5 Supplements Experts Can’t Agree On (And What I Do)

Mike HartnettEvidence-Based

7+ years researching longevity protocols. Runs a 20+ supplement daily stack. Built CoreStacks after losing his father to heart disease.

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Longevity experts agree on omega-3, vitamin D, magnesium, and creatine. They disagree on almost everything else. I’ve spent 7 years following Huberman, Attia, Sinclair, Johnson, and Stanfield — and on these 5 supplements, they flat-out contradict each other. One expert’s daily staple is another’s waste of money. Here’s where each expert stands and what I actually do with my own money.

1. NMN — The Biggest Divide

No supplement splits the longevity community more cleanly than NMN (nicotinamide mononucleotide). The battle lines are drawn and nobody’s budging.

Who takes it: Andrew Huberman includes NMN in his supplement stack at doses around 500mg-1g. David Sinclair has taken 1g daily for years and built much of his research career around the NAD+ pathway that NMN feeds. Bryan Johnson includes it in his Blueprint protocol.

Who skips it: Peter Attia has been publicly skeptical, arguing the human clinical evidence doesn’t justify the cost. Brad Stanfield has expressed caution, noting the gap between promising animal data and limited human trials.

What I do: I take 500mg of NMN daily. The mechanistic case — NAD+ declines with age, NMN restores it, NAD+ drives hundreds of cellular repair processes — is strong enough for me to place this bet at $50-80/month. I’ve written a full breakdown of why I side with Huberman over Attia on NMN, including what the research actually shows.

The core disagreement isn’t really about biology. Everyone agrees NAD+ declines with age and that NMN raises blood NAD+ levels. The fight is about what standard of evidence you require before spending money. Attia wants randomized controlled trials with clinical outcomes. Huberman and Sinclair accept mechanistic evidence plus surrogate markers. Neither position is unreasonable.

2. Resveratrol — Sinclair’s Flagship, Everyone Else’s Skip

Resveratrol was the original longevity supplement hype molecule, and David Sinclair was the man who launched it. His early research on sirtuins and resveratrol’s ability to activate them generated massive public interest. He takes 1g daily, mixed into yogurt for fat-soluble absorption.

Who takes it: Sinclair (1g/day). Johnson includes it in Blueprint.

Who skips it: Huberman doesn’t include it in his regular stack. Attia has expressed skepticism. Stanfield has reviewed the evidence and doesn’t take it. Rhonda Patrick has discussed resveratrol’s limitations, particularly its poor bioavailability.

What I do: I dropped resveratrol after taking it for several months. Zero noticeable difference in energy, sleep, or any biomarker I track. The clinical evidence in humans is underwhelming — most of the excitement comes from cell culture and animal studies. At $30-50/month for quality resveratrol, I reallocated that money toward supplements I could actually feel working.

The bioavailability problem is real. Oral resveratrol gets metabolized rapidly by the liver. How much actually reaches your tissues in active form is debatable. Sinclair addresses this by taking it with fat (yogurt), which may help absorption, but the fundamental pharmacokinetic challenge remains.

If you’re still considering it, I covered Sinclair’s full protocol and why resveratrol is central to his approach. My honest take: his personal conviction outpaces the published evidence for most people.

3. Ashwagandha — Huberman’s Sometimes, Attia’s Never

Ashwagandha (KSM-66 extract) is an adaptogen that’s gained popularity for cortisol reduction and stress management. It sits in a weird space — too mainstream for longevity purists, too “alternative” for evidence-based minimalists.

Who mentions it positively: Huberman has discussed ashwagandha on the Huberman Lab podcast in the context of cortisol modulation and has mentioned taking it during high-stress periods. He typically references the KSM-66 extract specifically.

Who skips it: Attia doesn’t discuss ashwagandha as part of his protocol. Sinclair doesn’t include it. Stanfield has reviewed it and doesn’t take it regularly. Johnson doesn’t feature it prominently in Blueprint.

What I do: I don’t take ashwagandha. Two things pushed me away. First, the cycling requirement — most recommendations suggest taking it for 8-12 weeks, then cycling off. I prefer supplements I can take consistently without managing on-off schedules. Second, thyroid concerns. Some studies have shown ashwagandha can increase thyroid hormone levels, which is a problem if your thyroid function is already normal.

