am j clin nutr 1984 sevenhuysen 584 8

8/12/2019 Am J Clin Nutr 1984 Sevenhuysen 584 8

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F rom the D epartm en ts o f F oods an d N utrition( G P S , CH and O ra l B io logy (C D ), U nivers ity o f M an -itob a, W inn ipeg , M anitoba , C anada .

2S uppo rted b y M an itob a M edica l Serv ices F oun da-tion and M ed ica l R esearch C o unc il o f C anada .

3A ddress rep rin t requests to : D r G us taa f P S ev en -hu ysen , D epartm en t o f F oods and N u trition , U nivers ityo f M anitoba , W inn ip eg , M anitoba , C anada R 3T 2N 2.

P resen t ad dress : K e llo gg Sa lada C anada , 6 700F inch S tree t, R exd a le , O n tar io , M gW 5P 2.

R ec ei ve d J ul y 15 , 1 983 .A ccep ted fo r pub lica tio n N ovem b er 15 , 198 3 .

T h e A m er ica n J ou rn a / o f C /in ica / N utr it io n 39 : A P R IL 984 p p 584 -588 . P rin ted in U S A 19 84 A m erican S oc ie ty fo r C lin ica l N utrition

58 4

D eve lopm en t o f sa liva ry a am y lase in in fan ts fromb irth to 5 m on ths 3G u sta a f P S even hu ysen , P /iD , C hr is tine H o lod insky ,4 M SC , a ndCohn D a w e s B S C B D S P h D

A B ST R A C T T he a-am ylase ac tiv ity in w h ole sa liva of tw o groups of in fan ts w as investiga tedf rom birth to 5 m on th s a t m o nth ly in te rva ls. Foo ds u sed in in fan t feed ing as w ell as he igh t andw eigh t w ere reco rded a t each m onth ly co llec tion period . a -A m y lase activ ity w as found to in creaserap id ly from low values a t b irth to ap prox im ate ly tw o- th ird s o f ad u lt va lues by 3 m onth s. L argev ar ia tion in a-am ylase ac tiv ity , e ith er per m l of sa liva o r per m g of pro te in , w as recorded . N osign ifican t re la tionsh ips o f a -am ylase ac tiv ity w ith w eigh t, w e ig h t fo r h eigh t, g row th ra te , o rp resence of sta rch -con ta in ing fo ods in the d ie t w ere fo und . In trodu ction of s ta rch -con ta in ingfood befo re 3 m onths o f ag e w o uld like ly lead to in ad eq ua te h ydro liza tio n of sta rch in so m ein fan ts . Am J C /in N u ir 1984 ;39 :584-588 .K E Y W O R D S a-A m ylase , in fan t, sa liva , g row th , in fan t d ie t

IntroductionS tarc h an d o th e r c om ple x ca rbo hy dra tes

are h yd ro ly ze d by a-a m y la se , en d -p rod uc tso f th is h yd ro ly sis be ing m alto se , g luc ose ,m a lto trio se , an d d ex trin s. a-A m yla se (1 ,4 -a -D -g lu ca n g lu c an oh yd ro la se , E C 3 .2 .1 .1 ),w h ic h is fou nd in bo th sal iva a nd pa nc rea ticsec re t ion , e n su res co m p le te hy d ro lys is o fs tarc h in the a lim en tary ca n al in m ost in d i-v id ua ls . In c om ple te hy d ro lys is w ill re du cethe e ne rgy av ailab le from ing e ste d s ta rc han d m a y re su lt in ba c teria l ferm en ta tion o fu nd ige s te d ca rbo hy dra te in th e c o lo n , ca u s-ing d ec re ase d a bso rp tio n o f o th er nu trie n ts(1 ). In ad eq ua te h yd ro ly s is c an o cc u r w he na c tiv i ty le v els o f sa l iva ry an d p an cre a tic a m -y la se a re in su ffic ie n t.

