate and all these things, but a lot of the butyrate producers are cross-feeders and they’re feeding off of other activities. So, when I see a very low carb person, I often see not only a huge drop in dietary fiber, but a drop in diversity of dietary fiber and a significant drop in resistant starch, which is a huge source of nutrients for the microbiome as well. Resistant starch is often called the third dietary fiber... But I lump it all together with anything that escapes digestion in the upper GI tract and ends up in your colon and is available for fermentation, and it’s a lot of things besides just dietary fiber. But I’m concerned about it for the exact reasons that you are. We don’t have the data. Nobody has done any nice clinical controlled trials, but when you starve the bacteria, you may see an increase in mucin degraders like Akkermansia and a few other ones. That shift in the pH is going to provide opportunities for pathogens to maybe bloom up that may cause some down-the-road, long-term problems. But again, maybe not. Nobody knows for sure, but if you’re shifting that pH and you’re not fermenting, you’re opening the pathogen’s door. It’s going to take a long time to unwind this, but I think the more low carb people we can get in the study, we can contribute to the conversation at least to the point where it can serve as a baseline for maybe more controlled clinical kinds of studies. But I would never recommend a low carb diet. I think you can eat lots and lots of healthy carbs and maintain your weight...The low carb thing is really terrifying to me from a microbiome perspective, but I want to couch that in saying that that’s not based on any data, so to speak. It’s just based on what we know about fermentation.
Source:
RHR: You Are What Your Bacteria Eat: The Importance of Feeding Your Microbiome – With Jeff Leach
I will echo, that Leach admits that he doesn't have enough data yet to make a definitive statement.
While Asprey is actually a big fan of Chris Kresser and Paul Jamiet — he's had them both on his own podcast and regularly recommends their diets as alternatives to his Bulletproof Diet — I think that Asprey will eventually need to address the problems with potential low-carb fermentation issues. Knowing Asprey, he'll probably just start selling his own line of Unmodified Potato Starch
.
It's also worth pointing out that Asprey is mostly focussed on brain performance. A low carb Ketogenic diet is probably ideal for strong brain performance, but probably isn't ideal for a strong immune response.
And what we see in the Paleosphere over the past few months is that a lot of Paleos are experimenting with Resistant Starch now — taking 1-4 Tablespoons of Bob's Red Mill Unmodified Potato Starch (retails for ~$3.99 for a bag) — and they are beginning to see that significant quantities of potatoes, cassava and other nutrient-dense starchy tubers/bulbs likely played a huge role in our evolution by providing our bodies with fermentable fibers that fed our microbiomes, improved out blood glucose control and provided us with energy and nutrition that sustained some cultures with sustenance
for months at a time.
Very interesting times!