Hormone therapy replaces declining hormones. NMN restores the cellular conditions that these hormones depend on. The two do not compete with one another. Here, you will learn what each of them achieves, where each reaches its limit, and why the most comprehensive approach addresses both levels at the same time.
The discussion surrounding hormone replacement therapy has changed fundamentally over the last five years.
For two decades after the Women's Health Initiative published its results in 2002, hormone therapy was prescribed only with extreme caution or refused altogether. This was based on findings that later proved to be exaggerated, were applied to groups for which the study was never designed, and were broadly misunderstood.
The result was a generation of women who suffered through perimenopause and menopause without adequate support. Who were denied a measure that would have significantly improved quality of life and long-term health for many. And who internalized the idea that struggling through this phase is simply part of being a woman.
This narrative is currently changing. Dr. Mary Claire Haver, Dr. Vonda Wright, and the growing number of menopause specialists who appeared on Huberman Lab and The Diary of a CEO in 2024 and 2025 are among the most prominent voices explaining: When prescribed correctly and at the right time, hormone therapy is not only safe for most women; it is among the most protective measures available for cardiovascular health, bone density, mental performance, and longevity.
In the United States, only 4% of eligible women use an approved hormone therapy. This gap between those who should have access and those who do is one of the greatest failings in women's health.
None of this makes NMN irrelevant to this topic. Rather, it means that hormone therapy and NMN address different levels of the same biological reality. And clearly understanding these levels is what enables a woman to make the most informed decisions about her own health.
Hormone therapy and NMN are not competing measures. They act on different levels of the same biology. Understanding both changes what is possible.
What hormone therapy really achieves
Hormone replacement therapy replaces the estrogen—and usually also the progesterone—that the ovaries produce in only declining amounts during perimenopause and stop producing entirely starting with menopause.
Estrogen has receptors throughout the body: in the brain, heart, bones, skin, gut, bladder, and musculature. Its decline therefore affects all these systems simultaneously.
Hot flashes, sleep disturbances, cognitive changes, mood swings, accelerated bone loss, increased cardiovascular risk, urogenital discomfort, as well as the metabolic changes that drive weight gain and insulin resistance—all of this is in part a consequence of estrogen withdrawal.
Hormone therapy replenishes estrogen to the point where the tissues that depend on it maintain their function.
If started early—ideally within ten years of menopause or before the age of 60, the window with the best data for cardiovascular benefit—it does not just manage symptoms. It protects.
Dr. Haver has stated multiple times that starting within this window is associated in some studies with a 50% reduction in the risk of cardiovascular disease and overall mortality.
Estrogen works better as a preventative than as a cure. The longer a woman's body has to go without estrogen, the higher the cumulative risk for the diseases that its absence accelerates. This is the case for hormone therapy that the medical community failed to communicate sufficiently for twenty years.
The later a woman enters menopause, the healthier she is regarding cardiometabolic diseases. It is the loss of estrogen that accelerates our path toward these diseases. The longer your body goes without estrogen, the higher the risk factor.
- Dr. Mary Claire Haver, MD
What hormone therapy cannot achieve
Hormone therapy replaces hormones. It does not restore the cellular energy environment in which hormonal processes occur.
For estrogen signals to work, cells need the metabolic capacity to respond to them. Progesterone production depends on an enzyme that requires NAD⁺ as a cofactor. The mitochondria that power hormone-sensitive cells need NAD⁺ to produce energy efficiently. And the DNA repair mechanisms that maintain the integrity of hormone-sensitive tissues need NAD⁺ for activation.
None of these processes are restored simply by adding more hormone. They depend on the cellular energy system that carries NAD⁺, and this system has declined in parallel with the hormonal changes of perimenopause.
This explains why some women continue to experience symptoms under hormone therapy that do not resolve completely with hormonal support alone: the persistent fatigue, the brain fog, the sleep that is not restorative despite stable hormone levels.
In these cases, the cellular energy level of the problem has remained untouched. The hormone signal is there, but the ability of the cells to respond efficiently to it is limited by the NAD⁺ decline that hormone therapy does not reach.
