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Scientific Opinion on the substantiation of health claims related to L-glutamine and growth or maintenance of muscle mass (ID 719, 722, 3185), faster restoration of muscle glycogen stores after strenuous exercise (ID 434, 699, 701, 723, 1569), skeletal muscle tissue repair (ID 721), maintenance of normal neurological function (ID 662, 700), increased attention (ID 700, 1570), improvement of working memory (ID 700, 1570), maintenance of defence against pathogenic gastro-intestinal microorganisms (ID 452), gut protein synthesis (ID 701), decreasing gut permeability (ID 701), and stimulating immunological responses (ID 1568) pursuant to Article 13(1) of Regulation (EC) No 1924/2006[sup]1[/sup] EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)2, 3 European Food Safety Authority (EFSA), Parma, Italy
Słowa kluczowe: L-glutamine   attention   defence   gastro-intestinal   glycogen stores   gut   health claims   microorganisms   muscle mass   neurological function   tissue repair   working memory  
ID:    3185      719      1569      1570      434      1568      699      700      701      723      721      662      722      452  
Produkty: Glutamina  

1. Charakterystyka żywności / składnika

The food constituent that is the subject of the health claims is L-glutamine.
Glutamine is a conditionally indispensable amino acid provided by mixed dietary protein intakes from different sources. It can also be consumed as a food supplement. The content of L-glutamine in foods can be measured by established methods.
The Panel considers that the food constituent, L-glutamine, which is the subject of the health claims, is sufficiently characterised.

2. Znaczenie oświadczenia dla zdrowia człowieka


2.1. Wpływ na wzrost i utrzymanie masy mięśniowej (ID 719, 722, 3185)

The claimed effects are “increasing cell swelling/volumization”, “muscle protein metabolism” and “improves muscles metabolism”. 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 growth or maintenance of muscle mass. Failure to increase muscle mass during growth and development, and the loss of muscle mass at any age, will reduce muscle strength and power.
The Panel considers that growth or maintenance of muscle mass is a beneficial physiological effect.

2.2. Szybsze regenerowanie mięśniowych zapasów glikogenu po intensywnych ćwiczeniach (ID 434, 699, 701, 723, 1569)

The claimed effects are “supporting glycogen replenishment”, “muscle function”, “metabolic stress, protein synthesis, gut permeability, carbohydrate metabolism” and “supporting glucose homeostasis”. The Panel assumes that the target population is adults performing strenuous exercise.
In the context of the proposed wordings, clarifications from Member States and references provided, the Panel assumes that the claimed effects refer to the faster restoration of glycogen stores in skeletal muscle after strenuous exercise.
The Panel considers that faster restoration of muscle glycogen stores after strenuous exercise might be a beneficial physiological effect.

2.3. Wpływ na regenerację mięśni szkieletowych (ID 721)

The claimed effect is “supporting exercise recovery”. The Panel assumes that the target population is adults performing resistance exercise.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to the rebuilding of structural protein within the skeletal muscle tissue after exercise that has caused muscle damage.
The Panel considers that skeletal muscle tissue repair is a beneficial physiological effect.

2.4. Utrzymanie prawidłowego funkcjonowania układu nerwowego (ID 662, 700)

The claimed effect is “nervous system” and “mental health”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings and the clarifications provided by Member States, the Panel assumes that the claimed effects refer to the maintenance of normal neurological function.
The Panel considers that maintenance of normal neurological function is a beneficial physiological effect.

2.5. Zwiększenie uwagi (ID 700, 1570)

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 increased attention (concentration).
The Panel considers that increased attention is a beneficial physiological effect.

2.6. Poprawa pamięci (ID 700, 1570)

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 improvement of working memory.
The Panel considers that improvement of working memory is a beneficial physiological effect.

2.7. Utrzymanie obrony przed patogenami przewodu pokarmowego (ID 452)

The claimed effect is “maintains healthy gastrointestinal tract and immune functions in stressful conditions”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings and the clarifications provided by Member States, the Panel assumes that the claimed effect refers to the maintenance of defence against pathogenic gastro- intestinal microorganisms.
The Panel considers that maintenance of defence against pathogenic gastro-intestinal microorganisms is a beneficial physiological effect.

