🌟 This Week's Top Insight: Rethinking NAD⁺ - It’s Not Your Muscles That Need It Most

🧬 This Week’s Study: A groundbreaking study published in Cell Metabolism just challenged one of the most popular assumptions in anti-aging field: that NAD⁺ decline in skeletal muscle is a key driver of aging. Researchers from the Treebak lab at the University of Copenhagen knocked NAD⁺ levels down by 85% in the skeletal muscles of adult mice—yet the animals aged normally. Grip strength, mitochondrial function, endurance, even their molecular “age clocks” all held strong across a two-year lifespan.

Lead author stated in the paper: “Lifelong muscle NAD depletion does not accelerate aging at the molecular or functional level.”

What does it mean to us:

This rewrites a popular narrative—especially among biohackers and celebrities who swear by NMN supplements or NAD⁺ infusions to fight aging. It turns out, muscle is surprisingly resilient to NAD⁺ loss. So where is NAD⁺ most needed? While muscle may not suffer much from NAD⁺ dips, our brain, immune cells, and ovaries do. These tissues are more vulnerable because they:

•Have low baseline NAMPT, the enzyme needed to recycle NAD⁺
•Are high consumers of NAD⁺ (especially during inflammation, DNA repair, and hormonal cycling)
•And show sharp NAD⁺ declines with age, often before symptoms appear.

The new mouse data suggest that many of the benefits seen from NAD⁺ precursors like NMN or NR, may not come from muscles, but actually from systemic or tissue-specific effects.

💬 Should I Still Take NAD⁺ Supplements?

If you’re < 40, metabolically healthy, and targeting general energy, you may not need them at all. Our body has a built-in NAD⁺ factory—and you can boost it naturally and effectively.

🧩 NAMPT, the NAD⁺-making enzyme, is activated by stressors like HIIT, fasting, cold showers, and sauna—and most tissues (especially muscle and liver) respond well. While these “pulses” are short-lived (4–12 hours) but if stack with repetition, we can create a meaningful long-term NAD⁺ boost.

💪 Action of the Week: Smart Habits for Building NAD+ naturally

These 4 accessible habits boost your body’s own NAD⁺—by raising NAMPT (your NAD⁺-recycling enzyme) and reducing CD38 (your NAD⁺-draining enzyme). Together, they increase NAD⁺ where it matters most: your brain, immune cells, liver, and more.

⏰ 1. Time-Restricted Eating 16:8

✅ Eat all meals within an 8-hour window (e.g., 9-5pm, or 12-8pm)
✅ Fast for the remaining 16 hours (water, black coffee, tea allowed)

Fasting activates AMPK, which boosts NAMPT in liver and adipose tissue and improving the ability to recycle NAD⁺ precursors.

🏃‍♀️ 2. HIIT or Endurance Training (3×/week)

Try this a simple HIIT protocol (~30 min):

1. Warm up: 5 minutes easy pace
2. 4 × 4 min intense intervals (e.g., running/cycling at 80–90% effort)
3. 3 min recovery (light pace) between each set
4. Cool down: 5 min

Exercise stimulates NAMPT in skeletal muscle and immune cells. Fasted HIIT in particular increases NAD⁺ by up to 30–40% in PBMCs (immune cells) and doubles NAMPT expression in muscle.

🥗 3. Daily Flavonoid Shot

Add 1 heaping Tbsp capers + 1 tsp dried parsley to any meal (salad, eggs, soups, etc.) Capers and parsley contain quercetin (~120mg) and apigenin (~45 mg), which are natural polyphenols that inhibit CD38, the main enzyme that degrades NAD⁺ with age. This reduces “leakage” and lets your NAD⁺ levels rise more effectively.

🧊🔥 4. Cold or Heat Exposure

Contrast Shower: 🚿 2 min cold (12–16 °C) → 5 min warm → repeat × 2

These “thermal stressors” trigger mitochondrial stress responses and up-regulate SIRT1, NAMPT, and other NAD⁺-related pathways. Cold increases brown fat activation and circulating nicotinamide. Heat activates repair enzymes and antioxidant genes.

If you're already using low dose NMN (250–500 mg/day) to support brain clarity, fertility, immunity, or recovery, the coolest part is: these habits make your supplement work better—by boosting NAD⁺ recycling and slowing its breakdown, so you get more “biological mileage” from every milligram.✈️

❓Ask Me Anything✨

Q: "Should I stop drinking protein shakes if PAA comes from phenylalanine?"- Maria asked after last week’s newsletter on phenylacetic acid (PAA).

A: Great question, Maria! There is no need to ditch your protein shake yet—phenylalanine itself isn’t the problem. The issue is when too much of it reaches the colon, where “bad” bacteria convert the excess into PAA. So pair your protein shake with fiber-rich ingredients like berries, oats, or chia seeds. This helps your small intestine absorb phenylalanine earlier, before it reaches your colon and becomes fuel for PAA-producing bacteria. So you can keep your shake, just blend it wisely! 🥣🧾

Disclaimer:

All contents are educational; not medical advice. Please discuss lifestyle changes with healthcare professional.

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Originally published on Longevity Newsletter