This is not a failure of hormone therapy. It merely shows that hormonal and cellular health are two independent levels of the same system, and that restoring one does not automatically restore the other.
The interaction between NAD⁺ and estrogen
The relationship between NAD⁺ and estrogen is not just that both decline in parallel. There is a direct biological interaction.
Estrogen influences NAD⁺ formation via its effect on NAMPT—the enzyme that constitutes the rate-limiting step of NAD⁺ production in most tissues. If estrogen drops, NAMPT activity drops, and NAD⁺ production is further impaired, in addition to the age-related decline.
This means that estrogen loss accelerates the NAD⁺ decline. And the NAD⁺ decline, in turn, weakens the cellular environment in which hormonal signals operate. Both processes reinforce each other, and their combined effect is more severe than either on its own.
Therefore, a hormone therapy that restores estrogen could partially support NAD⁺ production by restoring the NAMPT signaling influenced by estrogen. And NMN, which directly boosts NAD⁺, could improve cellular responsiveness to estrogen by restoring the mitochondrial and enzymatic function of hormone-sensitive cells.
The two measures could thus reinforce one another instead of just acting independently. This is part of the scientific reasoning for why women on hormone therapy who additionally restore NAD⁺ may experience improvements that hormone therapy alone did not fully provide.
Estrogen supports NAD⁺ production. NAD⁺ supports the cellular response to estrogen. Restoring both is more complete than doing only one of the two.
What the perimenopause window specifically demands
Perimenopause can begin as early as 35. Menopause occurs on average between 51 and 52 years of age.
In the decade or more that spans this transition, estrogen and NAD⁺ decline simultaneously. The hormonal situation becomes unstable, and the cellular energy system that supports hormonal function becomes increasingly exhausted. In this window, both levels of the problem build up, and both deserve attention.
Many women in early perimenopause are not yet eligible for hormone therapy. Their cycle may still exist, their symptoms may not yet reach the threshold for prescription, or their doctor may not have recognized the perimenopausal transition at all—which happens regularly because this phase is so poorly recognized in primary care.
For these women, restoring NAD⁺ is something they can address independently of any medical intervention, supporting the cellular environment in the years before hormonal treatment becomes the primary tool.
For women who are candidates for hormone therapy, NMN is not a replacement. It is a supplement that addresses precisely the level that hormone therapy does not reach.
An honest assessment of NMN and hormone therapy combined
Clinical studies investigating the combination of hormone therapy and NMN do not yet exist.
What does exist: the mechanistic evidence linking NAD⁺ to the cellular processes upon which hormonal function depends. The human studies on NMN, which show measurable improvements in metabolic and cellular function specifically in postmenopausal women. And the biological rationale for why it yields more complete results to restore both the hormone signal and the cellular capacity to respond.
The combination is biologically sound. The direct clinical evidence for it is still being built.
Equally true: NMN is not a replacement for hormone therapy where it is medically indicated. Women with significant perimenopausal or menopausal symptoms have the right to have a full conversation about hormonal support with a doctor who knows the current state of the data—and not to be turned away with references to the 2002 WHI study, which misled a whole generation of practitioners and patients.
The fact that currently only 4% of eligible women use hormone therapy says nothing about how many it could help. It says something about how poorly this conversation has been conducted for twenty years and how slowly the correction is reaching the women who need it.
If estrogen were carcinogenic, pregnant women, whose estrogen levels rise massively, would have to have higher rates of breast cancer. The longer your body is exposed to estrogen in some form, the better your scores on cognitive tests. Estrogen works better as a preventative than as a cure.
- Dr. Mary Claire Haver, MD
What women without hormone therapy should know
For women not on hormone therapy—whether because they have not yet reached the perimenopausal window, because there are contraindications, because their doctor never held the conversation, or because they consciously decided against it—the following applies: NMN does not replace the hormonal support that hormone therapy provides.
What it does provide is support for the cellular energy environment upon which hormonal function depends. And this environment deteriorates regardless of hormone status. It therefore benefits from being addressed independently.
