l-Tyrosine ameliorates some effects of lower body negative pressure stress

Dollins, Andrew B.; Krock, Larry P.; Storm, William F.; Wurtman, Richard J.; Lieberman, Harris R.

doi:10.1016/0031-9384(94)00278-d

Cited by 37 publications

(11 citation statements)

References 27 publications

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“…Since many forms of stress induce brain depletion of catecholamines, tyrosine may be useful in counteracting stress-related performance decrements under a variety of conditions. Although it has been difficult to demonstrate conclusively that tyrosine has beneficial effects in humans, the literature suggests that tyrosine has the potential to be an effective countermeasure under such conditions as cold stress [5], exposure to cold and hypoxia [16], noise [42], extended wakefulness [11] and lower body negative pressure [43]. The lack of conclusive evidence in the human literature is likely related to inconsistencies in the amount of physiological stress produced, differences in the cognitive tasks employed and the amount and timing of the tyrosine dose.…”

Section: Discussionmentioning

confidence: 99%

Tyrosine supplementation mitigates working memory decrements during cold exposure

Mahoney

Castellani

Kramer

et al. 2007

Physiology & Behavior

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In rats, dietary supplementation with the amino acid tyrosine (TYR) prevents depletion of central catecholamines observed during acute environmental stress. Concomitant changes in the animals' behavioral responses to stress suggest that TYR might have similar effects on central catecholamines and cognition in humans exposed to environmental stress. This study aimed to determine if severe cold exposure impairs human cognition and if dietary supplementation with TYR would ameliorate such deficits. Volunteers (N = 19) completed three test sessions on different days (35°C control/placebo, ∼10°C/placebo, ∼10°C/TYR) using a double-blind, within subjects design. During each session, volunteers completed two 90-minute water immersions and consumed a food bar (150 mg/kg TYR or placebo) before each immersion (total TYR 300 mg/kg). Cognitive performance, mood, and salivary cortisol were assessed. Cortisol was elevated in the cold (p b .01). Volunteers made fewer correct responses on a Matchto-Sample memory measure (p b .05) and reaction time (RT) and errors increased on a choice RT test (p b .01) in the cold. Self-reported tension (p b .01), depression (p b .05) and confusion (p b .01) also increased in the cold. When volunteers consumed TYR, correct responses increased on a Match-to-Sample memory measure (p b .05) and study time for the sample was shorter (p b .05), indicative of more rapid and accurate information processing. Finally, RT on the memory measure revealed a similar pattern across immersions for TYR and thermoneutral conditions, but not cold/placebo (p b .05). This study demonstrates cold exposure degrades cognitive performance and supplementation with TYR alleviates working memory decrements.

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Section: Discussionmentioning

confidence: 99%

Tyrosine supplementation mitigates working memory decrements during cold exposure

Mahoney

Castellani

Kramer

et al. 2007

Physiology & Behavior

Self Cite

117

111

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“…Acute tyrosine consumption in humans does improve measures of mood, and dopamine dependant cognition, psychomotor performance, and behaviour, across a variety of dissimilar stressors which are theorised to increase brain catecholamine activity (Dollins et al 1995;Banderet and Lieberman 1989;Mahoney et al 2007;Neri et al 1995;O'Brien et al 2007). One study has measured a net brain uptake of tyrosine during prolonged exercise (Nybo et al 2003); however, acute tyrosine supplementation did not improve either prolonged exercise capacity (Strüder et al 1998) or performance (Chinevere et al 2002) in temperate conditions.…”

Section: Introductionmentioning

confidence: 94%

Oral tyrosine supplementation improves exercise capacity in the heat

et al. 2011

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Increased brain dopamine availability improves prolonged exercise tolerance in the heat. It is unclear whether supplementing the amino-acid precursor of dopamine increases exercise capacity in the heat. Eight healthy male volunteers [mean age 32 ± 11 (SD) years; body mass 75.3 ± 8.1 kg; peak oxygen uptake ([Formula: see text]) 3.5 ± 0.3 L min(-1)] performed two exercise trials separated by at least 7 days in a randomised, crossover design. Subjects consumed 500 mL of a flavoured sugar-free drink (PLA), or the same drink with 150 mg kg body mass(-1) tyrosine (TYR) in a double-blind manner 1 h before cycling to exhaustion at a constant exercise intensity equivalent to 68 ± 5% [Formula: see text] in 30°C and 60% relative humidity. Pre-exercise plasma tyrosine:large neutral amino acids increased 2.9-fold in TYR (P < 0.01), while there was no change in PLA (P > 0.05). Subjects cycled longer in TYR compared to PLA (80.3 ± 19.7 min vs. 69.2 ± 14.0 min; P < 0.01). Core temperature, mean weighted skin temperature, heart rate, ratings of perceived exertion and thermal sensation were similar in TYR and PLA during exercise and at exhaustion (P > 0.05) despite longer exercise time in TYR. The results show that acute tyrosine supplementation is associated with increased endurance capacity in the heat in moderately trained subjects. The results also suggest for the first time that the availability of tyrosine, a nutritional dopamine precursor, can influence the ability to subjectively tolerate prolonged submaximal constant-load exercise in the heat.

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“…Reactions to acute stress involve activation of the peripheral and central nervous systems and the release of catecholamines, which depletes catecholamine stores, causing mood and cognitive impairments. Acute tyrosine administration (50 mg–2 g) has been shown to counteract impairments in attention, memory, and mood caused by stress, sleep restriction, and fatigue . However, to date, no studies have evaluated the interactive effects of tyrosine and caffeine on mood and cognitive performance.…”

Section: Introductionmentioning

confidence: 99%

Influence of energy drink ingredients on mood and cognitive performance

Childs

2014

Nutr Rev

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Sales of energy products have grown enormously in recent years. Manufacturers claim that the products, in the form of drinks, shots, supplements, and gels, enhance physical and cognitive performance, while users believe the products promote concentration, alertness, and fun. Most of these products contain caffeine, a mild psychostimulant, as their foremost active ingredient. However, they also contain additional ingredients, e.g., carbohydrates, amino acids, herbal extracts, vitamins, and minerals, often in unspecified amounts and labeled as an "energy blend." It is not clear whether these additional ingredients provide any physical or cognitive enhancement beyond that provided by caffeine alone. This article reviews the available empirical data on the interactive effects of these ingredients and caffeine on sleep and cognitive performance and suggests objectives for future study.

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l-Tyrosine ameliorates some effects of lower body negative pressure stress

Cited by 37 publications

References 27 publications

Tyrosine supplementation mitigates working memory decrements during cold exposure

Tyrosine supplementation mitigates working memory decrements during cold exposure

Oral tyrosine supplementation improves exercise capacity in the heat

Influence of energy drink ingredients on mood and cognitive performance

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