Itis postulated thatthey may act in the mammary gland as trapping mechanisms to accumulate the vitamins from blood plasma in to milk and in the gutto facilitate the ir absorption, both directly, and indirectly by preventing their uptake by intestinal microorganisms.There appears to be no <a href="http://www.targetmol.com/compound/Cholic-Acid">Targetmol's
Cholic Acid</a> decisive nutritional advantage in breastfeeding: the bottlefed baby generally thrives, despite suspicions that he may be more sus ceptible to gastrointestinal and respiratory infections, and perhaps also to a variety of less common maladies. The vitamin B, in sows milk is notaccessibleto vitamin B, requiring microorganisms, and milk folate might prove equally unavailable to folaterequiring species.Further,it could well beth atit is notonly the vitamindependent microbial species that are inhibited since, evenin species thatsynthesize vitamins, leakage fromthecells intothesurrounding medium constitutes a bu rden on synthesis during theearly phase of growth. The presence of external vitamin binders might incrcase this drain and so reduce growth ra te; and undertheconditions inthegutsmall changesin relative growth rates could have marked effects on the composition oftheflora.The vitamin binders in milk may have a complex physiological role.Theymay act in the mammary gland astrapping mechanismsto accumulatethevitamins from blood plasma into milk and in thegutto facilitate their absorption, bo th directly, a nd indirectly by preventing their uptake by intestinal microorganisms.The human milk was from one donor, inthe th mon th of lactation.A portion of this pepsin digest was furtherdigested with trypsin, as follows.The mixture was incubated formin at and itspH was again adjustedto by addition of. Thissmall selection is not of course representative of enteric organisms; thecultures were chosen largely for their ease of cultivation in defined media.The objectin this preliminary study wasto test the concept that vitamin B, and folate binders in milk might inhibit theuptake ofthe vitamins into bacteria, and so influence theecology of the gutmicroflora and the nutrition of thehost animal.Sodium acetate trihydrate was included at g final strength medium, and the content of and K,HPO, was reducedto, ugl, and mg thymidine were addedl.Theydemonstrated th atbacterial up take is a twostage process.Thepr ima ry uptake stage was rapid, independentof tempe ra tu re, anddid notrequire viable organisms.Thisphase was thoughttorepresent attachmentofthevitaminto receptor sitesonthecell wall.The second stage was slower, required actively metabolizing bacteria, and was presumed to reflecttran sport ofthevitamin in tothebacterial cell.Inthe presentstudy, firststage uptake was assessedby addition of chilled bacterial cultu re to ml conical centrifuge tubescontainingthetest preparations of radioactive vitamin, and immediately centrifuging for min atg.The super na tantfluid was decanted andthepellet of bacterial cells dispersedin ml ofthe app ropria te cultu re med ium bystirring with a glass rod.The suspension was centri fuged again andthesupe rna tantfluid decanted.It was presumed, therefore, th atnone was dependent on exogenous vitamin B.The sows milk bound ng added cyanocobalaminml, and a solution containing I mg I F mlbound ngml.Both binders were added in excess oftheamounts neededtobind thetest dose of ng cyanocobalamin: IF hadthecapacity tobind ng, a ndthesows milk ng.In seven ofthenine bacterial species tested, uptake of cyanocobalamin was clearly depressed bythebinders, mu ch more by themilk th anbytheIF.Toml portions of chilled culture were added nil cows milk, or. C O I I culture experiments might have been partly denatured during manufacture, it cannot be in ferred thatthe binders in porcine I F and sows milk a re necessarily dissimilar.