Table for one trillion, please
It may seem like a funny way to request a spot at your favorite healthy restaurant, but it’s actually pretty accurate.
In this New York Times article, Michael Pollan describes the one trillion, er, one-hundred trillion, microbes that sit down to dine with us at each meal. More than just creepy freeloaders, these guys have a profound impact on our health – maybe even more than genetics. Here’s how Pollan explains it:
“for every human cell that is intrinsic to our body, there are about 10 resident microbes — including commensals (generally harmless freeloaders) and mutualists (favor traders) and, in only a tiny number of cases, pathogens.
To the extent that we are bearers of genetic information, more than 99 percent of it is microbial. And it appears increasingly likely that this ‘second genome,’ as it is sometimes called, exerts an influence on our health as great and possibly even greater than the genes we inherit from our parents. But while your inherited genes are more or less fixed, it may be possible to reshape, even cultivate, your second genome.”
That’s good news, because modern life has not been kind to this second genome – often called our microbiome. Factors like processed foods, the overuse of antibiotics, environmental toxins and less time spent outdoors have drastically reduced the diversity of microbes we carry.
That’s a big deal, because as Pollan explains “Disorders in our internal ecosystem — a loss of diversity, say, or a proliferation of the ‘wrong’ kind of microbes — may predispose us to obesity and a whole range of chronic diseases, as well as some infections.”
Now it’s easy to gloss over this . . .
And think “yeah, yeah, lots of factors go into metabolism.” That’s true, but get this: In this study, researchers “took two groups of mice whose digestive tracts had been sterilized. In the first group, they colonized the mice’s intestines with flora from an obese cage mate. In the second group, they colonized the intestines with flora from a lean mouse. They then fed these two groups of mice the same diet for 2 weeks.” (source) The mice who received the microbes from the obese mouse gained more weight, despite comparable food intake and intake levels.
Other studies have demonstrated that microbes implanted from lean mice into overweight mice caused the mice to lose weight. To me, this research is not really about weight loss or gain, but rather a reminder that our lifestyle choices are impacted by the health of our internal microbiome.
So how do we encourage a diverse microbiome?
By serving up hearty meals for our one-hundred trillion, of course! According to Stanford microbiologist Justin Sonnenburg, “The safest way to increase your microbial biodiversity is to eat a variety of polysaccharides.” (source)
In case you are wondering, that’s smart guy speak for the things that nourish our gut bacteria – inulin, fiber and resistant starch for example. Now, you already know what fiber is and you may have heard of inulin, but chances are you are asking yourself . . .
What is resistant starch?
Unlike probiotics, which are beneficial bacteria that we take internally through supplementation or fermented foods, resistant starch is a prebiotic – or food for our bacteria.
Dr. Amy Nett explains it this way:
“Prebiotics are indigestible carbohydrates, or at least indigestible to us, that reach the colon intact and selectively feed many strains of beneficial bacteria. Prebiotics are generally classified into three different types: non-starch polysaccharides (such as inulin and fructooligosaccharide), soluble fiber (including psyllium husk and acacia fibers), and resistant starch (RS). Each of these types of prebiotics feeds different species of gut bacteria, but among these, RS is emerging as uniquely beneficial.” (source)
When beneficial bacteria feed on resistant starch, they produce short-chain fatty acids such as butyrate, which help to increase metabolism, decrease inflammation and improve stress resistance. (source)
How to incorporate resistant starch into meals
Bacteria have favorite foods just like we do, so I incorporate a variety of resistant starches to nourish different populations. There are three basic types of naturally occurring types:
Type 1 RS is “physically inaccessible, bound within the fibrous cell walls of plants. This is found in grains, seeds, and legumes.” (source)
Type 2 RS is “Starch with a high amylose content, which is indigestible in the raw state. This is found in potatoes, green (unripe) bananas, and plantains. Cooking these foods causes changes in the starch making it digestible to us, and removing the resistant starch.” (source) Tigernuts also belong to this category. They’re very sweet and can be eaten as a snack whole, or ground into a flour to make no-bake cookies with – my kids LOVE these resistant starch cookie dough bites. For info on the brand I use, check out the Pantry Staples section on this page.
Note: We don’t eat raw potatoes, but raw potato starch (not flour) can be consumed in smoothies. However, even after cooking potatoes there’s still a way to benefit from the resistant starch they contain. More info in the next paragraph.
Type 3 RS is “Also called retrograde RS since this type of RS forms after Type 1 or Type 2 RS is cooked and then cooled. These cooked and cooled foods can be reheated at low temperatures, less than 130 degrees and maintain the benefits of RS (6). Heating at higher temperatures will again convert the starch into a form that is digestible to us rather than ‘feeding’ our gut bacteria. Examples include cooked and cooled parboiled rice, cooked and cooled potatoes, and cooked and cooled properly prepared (soaked or sprouted) legumes.” (source)
In my kitchen, the preferred sources of resistant starch are cold potato salad with homemade mayo, tigernut flour cookies, rice and bean salad, dehydrated green banana chips, and smoothies made with green bananas or plantains – sometimes with an additional resistant starch flour added in. (Options are tigernut flour, green banana flour, plantain flour, and organic potato starch.)
We take care to vary the sources so that we don’t overfeed any particular population, and we include both soluble and insoluble fiber from lightly cooked, raw or fermented vegetables. Research suggests it works synergistically with resistant starch to encourage a diverse microbiome, and is especially important to include with RS2 starch found in green bananas, plantains and raw potatoes.
Is resistant starch for everyone?
Not necessarily. According to Dr. Nett, “If you experience marked GI distress with even small amounts of RS, this may be an indication of SIBO (small intestinal bacterial overgrowth) or microbial dysbiosis, and you may need to consider working with a healthcare practitioner to establish a more balanced gut microbiome through the use of herbal antimicrobials and probiotics before adding RS or other prebiotics.” (source)
Her advice: “If you choose to try supplementing with RS, start with small doses of about ¼ teaspoon once daily, and very gradually increase the amount as tolerated. Some increased gas and bloating is expected as your gut flora changes and adapts, but you do not want to feel uncomfortable. If you experience marked discomfort, then decrease the amount you’re taking for a few days until your symptoms resolve, and then try increasing again gradually.
Studies indicate that the benefits of resistant starch may be seen when consuming around 15 to 30 grams daily (equivalent to two to four tablespoons of potato starch). This may be too much for some people to tolerate, particularly in the setting of gut dysbiosis, and going above this amount is not necessarily beneficial.” (source)
My personal approach is a little less methodical. Though we did start slow to minimize the chance of discomfort/bloating, we now simply incorporate resistant starch into recipes when it makes sense. When I make tigernut flour cookies I don’t measure how much each one contains to ensure that everyone is getting the “ideal” amount. We just enjoy the cookies, potato salad, or whatever dish it is that’s feeding our 100 trillion. So far it has worked well for us.