the present invention provides an improved immunostimulatory dietary formulation which is a ready - to - use liquid formulation containing a high level of glutamine . the glutamine is present in a free peptide bound form , especially di - and / or tri - peptide , and is highly bioavailable and readily absorbed by the gut and subsequently metabolized . particularly suitable di - and tri - peptides for the present invention are l - alanyl - glutamine , l - glycyl - glutamine and mixtures thereof . useful sources of these peptides are hydrolyzed wheat protein and caseinate . the formulation can also have other dietary / nutritional ingredients including a fiber source , which is selected from soluble and insoluble fibers and mixtures thereof , that provides additional health benefits for the patient &# 39 ; s colon by promoting the production of short chain fatty acids and normalizing the water content of the patient &# 39 ; s stools . the present formulation is a liquid composition that is phase stable , i . e ., the formulation does not phase separate . the present formulation contains a glutamine - rich first amino acid source , preferably a wheat protein hydrolysate , and a second amino acid source , preferably caseinate , which stabilizes the first amino acid source . preferably , the primary source of amino acids in the present formulation is the first amino acid source . the glutamine - rich amino acid source provides peptide bound glutamine , especially di - and / or tri - peptides . preferably , the first amino acid source in the formulation makes up between about 65 wt % and about 85 wt %, more preferably between about 68 wt % and about 80 wt %, most preferably between about 70 wt % and about 75 wt %, of the total weight of the two amino acid sources . in addition , as a preferred embodiment , the two amino acid sources make up between about 1 wt % and about 20 wt %, preferably between about 3 wt % and about 8 wt %, more preferably between about 5 wt % and about 7 wt %, of the total weight of the formulation . suitable wheat protein hydrolysates for the present invention are highly hydrolyzed . at least 50 w / w % of the wheat protein hydrolysate has a molecular weight of less than 1 , 000 dalton , preferably less than 500 dalton . preferably , more than 80 wt % of the wheat protein hydrolysate has a molecular weight of less than 1 , 000 dalton and the wheat protein hydrolysate has less than 1 wt % of protein having a molecular weight higher than 10 , 000 dalton . it has been found that wheat protein hydrolysates contain bound glutamine , unlike soy protein hydrolysates which contain free glutamine . the term glutamine - rich as used herein indicates a protein source containing more than 20 % of its amino acids as glutamine . as indicated above , caseinate is preferred as the second amino acid source . it has been found that caseinate is not only a good source of the bound glutamine , but also enhances the phase stability of the liquid formulation . suitable caseinate for the present invention include sodium caseinate and calcium caseinate , which are widely available from commercial sources . preferably , the caseinate is not a significantly hydrolyzed caseinate . as a preferred embodiment of the present invention , the suitable caseinate is sodium caseinate . in contrast to the wheat protein hydrolysate , the non - hydrolyzed caseinate is composed largely of proteins with molecular weights in excess of 10 , 000 dalton . preferably , the second amino acid source makes up between about 1 wt % and about 3 wt %, more preferably between about 1 . 5 wt % and about 2 wt %, most preferably between about 1 . 7 wt % and about 1 . 9 wt %, of the total weight of the formulation . exemplary immunostimulatory formulations of the present invention have a glutamine - rich , di - or tripeptide ; a stabilizing protein source ; soluble and insoluble fiber ; a compound associated with the synthesis of polyamines ; a nucleobases source ; and polyunsaturated fatty acids , e . g ., omega - 3 - polyunsaturated fatty acids and omega - 6 - polyunsaturated fatty acids . suitable sources of the fiber include cellulose and its derivatives , gluten , soy , partially hydrolyzed guar , and mixtures thereof . the term “ a compound associated with the synthesis of polyamines ” as used herein is intended to include , but not limited to , arginine , arginine precursors , ornithine and the like , in their free amino acid or salt forms . of the compounds associated with the synthesis of polyamines , free arginine is preferred . preferably , the compound associated with the synthesis of polyamines makes up between about 0 . 5 wt % and about 3 . 5 wt %, more preferably between about 1 wt % and about 2 wt %, most preferably between about 1 . 4 wt % and about 1 . 