Newsletter #140: Fighting Leaky Gut & Exercising in the Afternoon 💪🏻
Welcome to the newest edition of the humanOS newsletter!
This week, we learned that eating a polyphenol-rich diet boosts beneficial gut bugs and helps maintain gut barrier integrity; people at high risk of developing type 2 diabetes may get added benefits from working out in the afternoon instead of the morning; and non-exercise movement may boost energy levels and improve well-being in individuals at high risk for depression.
Scroll down to learn more 👇🏼
This Week’s Research Highlights
🔵 A polyphenol-rich diet intervention may improve intestinal permeability.
The intestinal barrier is a complex structure that must selectively permit nutrients to enter the bloodstream, but also prevent toxins and pathogens from getting into circulation. When the barrier is healthy, tight junctions let the good stuff pass through and keep the bad stuff from getting out. But when intestinal barrier integrity is compromised, microorganisms and even food compounds can get into the blood, resulting in chronic immune activation and inflammation. To investigate how food bioactives affect intestinal barrier function, researchers randomly assigned 66 older participants into two different arms: a control diet (812 mg of polyphenols per day) versus a polyphenol-rich diet (1391 mg of polyphenols per day). Each intervention was eight weeks long, separated by an eight week washout period, after which participants were swapped into the opposite condition. When participants consumed the polyphenol-rich diet, serum zonulin levels significantly decreased. Zonulin is involved in tight junction modulation in the gut, and serves as a surrogate marker for intestinal permeability (higher zonulin, generally speaking, suggests greater intestinal permeability).
This was accompanied by a significant increase in fiber-fermenting and butyrate-producing gut bacteria. Butyrate has been shown to help maintain tight barrier function, and it has been previously suggested that the beneficial effects of fiber-rich dietary patterns like the Mediterranean diet may be attributed to boosted butyrate production.
💪🏽 Metabolically unhealthy subjects who exercise in the afternoon rather than the morning experience greater beneficial effects.
Researchers retrospectively compared the metabolic effects of exercising at different times of day in a group of metabolically compromised adults who were enrolled in a 12-week exercise program. Thirty‐two middle-aged subjects who were either at risk for or diagnosed with type 2 diabetes performed supervised exercise training either in the morning (8:00–10:00 am) or in the afternoon (3:00–6:00 pm). Compared to participants who trained in the morning, those who trained in the afternoon experienced superior beneficial effects of exercise training on markers of skeletal muscle insulin sensitivity and adipose tissue insulin sensitivity. They also experienced a greater reduction in fasting plasma glucose levels and fat mass, as well as greater improvement in exercise performance. Importantly, this study was a retrospective analysis of existing research data, and was not designed to test the effects of exercise timing on metabolism or exercise performance or to elucidate the mechanisms underlying these observations.
🧠 Non-exercise physical activity - like walking or going up stairs - enhances mental health in individuals who are susceptible to psychiatric conditions.
Physical activity has been linked to psychological benefits, as well as reduced rate of psychiatric conditions. However, “physical activity” encompasses a wide spectrum, ranging from structured exercise with high energy expenditure like playing soccer, to non-exercise movement like gardening or doing household chores. To better understand the impact of daily non-exercise activity on subjective well-being, researchers equipped 67 participants with hip accelerometers to measure physical activity, as well as GPS-triggered electronic diaries on their smartphones surveying the participants on how energetic they felt at that moment. After one week, the researchers found that the subjects felt more alert and more energetic directly after non-exercise activity. Furthermore, this feeling of vigor appeared to be crucial to the well-being and mental health of the subjects. But why specifically does non-exercise activity have this effect, and which brain regions play a role in this relationship? The research team took another 83 subjects and put them through the same protocol described above. However, this time, they also measured brain gray matter volume after the ambulatory assessment procedure. They determined that the subgenual cingulate cortex (sgACC) was a decisive neural correlate mediating the relationship between subjective energy and non-exercise physical activity. The sgACC is a key regulatory site for emotional processing, and low sgACC volume has been characterized as a risk factor for depression. In this study, participants with a lower volume of gray matter in the sgACC felt less energetic when they were physically inactive. However, after performing non-exercise activity, they felt a boost of energy - and that boost was greater than what was experienced by those with higher volume in that area. People at higher risk for depression may be more negatively impacted by a lack of movement - but may also stand to benefit more from higher activity throughout the day from the standpoint of mental health.
Question of the Week
🤔 You’ve probably heard before that the phrase "May you live in interesting times " is a translation of an old Chinese curse (feels kind of appropriate right now!). Is that true? And where precisely does it come from?
💡 Answer
Podcasts We Loved This Week
- David Raichlen: Wired to Run - Why Your Brain Needs Exercise. Via Nourish Balance Thrive Podcast.
- Jason Gill: Population Cardiometabolic Disease Risk - Impact of Strength, Fitness, & Activity. Via Sigma Nutrition.
- Johanna Mayer: Where Did The Word “Vaccine” Come From? Via Science Friday.
Products We Are Enjoying
Duolingo
If you want to begin the new year learning a new language, this is probably the easiest way to get started. Duolingo is a fun and accessible platform for language learning that offers bite-sized, image-driven lessons, and lots of positive reinforcement for daily use (according to the app, I am currently on a 294 day streak). Best of all, it’s free, though it does also provide a premium service if you are keen to avoid ads.
