Composition comprising carbohydrates and peptides which comprise tryptophan

The present invention relates to a formulation comprising tryptophan-containing peptides together with rapidly available glucose and slowly available glucose (i.e. “fast” and “slow” carbohydrates).

Recently, there have been various reports on the benefit which tryptophan is believed to have on several aspects of human behaviour, mood, brain function, brain development, when such tryptophan is taken up by the brain. Examples of such reports are WO 99/55174, WO 00/42868, WO 20051023017.

Tryptophan is an amino acid present in many proteins, like e.g. whey proteins, but also animal protein contains tryptophan. Tryptophan can be taken up in the blood, and from the blood into the brain, after ingestion of a protein which contains tryptophan. However, tryptophan is not the only amino acid taken up, and in fact when an average animal protein composition is ingested, the level of tryptophan taken up by the brain is so low due to competitive uptake of other amino acids that usually no significant effect can be observed attributable to tryptophan. Hence, most of the reports referred to above either use proteins or protein-fractions rich in tryptophan, or the free amino acid tryptophan (the latter optionally in combination with other free amino acids and/or proteins).

Use of tryptophan as free amino acids has disadvantages, in that food legislation in many countries limits the use of tryptophan as free amino acid in foodstuffs.

Tryptophan-rich proteins have natural limits to the level of tryptophan and its ratio to large neutral amino acids, which is relevant for uptake of tryptophan by the brain.

Recent insight is that peptides rich in tryptophan can be a good source to get sufficient tryptophan in the brain for the desired effects and may be easier applied in foodstuffs than free amino acids. Such peptides rich in tryptophan are preferably low in amino acids with which competition in uptake into the brain is believed to be high: the so-called large neutral amino acids (LNAA), which are: leucine, isoleucine, valine, tyrosine, phenylalanine (and depending on the definition of LNAA one uses also methionine). Hence, it is preferred to provide peptide preparations which contain a high level of tryptophan and have a high ratio tryptophan/LNAA. Methionine is considered not to have any beneficial metabolic effect in the context of this invention, and is thus for the purpose of this invention not considered as one of the LNAA.

EP 661004 discloses animal feed comprising tryptophan in combination with e.g. dextrin. Said composition is for maintaining growth and increase of body weight at high environmental temperatures when the animals have low appetite.

WO 2004/112803 discloses methods for managing the symptoms of premenstrual syndrome by providing a composition containing a protein having a high tryptophan/LNAA ratio, in combination with rapidly digestible carbohydrates.

WO 2006/130567 discloses methods for treating winter blues, seasonal affective disorder (SAD), and depressive disorders; and carbohydrate craving, weight gain, and mood symptoms associated with same, by administering to a subject a carbohydrate-rich composition with minimal protein content, or a carbohydrate-rich composition that contains tryptophan or a tryptophan-rich protein or peptide.

In US2003039739 compositions and methods of losing weight are described that are suitable for individuals susceptible to gastric hyperacidity or gastroesophageal reflux. The compositions include in part a snack food having two or more rapidly digestible carbohydrates, in which the foodstuff or an aqueous mixture of the foodstuff and water has a pH equal to or greater than about 6, and in which the snack is substantially protein-free. The experimental/test plan of the invention allocated the amounts of protein and carbohydrate differently at each meal and snack to ensure that following the lunch and dinner meals, the ratio of plasma tryptophan to that of the circulating large neutral amino acids is not decreased so that the ratio would be significantly elevated following the consumption of the carbohydrate-rich snack.

In W002/46210 a method for increasing the level of tryptophan in whey protein hydrolysates is described. In the method used, whey is first hydrolysed at acidic pH by one or more acid proteases, preferably by a pepsin, rennin, acid fungal protease, chymosin, papain, bromelain, chymopapain or ficin. The preferred incubation conditions are between pH 1.5 and 3.5 and were chosen to generate peptides having a hydrophobic nature. The hydrolysis is deliberately carried out in such a way that the tryptophan residues become incorporated in large, hydrophobic peptides. Due to the fact that tryptophan is present in relatively large peptides, the tryptophan uptake into the blood will be retarded hereby limiting the application possibilities of the preparation as a food or beverage ingredient, especially in combination with other proteins. Another disadvantage of the use of such large peptides is that such peptides may give rise to allergic reactions. Such reactions to whey proteins are well known.

