Sirtuins: What They Do and How to Support Them After 45

Sirtuins are a family of seven enzymes (SIRT1 to SIRT7) that help your cells manage energy, repair DNA and respond to stress. They need a molecule called NAD+ to work. The headlines often say a pill can switch them on. The human evidence is more mixed, and that is good news in one way: the habits and testing that make a real difference are within your reach.

This guide explains what sirtuins do, what raises or lowers their activity, which supplements have human data behind them, and how to find out whether this is even an issue for you.

TL;DR

• Humans have seven sirtuins. They are NAD±dependent enzymes that act as metabolic sensors, helping regulate DNA repair, inflammation and energy use.
• Resveratrol, often sold as a “sirtuin activator,” did not significantly change SIRT1 in a meta-analysis of 11 randomized trials.
• NAD+ precursors such as nicotinamide riboside reliably raise NAD+ in blood, but benefits for healthspan outcomes are still inconsistent.
• Exercise and weight loss (when metabolic health is off) have better-supported effects on SIRT1 than most capsules.
• Testing your own baseline beats guessing. That is where we start with our members.

What sirtuins are and what they do

Mammals have seven sirtuins, SIRT1 to SIRT7, and they are involved in cell growth, energy metabolism, stress resistance, inflammation, circadian rhythms, neuronal function and aging. Think of them as the maintenance crew of the cell. They remove small chemical tags (acetyl groups) from proteins, which changes how those proteins behave. Each removal burns one NAD+ molecule.

That last detail is the heart of the story. Sirtuins consume NAD+, alongside two other groups of NAD±using enzymes (PARPs and cADPRs). When NAD+ is plentiful and the cell is under the right kind of demand, sirtuins have what they need. If you want the full background on the fuel itself, our guide to NAD and its role in cellular energy goes deeper.

The seven sirtuins at a glance

You do not need to memorize them, but a few are worth knowing by name:

• SIRT1: the best studied. It links energy status to gene activity and is the one most supplement marketing refers to.
• SIRT6 and SIRT7: involved in DNA repair and chromatin. SIRT7 is the least studied of the family, though it has been connected with DNA damage repair and with age-related processes.
• SIRT2 to SIRT5: different jobs in different parts of the cell, from metabolism to stress response.

Researchers sometimes call SIRT1 the “metabolic sensor” of the group. As experts note, sirtuins help regulate cellular homeostasis, and they need both fuel (NAD+) and the right triggers to function well.

Why people over 45 hear so much about them

Sirtuins became famous because they are linked to lifespan in lab organisms. That is real science, but it is not the same as a proven human anti-aging switch. Leading researchers stress that we are still early in human longevity research, and that there is a wide gap between impressive rodent results and the mixed, often null, outcomes in human trials.

That does not make sirtuins irrelevant. It means the practical question changes from “which pill activates them?” to “what does my body actually need, and how do I give it the right signals?”

What increases SIRT1 in humans

This is the question most readers type next. Here is what the human data supports, from strongest to more tentative.

Exercise

A systematic review and meta-analysis of the SIRT1 response to exercise found that a single bout of high-intensity or fasted exercise increases skeletal muscle SIRT1 gene expression, while repeated resistance training alone increases blood SIRT1 levels. The authors conclude that exercise raises muscle SIRT1 expression acutely and blood SIRT1 enzyme levels over time.

The mechanism makes sense. Hard muscle work raises energy demand, which nudges the cell toward making more ATP and NAD+, the fuel sirtuins use.

Practical takeaways:

1. Keep strength training in your week. It is the form with the clearest blood-level signal.
2. Add some higher-intensity intervals if your doctor says your heart is ready for them.
3. Do not overdo fasted training. Talk with your clinician first if you take medication for blood sugar or blood pressure.

Weight loss, when metabolic health is off

A 2024 meta-analysis of randomized trials found that weight loss interventions significantly raised SIRT1 in people with metabolic disorders (a weighted mean difference of 1.2 ng/mL), while no significant effect showed up in healthy individuals.

That pattern appears again and again: sirtuin changes are more pronounced when there is metabolic stress to correct. If your numbers are already excellent, there may be little room to move.

Context matters, even with inflammation

It is tempting to treat high SIRT1 as “good” and low as “bad.” A 2024 systematic review and meta-analysis examined SIRT1 levels during inflammatory states, and the picture is more nuanced than the common belief that SIRT1 is simply anti-inflammatory. Biomarkers like this respond to your particular health state, which is why interpreting them alongside other labs matters.

What inhibits sirtuins

The cleanest way to lower sirtuin function is to starve them of NAD+ or compete for it. Other NAD±consuming enzymes draw from the same pool, and when the cycle is slow, less is recycled. The salvage pathway converts nicotinamide back into NMN and on to NAD+, so that recycling step matters.

Researchers are also developing sirtuin activators and inhibitors as drug candidates, which tells you the biology is active but not yet something to self-manage with a capsule. In daily life, the practical drags on your NAD+ economy are the ones you probably suspect: a sedentary routine, poor sleep and ongoing metabolic strain. We cannot claim a specific supplement or habit “blocks” sirtuins in people, because the research above does not establish that.

Supplements: what the human evidence shows

Resveratrol: the disappointing headline

The 2024 to 2025 review pooled 11 randomized controlled trials and found no significant impact on SIRT1 gene expression (SMD = 0.05) or serum levels (MD = -0.04). Some subgroup analyses hinted at benefits in specific conditions, but the data does not support resveratrol as a universal sirtuin activator.

NAD+ precursors: real effect on NAD+, uncertain effect on you

In the research we reviewed, daily oral NR at 100, 300 and 1,000 mg raised whole blood NAD+ by 22%, 51% and 142% within two weeks. That is a solid biochemical result. The harder question is whether a higher NAD+ number translates into better strength, energy or healthspan. A PRISMA-guided systematic review of NAD+ supplementation and the Nature Metabolism review both point to evidence that is still developing, with safety looking good and efficacy results varying.