In the ne w born in fa n t a -am ylase a ct iv ityle ve ls in sa liv a a re v ery lo w c om pa red w iththo se o f ad u lts a n d a -am yla se ac tiv ity le v elsin pa nc re atic se cre tio n a re n eg lig ib le (2 , 3 ,3a ). a-A m yla se a ctiv ity in bo th se cre tio nsh as be en fo un d to be s ign ific an t by 6 m o n th so f a ge (4 ). In fan ts h av e b ee n fo un d to m a in -ta in g as tric pH an d pe ps in c on ce n tra tio n atle ve ls in su ffic ie n t fo r p ro te in hy dro lys is , fo rlo ng er p erio ds o f tim e th a n a du lts 5 -7 .G astric p H of 4 .0 a nd ab ov e a llow s sal iva ry

a -am yla se to re m ain a c tive in th e sm a ll in -te s tine (2 , 7 ) a n d it ha s b e en po stu la te d tha tfo r in fa n ts sa liva ry a -a m y lase h as a n im po r-ta n t ro le in s ta rch hy dro lys is in the du o-de n um (8 ). A sim ilar ro le h as b ee n sug ge s te dfo r m am m a ry a-a m y la se (6 ).

T he firs t so lid fo od in tro du ce d in to th ein fa n ts d ie t is m o st c om m o nly ce re al (9 ), inw h ic h s ta rch is the m ajo r co ns titue n t. S al i-va ry a -a m y lase a c tiv i ty le ve l is a n im p orta n tind ic ato r o f th e a b ility to hy dro lyz e s ta rchin in fan cy . T he ra te o f de ve lo pm en t o f a-am y lase ac tiv ity in sa liva m ay be rele v an t torec om m en da tio ns m a de to p are n ts re ga rd -ing th e in tro du ction o f sta rc h -c on ta in in gfood s to in fa n ts , in v ie w o f the co m plic a tion srec o rd ed w ith in ad e qua te ca rbo hy dra ted ig e stion (1 , 9 a ).

A ssay s fo r a -am yla se a c tiv ity in hu m a n


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4 5A GE I MONT h S

SA L IV A R Y a-A M Y L A S E IN IN F A N T S 58 5

FIG 1 . Sa liva ry a-am ylase ac tiv ity from b irth to 5months .

sa liva h av e use d a va rie ty o f m e th od s, there su lts o fw h ich are n o t a lw ay s d ire ct ly co rn -pa rab le . T he m e tho d ch ose n fo r th is s tud ya llow s d ata to b e e xp re ssed in w a ys c om pa -rab le w ith a n um b er o f p re v io us s tu d ie s .M e t h o d s

A to ta l o f 29 in fan ts w as investiga ted . O bserv ationson 10 of th ese w ere m ade a t b irth , 1 , 2 , 3 , 4 , an d 5m onths , 7 days (g roup I). O bserva tio ns o n the re -m ain in g 1 9 w ere m ade a t 3 , 4 , and 5 m onths (g roupII), 7 d ays. A ll in fan ts w ere born a t the H ea lthS ciences C en tre in W inn ip eg , M anitob a, C anada , andw ere cons id ered hea lthy after rou tin e m ed ica l ex am i-na tio n . S ub jec ts inves tig a ted w ere a ll in fan ts fo r w h omconsen t from ph ysic ians and paren ts w as ob ta ined ,p ro v id ing a nonran dom sam ple . T o con tro l fo r th ec ircad ian rhy thm s in sa liv a flow ra te an d com po sition(10 ) assoc ia ted w ith the various sleep-w ake p atte rns o fthe in fan ts , a ll co llec tio ns of sa liva w ere taken a t th eadu lt peak flow tim e of b etw een 1 and 6 PM . A llsam p les w ere co llected 1 #{18 9}o 2 h p ast feed ing to en suretha t sam ples w ere co llec ted at p er io ds ofresting flo w ra teand com p osition . D aw es (10) conc luded tha t in ad u ltsco llec tion o f saliva sh ou ld take p lace 2 h afte r feed ing .T he con tribu tion of d iffe ren t saliva ry g land s to th evo lum e o f sa liva chang es w ith the leve l o f o ra l stim u-la tion . O ra l s tim ulation w ill a lso cau se th e concen tra -tions of p ro te in an d a-am ylase in the sec re tions tochang e b y v ary ing am o unts be tw een d if fe ren t saliva ryg land s (10 ). A ll sam ple co llec tions w ere m ade fromuns tim ulated sa liva to av o id these ch anges in concen-t ra ti on s. N o c he mi ca l s ti mu la nt s w er e used , nor w asthe ora l cav ity in ten tiona lly m echan ica lly stimulated.W h ole saliva w as co llec ted by su ction ca th ete r (A rg leD e L ee S uc tion C athe te r, s ize IO FR , trap size 10 m l,Sherwood M edica l Indus trie s , S t L ou is , M O ). T h e trapa ttach ed to the ca the ter w as no t used . S aliva w as draw nup by suction from the floor of the m ou th . Sa livasam ples w ere s to red in p las tic m ic ro cen tr ifu ge tub esand re frige ra ted to 4 #{17 6}Cith in 1 or 2 h . a -A m y laseac tiv ity w as assayed w ith in 24 h of re frige ra tio n . O nco m ple tion of th e assay sam ples w ere frozen and su b-sequen t ly a n al y ze d f o r t o t al p r o t ei n .

