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Category: The Endocrine System

  • Melatonin Supplements and Risks

    Potential risks associated with long-term melatonin use among adults with chronic insomnia were highlighted in a recent preliminary study presented at the American Heart Association’s Scientific Sessions 2025
    Led by Dr. Ekenedilichukwu Nnadi, a chief resident at SUNY Downstate Health Sciences University, the observational analysis examined over 130,000 patients, half of whom had documented chronic melatonin use (defined as a year or longer, including prescriptions or self-reported). None had prior heart failure or used prescription sleep aids at baseline.
    Key findings include a 90% increased relative risk of developing heart failure within five years for long-term users (4.6% incidence vs. 2.7% in non-users), a 3.5-fold higher likelihood of heart failure hospitalization (19% vs. 6.6%), and nearly double the all-cause mortality rate (7.8% vs. 4.3%). ahajournals.org
    The study emphasizes association rather than causation. Chronic insomnia itself may contribute to these effects through inflammation, elevated nighttime blood pressure, or stress hormone dysregulation. newsroom.heart.org
    The research highlights regulatory gaps: U.S. melatonin supplements are unregulated, with actual doses varying significantly (up to +478% or -83% from the labels), unlike the stricter prescription-only rules in the UK, EU, and Australia. nytimes.com
     Nnadi cautions against assuming “natural” equals safe, especially for nightly, multi-year use.
    He calls for randomized trials to clarify mechanisms, such as their impact on heart rhythm or metabolism.
    Experts like Columbia University’s Marie-Pierre St-Onge note melatonin’s lack of FDA approval for chronic insomnia treatment and urge short-term use only. washingtonpost.com

    Sleep specialist Dr. Muhammad A. Rishi recommends starting with 0.5–1 mg doses, limiting the duration to 1–3 months, and consulting a physician for persistent issues, as insomnia may signal underlying conditions such as sleep apnea or depression.
    The Council for Responsible Nutrition echoes this, advising that professional guidance is necessary for long-term sleep troubles.

    New Details from Additional Research
    While the study raises alarms, it aligns with growing scrutiny of melatonin’s real-world safety.
    Hazard ratios from the abstract confirm the risks: 1.90 for incident heart failure, 3.47 for hospitalization, and 1.80 for mortality, even after adjusting for confounders like age, comorbidities, and multiple prescriptions. ahajournals.org
     Confounding factors—such as users having more severe insomnia, co-occurring depression/anxiety, or polypharmacy with other sedatives—could explain much of the link. newsroom.heart.org
    Contrasting evidence suggests that melatonin’s antioxidant properties may benefit individuals with established heart disease. A 2023 meta-analysis of 10 trials (n=1,200) found that short-term use (up to 3 months) reduced systolic blood pressure by 3.5 mmHg and improved endothelial function in hypertensive patients.
    Animal studies suggest cardioprotective effects against ischemia-reperfusion injury, but human data is limited to small, controlled settings with pharmaceutical-grade doses—not the variable OTC products in Nnadi’s cohort.
    Recent U.S. trends amplify concerns: CDC data shows melatonin-related emergency visits rose 530% from 2019–2022, often from overdoses or accidental ingestion, particularly in children.
    A 2024 FDA warning highlighted inaccurate labeling in 25% of tested supplements, potentially leading to unintended high exposures that disrupt natural hormone rhythms over time.
    Experts urge caution without panic: NBC reports cardiologists view chronic use as a “red flag” for unmanaged insomnia rather than melatonin toxicity, recommending cognitive behavioral therapy for insomnia (CBT-I) as first-line treatment, which cuts heart risks by 40% in meta-analyses. nbcnews.com
     For at-risk groups (e.g., those with hypertension), monitoring heart rate variability via wearables during use is recommended.
    Read

    What stimulates normal melatonin secretion in the human body?


    Sources

    1. American Heart Association. “Long-term use of melatonin supplements to support sleep may have negative health effects.” November 2025. https://newsroom.heart.org/news/long-term-use-of-melatonin-supplements-to-support-sleep-may-have-negative-health-effects
    2. Nnadi, E. et al. “Abstract 4371606: Effect of Long-term Melatonin Supplementation on Incident Heart Failure, Heart Failure Hospitalization, and All-Cause Mortality in Adults With Insomnia.” Circulation. November 2025. https://www.ahajournals.org/doi/abs/10.1161/circ.152.suppl_3.4371606
    3. NBC News. “What taking melatonin could reveal about your heart health.” November 2025. https://www.nbcnews.com/health/health-news/taking-melatonin-reveal-heart-health-rcna241132
    4. News-Medical.net. “Long-term use of melatonin supplements linked to higher risk of heart failure and death.” November 2025. https://www.news-medical.net/news/20251103/Long-term-use-of-melatonin-supplements-linked-to-higher-risk-of-heart-failure-and-death.aspx
    5. The New York Times. “Is Melatonin Bad for Your Heart? Here’s What to Know.” November 2025. https://www.nytimes.com/2025/11/05/well/melatonin-heart-health-study.html
    6. The Washington Post. “New study links melatonin and heart failure. Don’t panic, experts say.” November 2025. https://www.washingtonpost.com/health/2025/11/03/melatonin-heart-failure-sleep-aid/
    7. Drugs.com. “Long-Term Melatonin Use for Insomnia Tied to Higher Risk for Heart Failure, Death.” November 2025. https://www.drugs.com/news/aha-long-term-melatonin-insomnia-tied-higher-risk-heart-failure-127448.html
    8. Powers Health. “Long-Term Melatonin Might Harm Heart Health, Study Says.” November 2025. https://www.powershealth.org/about-us/newsroom/health-library/2025/11/03/longterm-melatonin-might-harm-heart-health-study-says
    9. Wang, Y. et al. “Effects of melatonin supplementation on blood pressure: A systematic review and meta-analysis.” Hypertension Research. 2023. https://www.nature.com/articles/s41440-023-01275-5
    10. Cardinali, D. et al. “Melatonin and cardioprotection against ischemia/reperfusion injury.” Antioxidants. 2022. https://www.mdpi.com/2076-3921/11/3/543
    11. CDC. “Notes from the Field: Melatonin Poisoning — United States, 2019–2022.” MMWR. 2024. https://www.cdc.gov/mmwr/volumes/73/wr/mm7306a3.htm
    12. Irish, L. et al. “The role of sleep hygiene in promoting public health: A review of empirical evidence.” Sleep Medicine Reviews. 2015. https://www.sciencedirect.com/science/article/pii/S1087079214001255