WO 2008/052995 relates to tryptophan-containing peptides, which further may contain carbohydrates.

Insulin may selectively promote uptake of the LNAA by various tissues, thus making more tryptophan available for uptake in the brain, as the LNAA compete with tryptophan for uptake in the brain. Thus, considerable levels of plasma insulin may be beneficial for the desired effects of tryptophan on the brain. Such desirable effects are related to the field of brain function, alertness, sleep, mood, concentration, and related issues. High plasma insulin levels may be promoted by presence of fast digestible carbohydrates together with a tryptophan containing composition, but such may lead to either a dip in blood glucose e.g. about 2 hours after ingestion and/or not being able to maintain considerable levels of blood glucose for e.g. 3-4 hours for the brain to have maximum benefit of the tryptophan and/or for optimal brain function, alertness, sleep, mood, concentration, cognition in general and related fields.

Hence, there was a need for a composition providing both tryptophan in a form which allows good uptake in the brain, which is from an industrially-widely available source, has a high tryptophan/LNAA ratio, a low allergenicity, and which may be used in formulations (e.g. for humans, like e.g. children) which may be beneficial for one or more of brain functioning, alertness, sleep, mood, concentration, cognition, and related fields.

This has now been achieved (at least in part) by a formulation comprising at least two different water-soluble, tryptophan-containing peptides (or peptide composition), and wherein the tryptophan/LNAA ratio of the formulation is at least 0.15, preferably between 0.15 and 1.8, which formulation further comprises a rapidly available glucose (RAG) composition and a slowly available glucose (SAG) composition, wherein the RAG composition and the SAG composition are present in the edible composition in dry weight ratio\'s of: RAG composition: SAG composition between 1:0.5 and 1:4, preferably between 1:0.8 and 1:3, more preferably between 1:1 and 1:3. It is these ranges that are believed to be both beneficial to tryptophan-uptake and to brainfunction, also over several hours.

Preferably, in the formulation according to this invention the weight ratio of the tryptophan-containing peptides: RAG composition is between 1:2 and 1:20, preferably between 1:3 and 1:15, more preferably between 1:3 and 1:8. It is these ranges that are believed to be both beneficial to tryptophan-uptake and to brainfunction, also over several hours.

It is also preferred herein that the formulation according to the present invention comprises 0.5 to 5% (preferably 0.8 to 3%) of dry weight of the tryptophan-comprising peptide composition on ready to consume product, as such allows easy formulation of consumable products, e.g. drinks, which have an acceptable volume and tryptophan concentration.

A further embodiment of this invention is a formulation comprising at least two different peptides selected from di- or tripeptides, whereby two peptides selected from di- or tripeptides are each present in an amount of at least 5 mol % of the total amount of di- and tripeptides, and in which more than 30 mol % of the total tryptophan is present as peptide bound tryptophan, and preferably more than 40 mol %, more preferably more than 50 mol %, even more preferably more than 60 mol %, still more preferably more than 70 mol % and most preferably more than 80 mol % of the peptide-bound tryptophan is present in the form of a di- or a tripeptide, preferably the formulation has a tryptophan/LNAA ratio of more than 0.15, preferably between 0.15 and 1.8, which formulation further comprises a rapidly available glucose (RAG) composition and a slowly available glucose (SAG) composition, wherein the RAG composition and the SAG composition are present in the formulation in dry weight ratio\'s of: RAG composition: SAG composition between 1:0.5 and 1:4, preferably between 1:0.8 and 1:3, more preferably between 1:1 and 1:3. In the above, it may further be preferred that the (dry) weight ratio of the tryptophan-containing peptides: RAG composition is between 1:2 and 1:20, preferably between 1:3 and 1:15, more preferably between 1:3 and 1:8. It is these amounts and ranges that are believed to be both beneficial to tryptophan-uptake and to brainfunction, also over several hours.

Rapidly available glucose (RAG) compositions and slowly available glucose (SAG) compositions are defined in the “detailed description of the invention”.

It is also preferred herein that the formulation according to the present invention comprises 0.5 to 5% (preferably 0.8 to 3%) of dry weight of the tryptophan-comprising peptide composition on ready to consume product.