H eigh t and w eigh t w ere record ed each m o nth a t thetim e of sa liva co llection . H e ig h t w as m easured to thenearest 0 .5 cm us in g an In fan tom eter (G rafco In fan to -m ete r, no 28 67-13 34 , G raham -F ie ld S urg ica l C o Inc ,New Hyde Park NY . The mean of two measurementsw as recorded . W eigh t w as m easu red to the neares t gw ith a portab le beam balan ce. W eigh t o f d iap ers w asaccou n ted fo r. P ro ced ures fo r h eigh t an d w eigh t m eas-u rem en ts w ere th ose descr ib ed by Jelliffe (11).

A n in te rv iew w ith the m other p rov id ed a lis t o f foods ,inc lud ing b reas t m ilk or fo rm ula , fed to the in fan t a tth e tim e m easurem en ts w ere tak en . A ll m easu rem en ts,i n t er v i ew s a n d s a l iv a c o l l e ct i o n to ok p lace in the hom e.A ll p rocedures w ere ap proved by the U n iv ersity o fM anitoba E th ica l R ev iew C om mittee .

A ss ay s o f a -a my la se a ct iv it y we re carried o ut u si ngthe m ethod of B ern fe ld (12). A un it o f ac tiv ity w asexpressed as 1 m g o f m altose re leased per m in u te a t

30#{176}C ,H 6 .9 f rom sta rch so lu tion . T he s ta rch so lu tio nw as m odified as desc ribed b y S trum ey er (1 3). T hephospha te buffer con ta ined 0 .06 M N aC 1. A bs or ba nc ew as read at 540 nm on a S P6 -300 P ye U n icam Spec tro -pho tomete r .

E stim ation of the pro tein con ten t o f sa liva sam plesw as carr ied ou t accord ing to the m ethod of L ow ry e t a l(14) . A b sorbance w as read a t 60 0 nm and va lues w ereexpressed as m g of p ro te in per 10 0 m l o f sa liva . S pecificac tiv ity o f in fan t sa liva w as defined as the a-am ylaseac tiv ity record ed per m g of to tal p ro te in . A c tiv ity perm l of sa liva an d ac tiv ity p er m g o f pro te in w ere record edfo r e ac h o bs er va tio n.

R e s u l t sD ev elop m e n t o f a-a m y la se a ctiv ity pe r m l

o f w h o le saliv a va ried c on side rab ly b etw e e nin fa n ts a s sh ow n in F ig u re A t b irth th em a jo rity o f in fan ts ha d ne g lig ib le a-a m y la seac tiv ity in saliva a s show n in T a b le 1 . B y 2m o n th s th e m a jo ri ty o f in fa n ts h ad a p pre -c iab le le ve ls o f a-a m y la se a nd by 3 m o n th ssev era l in d iv idu a ls h ad re a ch ed 90 o r m o reo f a -a m y lase a ctiv ity U /m I. It w ou ld see mthat 90 U/ml is e qu iv ale n t to a du lt lev els ,w h ic h range from 70 to 3 00 U /m l (1 5 , 16 ).F ig u re 1 de m o nstra te s th e g rea t v ariab ilityin a -am ylase co n ten t. A t 5 m o n th s th e m a -

-J

ClFz

I->I4Li l4-J


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T A B L E 1M ean va lues (S D ) fo r p ro te in con ten t an d cv -am ylaseactiv ity by age-g rou p I

