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What’s Up With Your Gut? – Beneficial Bacteria and Good Digestive Health

Posted Apr 20 2010 10:09am

4197076733 2b2b540b4bEveryone knows (well, not everyone, but anyone who’s probably reading this) how crucial the early days of an infant’s life are for establishing good habits and healthy patterns for the rest of its life. What the mother eats while pregnant, what the child eats, delivery methods, breastfeeding duration, heck, whether you read to your children or plop them down in front of the TV – everything helps lay the groundwork for the rest of their lives. Exposure to bacteria is another growing concern for parents. Too little bacteria, and we risk allergies and significantly compromised immune systems later on. Too much isn’t as much of an issue, though we should avoid obviously harmful bacteria. It’s my general sense that most kids these days get far too little bacteria in their lives. They’re swaddled in protective clothing, forbidden from touching (or, perish the thought, licking) things, and doused in antibacterial liquid every other hour. How many kids play in the dirt nowadays? Build forts? Turn over stones in search of bugs? Roughhouse with friends? Far too few, I’d imagine.

While beneficial bacteria reside throughout our bodies, gut bacteria may be the most important of all. A substantial part of our immune system depends on these healthy flora (which will be the subject of a future post). People try to go about obtaining beneficial gut bacteria in ridiculous, counterproductive ways , but at least there’s a sizable public awareness of the subject. Most reasonably health conscious folks these days at least recognize the word “probiotic,” while many researchers are beginning to understand that the bacteria present in breast milk (Bifidobacterium) offers considerable benefits to an infant’s intestinal microbiota . Low levels of Bifidobacterium have also been linked to higher rates of eczema in human children, while giving chubby rats a Bifidobacterium supplement slimmed them down and improved their lipids . Breastfeeding has also been linked to lower rates of asthma in children – is Bifidobacterium involved here, too? There’s a good chance; the author of this study co-authored one last year that found “children who received antibiotics in the first year of life were at higher risk of developing asthma later on.” Obviously, antibiotics can kill both harmful and beneficial bacteria.

Gut flora is responsible for breaking down carbohydrates into short chain fatty acids. If you consider our gut flora to be foreigners – permanent alien residents, put another way – then you might say that humans cannot fully utilize starches without outside help. Technically, those gut organisms are foreign born, but a human without gut microbes is like America without its rich and storied history of immigration; immigrants made America and gut microbes make us whole. Indeed, we’re wholly dependent on our gut flora. You might even say we’re more microbe than man (gut flora outnumber the cells of our bodies by 10 to 1).

Until we’re born, the fetal gut is sterile. It’s just sitting there, accepting pre-digested nutrition from the mother, taking up space and generally living the slacker’s dream. But it works. The fetus doesn’t need a teeming, active gut, because all the work is done by mom’s gut flora. They’re breaking down the polysaccharides and the sugars, converting it into usable fuel, and diverting a portion of it all to the child. In a way, then, the kid is dependent on gut flora, just as much as you or I are. Once he (or she) is out of the womb, the child needs his own intestinal team. He’ll be eating, which requires digestion, and good digestion (especially of carbohydrate) just doesn’t happen without gut flora. He needs gut flora, and he needs it relatively quickly. That’s where the birthing process comes in.

Traditionally, birth allows the passage of microbes from mother to the sterile infant gut, a relatively quick process. Gut colonization isn’t exactly a “feature” of the birthing process, however, and it’s not like there’s a specific pathway designed for the flora to travel from mother to child. No, gut colonization arises organically. It’s common sense, really, if you consider what child birth actually is: a somewhat chaotic, unsanitary event, where fluids are being exchanged, stuff is sloshing around and mixing together, with this vulnerable baby in the midst of it. You’ve got a helpless infant sporting a fecund, totally accessible gastrointestinal tract and a perpetually open mouth. He’s just kind of lying there, maybe crying a bit, but he’s incredibly open to suggestion. To gut flora, this is prime real estate, ripe for the taking. By the time the cord is snipped and the infant’s butt’s got a handprint on it, the baby’s upper gastrointestinal tract has been partially populated with bacterial strains derived from the mother’s feces and the surrounding environment (the air, others in the room, etc). Breastfeeding provides another ongoing source of bacteria. It takes about a month for a newborn to establish a solid population of gut flora, and another year for it to resemble an adult’s gut contents. (Any wonder why C-section, bottle-fed babies might get off to a slow start?)

