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Today’s Health Upgrade

• Artificial sweeteners and your brain

• Creatine risks

• A new fix for knee pain?

• Why you really keep grabbing your phone

Health
Does Diet Soda Damage Your Brain?

Yesterday's breakdown about TV and brain aging brought in a flurry of new questions from all of you.

The most common request was a review of the recent coverage suggesting that artificial sweeteners harm your brain. A deeper look at the root of the conversation helps explain why there's no reason to panic.

We'll start with what you care about: There's no human research showing sweeteners damage brain cells.

The new commentary is based on studies examining erythritol. There's one study in particular that took cells lining the tiny blood vessels in the brain, cultured them in a dish, and bathed them in erythritol — about the amount in one sweet drink (roughly 30 grams) — for three hours. Then they looked at how the cells behaved.

The treated cells made less of the molecule that keeps blood vessels relaxed and open, more of the one that tightens them, and were slower to release the body's built-in clot-buster when challenged. On paper, that's the kind of change you'd rather not see in a blood vessel.

But this was cells in a dish, not a person. Nobody drank anything. There was no mouth, no gut, no bloodstream, no body doing what a body does with what you eat.

The cells were exposed to a single dose at once and submerged in it for three hours. That's arguably the most important detail because it's roughly 150 times the amount the heaviest sweetener users in real-world studies consume in a full day.

So not only was it based on non-real-world scenarios, the conclusions were hypothetical. It's hard to say a sweetener increases stroke risk when nobody had a stroke because there was nobody to test. The study measured cell chemistry, not a single real outcome in a single real human.

And when you do look at real people, the fear shrinks fast because the data doesn't back up the extreme warnings.

There's one study about a "threefold dementia risk" that came from an analysis of fewer than 100 cases of stroke and dementia. But once researchers accounted for diabetes and blood pressure, the association no longer held up. 

If you're worried about your brain, The Lancet Commission identifies 14 factors that actually affect dementia risk, including blood pressure, blood sugar, cholesterol, hearing, movement, and smoking. Diet soda isn't on the list because there's no evidence showing a close relationship.

Together With Momentous
What Are The Real Risks Of Creatine?

Reader question: "I see so much about creatine, but what's the biggest risk of using it? What are the downsides?"

The answer is a bit of a letdown, but in the best way possible: for a healthy adult, creatine is about as low-risk as supplements get, while offering legitimate research-based benefits.

The scariest-sounding risks are linked to what’s in the tub, and the reality of not being able to trust what’s on the label. 

Creatine is one of the most researched supplements. It has decades of studies, long-term trials, and tests where they mega-dose as much 30 grams a day for five years. And time after time, creatine holds up as one of the cleanest safety records on the shelf. So the truthful answer isn't a scary headline. It's a short list of small, mostly avoidable things, plus one group that should check with a doctor.

Risk 1: What's in the tub. Supplements get regulated after they hit the shelf, not before, so what's in the container can drift from what's on the label. When researchers test sports supplements, an uncomfortable number of products come back dirty. 

One review found that up to 50% of products tested positive for banned substances, and a larger review of 50 studies covering more than 3,000 supplements found over 28% contained undeclared drugs, including anabolic steroids. 

And many creatine products don’t even have any creatine and instead are stuffed with other, sometimes illegal, performance-enhancing ingredients. 

Or, they use forms of creatine — like Creatine HCL — that aren’t backed by decades of published research. 

Creatine monohydrate is a single, affordable ingredient, which puts it near the safe end of the shelf. 

You erase most of the risk with one habit: buy a third-party-tested tub.

Risk 2: Your stomach, if you mega-dose. The side effect that shows up is stomach trouble, but it depends on how much you take, not creatine itself.

At 3-5 grams, most people have no issues. But in a trial of 59 people, a single 10-gram serving increased the risk of GI issues. Split that same 10 grams into two 5-gram doses, and it was no different from placebo. 

Risk 3: The one group that should pause. If you have an existing kidney disease, talk with your doctor.

Not because creatine has been shown to damage kidneys — a thorough review of the literature found no compelling evidence of that in healthy or clinical populations. 

It's because creatine can affect creatinine levels, which are the blood marker doctors use to monitor kidney function. That rise is a normal byproduct of taking creatine, not a sign of damage. But if your kidneys are already compromised, you don't want to blur the gauge you're steering by. That's a conversation for your doctor if you have a health condition, not a warning for everyone else.

So the whole risk really comes down to one question: can you trust the tub? 

