The gut you’ll have in 10 years is being built right now.
Because yes your gut has an age, but it isn’t necessarily the one on your birth certificate.
Two 70-year-olds can have guts in completely different shape - what separates them are often medications, illness, and spells of being less active that stack up over time.
Which I actually think is oddly reassuring, because it means your gut health isn’t written in stone, not at 50, and not at 70 either.
Some of the changes in your gut are down to ageing itself. But quite a lot of it isn’t, and that’s the more useful half.
Before we get into the why, one thing you can do today
Get a toilet footstool. Sitting on a standard loo leaves a slight kink in the last stretch of your gut. Resting your feet on a step lifts your knees slightly above your hips, which opens that angle up and makes things easier to pass without straining. A stack of books also works just as well (!)
Your gut is surprisingly resilient to aging, compared with many of your other organs.
A key reason is that your gut is able to rebuild itself, the lining of your small intestine renews every few days, so a gut that's taken a battering (within reason) can come back in a way a heart or a kidney simply can't.
The other is that it’s built to handle far more than everyday life asks of it, most of the time it’s working at just a fraction of its limit. It’s a bit like being able to run a marathon when the only task in front of you is a walk, there’s a lot of capacity there that simply isn’t needed day to day.
Its sheer size adds to this, the gut is very long, and its lining is finely folded in certain places, so the surface area doing the work is vast. That gives it some wiggle room to spare before absorption is affected.
So the everyday job sits well within what the gut can do.
It’s only on the rare days when something goes wrong or there’s extra stress that this spare capacity gets called on, and that’s what’s happening in an aging gut.
The safety margin slowly narrows, and a problem tends to show only when something else, an illness, a new medication, a spell of being less active, pushes past what it’s able to manage.
The gut doesn’t dramatically change solely thanks to aging itself, instead, your gut is often largely affected by what’s happening elsewhere in the body. Everyday things like medication, illness and moving less all play a part in your gut’s wear and tear capacity, and each of those tends to become more common as we get older.
Stomach acid holds up better than you’d think. It’s a common idea that acid fades as we age, but in a healthy stomach it mostly stays put. When it does dip, it’s usually a long term stomach infection called H. pylori or certain acid-lowering meds, not age on its own.
Your stomach empties a little more slowly. After a big meal, food sits there longer than it used to, which is part of why you might feel full sooner than you once did. Further down, big changes are less common - but the gut's nerve signals do slow a little with age, which can make the gut less responsive than it once was. When significant slowing happens, less movement, less fibre and fluid, and new medications often play a large part.
The lining of the gut may make less protective mucus. Lining the surface of your gut is a slippery layer of mucus that helps the gut contents slide through smoothly, while protecting the gut wall. As you age, the number of cells that make the mucus can start to dwindle, so there’s less mucus to go around, less lubrication helping things pass smoothly through at a timely pace. This is hard to measure in humans though, a lot of the detail is based on mice studies.
Your gut microbes change, though not always for the worse. You've probably heard that the variety of microbes in your gut drops with age. That seems to mostly come from studies in care homes, where the food is repetitive and the medications many. In older people who are eating well and living independently, that diversity usually holds up - so how fit and well you are for your age matters here.
So far I’ve been telling you that what looks like aging usually isn’t. Menopause is where that changes, because here the hormones really are acting on the gut itself.
Receptors, the docking sites cells use to pick up oestrogen and progesterone, sit all along the gut wall, including on the nerves that control how the gut moves. Most of what we know about what those receptors do there comes from animal studies. Plenty of women notice their gut changes around this time, though how much of that is the hormones, and how much is the sleep, the stress and the everything-at-once of midlife, isn’t settled.
Your hormones influence your gut, and your gut has a hand in your hormones, it runs both ways.
Certain gut microbes carry an enzyme that can reactivate oestrogen your body has packaged up for disposal, letting some of it be reabsorbed, though how much difference that makes isn’t yet clear in humans.
When oestrogen falls, most of the bone loss happens at the bone itself. But it also affects how well you absorb calcium, so you take up a little less from your food, and to keep blood levels steady the body draws more from your bones.
Having said all this, there’s still so little we truly know.
Women’s health research is drastically underfunded, something I find deeply frustrating. It’s one reason I can see why women are so often left piecing things together from friends or social media, because they’re not getting the answers elsewhere. I’m thinking of doing a dive into menopause and the gut in a future post, so let me know in the comments if this would interest you.
So how do you super-age?
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