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Today’s Health Upgrade

• Do psychedelics offer brain benefits?

• How to upgrade your microbiome

• (Hot) bath time vs. sauna time: A comparison

In The News
Can Psychedelics Change Your Brain For the Better?

Scientists have spent years trying to understand whether psychedelics do something meaningful to the brain beyond the experience itself, and a new study offers a new perspective.

A new study found that a single high dose of psilocybin (better known to some as “magic mushrooms”) produced measurable brain changes and improvements in well-being one month later. But that’s only part of the story. 

Scientists gave healthy adults with no prior psychedelic experience either a very low "placebo" dose or a 25 mg dose of psilocybin, four weeks apart. During the high dose, brain activity showed a spike in neural signal complexity. This means the brain is generating more varied, less predictable patterns than usual.

One month later, brain scans showed changes in the white-matter pathways connecting the front of the brain to deeper structures. White matter is good because it helps your brain process, learn, and communicate.

Participants also reported feeling greater psychological insight and well-being, and performed better on one measure of mental flexibility.

It fits a broader story scientists are piecing together about how psychedelics might influence the brain's capacity to change, which is why research in this area keeps advancing.

That said, we can’t jump to too many conclusions. The primary thing the researchers set out to measure — lasting functional brain change — was largely absent.

The white-matter changes are promising, but also somewhat ambiguous and not necessarily unique. For example, white matter improvement in your brain appears during meditation and when learning new skills. So it’s not to say you need a hallucinogen to trigger these types of changes.

The reason psilocybin research is worth following is that it may eventually reveal how the brain shifts into a more changeable state and whether that window could help people who haven't responded to other treatments. That's a meaningful question.

What we can say with more confidence is that the adult brain does change, and we've known for years what moves the needle. 

Aerobic exercise and resistance training increase the size of the hippocampus, the brain region central to memory and learning, an effect replicated across dozens of trials. Learning a genuinely new skill produces measurable structural changes with sustained practice; researchers have seen it in people learning to juggle, pick up a language, and master an instrument.

Sleep clears waste from the brain overnight through a process that is fully activated only during deep rest. And chronic poor sleep disrupts it in ways that accumulate.

For now, the most reliable levers are the unglamorous ones. Consistent exercise. Learning something hard. Protecting your sleep. The evidence behind those isn't new, but it's as strong as it gets.

Together With Momentous 
Your Microbiome Has An Important Request (For Better Gut Bacteria)

The gut health conversation tends to get complicated fast. But a growing body of research keeps pointing back to something simpler: the food you eat and how often you eat it.

A high-quality meta-analysis of randomized controlled trials found that regular polyphenol intake, from foods like berries, tea, pomegranate, and olive oil, significantly improved gut health and reduced a key marker of gut-driven inflammation.

Participants consumed an average of roughly 450 mg of phenolic compounds daily for about five weeks. That led to a significant reduction in harmful bacteria and an increase in beneficial bacteria in a healthier microbiome. And a compound tied to chronic low-grade inflammation also dropped meaningfully. 

What was interesting was that polyphenols did not significantly increase short-chain fatty acid production, including butyrate, the compound most often credited with protective effects in gut health. If you've read that berries boost butyrate, this study doesn't support that, at least not over five weeks in this population. 

What the research does support is a consistent pattern: Regularly eating polyphenol-rich foods appears to shift gut bacteria toward a more favorable direction and may reduce the background inflammation that accumulates over the years.

If you want to improve your gut health, here’s your two-part plan:

Step 1: Add more polyphenol-rich foods like blueberries, strawberries, raspberries, cherries, plums, apples, spinach, artichokes, olives, beans, dark chocolate, coffee, and tea. 

Those polyphenols help reshape what’s living in your gut. But the bacteria that have shifted still need fuel to do their jobs, and the primary fuel for a healthy gut ecosystem is fiber, specifically the type most Americans rarely get enough of.

Step 2: Eat more resistant starch and soluble fiber.

Resistant starch is the fiber that reaches your colon intact, bypassing digestion in the small intestine. Once there, it feeds the bacteria most responsible for producing butyrate — the compound that nourishes your gut lining, supports the gut barrier, and underlies most of what the science associates with a healthy microbiome. And according to research, resistant starch produces more butyrate than any other fiber type.