6 wt %, of the total weight of the formulation . nucleobase sources suitable for use in the compositions of the present invention include natural nucleobases , nucleosides , nucleotides , rna , dna , equivalents thereof and / or mixtures comprising one or more of these compounds . natural nucleobases include the purines , i . e ., adenine and guanine , as well as the pyrimidines , i . e ., cytosine , thymine and uracil . natural nucleosides also include the ribose nucleosides adenosine , guanosine , uridine and cytidine and the deoxyribose nucleosides deoxyadenosine , deoxyguanosine , deoxythymidine and deoxycytidine . natural nucleotides include the phosphate esters of natural nucleosides , such as the monophosphates adenylate ( amp ), guanylate ( gmp ), uridylate ( ump ), cytidylate ( cmp ), deoxythymidylate ( dtmp ) deoxycytidylate ( dcmp ), as well as the diphosphates and triphosphates of natural nucleosides such as adp and atp . preferably , the nucleobase makes up between about 0 . 1 wt % and about 0 . 3 wt %, more preferably between about 0 . 15 wt % and about 0 . 2 wt %, most preferably between about 0 . 17 wt % and about 0 . 18 wt %, of the total weight of the formulation . polyunsaturated fatty acids are well known in the art as those having two or more double bonds per molecule and are available from a variety of plant , animal and synthetic sources . preferred polyunsaturated fatty acids ( pufa ) for use according to this invention include the omega - 3 pufa and omega - 6 pufa and mixtures thereof . examples of omega - 3 pufa particularly appropriate for use in the compositions of the invention include eicosapentaenoic acid ( epa ) and docosahexaenoic acid ( dha ). the omega - 3 and the omega - 6 pufa useful in this invention may be in the free acid form or in a form suitable for the physiological supply of omega - 3 or omega - 6 pufa , such as the triglyceride form . suitable sources for such omega - 3 pufa include linseed oil , canola oil and fish oils such as menhaden oil , salmon oil , mackeral oil , cod oil , herring oil , sardine oil , capelin oil and blends thereof . the amount of omega - 3 pufa to be administered will inter alia depend on the type of treatment , the subject to be treated and the like . thus , where the subject to be treated is an adult person a satisfactory immunostimulatory response is , in general , obtained with compositions of the invention formulated to allow a daily dosage of from about 0 . 1 to 20 grams , preferably from 0 . 1 to 15 grams , most preferably from 0 . 15 to 10 . 0 grams of omega - 3 fatty acids . examples of omega - 6 pufa particularly appropriate for use according to the invention include linoleic acid and arachidonic acid ( eta ), linoleic acid being most preferred . examples of suitable omega - 6 pufa sources include vegetable oils . preferred are omega - 6 pufa sources having a high linoleic acid content such as safflower oil , sunflower oil , soya oil , cotton oil and corn oil . the amount of omega - 6 pufa to be supplied will inter alia depend on the type of treatment , the subject to be treated and the like . typically , the compositions of the invention will provide for a daily dosage of from 0 . 1 to 20 grams , preferably 0 . 15 to 15 grams , most preferably 0 . 5 to 10 grams of omega - 6 pufa . the formulation of the present invention preferably has a dispersion enhancing agent . suitable dispersion enhancing agents include glycerides , e . g ., mono - and di - glycerides and mixtures thereof . the dispersion enhancing agent is added between about 0 . 05 wt % and about 0 . 5 wt %, preferably between about 0 . 1 wt % and about 0 . 3 wt %, more preferably between about 0 . 15 wt % and about 0 . 25 wt %, most preferably between about 0 . 18 wt % and about 0 . 22 wt %, based on the total weight of the formulation . the formulation may additionally contain vitamins and minerals . examples of suitable vitamins include vitamin a , vitamin d , vitamin e , vitamin k , vitamin c , folic acid , thiamine , riboflavin , vitamin b 6 , vitamin b 12 , niacin , biotin and panthotenic acid in their pharmaceutically acceptable forms . examples of mineral elements that are suitable for incorporation in the formulation of the invention include sodium , potassium , calcium , phosphorus , magnesium , manganese , copper , zinc , iron , selenium , chromium and molybdenum in pharmaceutically acceptable form . in particular , the formulation has beta - carotene ( vitamin a ), vitamin e , vitamin c , thiamine , vitamin b 12 , choline , selenium and zinc in pharmaceutically acceptable form . typically , the amounts of the above - indicated components in the formulation of the present invention suitable to meet the daily requirements of a patient suffering from depressed host defense mechanisms will comprise from 3 to 40 grams of arginine , or a physiologically equivalent amount of another compound associated with the synthesis of polyamines or of a mixture of such compounds in association with from about 0 . 