A ge A m y lase a ctiv ity P ro tein S p ec if ic a ct iv it y U / m i sal i va mg CO m i U /m g pro ie in

B irth 1 1 9 .9 9 .2 7 294 .0 70 .9 7* 45 5 .031 11 28 .3 27 .3 9 240 .4 98 .9 9 14 .3 11 .1

2 1 1 48 .7 46 .4 10 1 43 .3 76 .6 10 34 .5 26 .03 1 1 57 .2 40 .7 10 1 40 .2 45 .5 10 4 3 .0 26 .64 10 52 .6 37 .4 10 1 1 2 .5 34 .9 10 50 . 1 40 .85 1 0 58 .1 28 .3 10 1 38 .5 58 .0 1 0 51 .1 29 .8

a N um bers o f su b jects .

T A B L E 2M ean va lues ( S D ) fo r a -am ylase ac tiv ity andp ro te in con ten t by age-g roup II

A ge A m yia se a ctiv ity P ro tein S pe cific ac tiv ityU / m i saliva m g /H X I m l U /m g pro le in

3 1 9* 31 .3 2 2 .0 11 7 5 .4 28 .2 11 35 .0 22 .24 1 8 4 1 .0 28 .8 11 90 .8 25 .9 18 44 .4 2 6 .85 1 9 5 9 .2 39 .7 19 1 06 .2 62 .0 19 59 .9 35 .9

a N um bers o f su b jects .T A B L E 3M ean w t ( SD ) and gro w th rate a teach co llec tion period

wtAg e

Groupi ro u p l iGrowth#{ 176} N CH S s tan dard

rou p i r o u p li M g g g /d a g /da ; m ean g

B irth 3627 56 7 3230 3 2701 5 2 2 1 8 3 2 3 3 1 3 3 9 8 4 2 92 5 7 5 4 8 1 8 3 1 5 4 7 5 33 6 2 9 9 8 8 2 6 1 8 1 3 4 2 5 8 2 1 1 1 5 4 5 9 84 7 1 2 1 2 1 6 9 7 4 1 4 7 2 3 8 2 2 2 6 3 6 8

5 7 6 4 4 9 7 7 7 4 1 1 2 5 7 2 7 9 2 6 6 3 7 3

T A B L E 4L inear reg ression ana ly sis fo r g roup I

S G row th ra tes: the w t a t th e prev ious m on th sub trac ted from the w t a t the cu rren t m onth d iv ided by thenum b er ofdays b etw een th e tw o m easurem en ts.

T A B L E 5L inear reg ression ana lysis fo r g roup II

58 6 SE V E N H U Y SE N E T A L

Inde pe nde ntDe pe nde nt va r ia b le s

A m yla se ac tiv ity S pe cific ac tiv ityvar iab le U m i s a l iva (U /m g p ro tein )r p r p

A ge (days) 0 . 16 0 .00 08 0 .2 4 0 .0001W t (g ) 0 .26 0 .000 1 0 .27 0 .0 01G row th (g /day) 0 .00 0 .8 1 5 0 .003 0 .7 0

jo rity o f in fa n ts ha d ac h iev ed 85 % o r m o reo f a du lt le ve ls (T ab le 2 ).

N o ne o f the v aria b i lity in sa liva ry a -am -y lase ob serv ed be tw e en in fan ts co u ld b e e x -p la ine d b y v aria tio n in g row th in d ic a to rs o rth e p re sen ce in th e d ie t o f fo od s c o n ta in ings tarc h . N e ithe r g row th ra te s n o r ab so lu tein cre ase s in w e igh t, sh ow n in T a b le 3 , c o r-

Inde pe nde ntDe pe nde n t va r ia b le s

A mylase activity S pe ci fi c a ct iv it yv aria b le (U /m i sa liva ) U/m g p ro te in

r p r pA ge (days) 0 .42 0 .00 1 0 .05 0 .10W t ( g ) 0 .27 0 .00 1 0 .002 0 .71G row th (g /d ay ) 0 .04 0 .05 0 .02 0 .28

re la te d w ith e ith er a-a m yla se a ctiv ity pe r m lo f sal iva o r p er m g o f to ta l p ro te in (sp ec ifica ct iv ity ) in e ith er o f the g rou ps s tud ie d . In -c rea ses in w eigh t d iv ide d by in c rea ses inhe ig h t be tw e en m on th ly ob se rva tio ns d idno t c o rre la te w ith a b so lu te ch an ge s in aa m y la se ac tiv ity . R e g ress ion o f a-a m y la sea ct iv ity v alu e s ove r a ll 5 m on ths sim u lta ne -