You can find resistant starch in green bananas, beans, cooked and cooled rice, pasta, or potatoes. Or, you can get it in Fiber+.

We built Fiber+ as our first and only Pump Club supplement to address the fiber gap and provide an innovative solution to provide resistant starch, soluble, and insoluble fiber in one formula.

Most fiber supplements work on regularity. Fiber+ is designed around improving the whole gut ecosystem. It combines three fiber types that work through complementary mechanisms: psyllium husk for cholesterol support and satiety; rice bran hull for mechanical transit and gut barrier protection; and resistant starch — the differentiator. In a clinical study, participants who consumed resistant starch daily showed significantly greater increases in two bacterial species identified by polyphenol research as markers of a healthier gut.

The polyphenols shift the composition. The resistant starch feeds what you've built. They're not competing strategies; they're the same strategy working on different parts of the system.

Because you’re an APC reader, you get 35% off your first subscription order or 14% off a one-time purchase with code PUMPCLUB at checkout. No catch. Just enter the code, and the discount applies automatically.

Polyphenols set the table. Fiber+ keeps the ecosystem fed.

Health 
Your Hot Bath Might Outperform An Infrared Sauna

Saunas have become a popular wellness investment, sold as a more efficient path to all the benefits of traditional heat therapy. The pitch is compelling. And the science is promising. But a new head-to-head study put three major heat therapy options to the test, and the results don't quite match the marketing.

Researchers found that hot water immersion — such as a simple hot bath — produced significantly stronger cardiovascular and immune responses than far-infrared saunas.

Twenty healthy adults completed three forms of heat therapy on separate days in randomized order: a 45-minute hot bath at roughly 105°F, three 10-minute rounds in a traditional sauna at 176°F, and 45 continuous minutes in a far-infrared sauna between 113 and 149 degrees Fahrenheit (Far-infrared saunas use deeper wavelengths). Researchers measured core temperature, the amount of blood the heart pumped per minute, and immune markers both immediately after each session and at 24 and 48 hours later.

Hot-water immersion raised the core temperature by 1.1°C. The traditional sauna raised it by 0.4°C. And the infrared didn’t appear to increase it at all. Cardiovascular response followed the same pattern. 

Interestingly, only hot-water immersion triggered a meaningful increase in immune-signaling molecules, a response not observed after either sauna type.

Scientists believe the results were due to physics.

Water transfers heat to the body roughly 25 times more efficiently than air, producing a stronger whole-body response. Raising your core temperature appears to be the key driver behind heat therapy's physiological effects, and not all modalities do it equally.

That said, for many, it’s easier to sit in hot air than in a scalding hot bath.

Because we remind you not to overreact, this was a single-session study of 20 young adults. A one-time response doesn't tell us how these different variations compare over months of consistent use. And there are many other reasons to consider using a sauna. (And reasons why you might need to consult with your doctor.)

Still, if you're choosing a heat therapy practice for recovery or cardiovascular support, the type of heat matters more than most people realize. And a bath could be a suitable option.

Traditional saunas have the most established research and health benefits (from heart health to VO2 max), but they can be more expensive. Infrared is not necessarily bad, but the research is much more limited, and, unless you can get it hotter, the benefits might not be the same.

The Positive Corner of The Internet
About Arnold’s Pump Club Editorial Standards

We do things a bit differently here, starting with transparency.

1. The Content: All APC emails are researched, written, and fact-checked by the APC editors (see bottom of the email), with written contributions from Arnold (noted with “Arnold’s Corner”). Links take you to original studies (not second-hand sources).

2. Does AI play a role? Not for the primary content, but it is used in two ways. The main items are original content written by the APC team. The summaries at the end are AI-generated based on the human-written content above. We also use an AI tool to review our interpretations of the research and ensure scientific accuracy. We don’t assume AI is right, but we use technology to hold ourselves accountable.

3. Yes, we have partners (all clearly noted). Why? Because it allows us to keep the APC emails free. We first test products, and then reach out to potential partners who offer ways to help you improve every day. The bar is set high, and to date, we have turned down millions in ad deals. (Example: we will not partner with any non-certified supplements or those without evidence in human trials). If we won’t buy the product, we won’t recommend it to you. And if there’s no evidence it works, then there’s no place for it here.

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Publisher: Arnold Schwarzenegger​

Editors-in-chief: Adam Bornstein and Daniel Ketchell