Raising kids isn’t just about bringing new organisms into the world. It’s also important to prepare them for what lies ahead, and the only way to ensure adequate preparation is with exposure and personal experience. Shortchanging kids now, whether by maintaining the ultra-sterile environment (Purel everywhere, no physical skin-to-ground/dirt/skin contact, zero exposure to the outside world, lots of antibiotics, etc) at all costs or feeding them a purely refined food diet, sets them up for poor health in the future. Getting enough gut flora is one huge step in the right direction, but there’s a bit more nuance, as researchers are learning. Getting a wide enough variety of gut flora is just as, if not more important in the path to good digestive health – and that goes for kids, teens, and adults, as well as infants.

Accelerated Evolution

Bacteroides plebeius is a common microbe that lives in the human gut, issuing various digestive enzymes to deal with various types of food. It’s a pretty basic example of gut flora, but researchers noticed something very strange while studying a marine species of Bacteroidetes. Zobellia galactanivorans, which lives on a type of red seaweed, contains a specialized enzyme designed for the cleaving of porphyran, a polysaccharide found in red seaweed. Simply put, this specific enzyme was meant to digest seaweed. The researchers searched the gene-sequence databases and found that the same enzyme was also present in human-borne B. plebeius. How did the digestive enzymes of an obscure marine microbe get incorporated into human gut flora? They looked a little harder and found that it was only present in Japanese B. plebeius, not North American. They had their answer.

When humans began arriving in Japan, around 40,000 years ago, seaweed became a staple. And, while most seaweed sold in stores is roasted (and therefore sterile), Paleolithic seaweed eating conditions were considerably less “sanitary.” Folks were eating lots of raw seaweed, teeming with bacteria, and those bacteria were communicating with the already present gut flora. We already know that bacteria enjoy accelerated evolution via gene transfer on a regular basis, but this was the first research to confirm that gut microbes learn from other microbes. They aren’t static. Our gut flora actually receives genetic information from foreign microbes passing through, borne by the food we eat, and they can alter their own genetic code to incorporate the new material.

That’s exactly what happened. Ancient human guts were exposed to new strains of bacteria with new digestive enzymes, and information was exchanged. Genetic code was transferred. And it happened really quickly; according to lead researcher Jan-Hendrik Hehemann, “a bacterium that can’t digest nori one day, can the next.” If those early Japanese had been eating grocery store nori, roasted and months-old, would they have been able to break down the prophyran? No. The seaweed had to be fresh, it had to be raw, and bacteria had to present and alive to survive the trip into the gut. Today’s sterile, refined fare is absent bacteria – good or bad. We irradiate , we pasteurize, we sterilize, and we roast everything that goes into our mouths. Is it any wonder we’ve got widespread health problems?

Clearly, humans evolved in a bacteria-rich environment. The food we ate, the ground upon which we slept, and even the water we drank sent a steady stream of microbial diversity into our bodies – and this went on for hundreds of thousands of years. It made for occasionally lethal infections, but it also made possible the digestion of a wide variety of foods, an ability that we continue to enjoy today. But that seems to be changing. Food is losing its bacterial kick, unless you go out of your way to incorporate microbes into your diet. In the past, as food became more “sterile” and we moved into cities and became successful with agriculture, fermented foods became staples. Nearly every traditional cuisine uses fermentation, in fact. Did they suspect something was missing with the increased refinement of the food supply? Maybe, but either way, they maintained a steady level of bacteria in their diets. We, for the most part, do not.

What Does This Mean?

This shows the probable arc of our evolutionary relationship with food. As we evolved and ate new foods, our gut flora evolved as well. It’s quite remarkable, really, and it shows just how fast evolution can occur. Humans don’t change that quickly, of course, but our gut microbes do, and we in turn change with our gut.

I think everyone of all ages, but kids especially, should eat a wide variety of foods. Avoiding refined foods isn’t enough. You’ve got to actively seek out new foods, “living” foods and raw foods. Don’t become a raw foodist , mind you. Just experiment. Try fermented foods , like kefir or sauerkraut . If most soil wasn’t filled with pesticides, heavy metals and other unknowns I’d probably even encourage you to eat some dirt . Since grubbing on dirt isn’t practical (or appetizing, for that matter) I also recommend supplementing with probiotics. If anything, we owe it to our next of kin to fill our bellies with tons of organisms.

What are your thoughts on gut health? Does it even cross your mind? Is this new to you? Or do you have a plan of attack to keep your gut happy? Fermented foods? Supplements? Share your thoughts in the comment board. Thanks, everyone, and Grok on!

AJCI Flickr Photo (CC)
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