ID 596 -
Tryptofan
PL: Tryptofan
EN: Trytophane
Pdf: L-tryptophan
Oświadczenie (2)
- zdrowia psychicznego
- psychiczne i nerwowe funkcji
1. Charakterystyka żywności / składnika
The food constituent that is the subject of the health claims is L-tryptophan.
L-tryptophan is an indispensable amino acid provided by mixed dietary protein intakes from different sources. L-tryptophan can also be consumed in the form of food supplements. The content of L-tryptophan in foods can be measured by established methods.
The Panel considers that the food constituent, L-tryptophan, which is the subject of the health claims, is sufficiently characterised.
2.1. Utrzymanie prawidłowego snu (ID 596, 1671)
The claimed effects are “mental health” and “mental and nerve function”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effects refer to the maintenance of normal sleep. Normal sleep, including normal sleep onset latency, efficiency, duration and quality can be measured by validated methods.
The Panel considers that maintenance of normal sleep is a beneficial physiological effect.
2.2. Poprawa nastroju (ID 596)
The claimed effect is “mental health”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to positive mood, which is a well-defined psychological construct and which can be measured by validated tests.
The Panel considers that enhancement of mood might be a beneficial physiological effect.
2.3. Udział w prawidłowym przebiegu procesów poznawczych (ID 596)
The claimed effect is “mental health”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to cognitive function, which includes memory, attention (concentration), learning, intelligence and problem solving, which are well-defined constructs and which can be measured by validated psychometric cognitive tests.
The Panel considers that contribution to normal cognitive function is a beneficial physiological effect.
3.1. Utrzymanie prawidłowego snu (ID 596, 1671)
A number of references provided for the scientific substantiation of the claim did not address relevant endpoints with respect to sleep, or did not report on L-tryptophan. Four references were narrative reviews and did not provide any original data for the scientific substantiation of the claimed effect. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
Three placebo-controlled studies examined the effects of L-tryptophan on measures of sleep.
Hartmann and Spinweber (1979) studied the effects of either 0 g, 0.25 g, 0.5 g or 1 g of L-tryptophan taken 20 minutes prior to bedtime on sleep latency and efficiency (defined as the ratio of total sleep time over total time in bed) in 15 normal males with mildly disturbed (insomniac) sleep (i.e. reporting sleep latencies over 30 minutes). The Panel notes that there were insufficient details on treatment regimens, including the nature of the products administered, on whether participants and researchers were blind to the dose, and on how the treatments were counter-balanced, and that there were other weaknesses, including the small number of subjects and the use of acute doses of L-tryptophan on only one occasion. The Panel notes that no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.
Hudson et al. (2005) conducted a double-blind, randomised placebo-controlled trial on the effects of L-tryptophan on measures of total sleep time, sleep efficiency, time awake, and sleep quality in 57 adult subjects who met the DSM IV criteria (Diagnostic and Statistical Manual of Mental Disorders, 4th edition) for primary insomnia. Subjects were asked to stop sleep medication during the trial. Sleep measures were obtained by completion of sleep diaries. The Panel notes that patients
received various food bars, which varied in L-tryptophan content, and primary analysis showed that L-tryptophan had no effect on measures of sleep across the three weeks of the study.
The third study evaluated sleep onset latency and sleep quality in 10 patients with sleep disturbance who were administered 5 g of L-tryptophan by intra-venous infusion compared to physiological saline solution (Korner et al., 1986). The Panel notes that L-tryptophan was given intravenously at a dose greater than the conditions of use provided in the consolidated list. The Panel notes that no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.
In weighing the evidence, the Panel took into account that the only intervention study which could be used to substantiate the claimed effect found no effect of L-tryptophan on measures of sleep.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-tryptophan and maintenance of normal sleep.