The enzyme that produces progesterone requires NAD⁺ as a cofactor. Supporting this enzymatic process via the restoration of NAD⁺ improves the efficiency of progesterone production that is still possible with the body's current hormonal capacity.
And the cellular energy systems that supply estrogen-sensitive tissue throughout the body—brain, cardiovascular system, bones, skin—benefit from restored NAD⁺, regardless of whether estrogen is supplied from the outside.
This is no replacement for what hormone therapy achieves. It is support for the cellular level underneath. And that support counts, whether hormone therapy is part of the picture or not.
Hormone therapy is one of the most underutilized, effective, and misunderstood measures in women's health. NMN addresses a different level of the same biological problem.
Neither replaces the other, and neither makes the other superfluous. Dealing completely with the hormonal and cellular changes of the perimenopausal transition addresses both: the hormone signal and the cellular capacity to receive it.
This is not a complicated formula. It just requires understanding what each level of the problem actually consists of before deciding how to approach it.
Sources
- Haver, M. C. (2024, June 3). How to navigate menopause and perimenopause for maximum health and vitality. Huberman Lab Podcast. https://www.hubermanlab.com/episode/dr-mary-claire-haver-how-to-navigate-menopause-perimenopause-for-maximum-health-vitality
- Haver, M. C., Wright, V., Sims, S., & Crawford, N. (2025, October 16). Hormone & fertility experts: We've been lied to about women's health. The Diary of a CEO with Steven Bartlett.
- Yoshino, M., Yoshino, J., Kayser, B. D., et al. (2021). Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science, 372(6547), 1224–1229. https://doi.org/10.1126/science.abe9985
- Covarrubias, A. J., Perrone, R., Grozio, A., & Verdin, E. (2021). NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology, 22(2), 119–141. https://doi.org/10.1038/s41580-020-00313-x
- Cherradi, N., Defaye, G., & Chambaz, E. M. (2014). Mitochondrial 3β-hydroxysteroid dehydrogenase and NAD+ cofactor dependence. Journal of Biological Chemistry. https://doi.org/10.1074/jbc.M111.292490
- Imai, S. I., & Guarente, L. (2014). NAD+ and sirtuins in aging and disease. Trends in Cell Biology, 24(8), 464–471. https://doi.org/10.1016/j.tcb.2014.04.002
- McKinsey Health Institute & World Economic Forum. (2024). Closing the women's health gap: A $1 trillion opportunity. https://www.mckinsey.com/mhi/our-insights/closing-the-womens-health-gap-a-1-trillion-dollar-opportunity-to-improve-lives-and-economies
Red light therapy vs. NMN: same goal, different paths
Red light therapy and NMN are among the most discussed approaches in the longevity and biohacking space. Both target the mitochondria. Both are backed by serious science. Here, you will learn what each of them actually achieves, where they stop, and why this difference is important for application.
Red light panels have become a fixed part of the biohacking debate. Influencers stand in front of them every morning. Clinics offer sessions at premium prices. The devices themselves cost between several hundred and several thousand euros, and the marketing behind them promises far more than the research currently provides.
That does not mean they do not work. The science behind photobiomodulation—the clinical term for what red light therapy does—is real, the mechanisms are documented, and the therapeutic applications are increasing.
But the question one should ask before making a major purchase for a panel or a supplement is not simply whether it works. Rather: exactly what it acts upon, and whether that is the problem you actually have.
Red light therapy and NMN meet in a common goal: the mitochondria. Both improve mitochondrial function, both have documented effects on cellular energy production, and both are backed by research that goes beyond marketing.
But they reach the mitochondria through different paths, affect different aspects of cell function, and differ greatly in what they address beyond the mitochondria themselves. Understanding this difference determines whether you are spending your money strategically or redundantly.
Red light therapy and NMN both improve mitochondrial function. One acts from the outside in via a specific wavelength of light. The other from the inside out via the restoration of NAD⁺. That is not the same path to the same destination.
What red light therapy really does
Red light therapy, professionally called photobiomodulation, works with specific wavelengths of red and near-infrared light, typically between 630 and 850 nanometers.
