What Inhabits Your Gut Could Inhibit Your Cycling — or Help It

By Kevin Kolodziejski

Ube ice cream, anyone?

In the Philippines where it’s grown, the type of yam needed to make this flavor goes by the same name (pronounced “ooh-bay”) but in the U.S. is sometimes called the purple yam. According to Christine Yu and Josey Murray in an article for the June 2021 issue of Women’s Health, the ube has been used in all sorts of dishes and desserts in the Asian country of 7,000 islands for a long time, meaning “it’s very time tested and taste approved.”

Speaking of approval, when I showed a picture of the pleasingly purplish ice cream to family members and a few cyclists, it got the oh-my-god-does-that-look-good look. When I explained its taste is creamy and nutty, yet mellow with hints of vanilla and coconut, that amalgamation got two thumbs up from all — and me to search for more ube info.

Ube Info of General Interest

While it contains a few more calories per ounce, a bit more fiber, and a tad less protein, the ube is close to the nutritional equivalent to the sweet potato — a veggie that makes just about every superfoods’ list. (Though the predominant type of antioxidant in both differs, both help your health.) A New York Times article forecasting how we’ll eat in 2023 dubbed the ube Tuber of the Year, mentioned it’s included in many food-trends-for-the-year articles, and reported it’s now being used in the U.S. in pies, waffles, lattes, and a version of a pina colada as well as the aforementioned ice cream.

While I seriously doubt the ube will ever cause Ben & Jerry’s, Baskin-Robbins, or Häagen-Dazs to add a flavor, I’m serious about something else. Providing the sort of information about health and fitness and insight about motivation that not only increases your general knowledge but also produces a spillover effect that betters your pedaling. Because of that, the discussion now shifts to a health and fitness matter equally as trendy as the ube — though pictures about it won’t exactly incite your appetite. The over 100 trillion microbial cells that inhabit your gut and play a far larger role in your health than we ever imagined as little as 10 years ago.

Gut Health Info of Particular Interest

Proof of just how trendy research about gut health is right now can be found in a folder on my MacBook Pro. Labeled new@guthealth, it contains 60 articles I deemed important enough to save.

One of particular interest to exercisers chronicles research using mice that suggests the specific makeup of the 100 trillion microbial cells in your microbiome might be why you get what’s often called the runner’s high during and after any sort of aerobic exercise — or not. It also could explain how you can be so enthusiastic to exercise — yet your spouse not so much. In essence, the study, was constructed to answer a simple question. When kept inside a cage containing an exercise wheel, why do some mice run on it a lot and some do not?

So the researchers searched for any biological traits, genetics included, that would explain what makes a mouse become the former rather than the latter. They found nothing concrete — until they got to the mice’s gut microbiomes.

What lived in the guts of the mice who ran a lot differed from the ones who did not. That led the researchers to give the mice that liked to run antibiotics designed to kill off those differing types.

The Death of Gut Bacteria Kills the Mice’s Desire to Run

On average, the distance they now covered was cut in half. When the mice were taken off the antibiotics, however, they returned to running nearly as far as before.

As the researchers worked on, they uncovered an intriguing gut-brain connection. At the risk of oversimplifying it, they found a healthy gut biome sends messages to the brain not to produce a compound that counteracts dopamine — the “feel-good” hormone that gives you a sense of pleasure and also the motivation to do more of whatever’s causing it, according to the Cleveland Clinic website. So it stands to reason that if you’re eating the sort of foods that feed the good gut bacteria instead of the bad and the production of that anti-dopamine compound is greatly reduced, the effect of dopamine when you do aerobic exercise is enhanced.

Positively Addicted to Exercise

In my case, once I’m fully warmed up and have at least one hard climb under my belt, I feel like a junkie shooting up some pretty good stuff. If you don’t get quite the same rush, it could very well be that it’s your way of eating that’s keeping you from it. And if you think I’m a bit over the top about how great exercise in conjunction with healthy eating can make you feel, consider the four adjectives the Cleveland Clinic selects to characterize how you feel when your dopamine level is optimal.