2.8. Jelitowa synteza białek (ID 701)

The claimed effect is “metabolic stress, protein synthesis, gut permeability, carbohydrate metabolism”. The Panel assumes that the target population is the general population.
In the context of the clarifications provided by Member States, the Panel assumes that the claimed effect refers to gut protein synthesis.
The Panel considers that gut protein synthesis is not a beneficial physiological effect per se, but needs to be linked to a beneficial physiological or clinical outcome. The Panel notes that no evidence has been provided on the context in which the claimed effect could be considered as a beneficial physiological effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and a beneficial physiological effect related to gut protein synthesis.

2.9. Zmniejszenie przepuszczalności jelit (ID 701)

The claimed effect is “metabolic stress, protein synthesis, gut permeability, carbohydrate metabolism”. The Panel assumes that the target population is the general population.
In the context of the clarifications provided by Member States, the Panel assumes that the claimed effect refers to decreasing gut permeability.
The Panel considers that decreasing gut permeability is not a beneficial physiological effect per se, but needs to be linked to a beneficial physiological or clinical outcome. The Panel notes that no evidence has been provided on the context in which the claimed effect could be considered as a beneficial physiological effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and a beneficial physiological effect related to decreasing gut permeability.

2.10. Stymulowanie odpowiedzi immunologicznej (ID 1568)

The claimed effect is “immune health”. The Panel assumes that the target population is the general population.
In the context of the clarifications provided by Member States, the Panel assumes that the claimed effect refers to stimulating various immunological responses such as increasing mononuclear cell proliferation, cytokine production and nasal IgA after exercise.
The Panel considers that the evidence provided does not establish that stimulation of mononuclear cell proliferation, cytokine production and nasal IgA is a beneficial physiological effect per se.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and a beneficial physiological effect related to the stimulation of mononuclear cell proliferation, cytokine production and nasal IgA.

3. Naukowe uzasadnienia wpływu na zdrowie człowieka - 

The references provided for the scientific substantiation of these claims included textbooks and narrative reviews which did not provide original data for the scientific substantiation of the claim. Human, animal and in vitro studies on food constituents other than L-glutamine alone (e.g. branched- chain aminoacids (BCAA); N-acetyl-cysteine; mixtures of whey protein plus BCAA or arginine plus L-glutamine; mixtures of soy lecithin, sodium dihydrogen phosphate, thiamin, pyridoxine and L- glutamine; mixtures of glycine, niacin, and glutamine), on glutamine given intravenously, on health outcomes (e.g. treatment of chronic disease or pathological conditions, morbidity and mortality in pre- term infants, use in enteral nutrition) unrelated to the claimed effects, or on the effects of intense training on plasma and tissue concentrations of L-glutamine, were also provided. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claims.

3.1. Wpływ na wzrost i utrzymanie masy mięśniowej (ID 719, 722, 3185)

A claim on protein and growth or maintenance of muscle mass has already been assessed with a favourable outcome (EFSA Panel on Dietetic Products Nutrition and Allergies (NDA), 2010).
Glutamine is a component of dietary protein, and both endogenous and exogenous glutamine contribute to protein synthesis.
No references which addressed the effects of L-glutamine consumption on growth or maintenance of muscle mass were provided. No evidence has been provided that L-glutamine in addition to normal protein intake has an additional role in muscle mass.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and growth or maintenance of muscle mass, apart from the well established role of protein on the claimed effect.

