Doctor's Best L-Tyrosine 500mg 120 VegeCapsules – Amino Acid for Mental Focus, Mood & Stress Resilience

Doctor's Best L-Tyrosine provides 500mg of the amino acid L-tyrosine per capsule — a direct precursor to the catecholamine neurotransmitters dopamine, norepinephrine, and epinephrine, as well as to thyroid hormones (T3 and T4). L-tyrosine supplementation supports cognitive performance under stress, mental focus, mood, alertness, and resilience during physically or mentally demanding periods. Vegan, non-GMO, and manufactured to GMP standards.

• L-Tyrosine 500mg — precursor to dopamine, norepinephrine, and epinephrine
• Supports mental focus, alertness, and cognitive performance under stress
• Supports mood and resilience during demanding periods
• Also a precursor to thyroid hormones T3 and T4
• 120 VegeCapsules — GMP certified, non-GMO

Frequently Asked Questions

What does L-Tyrosine do for the brain?

L-Tyrosine is the amino acid building block for the catecholamine neurotransmitters — dopamine (involved in motivation, reward, and pleasure), norepinephrine (attention, focus, and stress response), and epinephrine (adrenaline). Supplementation can replenish these neurotransmitters during high-demand periods when tyrosine availability in the brain becomes a limiting factor, improving working memory, focus, and cognitive flexibility under stress.

When is L-Tyrosine most useful?

L-Tyrosine is most effective during cognitively or physically demanding situations — exam periods, shift work, sleep deprivation, military training, and high-stress work environments. Research shows it helps maintain cognitive performance when norepinephrine and dopamine are being rapidly depleted by stress. It is less effective as a general daily cognitive enhancer in low-stress conditions.

Can L-Tyrosine support thyroid function?

Yes. Tyrosine is an essential building block of thyroid hormones T3 (triiodothyronine) and T4 (thyroxine). People with low thyroid function or hypothyroidism related to nutritional insufficiencies may benefit from ensuring adequate tyrosine availability. However, for diagnosed hypothyroidism, consult your endocrinologist before adding tyrosine supplements.

When should I take L-Tyrosine?

Take on an empty stomach 30–60 minutes before a cognitively demanding task or before a period of high stress. Some people take it first thing in the morning for day-long mental clarity. Avoid taking too late in the day as the stimulatory effects (via catecholamine synthesis) may interfere with sleep if taken in the evening.

Who should avoid L-Tyrosine?

People taking MAOIs (monoamine oxidase inhibitors) should not take L-Tyrosine — this combination can cause dangerous hypertension. Those with hyperthyroidism or Graves' disease should also avoid supplemental tyrosine as it may overstimulate thyroid hormone production. People with phenylketonuria (PKU) may already have high tyrosine — check with your doctor.