Hormone Optimization for Longevity: What the Evidence Supports

Hormones regulate virtually every physiological process: from metabolism and body composition to mood, cognition, and immune function. Their decline with age is not a subtle process. Testosterone, growth hormone, DHEA, and thyroid hormones all follow predictable downward trajectories that correlate with the clinical features of aging.

The question for longevity medicine is whether restoring these hormones to youthful levels improves healthspan, and at what risk.

Testosterone

Testosterone levels in men decline approximately 1-2% per year after age 30. By age 60, many men have levels that would have been classified as hypogonadal at age 25. Women also produce testosterone (at lower levels) and experience age-related decline.

The evidence: A 2012 study in the Journal of Clinical Endocrinology & Metabolism followed over 800 male veterans and found that testosterone treatment in men with low testosterone was associated with reduced all-cause mortality compared to untreated men. Other studies show improvements in lean body mass, bone density, insulin sensitivity, and mood.

The nuance: Testosterone replacement therapy (TRT) is not without risk. It can affect hematocrit (red blood cell concentration), lipid profiles, and prostate health. The relationship between TRT and cardiovascular risk has been debated; some studies show benefit, others show neutral or mixed signals. Careful monitoring is essential.

Practical approach: Men with symptoms of low testosterone (fatigue, reduced libido, loss of muscle mass, cognitive fog) should have total and free testosterone, SHBG, and estradiol tested. Treatment decisions should be individualized based on symptoms, levels, and risk factors.

DHEA (Dehydroepiandrosterone)

DHEA is the most abundant steroid hormone in the human body and serves as a precursor to both testosterone and estrogen. DHEA levels peak in the mid-20s and decline by approximately 80% by age 75.

The evidence: A 2013 review in the Journal of Clinical Endocrinology & Metabolism examined DHEA replacement in aging men and women. Findings included modest improvements in bone mineral density, skin health, and sexual function in women. Effects in men were less consistent, likely because DHEA's primary downstream conversion is to testosterone, which can be addressed more directly.

Practical approach: DHEA supplementation (25-50 mg/day) is available over the counter and has a favorable safety profile at physiological replacement doses. However, because DHEA converts to sex hormones, monitoring estrogen and testosterone levels during supplementation is advisable.

Thyroid Hormones

Thyroid function affects metabolic rate, energy, body temperature, and cognitive function. Subclinical hypothyroidism (mildly elevated TSH with normal free T4) becomes increasingly common with age and is associated with fatigue, weight gain, and cognitive slowing.

The evidence: A 2017 individual participant data analysis published in JAMA Internal Medicine examined over 55,000 individuals and found that subclinical hypothyroidism was associated with increased risk of coronary heart disease events and mortality, particularly when TSH exceeded 10 mIU/L. The data for mild TSH elevations (4.5-10) was less clear-cut.

Practical approach: Comprehensive thyroid testing should include TSH, free T4, free T3, and thyroid antibodies. Isolated TSH measurement can miss patterns of poor T4-to-T3 conversion that produce symptoms despite "normal" labs. Treatment of subclinical hypothyroidism should be individualized based on symptoms, antibody status, and cardiovascular risk.

Growth Hormone and IGF-1

Growth hormone (GH) secretion declines approximately 14% per decade after age 30, a process termed somatopause. Low GH is associated with increased visceral fat, decreased lean mass, reduced bone density, and impaired recovery.

While synthetic GH injection can reverse these changes, concerns about cancer risk (IGF-1 is a growth factor) and cardiovascular safety have limited its adoption for anti-aging purposes. Growth hormone secretagogues (peptides like CJC-1295 and ipamorelin) offer a more physiological approach by stimulating the body's own GH production in natural pulses.

A Systems Approach

Hormones do not operate in isolation. Cortisol affects testosterone. Thyroid function influences metabolic hormones. Insulin resistance impairs sex hormone binding. Effective hormone optimization requires a systems-level assessment rather than treating individual hormones in isolation.

Practical Takeaways

• Age-related hormone decline is real and measurable, with clinical consequences
• Testosterone replacement in symptomatic men with confirmed low levels has a favorable evidence profile when monitored properly
• DHEA supplementation is low-risk and may benefit women more than men
• Thyroid optimization requires comprehensive testing beyond TSH alone
• Growth hormone secretagogues offer a safer alternative to direct GH injection
• Lifestyle foundations (sleep, exercise, body composition, and stress management) profoundly influence hormone levels and should be optimized before or alongside any hormonal intervention
• All hormone therapy should be supervised by a clinician with regular blood work monitoring

References

1. Lincoff AM, et al. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE trial). *N Engl J Med.* 2023 Jul. PMID 37326322. [https://pubmed.ncbi.nlm.nih.gov/37326322/](https://pubmed.ncbi.nlm.nih.gov/37326322/)
2. Pencina KM, et al. Efficacy of Testosterone Replacement Therapy in Correcting Anemia in Men With Hypogonadism: A Randomized Controlled Trial. *JAMA Netw Open.* 2023 Oct. PMID 37889486. [https://pubmed.ncbi.nlm.nih.gov/37889486/](https://pubmed.ncbi.nlm.nih.gov/37889486/)
3. Nair KS, et al. DHEA in elderly women and DHEA or testosterone in elderly men. *N Engl J Med.* 2006 Oct. PMID 17050889. [https://pubmed.ncbi.nlm.nih.gov/17050889/](https://pubmed.ncbi.nlm.nih.gov/17050889/)
4. Iglesias P, et al. Hormone deficiency and cardiovascular disease: clinical impact, treatment strategies, and perspectives. *Expert Rev Cardiovasc Ther.* 2026 Apr. PMID 41904647. [https://pubmed.ncbi.nlm.nih.gov/41904647/](https://pubmed.ncbi.nlm.nih.gov/41904647/)