  • Our Endocrine Glands

    The endocrine glands are specialized organs that secrete hormones directly into the bloodstream to regulate various bodily functions. Below is a concise overview of the major endocrine glands and their primary roles:
    1. Pituitary Gland (often called the “master gland”)
      • Location: Base of the brain
      • Role: Controls other endocrine glands and regulates growth, metabolism, reproduction, and stress response through hormones like growth hormone (GH), thyroid-stimulating hormone (TSH), and adrenocorticotropic hormone (ACTH).
    2. Thyroid Gland
      • Location: Neck, below the Adam’s apple
      • Role: Regulates metabolism, energy levels, and body temperature via thyroid hormones (T3 and T4). Also influences heart rate and growth.
    3. Parathyroid Glands (four small glands)
      • Location: Behind the thyroid
      • Role: Control calcium and phosphorus levels in bones and blood through parathyroid hormone (PTH), essential for bone health and muscle function.
    4. Adrenal Glands (two glands)
      • Location: On top of each kidney
      • Role:
        • Adrenal Cortex: Produces cortisol (stress response, metabolism) and aldosterone (blood pressure, electrolyte balance).
        • Adrenal Medulla: Releases epinephrine and norepinephrine (fight-or-flight response, heart rate, energy mobilization).
    5. Pancreas (has both exocrine and endocrine functions)
      • Location: Behind the stomach
      • Role: Regulates blood sugar levels through insulin (lowers blood glucose) and glucagon (raises blood glucose).
    6. Pineal Gland
      • Location: Center of the brain
      • Role: Secretes melatonin, which regulates sleep-wake cycles and circadian rhythms.
    7. Gonads (Ovaries in females, Testes in males)
      • Location: Pelvis (ovaries), scrotum (testes)
      • Role:
        • Ovaries: Produce estrogen and progesterone for reproductive development, menstrual cycle, and pregnancy.
        • Testes: Produce testosterone for sperm production, muscle growth, and male sexual characteristics.
    8. Hypothalamus (technically a brain region but functions as an endocrine gland)
      • Location: Brain, above the pituitary
      • Role: Links the nervous and endocrine systems by releasing hormones that stimulate or inhibit the pituitary gland, regulating hunger, thirst, body temperature, and hormone production.
    9. Thymus (more active in childhood)
      • Location: Upper chest, behind the sternum
      • Role: Secretes thymosin, which supports immune system development by aiding T-cell maturation.
    These glands work together to maintain homeostasis, coordinating processes like growth, metabolism, reproduction, stress response, and immune function. Hormonal imbalances can lead to disorders like diabetes, hypothyroidism, or adrenal insufficiency. If you’d like detailed information on any specific gland or hormone, let me know!

  • Saturated Fat and Steroid Hormones

    Saturated fat is found in animal fat and certain plant fats, such as coconut, coconut oil, palm, and palm kernel oil.
    It plays a key role in producing steroid hormones because cholesterol, a precursor to steroid hormones, is derived partly from dietary fats, including saturated fats. 
    1. Cholesterol as a Building Block: Steroid hormones (e.g., testosterone, estrogen, cortisol) are synthesized from cholesterol in the adrenal glands, testes, ovaries, and other tissues. The liver uses saturated fats, found in foods like butter, eggs, and meat, to produce cholesterol via the mevalonate pathway.
    2. Dietary Saturated Fat and Cholesterol Levels: Consuming adequate saturated fats supports endogenous cholesterol synthesis, ensuring sufficient raw material for hormone production. While the body can synthesize cholesterol independently, dietary saturated fats can increase circulating low-density lipoprotein (LDL) cholesterol, which cells use to produce hormones.
    3. Hormone Synthesis Process: In the body, cholesterol is converted into pregnenolone, the “mother hormone,” through enzymatic reactions in the mitochondria. Pregnenolone is then transformed into various steroid hormones via pathways involving enzymes like cytochrome P450. Adequate cholesterol availability, influenced by saturated fat intake, supports this process.
    4. Balance and Moderation: Excessive saturated fat intake may not directly boost hormone production beyond the body’s needs, as feedback mechanisms tightly regulate hormone synthesis. However, very low saturated fat diets could limit cholesterol availability, potentially impacting hormone levels, especially in individuals with high hormonal demands (e.g., athletes, pregnant women).
    5. Contextual Factors: The impact of saturated fat on hormone production varies based on genetics, overall diet, and lifestyle. For example, diets high in processed carbs alongside saturated fats may disrupt hormonal balance by increasing insulin resistance, which can affect steroid hormone regulation.

    Key Takeaway: Saturated fats contribute to steroid hormone production by supporting cholesterol synthesis, but the relationship is complex and depends on dietary balance and individual needs. Moderation and a nutrient-dense diet are crucial for optimal hormone health.
    If you would like to dive in further, read  Saturated Fat and Steroid Hormones: Biochemical Mechanisms