The cortisol reduction data is actually decent. Multiple human studies show KSM-66 lowers cortisol and self-reported stress. If chronic stress is your primary concern, it might be worth trying. But cortisol management through sleep, exercise, and stress reduction practices is free and more sustainable.

If you’re interested, a quality KSM-66 ashwagandha runs about $15-20/month. Not expensive, but I’d rather put that toward the consensus stack.

4. AG1 / Greens Powders — Johnson Yes, Everyone Else Quiet

AG1 (Athletic Greens) is the supplement that launched a thousand podcast sponsorships. At $79/month, it’s positioned as a comprehensive nutritional insurance policy — 75 vitamins, minerals, and whole-food ingredients in one scoop.

Who takes it: Johnson has included AG1 in his protocol. Huberman has had AG1 as a podcast sponsor, which muddies the waters between personal endorsement and paid promotion. Several other podcasters and influencers promote it.

Who skips it: Attia doesn’t take it or recommend it. Sinclair doesn’t include it. Stanfield has reviewed greens powders and found them overpriced relative to their evidence base. Rhonda Patrick focuses on targeted supplementation rather than all-in-one products.

What I do: I don’t take AG1 and never have. My reasoning is simple math. At $79/month, AG1 costs more than my entire 4-supplement consensus stack combined. The doses of individual ingredients in AG1 are often below what clinical studies used. You’re paying a premium for convenience and branding, not for optimal dosing.

For example, AG1 contains 100mg of magnesium. Most experts recommend 300-400mg of magnesium daily. AG1 contains some omega-3, but nowhere near the 2-3g of EPA/DHA that Huberman and Attia recommend. You’d still need standalone supplements to hit therapeutic doses.

If you want to see how AG1 compares to targeted supplementation, I reviewed the best AG1 alternatives. Spoiler: buying individual supplements at proper doses costs less and gives you better coverage.

5. Metformin for Non-Diabetics — Attia’s Famous U-Turn

This one isn’t technically a supplement — it’s a prescription diabetes medication. But the metformin-for-longevity debate has been one of the most public disagreements in the field, and Attia’s reversal made headlines.

Background: Metformin activates AMPK, mimics some effects of caloric restriction, and observational data suggested diabetics on metformin lived longer than non-diabetics. This generated enormous excitement about metformin as a longevity drug. The TAME trial (Targeting Aging with Metformin) was designed to test this directly.

The U-turn: Attia previously discussed metformin favorably for longevity in non-diabetics. He publicly reversed this position after data emerged showing metformin blunts exercise adaptations — specifically, it reduced the mitochondrial benefits of aerobic exercise and the hypertrophy response to strength training. Since Attia considers exercise the most powerful longevity intervention, anything that undermines exercise is a non-starter.

Who still takes it: Johnson includes metformin in Blueprint, though he skips it on exercise days (the same approach Sinclair uses). Sinclair has discussed taking metformin except on days he exercises.

What I do: I don’t take metformin. It’s prescription-only and not something I’d pursue without a physician’s direct guidance specifically for longevity purposes. The exercise-blunting data was enough to close the door for me. I exercise 5 days a week, and undermining those gains for a speculative longevity benefit doesn’t make sense.

The TAME trial results, when they arrive, may change the calculus. Until then, metformin for non-diabetics is a decision for people working closely with their doctors, not something to self-prescribe based on podcast discussions.

The Pattern: Start With Consensus, Then Decide

Looking across all five disagreements, a pattern emerges. The experts who disagree on NMN, resveratrol, ashwagandha, AG1, and metformin mostly agree on the basics: omega-3 fatty acids, vitamin D3+K2, magnesium, and creatine. Four supplements, about $40-50/month, with decades of clinical trial data behind them.

Everything else is a judgment call. I’ve mapped exactly where all six experts align and diverge in the full expert agreement breakdown. The Research Hub lets you compare every supplement across experts visually.

*Except on exercise days

My rule of thumb: cover the consensus four first. If you have budget left and specific health goals, add one or two speculative picks based on your own research and bloodwork. The Stack Quiz can help you figure out which extras might make sense for your situation.

For a deeper look at how I arrived at my current 8-supplement stack — including the ones I dropped and why — read about the supplement mistakes that taught me the most and the Johnson vs Attia comparison that shaped my philosophy.

If budget is your primary concern, I’ve worked out how to get the most value at every price point in my guide to what a longevity stack actually costs.

This content is for informational purposes only. Consult your healthcare provider before starting any supplement protocol.