3.2. Szybsze regenerowanie mięśniowych zapasów glikogenu po intensywnych ćwiczeniach (ID 434, 699, 701, 723, 1569)

Two references which assessed the effects of L-glutamine consumption on muscle glycogen stores after exercise were provided.
In the study by Bowtell et al. (1999) seven male subjects participated in three trials, in each of which they received one of three different drinks by systematic rotation: 18.5 % (wt/vol) glucose polymer solution (containing glucose, maltose, maltotriose, tetrasaccharide, pentasaccharide and “higher sugars”), a solution containing 8 g glutamine, or 18.5 % glucose polymers containing 8 g glutamine. Tests were undertaken one month apart. On each test day, subjects followed a validated standard exercise protocol designed to deplete of glycogen both type I and type II muscle fibres. A muscle biopsy was taken from the quadriceps femoris muscle within 15 min of the end of exercise. Within 20 min, a 2 h constant [1-13C]glucose intravenous infusion started at a rate of 8.5 mg/kg/h for the first 30 min after a 9 mg/kg bolus of [1-13C]glucose. Subjects then consumed the test drinks (330 mL) within 2 min of the start of the infusion. Second and third quadriceps femoris muscle biopsies were taken after 1 and 2 h of recovery. No significant differences with respect to the average rate of net muscle glycogen storage during the 2 h of recovery after exercise were observed between the test drinks. The Panel notes that this study does not show an effect of L-glutamine on the restoration of muscle glycogen stores after strenuous exercise.
In the study by Van Hall et al. (2000) eight trained subjects were studied during 3 h of recovery while consuming one of four drinks in random order. Drinks were ingested in three 500 mL boluses. Each bolus of the control drink contained 0.8 g/kg body weight of glucose. The other drinks contained the same amount of glucose and either 0.3 g/kg body weight of glutamine, or a wheat hydrolysate (26 % glutamine), or a whey hydrolysate (6.6 % glutamine). On each test day (7 days apart), subjects followed a validated standard exercise protocol for glycogen depletion. A biopsy was taken from the quadriceps muscle 15 min after the end of exercise, and the first bolus was taken immediately thereafter. The other boluses followed after 1 and 2 h of recovery. A second muscle biopsy was taken after 3 h of recovery. The rate of glycogen re-synthesis in skeletal muscle was not significantly different between the four test drinks. The Panel notes that this study does not show an effect of L-glutamine on the restoration of muscle glycogen stores after strenuous exercise.
In weighing the evidence, the Panel took into account that the two studies from which conclusions could be drawn for the scientific substantiation of the claim did not show an effect of L-glutamine consumption on the restoration of muscle glycogen stores after strenuous exercise.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and faster restoration of muscle glycogen stores after strenuous exercise.

3.3. Wpływ na regenerację mięśni szkieletowych (ID 721)

No references which addressed the effects of L-glutamine consumption on skeletal muscle tissue repair in humans were provided.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and skeletal muscle tissue repair.

3.4. Utrzymanie prawidłowego funkcjonowania układu nerwowego (ID 662, 700)

No references which addressed the effects of L-glutamine consumption on neurological function were provided.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and maintenance of normal neurological function.

3.5. Zwiększenie uwagi (ID 700, 1570)

No references which addressed the effects of L-glutamine consumption on measures of attention were provided.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and increased attention.

3.6. Poprawa pamięci (ID 700, 1570)

No references which addressed the effects of L-glutamine consumption on measures of working memory were provided.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and improvement of working memory.

3.7. Utrzymanie obrony przed patogenami przewodu pokarmowego (ID 452)

Rohde et al. (1996) investigated the effects of physical exercise (i.e. triathlon) on immune markers and serum amino acid concentrations in eight male tri-athletes. The Panel notes that this study did not report on L-glutamine intakes.
Castell et al. (1996) studied ultra-marathon (n=27), marathon (n=88), middle-distance (10 and 15 km; n=41) runners and rowers (n=45) undergoing training. Both males and females were included. Glutamine (5 g in 330 mL mineral water) or placebo (maltodextrin) were given immediately after and 2 h after a test exercise on a double-blind basis. Randomisation is not mentioned. The athletes were given a questionnaire to monitor infections according to specified symptoms for seven days after the test exercise. Gastro-intestinal infections were included for analysis in addition to airway infections. The incidence of infections in the seven-day period was only reported for marathon and ultra- marathon runners. The Panel notes the lack of information about randomisation, that no detailed information about the questionnaires used for the diagnosis of infections was provided, that the number of non-responders and the gender distribution were not indicated, and that it is unclear why some sub-groups of athletes were excluded from the statistical analysis. The Panel considers that owing to important methodological limitations no conclusions can be drawn from this study for the scientific substantiation of the claim.
The Panel concludes that a cause and effect relationship has not been established between the consumption of L-glutamine and maintenance of defence against pathogenic gastro-intestinal microorganisms.

