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PUMPING IRONY: Gut Instincts

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Gut Instincts

New research suggests we can live longer by altering conditions in our microbiome, but who wants to spend a few extra years fixating on their bowels?

One of the chief annoyances that accompanies advanced middle age is the sense that you ought to be constantly attuned to any and all indications that your body is betraying you. The medical profession is the primary culprit, of course (I got a call last week from my doctor requesting that I come in so they could take my blood pressure!), but it’s really a kind of cultural fixation, especially among the senior set. I can’t tell you how many times I’ve endured conversations about the polyps revealed by a pal’s recent colonoscopy or some mysterious cyst that suddenly appeared on a part of someone’s anatomy I have no interest in viewing.

So, I’m not sure what to make of recent groundbreaking research suggesting that I should be paying more attention to my gut microbiome, the microbial assemblage that rules my digestive system — and perhaps my brain. Scientists have lately been focusing on the inner workings of our innards to explain everything from autism to Parkinson’s, and while this is hardly news to anyone who read Adelle Davis (“You are what you eat.”) in the early ’70s, it does seem to represent a tiny step forward for our often clueless medical-industrial complex.

But, as tends to be the case with most other health-related insights, this sudden infatuation with the gut microbiome has encouraged the sort of prescriptive musings guaranteed to make geezers fixate even more than usual on what’s going on in their bowels. This doesn’t just generate more awkward barroom conversations; it’s liable to lead to a certain level of frustration. There’s not much you can do to prevent your gut’s bacteria from going rogue as you age.

Swedish researchers in 2016 reviewed numerous studies and concluded that the aging process is not kind to our guts. In fact, bacterial diversity begins to decline almost as soon as we move through toddlerhood. By the time we reach retirement age, our gut microbiota are about as diverse as Trump’s cabinet.

Writing in the journal Nutrition and Healthy Aging, lead study author Manish Kumar, a postdoctoral student at Chalmers University of Technology, blames this on our deteriorating immune function. “A major negative consequence of aging is immunosenescence, which can be defined as a decline in the functionality of the immune system, which can cause a chronic low-grade inflammatory status in the gut,” he explains. “Immunosenescence can therefore cause unfavorable changes in the composition and structure of the gut microbiota in older people.”

Simply stated, the older we get, the fewer firmicutes (good bacteria) we tend to harbor and the more bacteroidetes (bad bacteria) move in.

Kumar and his team acknowledge that ramping up your fiber intake, boosting your vitamin D, and taking prebiotics and probiotics can temporarily balance your gut’s bacterial composition, but they’re skeptical that these tweaks will provide any long-term benefits. “The connections between diet, microbes, and host are only partially known,” he notes.

Meng Wang, PhD, is similarly skeptical about the powers of probiotics (they don’t tend to colonize the gut very effectively, she admits), but she’s positively effusive about the potential of colanic acid to cure what ails our aging microbiome — and extend our lifespans.

Wang, an associate professor at the Baylor College of Medicine who specializes in the molecular genetics of aging, recently led a study that used various E. coli strains to identify the specific molecule involved in balancing the microbiota of some 4,000 C. elegans worms — a popular lab subject due to its biological similarities to humans. Twenty-nine of these strains extended the lifespan of the worms by 10 percent or more, Ed Yong reports in The Atlantic.

“Several of these life-extending bacterial strains behaved predictably — they influenced networks of worm genes that are already known to influence the aging process,” Yong notes. “But two strains did something unexpected. Their missing genes are involved in making colanic acid — a type of sugar found on the surface of many gut microbes. And these particular microbes, because of their deleted genes, were producing unusually large amounts of colanic acid. And when [researchers] stopped them from doing so, they no longer extended the worm’s lives. Colanic acid was the key.”

Wang concluded that colanic acid stimulated the mitochondria in the worm’s cells to make extra copies of themselves while activating a collection of genes that help the mitochondria cope with stressful conditions. Why this occurs may have something to do with the fact that mitochondria evolved eons ago from a single bacterium and may retain enough of their former characteristics to communicate with their modern cousins. “It’s just amazing to me that after so many years of separation, they can still talk to each other,” says Wang.

The idea, of course, is to develop some life-extending probiotic based on the colanic acid results, a process that even Wang admits is a bit far-fetched. “Making people live longer and healthier is very different from treating diseases,” she says. “If I talk to a patient and say I have a magic drug that can cure their disease but has side effects, I think they’d take it. But if you tell a healthy person that you have a compound that would extend their life by five years, but has side effects we don’t know about . . . I would be hesitant. That’s why I’m looking to the microbiome. Maybe we can find natural compounds that come from the microbes that we can use to boost our health. They’d be safe because they’re already there.”

I’m all for holistic approaches to healthcare, but I’m having trouble working up much enthusiasm about a future in which geezers are washing colanic-acid pills down with their Budweiser while worrying aloud about the ratio of firmicutes to bacteroidetes residing in their intestines. All that angst can’t be good for a guy’s mitochondria.

is an Experience Life deputy editor who explores the joys and challenges of aging well.

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