The goal of this clinical trial is to learn if a dietary supplement called Miricell works to improve cellular health and signs of healthy aging in adults. It will also learn about the safety of Miricell.

The main questions it aims to answer are:

• Does Miricell improve markers of autophagy, which is the body's natural process for recycling damaged cells?
• Does Miricell support brain health, metabolic health, and visible signs of aging?
• What medical problems, if any, do participants experience while taking Miricell?

Researchers will compare Miricell to a placebo (a look-alike capsule that contains no active ingredients) to see if Miricell works better to support healthy aging.

Participants will:

• Take either one Miricell capsule or a placebo every day for 12 weeks with a morning meal.
• Visit the research clinic four times over the course of the study for checkups and tests.
• Complete memory and thinking tests, track their daily physical activity, and give blood samples to measure health changes.

This randomized, double-blind, placebo-controlled, parallel-group clinical trial evaluates the physiological impacts of a standardized spermidine ingredient (Miricell®) over a 12-week intervention period.

Participants are randomized in a 1:1 ratio into one of two parallel groups. To ensure rigorous double-blind conditions, investigators, research site staff, and participants remain masked to group allocations throughout the duration of the trial. Investigational products are supplied in identical-looking, opaque capsules packaged in coded bottles to prevent accidental unblinding. The randomization schedule is maintained securely and will only be broken in the event of a medical emergency requiring immediate knowledge of the treatment assignment.

To minimize confounding variables related to endogenous autophagy activation and variable background polyamine intake, strict lifestyle compliance measures are enforced across both groups:

• Participants receive detailed instructions to avoid altering their baseline intake of polyamine-rich foods (such as aged cheeses, fermented soy, and specific grains/mushrooms) to ensure nutritional stability.
• Dietary tracking is deployed at multiple intervals to longitudinally verify caloric and macronutrient consistency throughout the study period.
• Prior to scheduled laboratory evaluations, participants must replicate their individual 24-hour baseline diet, abstain from alcohol and heavy physical exertion for 24 hours, avoid caffeine for 12 hours, and maintain a strict 10-hour overnight fast.

Participant safety is continuously monitored by the investigative medical staff. All local or systemic adverse events are systematically evaluated and categorized by clinical severity. Internal data monitoring and quality assurance reviews are performed regularly by designated site staff to guarantee protocol adherence and regulatory compliance. Backup blood samples are kept from each visit to protect against any laboratory or processing errors.

INCLUSION CRITERIA:

• Provide voluntary signed and dated informed consent.
• Be in fair health as determined by medical history and routine blood chemistries.
• Age between the ages of 40 and 70 (inclusive).
• Body weight of at least 110 pounds.
• Normotensive (seated, resting systolic blood pressure <140 mm Hg and diastolic blood pressure < 90 mm Hg. If the first measurement is slightly elevated above these limits, the subject will be given a brief (5-minute) rest period, and two more measurements will be taken. The average of all three measurements will be used to determine eligibility.
• Normal seated, resting heart rate (<90 per minute).
• Willing to duplicate their previous 24-hour diet, refrain from alcohol for 24 hours, exercise for 24 hours prior to each trial, caffeine for 12 hours prior to each trial, and fast for 10 hours prior to each of the treatments.
• Participant agrees to maintain existing dietary and physical activity patterns throughout the study period.
• Participant is willing and able to comply with the study protocol.
• If a dietary supplement was initiated within the past month, the participant is willing to discontinue supplement use followed by a 2-week washout prior to participation in the study.
• Able to provide an adequate blood draw.

EXCLUSION CRITERIA:

• Use of probiotics, postbiotics or antibiotics within the past month.
• A history of unstable or new-onset cardiovascular/cardiorespiratory, liver, or renal disease.
• The participant's alcohol consumption is more than two standard alcoholic drinks per day or more than 10 drinks per week or has a history of drug/alcohol abuse or dependence.
• History of diabetes (any form) or any endocrine disorder.
• Fasting blood sugar of > 125 mg/dL.
• Current smokers who smoke 11 or more cigarettes per day (i.e. light smokers will be enrolled if they meet all other criteria).
• History of hyperparathyroidism or an untreated thyroid disease.
• History of malignancy in the previous five years except for non-melanoma skin cancer (basal cell cancer or squamous cell cancer of the skin).
• Chronic inflammatory condition or disease (e.g., rheumatoid arthritis, Crohn's Disease, ulcerative colitis, lupus, HIV/AIDS, etc.).
• Previous medical diagnosis of gout or fibromyalgia.
• Any female who is pregnant, trying to become pregnant, is less than/or equal to 120 days postpartum, or any current women who are nursing.
• Women who participate in this study must agree to the use of contraception for the duration of the study, and any sexually active woman will have to take a negative pregnancy test prior to enrolling. Women of childbearing age (any woman prior to menopause), regardless of their use of contraception, will be provided a urine pregnancy test kit at their screening visit and take the test in private using the female lavatory after signing an informed consent.
• Known allergy or sensitivity to any ingredient in the test formulations as listed on the product label.
• Any other diseases or conditions that, in the opinion of the medical staff, could confound the primary endpoints or place the subject at increased risk of harm if they were to participate.