Happy. Alert. Focused. Motivated.

If those four words don’t usually apply to you and you want them to, experiment with your diet as a way to aid your gut microbiome. Vague advice, for sure, but here’s why it needs to be. A study published in the June 12, 2019 issue of Cell Host & Microbe using humans and their pooh explains why a vegetable seen as a superfood and is oh-so good for my gut health may not be quite as good for yours.

The contradiction “kind of makes sense” to Dan Knights, the researcher and the associate professor in the Department of Computer Science & Engineering at University of Minnesota who spoke to Live Science in 2019 about the study. It does so because of what he calls “dark matter” in foods — elements besides the vitamins, minerals, and micronutrients that nutritional labels typically don’t list and scientists don’t usually consider. The impact of dark matter on diet via the gut microbiome clearly comes to light in the aforementioned study.

‘Dark Matter’ Matters

Knights and his colleagues had 34 healthy volunteers write down every bit of food and drink they consumed for 17 consecutive days. All the while, the volunteers provided stool samples. The researchers then used what’s called shotgun metagenomics, which “allows researchers to comprehensively sample all genes in all organisms present,” as explained by Illumina.com. This enabled them to evaluate the abundance and the diversity of the microbes in the volunteers’ guts — and recognize the role of dark matter.

As they compared the volunteers’ food-and-drink journals to the stool samples, the researchers searched for clear-cut relationships between consuming certain foods and the existence or abundance of bacteria in the gut microbiome. And they found them. What they didn’t find was much of a pattern.

While they detected 109 such relationships in the group as a whole, only 8 of those relationships were shared by more than 2 volunteers. And in 5 of those instances, the food consumed had opposite effects. In other words, a single vegetable like broccoli could cause a certain good bacteria to multiply in one person yet not in another.

The logical explanation for this is that the effect of a food’s dark matter is a highly personalized one. That’s to be expected, Knights’ explains, since each person whose body digests dark matter possesses a unique mixture of gut microbes — which leads to a different sort of dark matter.

The Second Dark Matter

While prior studies have established about 70 percent of your immune system resides in your gut and that good gut bacteria certainly support it, one published in the September 15, 2022 issue of Cell using mice shows how bad bacteria weaken it. And that bad bacteria gain strength from poor eating. In this specific case, the poor eating was created by feeding mice what Americans typically eat. It’s sometimes called the Western-style diet and is always too full of fat and sugar.

Before feeding the mice a variant of the Western-style diet, however, the researchers worked their magic so that the mice’s guts were replete with a bacterium that goes by the abbreviation SFB, the preferred food of an immune cell in mice that’s abbreviated as TH17. After four weeks on this diet the mice had gained weight and developed glucose intolerance and insulin resistance (the holy, as in cow, trinity for type 2 diabetes) and that was no surprise. What was closer to one was what happened to the SFB bacteria that had been thriving inside the mice’s guts before they began the Western-style diet. Now they were few and far between.

In their place: a bad bacteria that thrives on sugar. As a result — and this is a serious result — the mice lost TH17 immune cells.

In short, in the same way proper combination of amino acids, fatty acids, vitamins, and minerals can cause gut bacteria that helps your health to thrive and multiply, too much sugar helps the gut bacteria that doesn’t.

---

Kevin Kolodziejski began his writing career in earnest in 1989. Since then he’s written a weekly health and fitness column and his articles have appeared in magazines such as “MuscleMag,” “Ironman,” “Vegetarian Times,” and “Bicycle Guide.” He has Bachelor and Masters degrees in English from DeSales and Kutztown Universities.

A competitive cyclist for more than 30 years, Kevin won two Pennsylvania State Time Trial championships in his 30’s, the aptly named Pain Mountain Time Trial 4 out of 5 times in his 40s, two more state TT’s in his 50’s, and the season-long Pennsylvania 40+ BAR championship at 43.