Wnioski

On the basis of the data presented, the Panel concludes that:
The food constituent, L-glutamine, which is the subject of the health claims, is sufficiently characterised.
Growth or maintenance of muscle mass (ID 719, 722, 3185)
The claimed effects are “increasing cell swelling/volumization”, “muscle protein metabolism” and “improves muscles metabolism”. The target population is assumed to be the general population. Growth or maintenance of muscle mass is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and growth or maintenance of muscle mass, apart from the well established role of protein on the claimed effect.
Faster restoration of muscle glycogen stores after strenuous exercise (ID 434, 699, 701, 723,
1569)
The claimed effects are “supporting glycogen replenishment”, “muscle function”, “metabolic stress, protein synthesis, gut permeability, carbohydrate metabolism”, and “supporting glucose homeostasis”. The target population is assumed to be adults performing strenuous exercise. Faster restoration of muscle glycogen stores after strenuous exercise might be a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and faster restoration of muscle glycogen stores after strenuous exercise.
Skeletal muscle tissue repair (ID 721)
The claimed effect is “supporting exercise recovery”. The target population is assumed to be adults performing resistance exercise. Skeletal muscle tissue repair is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and skeletal muscle tissue repair.
Maintenance of normal neurological function (ID 662, 700)
The claimed effects are “nervous system” and “mental health”. The target population is assumed to be the general population. Maintenance of normal neurological function is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and maintenance of normal neurological function.
Increased attention (ID 700, 1570)
The claimed effect is “mental health”. The target population is assumed to be the general population. In the context of the proposed wordings, it is assumed that the claimed effect refers to increased attention. Increased attention is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and increased attention.
Improvement of working memory (ID 700, 1570)
The claimed effect is “mental health”. The target population is assumed to be the general population. In the context of the proposed wordings, it is assumed that the claimed effect refers to improvement of working memory. Improvement of working memory is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and improvement of working memory.
Maintenance of defence against pathogenic gastrointestinal microorganisms (ID 452)
The claimed effect is “maintains healthy gastrointestinal tract and immune functions in stressful conditions”. The target population is assumed to be the general population. Maintenance of defence against pathogenic gastro-intestinal microorganisms is a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and maintenance of defence against pathogenic gastro-intestinal microorganisms.
Gut protein synthesis (ID 701)
The claimed effect is “metabolic stress, protein synthesis, gut permeability, carbohydrate metabolism”. The target population is assumed to be the general population. Gut protein synthesis is not a beneficial physiological effect per se, but needs to be linked to a beneficial physiological or clinical outcome. No evidence has been provided on the context in which the claimed effect could be considered as a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and a beneficial physiological effect related to gut protein synthesis.
Decreasing gut permeability (ID 701)
The claimed effect is “metabolic stress, protein synthesis, gut permeability, carbohydrate metabolism”. The target population is assumed to be the general population. Decreasing gut permeability is not a beneficial physiological effect per se, but needs to be linked to a beneficial physiological or clinical outcome. No evidence has been provided on the context in which the claimed effect could be considered as a beneficial physiological effect.
A cause and effect relationship has not been established between the consumption of L-glutamine and a beneficial physiological effect related to decreasing gut permeability.
Stimulating immunological responses (ID 1568)
The claimed effect is “immune health”. The target population is assumed to be the general population. In the context of the clarifications provided by Member States, it is assumed that the claimed effect refers to stimulating various immunological responses such as increasing mononuclear cell proliferation, cytokine production and nasal IgA after exercise. The evidence provided does not establish that stimulation of mononuclear cell proliferation, cytokine production and nasal IgA is a beneficial physiological effect per se.
A cause and effect relationship has not been established between the consumption of L-glutamine and a beneficial physiological effect related to the stimulation of mononuclear cell proliferation, cytokine production and nasal IgA.