1 to 4 . 0 g of nucleobase source , of 0 . 1 to 20 g omega - 3 fatty acids and from 0 . 1 to 20 gm , omega - 6 fatty acids . such unit daily amount will conveniently provide an energy supply of from 750 to 3500 kcal / day . the immunostimulatory compositions of this invention are suitable for use in patients who suffer from depressed host defense mechanisms , such as patients who suffer from depressed host defense mechanisms as a result of post - surgical trauma , cancer , chemotherapy / radiation therapy , sepsis , trauma , bums , immunosuppressive drug therapy , malnutrition , transfusion - induced immunosuppression and the like . it has indeed been observed that the body , when under severe stress , cannot readily mobilize the nutrients necessary to secure a normal immune function . the administration of the compositions of the invention allows to maintain , restore and enhance the immune function where desired . the immune system reacts surprisingly quickly and favorably to the administration of these compositions . such compositions may accordingly be employed to enhance a depressed host defense mechanism , to restore a normal immune function in a human with a deficient immune response , to enhance the development of the immune system in a developing human , to enhance a senescent immune system of a human and the like . the invention accordingly also provides the composition of the invention for use in a method of maintaining or stimulating the immune system of a patient , in need of such treatment . the following examples are provided to more specifically define and set forth the compositions useful as immunostimulatory dietary formula . they are for illustrative purposes only , and it is recognized that changes and alternatives may be made thereto that are not contemplated herein . it is to be understood then that to the extent any such changes or alternatives do not materially alter the makeup or function of these compositions , any such changes are deemed to fall within the spirit and scope of the invention as defined by the claims that follow . an immunostimulatory dietary formula of the present invention is prepared from the following components in their respective amounts . the percentage amounts are in terms of weight percent . 4 a mixture of 79 % palm kernal oil and 21 % sunflower oil 8 a blend of lysine acetate , l - leucine , l - threonine , l - histidine , l - tryptophan , l - methionine , and l - valine 9 a blend of maltodextrin ( 38 . 8 %), beta carotene - 1 % ( 20 %), vitamin e acetate - 50 % ( 14 %), vitamin a palmitate ( 5 . 7 %), zinc sulfate ( 4 %), ferrous sulfate ( 4 %), biotin - 1 % ( 2 . 6 %), calcium pantothenate ( 2 . 4 %), niacinamide ( 1 . 8 %), vitamin k ( 1 . 7 %), copper gluconate ( 1 . 1 %), vitamin b12 ( 0 . 9 %), folic acid - 10 % ( 0 . 8 %), vitamin d3 ( 0 . 5 %), manganese sulfate ( 0 . 5 %), pyridoxine # hcl ( 0 . 4 %), potassium iodide ( 0 . 3 %), thiamine hcl ( 0 . 3 %), riboflavin ( 0 . 2 %), chromic acetate ( 0 . 04 %), sodium molybdate ( 0 . 01 %), and sodium selenite ( 0 . 01 %). the components are mixed together and blended using standard equipment . this level of caseinate was found to give an excellent emulsion while still maximizing the amount of glutamine supplied by the formula at a particular protein level . the formulation is stable and does not separate . example 1 is repeated except the levels of hydrolyzed wheat protein are decreased to 4 . 0 % and 3 . 3 % while keeping the total content of the two protein sources . the formulations have more superior emulsion stability , but contain lower amounts of bound glutamine . example 1 is repeated except caseinate is removed from the formulation . when the formulation is stored at room temperature , the formulation separated with two to three days . this example clearly demonstrate that the formulation produced in accordance with the present invention is a stable formulation . the ready to feed , liquid formulation of the present invention , which contains glutamine , is stable and provides stable peptide bound glutamine that is readily bioavailable .
the present invention is an immunostimulatory composition that bolsters or enhances the immune system in injured , diseased , traumatized or otherwise critically ill patients whose own immune system has been compromised thereby . the ready to feed , liquid formulation comprises glutamine which is stabilized and highly bioavailable in the form of a peptide bound glutamine . other components comprise the free amino acids such as arginine , a nucleobase such as rna and omega - 3 and omega - 6 - polyunsaturated fatty acids .