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Good morning. It’s Tuesday, January 7th.

In today’s email:

• Learn: A Cold Nose

• Measure: Estimated Glomerular Filtration Rate (eGFR)

• Explore: Sedona, AZ

• In the News: New Surgeon General Warning

Stat of the Day

The amount your nose increases the temperature of the air before it enters your body and hits your lungs. (NIH)

Learn

A Cold Nose

"Cover your face and head so you don’t catch a cold.”

Turns out, mom wasn’t just making that up – it’s real science.

It’s cold out there! An “arctic blast” has taken over some of the U.S. (and apparently we name winter storms now). It feels like 0°F for my sister in MSP today and that’s a heat wave compared to the past weekend. Though I bet they won’t complain as much as my neighbors here in FL who get real scared when it dips into the 40’s.

Turns out - we actually do get sick more when it’s this cold.

A groundbreaking study from Mass General Hospital and Northeastern University just figured out why we get sick more often in winter. And it all starts with our nose.

You know that sting you feel in your nose when you first get outside and take a breath in the bitter cold? That sting actually tells us more than we realize.

Our nose isn't just for breathing or smelling. It's our body's first line of defense against airborne threats*. Here’s a few of the key functions of the nose:

• Senses the temperature

• Detects viruses 

• Fights bacteria

• Kicks into gear the soldiers in our immune system

But when our nose gets too cold, this entire defense system starts to break down.

*Our nose is like a personal air filter - it not only traps incoming invaders, it humidifies the air coming into our body and sterilizes it before it hits our lungs.

THE 9-DEGREE DIFFERENCE

Just a 9°F drop in nose temperature can disable about 50% of the billions of virus and bacteria-fighting cells in our nostrils.

That’s not a big swing in temperature. Our nose is normally at a balmy ~95°F (35°C). It warms up the outside air coming into our body by about 40°F. But that means that any temp below 45°F will crush our immune function - and it only takes a few minutes of exposure for this to happen.

WHY IT MATTERS

Your nose is constantly at war with pathogens. It’s one of the many reasons we should always breathe through our nose, not our mouth.

Every breath brings in potential invaders. Under normal conditions, our nasal passages are like a well-defended fortress, with specialized cells called extracellular vesicles (EVs) patrolling the walls.

These EVs swarm and destroy viruses, alert our immune system, and strengthen our mucus barriers. That runny nose isn’t from the invader - it’s from our nose creating more mucus to help keep the invaders from getting further into our body.

But when cold air hits, these defenders literally slow down. It's like watching our security team move in slow motion while intruders sprint past them.

QUICK WINS FOR WINTER WELLNESS

So what can we do about it? Here are evidence-based strategies to keep your nasal defenders strong:

1. Always Breathe Through Your Nose. Your nose warms air better than your mouth. Make it a habit, especially during winter exercise.

2. Keep Moving. Exercise increases blood flow to your nose, helping maintain optimal temperature.

3. Stay Hydrated. Warm fluids like tea, soup, and hot water help maintain nasal temperature and moisture.

4. Scarf or Neck Gaiter. If it’s super cold out, don’t be too tough for a scarf. Creating a barrier of warm air around your nose can prevent the 9°F drop in air coming into your lungs and keep us healthy.

5. Use a Humidifier. Indoor heating dries out nasal passages so we need to offset the dry air to keep our nose ready to fight.

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Measure

eGFR

Think of your kidneys as the body's sophisticated filtration system. Every day, they filter about 150 quarts of blood! eGFR tells us how well this filtration system is working and is a key early indicator of potential kidney issues.

WHY IT MATTERS

Our kidneys aren't just filters - they're chemical factories that:

• Balance minerals in our blood

• Control blood pressure

• Make hormones

• Activate Vitamin D

• Remove waste products

When kidney function declines, it can affect everything from bone health to heart function. The scary part? You might not feel any symptoms until kidney function is significantly reduced. Low eGFR is also linked to cognitive decline and overall mortality.

TEST PREP

Everyone should get this test as part of their annual comprehensive metabolic panel.

Before the test be sure to fast for 8+ hours and stop any medication (including ibuprofen) for 12+ hours - consult with your doctor first.

TEST RESULTS

• Optimal range = greater than 90 mL/min/1.73 m² (consistently)

• Risk range = 60-89 mL/min/1.73 m²

NOTE: Your results might just say <90 or <60. Confirm with your doctor if you have a specific result and shoot for the optimal range!

If results are below 90, consult with your trusted medical partner. Don’t wait until results drop below 60 - this means trouble and is a lagging indicator of kidney stress!

QUICK WINS IF YOUR eGFR IS SUBOPTIMAL

1. Hydration: Start your day with 16oz of water and a ¼ tsp of Pink Himalaya salt, followed by 1 cup of water per hour until 6pm.

2. Diet: Add kidney-supporting foods like beets, berries, garlic, onions, celery and avoid processed foods with phosphorus additives.

3. Environment: Avoid NSAIDs as much as possible, limit alcohol, and avoid chemicals in your home (get air and water filters).

4. Nutrients: Confirm levels of Vitamin D and Magnesium (if low, consider supplements).

5. Sleep: 7-8 hours supports repair and regeneration.

eGFR is your kidney function scorecard. While you can't feel your kidneys working, this number tells you how well they're doing their job. Get it checked annually and take action early if it starts to decline.

Explore

Sedona, AZ

Thinking about trips for 2025? Got the perfect spot for either a couples retreat or a group - Sedona.

Why Sedona? Red rock hiking trails right from your hotel, with plenty of spots for a morning mediation or stretch, plus world class spas that aren’t as expensive as bigger cities.

Try to sneak away for a few days before mid-June to beat the crowds, and the heat and drenching sweat. It might still be cool - especially at night - but that’s perfect for some active hikes up a few hundred feet.

If you go - make sure to do Cathedral Rock Trail before it gets too hot and packed with other hikers. It’s only 1.2 miles, but it’ll give you a little challenge. But you can’t go wrong with any of these trails.

It’s a special place for the Thrive25 family - Max and his wife shared their vows on the top of the red rocks two days before their wedding!

H&L in the News

Alcohol’s Hidden Cancer Risks: The Surgeon General calls for cancer warnings on alcohol, citing links to seven malignancies. With growing evidence, Congress faces pressure to act. (NYTimes)

Embrace Pain, Build Resilience: Discover how radical acceptance helps navigate life's toughest challenges, transforming pain into emotional strength. Learn to cope, let go, and find peace in the present. (Washington Post)

Park Smarter, Explore Better: Timed-entry reservations return to top national parks in 2025. Learn how to beat the crowds and secure your spot for iconic hikes, sunrises, and scenic drives with these expert tips. (Outside)

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We’re 40-something dads that felt our bodies and minds start to slow down and we’re not ready for that. We found too much information on every subject. So we started Thrive25 to transform what we’ve learned into something useful for the rest of us to spend just 5 min a day to optimize our health & longevity.

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To health!