Momentous built the Signature Spec Creatine around that exact trust problem. Every batch runs through six verification stages and gets checked by outside labs before it ships. Then it's certified by NSF for Sport and by SuppCo's TESTED program, which buys the product off a real shelf and checks it against the label the way you would at home.

If you’re going to take a product that actually works, don’t leave yourself vulnerable to the only risk.

APC readers get 35% off a subscription or 14% off a one-time order when you use the code PUMPCLUB at checkout. 

If you’re looking for workout benefits, the research suggests 3-5 grams of creatine monohydrate per day. If you’re more interested in cognitive benefits, then you might need 10 grams per day, and the benefits appear to be stronger the older you are. 

On Our Radar 
A Surprising New Target for Knee Pain: Your Gut

For cranky, arthritic knees, exercise is the best-tested thing you can do. But a new trial looked somewhere else and came back with something worth keeping an eye on.  

A fermentable fiber appeared to take the edge off arthritic knee pain, an early hint that the gut may be another way to help cranky joints.

Researchers enrolled adults with diagnosed knee osteoarthritis and divided them into four groups: one group stirred a daily 20-gram scoop of inulin (a fiber) into their food. One followed a digital physical-therapy program. One did both. The last got a placebo.

Other than the placebo group, everyone got better, but not equally. Exercise beat fiber for pain relief, and doing both together led to the biggest drop of all.

The approaches also helped in different ways. 

Exercise made people more functional: they could rise from a chair more times in 30 seconds and moved more steadily on their feet. 

The fiber helped some with soreness and reduced the sensitivity to pressure. The researchers aren’t sure why the fiber made a difference, so that’s a reason not to overstate the claims. 

And, as we’ve told you many times before, approximately 95% of people don’t get enough fiber in their diet. And a sufficient amount of fiber is linked to everything from weight loss and better cardiovascular health, to a lower risk of diseases like diabetes. 

So if eating more fiber also might help reduce knee pain, instead of viewing that as a primary purpose of taking fiber, it’s just one more benefit from a habit you want to build regardless. 

If you want to follow what they did in the study, participants mixed 20 grams of inulin into their daily diet. 

Better Questions, Better Solutions
Are You Distracted, Or Creating An Escape?

You sit down to lock in. This is the block where you finally make progress, and nothing is going to stop you.

Ten minutes in, your hand drifts toward your phone. No buzz. No notification. No trigger at all. It's easy to blame the phone — it's built to keep you hooked. But the phone isn't the whole story.

Old question: How do I block out distractions?
Better question: What am I trying to escape the second I interrupt myself?

Here's why the second question can help you improve focus and concentration without any added text or guilt: When researchers watched people work, they found that close to half of our interruptions — around 44% — don't come from the outside at all. No coworker, no ping, no alert. They come from us. 

So even in a silent room with your phone in a drawer, roughly half the pull is still there, and it's coming from the inside.

In a separate experiment, people were more likely to interrupt themselves the moment the work stopped feeling like it was going anywhere. When they got stuck, or the task started to drag, or they couldn't feel any progress. And those self-interruptions came at a price: their accuracy dropped. 

In the moment, it might seem like the pull of your phone is random. But the studies suggest it’s probably not. It's a tiny escape hatch from a moment that just got uncomfortable.

That same workplace research found the more people got interrupted from the outside, the more they went on to interrupt themselves afterward. 

This is the part that has likely infiltrated all of our lives. We are now connected to phones, email, and many forms of technology that keep us in touch. And all of those notifications, reminders, and messages train the habit. 

You're being trained to give yourself something to react to, even once things finally go quiet.

Put those together, and one thing becomes clear: blocking notifications only solves half the problem. You can leave your phone in another room and still walk away from the task the second it gets hard or uncomfortable.

That's why white-knuckling your way to focus so often fails. You're trying to power through a moment of friction without knowing what you’re fighting, so the friction wins.

Here’s a three-step process that will give you a better chance of improving focus and undercutting the distractions.

1. Catch the drift: The next time your hand reaches for no reason, don't wrestle it. Just ask one question: what just got uncomfortable?

2. Name it out loud or on paper, and be specific: "I don't know how to start this section." "I'm dreading this email." "I have no idea what the next step is." Naming turns a vague urge into a small, solvable problem.

3. Shrink it, then do five minutes. Cut the task down until it's almost too easy, and do only that for five minutes. Not the daunting email, just the first couple of sentences or bullets of what you want to say. You’ll finish it, but the goal right now is to resist the urge and start on the task your mind is trying to get you to avoid. 

None of this is about defeating distraction. It's about removing the reason you were going to leave in the first place.

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 by “Together With”). 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