If you want to compare options, see our guides on nicotinamide mononucleotide for adults 45+ and the best evidence-based supplements for longevity after 40.

NR versus NMN in the US

The regulatory picture affects what you can buy. According to the Food Frontiers review, NR has GRAS status for food use and is widely sold as a supplement, while the FDA has restricted NMN as a dietary supplement because it is being investigated as a drug. That can influence quality, availability and cost. Choose professional-grade products with third-party quality standards, and check with your clinician before starting anything, especially if you take prescription medication or have a health condition.

A fair look at non-supplement tools

Supplements are only one of several levers people try for cellular energy. Others include light-based and recovery therapies. We have not seen strong human sirtuin data for them, so treat them as complements to training, sleep and nutrition rather than substitutes. If you are curious about one example, this overview of photobiomodulation benefits and dosage explains how red light sessions are typically used.

Our perspective: test first, then decide

At Healthspan Holistic we work with adults between 45 and 75 who are tired of guessing. We see the same pattern often: someone reads that sirtuins hold the secret to aging, buys a bottle of something, and feels nothing. The problem is rarely effort. It is that nobody checked where they started.

The research points the same way. Sirtuin responses are strongest where there is metabolic stress or a low baseline, and weakest in people who are already well. A sensible plan starts with data: inflammation, metabolic markers, nutrient status and, where it fits, NAD+. From there, a coach and a practitioner can match training, food and supplements to what your own labs show, then retest to see whether anything moved.

We also believe in honest expectations. NAD+ precursors are well tolerated and may help some people, but they are not a magic bullet. Exercise, sleep, protein, and a calm stress load are the foundation that gives any supplement something to work with.

— Chris

Which labs help you act on sirtuin science

Sirtuin enzymes themselves are not a routine blood test, so we look at the picture around them. These are the tests our members most often start with, at the published prices:

• NAD Lab Test: measures your NAD+ levels, the fuel sirtuins depend on.
• Inflammation Panel, $272.97: useful because SIRT1 behavior shifts with inflammatory state.
• Metabolic Panel, $257.27: shows the metabolic strain that predicts who responds most to lifestyle changes.
• Vitamin D, 25-Hydroxy Test, $154.97: a simple nutrient baseline many adults over 45 have never checked.

You can browse all of them on our blood work and labs page. For background on why we lean on testing, read why test your blood and our overview of functional lab tests. If genetics interest you, see genetic testing for longevity.

Start with your own numbers

Ready to stop guessing? Pick a panel, review the results with a coach, and build a plan that fits your body. Our lab testing and health coaching services are built for exactly this.

1st Time Customers can take advantage of our BUY 1 GET 1 50% OFF special offer on all supplements.

A practical sirtuin-friendly plan

Here is a simple sequence you can begin this week.

1. Get a baseline. Test inflammation, metabolic markers, vitamin D and NAD+ so you know your starting point.
2. Train for it. Two to three strength sessions weekly, plus one or two higher-intensity efforts if your clinician agrees.
3. Eat for metabolic health. Protein at every meal, plenty of colorful plants, and fewer refined carbs. Our piece on how nutrition transforms aging has ideas.
4. Protect sleep and circadian rhythm. Regular wake times and morning light support the whole system.
5. Consider a targeted supplement, not a stack. If labs and your clinician support it, add one thing at a time.
6. Retest in a few months. Keep what moved your numbers and drop what did not.

For a wider view, our guide to proven ways to improve longevity and healthspan puts these steps in context.

FAQ

What do sirtuins do?

Sirtuins are NAD±dependent enzymes that modify proteins to help cells manage energy, repair DNA, control inflammation and respond to stress. Humans have seven of them, SIRT1 to SIRT7. They are often described as metabolic sensors because their activity follows the cell’s energy state.

What increases SIRT1?

The best human evidence is for exercise: a meta-analysis found acute increases in muscle SIRT1 expression and higher blood SIRT1 with repeated resistance training. Weight loss raises SIRT1 in people with metabolic disorders but not in healthy people. Supplements like resveratrol have not shown a consistent effect.

What inhibits sirtuins?

Sirtuins slow down when NAD+ is scarce or when other NAD±consuming enzymes compete for it. Researchers are also designing drug-like inhibitors in the lab. We cannot point to a proven everyday food or habit that directly inhibits sirtuins in people, so focus on protecting NAD+ through activity, sleep and metabolic health.

Is NMN or NR better for supporting sirtuins?

Both raise NAD+, and neither has proven it improves healthspan outcomes. In the US, NR has GRAS status and is widely available, while NMN has been restricted as a supplement by the FDA. Talk with your clinician about which, if either, fits your situation.

Sources

• Impact of resveratrol supplementation on human Sirtuin 1: systematic review and meta-analysis
• The effect of weight loss therapies on sirtuin 1 regulation (BMC Nutrition)
• An updated review on NMN and NR (Food Frontiers)
• NAD+ precursor supplementation in human ageing (Nature Metabolism)
• Dietary supplementation with NAD±boosting compounds in humans (Journals of Gerontology)
• The relationship between SIRT1 and inflammation (Frontiers in Immunology)
• SIRT7 in the aging process
• A systematic review and meta-analysis of the SIRT1 response to exercise
• Current trends in sirtuin activator and inhibitor development
• NAD+ supplementation for anti-aging and wellness: a PRISMA-guided systematic review
• Nicotinamide riboside and pterostilbene on muscle regeneration in elderly humans (ClinicalTrials.gov)

This article was produced with AI assistance and reviewed for accuracy. It is provided for general information only and is not professional advice.