3.2. Poprawa nastroju (ID 596)
A number of references provided for the scientific substantiation of the claimed effect did not address relevant endpoints with respect to mood, or did not report on L-tryptophan. Two were narrative reviews which did not contain any original data that could be used for the scientific substantiation of the claim. Korner et al. (1986) studied the effects of L-tryptophan administered by intra-venous infusion against saline in 10 patients with sleep disorders. The Panel notes that none of these studies examined the effect of oral L-tryptophan administration in relation to mood. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
Eight studies reported the effects of L-tryptophan on mood in patients with a range of psychiatric disorders which included Seasonal Affective Disorder, depression and bulimia nervosa. The Panel considers that the evidence provided does not establish that patients suffering from psychiatric disorders are representative of the general population with regard to mood, and that it is not possible to use the results of these studies to draw conclusions on the effects of consumption of L-tryptophan in the general population.
Three randomised, double-blind controlled trials reported on the effects of L-tryptophan on mood in normal healthy adults.
The first by Young et al. (1985) studied the impact of dietary L-tryptophan on measures of mood in 36 adult men. Three groups received 100 g of identical amino acid mixtures which contained either 0 g, 2.3 g or 10.3 g of added L-tryptophan. The amino acids were mixed with 300 mL water, 10 mL chocolate syrup and a small amount of saccharin to mask the flavour. Amino acid mixtures were administered at 8 a.m., after an overnight fast. Measures of mood, including a depression scale (the Multiple Affect Adjective Checklist) and a measure of dysphoria (uncomfortable mood), were taken at baseline and 5 hours after the ingestion of the amino acid mixtures. The Panel notes that the study was designed to assess the effect of acute L-tryptophan „depletion‟ on mood. The Panel considers that no conclusions can be drawn from this study with respect to the effect of consumption of L-tryptophan.
The second study (Leyton et al., 2000) investigated the effects of acute L-tryptophan „depletion‟ on mood in 41 adult women. The day before testing, all women ate a low protein diet provided by the researchers and fasted from midnight. Participants were randomly assigned to three diet groups, each of which received a different amino acid mixture. The first was an 86 g nutritionally balanced amino acid mixture including 2.3 g of L-tryptophan; the second was similar but deficient in L-tryptophan; and the third was similar to the first but deficient in phenylalanine and tyrosine. Five hours after
ingestion, participants underwent a psychological challenge involving the Trier Social Stress Test in which they prepared and delivered a short presentation for an imaginary job interview which was recorded on video. Participants completed several mood scales prior to ingesting the amino acid drink, 5 hours after ingestion, and immediately following the Trier Social Stress Test. The Panel notes that the study design did not include an L-tryptophan supplemented group, and that the study was designed to assess the effect of acute L-tryptophan „depletion‟ on mood. The Panel considers that no conclusions can be drawn from this study with respect to the effect of consumption of L-tryptophan.
The third study was a cross-over study of 46 healthy adults who scored highly on a scale of quarrelsomeness (aan het Rot et al., 2006). The treatment group took 1 g of L-tryptophan with meals three times per day for 15 days. The authors reported that the control group took an identical placebo but the constituents were not identified. A 6-day inter-treatment interval was included to ensure wash- out, followed by 15 days of the second treatment. Affect was measured by rating scales completed after social interactions in daily life. Social behaviour was measured by self-rating scales which listed agreeable, quarrelsome, dominant and submissive behaviours. Social perception scores were obtained by having participants rate the behaviour of the person with whom they interacted most in the social interaction. The Panel notes that the data emanating from this study were compromised by a significant treatment x order interaction for affect (p<0.001), for which reason no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-tryptophan and enhancement of mood.
3.3. Udział w prawidłowym przebiegu procesów poznawczych (ID 596)
The references provided for the scientific substantiation of the claim did not address relevant endpoints with respect to cognitive function, or did not report on L-tryptophan. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-tryptophan and contribution to normal cognitive function.
Warunki i możliwe ograniczenia stosowania oświadczenia
Up to 3 grams per day