The Wellness Brew - Issue 17

Happy Fourth of July weekend!

Whether you are grilling, watching fireworks, or enjoying some time with the family, we hope you have a great weekend celebrating America’s 250th birthday. We’re keeping this week’s issue shorter and lighter than usual, but don’t worry, we’ll still include a few tips.

First, we filtered the noise — here's what's worth knowing this week.

A 2022 Northwestern study published in PNAS tested what happens to your body when you sleep in a room with even moderate ambient light versus a nearly dark one. Researchers measured cardiovascular and metabolic markers in healthy adults after a single night of each. The results were striking. One night of sleeping in a room with 100 lux of ambient light (roughly what you get from a bright hallway light or streetlight through thin curtains) elevated nighttime heart rate, decreased heart rate variability, and increased next-morning insulin resistance compared to sleeping in a dim room (under 3 lux). The driver appears to be sympathetic nervous system activation, meaning the "fight or flight" response stays partially online while you sleep. The practical takeaway is simple. Close the blinds, cover the LED lights on electronics, and consider blackout curtains if you have not already. — Mason et al., PNAS, 2022.

A 2024 study published in Frontiers in Physiology by researchers at the University of Bath tested whether short bursts of high-intensity cycling could mobilize hematopoietic stem cells (the type used in bone marrow transplants) more effectively than steady moderate-intensity riding. The result: as little as 2 x 2-minute intervals at 90 to 95 percent of max heart rate increased circulating stem cell concentration by roughly 60 percent above rest. Steady 30-minute moderate cycling produced smaller and less consistent increases. A follow-up 2025 study confirmed that intermittent short intervals sustained the elevated cell counts across a 3-hour window. Intensity is a lever that steady state exercise cannot replicate. Even a few short hard efforts in the middle of an otherwise moderate workout meaningfully changes what happens in the body. — Baker et al., Frontiers in Physiology, 2024.

Jeremy Grantham, the 87-year-old investor known for calling the dot-com bubble and the 2008 housing crash, appeared on The Diary of a CEO last week. Most of the interview covered his warning about an AI-driven stock bubble. But he also spent significant time on what he considers the underappreciated public health crisis of our era: declining human fertility. His data: sperm counts have fallen from 100 million/mL in 1970 to 35 million/mL today (a 65 percent decline), and the rate of decline is now roughly 2.5 percent per year and accelerating. Grantham, whose foundation has funded 15 years of research on this question, argues the primary driver is everyday chemical exposure. Phthalates in cosmetics and food packaging. BPA. PFAS in water and cookware. Pesticide residues on conventional produce. His argument connects to a Harvard study of 180 men at a fertility clinic where those eating the least pesticide-contaminated produce had double the sperm count of those in the highest exposure quartile. Worth listening to if you have not seen it. — Grantham on The Diary of a CEO, 2026.

Fourth of July weekend has a way of making people feel guilty about what they eat and drink. The barbecue is calling. The beer is cold. The dessert table is real. And somewhere in the back of your mind is the voice saying you should be "clean" all weekend.

Let it go. 

The evidence on ultra-processed food and long-term health is genuinely striking. A 2024 umbrella review published in the BMJ pooled 45 meta-analyses covering 9.9 million people and found direct associations between ultra-processed food consumption and 32 different health outcomes, including all-cause mortality, cardiovascular disease, type 2 diabetes, cancer, and depression. A follow-up 2025 systematic review of 18 cohort studies covering 1.1 million people found that the highest ultra-processed food consumers had a 15 percent higher risk of all-cause mortality compared to the lowest.

Here is the important part. That data is about the pattern, not the exception.

Your daily diet is where the leverage sits, not one weekend. The person who eats whole foods 90% of the time is not undermined by one day (or weekend) of a few cheats. The July 4th barbecue is not the problem. The daily morning packaged breakfast is. The beer this weekend is not the problem. The daily can of soda with lunch is.

So this weekend, if you are grilling a burger, enjoy it. If you are drinking beer with friends, drink it. If you are eating cake at a Fourth of July party, eat it. The people who obsess over every meal are not measurably healthier than the people who eat well most of the time and enjoy themselves occasionally.

Consistency compounds. Perfection is unsustainable.

These are tips, not rules. Use them as you wish.

1. Pick better drinks when you have the choice. Spirits with soda water and lime beat sugary cocktails. Dry red wine beats sweet cocktails and hard seltzers. Light beer beats regular. If you are drinking, alternate with water. Dehydration is what turns a fun Saturday into a rough Sunday.

2. Prioritize protein and vegetables at the barbecue. A grass-fed burger is a good meal. Grilled chicken, ribs, steak, and vegetables are all fine. The problems come from everything else: sugary sauces, packaged sides loaded with seed oils, and the endless bowl of chips. Fill your plate with the main event.

3. Sleep matters more than the drink. The single biggest predictor of how you feel Monday is how much you slept, not what you drank. Protect the seven hours even if you get to bed later than usual.

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Wellness, filtered.

The Wellness Brew

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Disclaimer: The Wellness Brew is for informational purposes only and does not constitute medical advice. The content published here is not intended to diagnose, treat, cure, or prevent any disease or health condition. Always consult a qualified healthcare professional before making any changes to your diet, supplement routine, or lifestyle.