In this range, light penetrates the skin and is absorbed by a protein in the mitochondrial respiratory chain: cytochrome c oxidase. It is the final enzyme in the process by which mitochondria extract ATP from oxygen.
If cytochrome c oxidase absorbs red and near-infrared light, it becomes more active. The mitochondria to which it belongs produce ATP more efficiently. The cells that depend on them work better. And the surrounding tissue recovers faster, regenerates more actively, and is less susceptible to inflammation.
Documented effects include accelerated wound healing, reduced inflammation in the treated tissue, better skin quality, fewer joint pains, and, in some protocols, improved hair follicle activity.
There are also initial indications of cognitive and mood-related effects from near-infrared light on the head, as well as systemic effects from full-body panels that go beyond the directly treated tissue. The research is real, the mechanisms are biologically plausible, and the fields of application continue to grow.
What red light therapy cannot do
The biggest limitation lies in the penetration depth and the reach within the body.
Red light penetrates about 5 to 10 millimeters into the tissue. Near-infrared light reaches deeper, possibly a few centimeters. But the further light travels through tissue, the more it scatters, and the lower the dose that reaches the target.
Surface-level tissues therefore receive effective photobiomodulation: skin, superficial musculature, joints close to the surface. The liver, the brain, the cardiovascular system, the ovaries, the uterus, the deep musculature responsible for systemic energy metabolism—these areas are not reliably reached by devices for home use at typical doses and application times.
Red light therapy also does not restore NAD⁺ levels. It does not address the NAD⁺ decline that drives mitochondrial dysfunction throughout the body. It stimulates the mitochondria in the treated tissue via an optical mechanism. However, it does not replenish the coenzyme that the mitochondria in all other tissues—brain, heart, liver, endocrine system—need for efficient oxidative phosphorylation.
A red light panel can improve facial skin, dampen knee inflammation, and possibly stimulate hair follicles on the scalp. It cannot restore the cellular energy environment behind persistent exhaustion, increasingly difficult cycles, non-restorative sleep, and cognitive decline—that is, behind the systemic manifestations of NAD⁺ decline.
NAD⁺ is the most important molecule in human biology that most people have never heard of. Its decline explains a remarkable part of what we call aging, and restoring it via NMN is the most direct approach available.
What NMN does that red light therapy cannot
NMN restores NAD⁺ throughout the entire body: in every cell, every tissue, and every organ that lacks the molecule needed to drive mitochondrial energy production.
It is taken orally, enters the bloodstream within minutes, reaches cells via the Slc12a8 transporter, and is converted into NAD⁺ exactly where it is needed most.
The brain, heart, liver, muscles, endocrine system, immune system, and DNA repair mechanisms all benefit from restored NAD⁺ in a way that superficial light treatment cannot achieve.
Exhaustion that does not resolve with sleep is a systemic cellular energy problem. Sleep that is not restorative is a problem of the internal clock and therefore dependent on NAD⁺. A more difficult luteal phase is a problem involving an NAD⁺-dependent hormonal enzyme. These are not problems that red light on the body's surface addresses.
NMN also activates sirtuins, the family of proteins that regulate DNA repair, inflammation, metabolic function, and the pace of cellular aging.
Sirtuin activation is a systemic longevity mechanism that extends far beyond any tissue that red light can reach. And it is the reason why NMN is relevant not just to how you feel this month, but to the trajectory of your aging over the next decade.
Red light therapy does not activate sirtuins. It does not address the epigenetic shifts, genomic instability, mitochondrial dysfunction, and cellular aging that accumulate with NAD⁺ decline and form the biological basis of aging at the cellular level.
The problem with access and consistency
Red light therapy requires equipment, time, and a regularity that is difficult for most people to maintain.
A clinical-grade panel costs between several hundred and several thousand euros. It requires daily or near-daily sessions of ten to twenty minutes, with appropriate distance and sufficient coverage to achieve relevant effects.
