Why is a supplement containing parsley (Petroselinum crispum) leaf powder, thyroid powder (from Bovine), L-Tyrosine, pituitary powder (from porcine), adrenal powder (from porcine), L-Cystine, and L-Cystine hydrochloride (L-Cyst HC) recommended to be taken at night before bed?

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Last updated: March 27, 2025View editorial policy

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From the Research

The supplement containing parsley leaf powder, bovine thyroid powder, L-tyrosine, porcine pituitary and adrenal powders, L-cystine, and L-cysteine HCl is likely recommended for nighttime use because many of these ingredients support overnight hormone regulation and recovery processes. Taking it before bed allows the thyroid and adrenal components to work during the body's natural hormone production cycle, which is most active during sleep. L-tyrosine serves as a precursor for thyroid hormones and neurotransmitters, while the glandular extracts (thyroid, pituitary, adrenal) may provide building blocks for the body's own hormone production. The amino acids L-cystine and L-cysteine support detoxification and tissue repair that occurs during sleep. Additionally, nighttime administration minimizes potential stimulatory effects from thyroid components that might otherwise cause daytime restlessness. The parsley may aid in reducing overnight fluid retention. This timing aligns with the body's natural circadian rhythm for hormone production and cellular repair, potentially optimizing the supplement's effectiveness while minimizing disruption to daytime energy levels.

Some studies suggest that certain supplements, such as those containing thyroid and adrenal components, may have interactions with other medications or have adverse effects in certain individuals 1, 2. However, the current evidence does not provide a clear answer to the question of why this specific supplement is recommended for nighttime use. A study on the effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands found that tyrosine may be beneficial for cognitive performance, particularly in short-term stressful and/or cognitively demanding situations 3. Another study on the evidence-based use of levothyroxine/liothyronine combinations in treating hypothyroidism found that combination therapy may be beneficial for some patients, but the evidence is not consistent 4, 5.

Key points to consider:

  • The supplement contains ingredients that support overnight hormone regulation and recovery processes
  • Nighttime administration may minimize potential stimulatory effects from thyroid components
  • The supplement's effectiveness may be optimized by taking it before bed, aligning with the body's natural circadian rhythm for hormone production and cellular repair
  • Potential interactions with other medications or adverse effects in certain individuals should be considered 1, 2

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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