Overview
Amino acid substrate paired with iodine to form thyroid hormones.
- Dietary protein from animal sources (meat, fish, eggs, dairy) and plant sources (soy, legumes, grains)
- Free-form amino acid powders and capsules
- Targeted pre-workout, recovery, or sleep formulations
- Free-form crystalline powder
- Capsules or tablets
- Pre-mixed recovery or hydration beverages
- Time-release formulations
Mechanism of action
Tyrosine + iodine → MIT/DIT → T4/T3.
- · Tyrosine + iodine → MIT/DIT → T4/T3
Effects on the body
Organ system effects
L-Tyrosine (Thyroid Substrate) supports mitochondrial ATP production and fatigue resistance.
Evidence-based benefits
Cognitive support under stress
Moderate evidencePotential side effects
- · L-Tyrosine (Thyroid Substrate) is generally well-tolerated at evidence-based doses
- · Mild GI discomfort (nausea, loose stools, or bloating) possible at higher intakes
- · Headache or transient fatigue reported by a small fraction of users
- · Allergic or hypersensitivity reaction (rash, itching, swelling)
- · Sleep disturbance if taken late in the day
- · Discontinue and seek medical advice if symptoms are severe, persistent, or include difficulty breathing
Drug interactions
Supplement interactions
- A high-quality multivitaminCovers micronutrient cofactors that support most supplement pathways.
- Omega-3 (EPA/DHA)Foundational anti-inflammatory support that complements most regimens.
No specific avoidances listed.
Dosing & bioavailability
Where to buy
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Third-party testedIndependently verified L-Tyrosine (Thyroid Substrate) — look for USP, NSF, or Informed Sport seals on the label for purity and dose accuracy.L-Tyrosine (Thyroid Substrate) third party tested NSF
CapsulesPre-measured L-Tyrosine (Thyroid Substrate) capsules — easiest for travel and consistent daily dosing without scoops or scales.L-Tyrosine (Thyroid Substrate) capsules
PowderBulk unflavored L-Tyrosine (Thyroid Substrate) powder — best cost-per-gram and flexible dosing for stacking or mixing into drinks.L-Tyrosine (Thyroid Substrate) powder unflavored
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L-tyrosine, thyroid hormone synthesis, and stress performance
Jongkees BJ, et al.
Review of tyrosine on cognition and thyroid substrate.
Precursor for T3/T4; performance benefits under stress.
PubMed: L-Tyrosine (Thyroid Substrate) — Cognitive support under stress
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