Studies with the strongest effects usually work with controlled protocols that are difficult to replicate with home devices. And when the sessions end, the effects end. There is no systemic build-up over time here, as created by the gradual NAD⁺ restoration through consistent NMN intake.
According to what the science shows, the benefits of daily NMN intake build up over weeks and months through the progressive restoration of NAD⁺ levels. Cellular improvements accumulate as the energy environment throughout the body improves.
Sleep quality, hormonal function, mental clarity, and metabolic efficiency improve gradually and remain improved as long as intake continues. The daily effort is minimal: powder in water, taken in the morning. The systemic benefit is continuous.
Red light therapy acts on what it reaches. NMN can act on everything. This is not a criticism of red light therapy. It is an accurate description of where both start.
Is there a case for using both?
The honest answer is: yes, for specific applications.
Red light therapy has documented effects on skin quality, wound healing, joint pain, and hair follicle activity that NMN does not generate via the same mechanism and with the same local precision.
If skin quality and hair growth are the primary goals, a well-planned red light protocol for the scalp and face combined with NMN addresses both: the local tissue stimulus and the systemic cellular conditions that determine how well the tissue responds to that stimulus. For these goals, the combination is more complete than either measure alone.
For the bigger picture of systemic energy, hormonal health, sleep, mental performance, and metabolism—that is, for the entire symptom profile of NAD⁺ decline in one's 30s and 40s—NMN is the more relevant primary measure. Red light therapy is then a supplementary tool for specific tissues, not the solution to the core problem.
The research base on the systemic effects of NMN fits the symptoms most women in this age group experience more directly than the research base on what home red light devices achieve systemically.
The cost-benefit question
A clinical-grade red light panel is a significant investment with a noticeable time commitment and a benefit that acts primarily locally and ends with the application.
NMN is a daily supplement with systemic benefits that build up over time and address the cellular mechanisms behind the most important health changes of midlife.
For a woman who has to choose between the two on a limited budget, the question is clear: which of these addresses the problem you actually have?
Persistent exhaustion, poor sleep, worsening hormonal issues, declining mental performance, and a resistant metabolism are NAD⁺ issues. They are not problems that red light therapy was designed to solve. And panel marketing, which has raced well ahead of the evidence for systemic effects, should not obscure this difference.
Red light therapy is a serious measure with real science behind its local, tissue-specific effects. NMN is a serious measure with real science behind its systemic cellular effects.
Both reach the same goal, the mitochondria, from different directions, at different depths, and with different consequences. Which direction your problem needs to be addressed from is the only question that matters when you decide what belongs in your routine, what fits your budget, and what you need first.
Sources
- Hamblin, M. R. (2016). Shining light on the head: Photobiomodulation for brain disorders. BBA Clinical, 6, 113–124. https://doi.org/10.1016/j.bbacli.2016.09.002
- Covarrubias, A. J., Perrone, R., Grozio, A., & Verdin, E. (2021). NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology, 22(2), 119–141. https://doi.org/10.1038/s41580-020-00313-x
- Grozio, A., Mills, K. F., Yoshino, J., et al. (2019). Slc12a8 is a nicotinamide mononucleotide transporter. Nature Metabolism, 1(1), 47–57. https://doi.org/10.1038/s42255-018-0009-4
- Yoshino, M., Yoshino, J., Kayser, B. D., et al. (2021). Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science, 372(6547), 1224–1229. https://doi.org/10.1126/science.abe9985
- Imai, S. I., & Guarente, L. (2014). NAD+ and sirtuins in aging and disease. Trends in Cell Biology, 24(8), 464–471. https://doi.org/10.1016/j.tcb.2014.04.002
- Kim, M., Seol, J., Sato, T., et al. (2022). Effect of 12-week intake of NMN on sleep quality, fatigue, and physical performance. Nutrients, 14(4), 755. https://doi.org/10.3390/nu14040755
- Massudi, H., Grant, R., Braidy, N., et al. (2012). Age-associated changes in oxidative stress and NAD+ metabolism in human tissue. PLOS ONE, 7(7), e42357. https://doi.org/10.1371/journal.pone.0042357