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S A L IV A R Y a-A M Y L A SE IN IN FA N T S 587

o us ly w ith a ge , w e ig h t, an d g row th ratesh ow ed s ign ific an t re la tion sh ips w ith bo thag e an d w eigh t a s show n in T a b les an d In a dd itio n , s ig n ific a n t re la tio nsh ips w e refo un d be tw ee n ag e an d w eigh t a nd a m yla sesp ec ific a ctiv ities fo r th e 0 - to 5 -m on th g ro up(T ab le 4 ). T h e p re sen ce o f s tarc h in in fa n td ie ts w a s n o t a sso cia te d w ith h ig he r va lu eso f sa liva ry a-a m y la se a ct iv ity th an w e refo un d in in fa n ts w ith ou t s ta rch in th e d ie t .

S ta rc h -c on ta in in g foo ds w ere fe d a s ea rlyas 1 m o n th o f ag e. In b o th g ro up s I a nd II3 6% o fin fa n ts c on sum ed ce re al a t 3 m o n ths(fo u r a nd sev en in fa n ts, resp ec tiv ely ). A t 5m on ths ap p ro x im ately 7 2% c on sum ed ce r-ca l in th e tw o g roup s (e igh t a nd 14 in fan ts ,re spe c tive ly ). O n ly th re e o f 29 in fa n ts c o n -su m e d fo od ite m s o th er tha n c e rea l a s the irfi rst so lid food . T he p ro port ion o f g roup Iin fa n ts b rea s t-fe d a t 3 a n d m onths w as80% . F o r g rou p II in fa n ts p ro po rtion s w ere63 a nd 52 % a t 3 a nd 5 m on ths , re spe c tive ly .A c tiv itie s w e re no t co ns is te n tly h igh er du r-ing the m on ths a fter the firs t in tro du ction o fs tarc h -c o n ta in ing fo od s .

I n t h e g r o u p o f c h ild re n inv e stiga te d , nos ign ific an t e ffec t on g row th ra te c ou ld beob serv ed fro m th e in trod uc tio n o f starc h -c on ta in in g foo ds in to th e d ie ts o f ch il-d ren w ith low sa liv ary a-a m y la se . N eithe rc ha ng es in g ro w th ra te n o r e st im a te d v aria -tio n w ith ex pe cted g row th rate s w e re fo un dto b e d iffere n t be tw e en c h ild ren w ith h ig ho r low lev els o f a-a m yla se . N o effe c ts w e reobs e rve d wh e t h e r t h e s a mp l e wa s groupe da c c o r di n g t o hi g h o r l ow l e v e l s o f s a l i -v a r y a - amy l a s e a b o v e a n d b e l o w 5 0 , 3 0 , o r20 U /m l. F ish e rs e xa c t te st a nd M an n W hit-ne y U te s t w e re use d wi t h e a c h o f t h e t h r eeg r o up s s ep a r a t e l y .D is c us s ion

Th e f i n d i n g s a re ch a rac te rize d b y larg ev aria tio ns in th e a-a m yla se ac tiv ity o f thesa liv a in in fa n ts. T h e ac tiv ity le ve ls sho wtha t som e ind iv id ua ls h av e de v elo pe d a du ltlev els b y 3 m o n th s. T he rate o f inc rea se ina -a m y lase ac tiv ity ap pe are d t o s l o w d o w nf r o m t he 3 r d mo n t h o n . Ro s s i t er e t a l 1 7fo un d a s im ila r re la tion sh ip be tw e en th eac tiv ity le ve ls o f s tim u la ted sal iva at th e 3 rda n d 6 t h mo n t h . Al t h o u g h Ross i ter e t a l 1 7

u se d a d iffere n t m e tho d fo r en zy m e assa y , ita p pe ars tha t a fter c onv e rs io n , th e m e a n a c -t iv it ies re po rte d a re o f co m pa rab le m ag n i-tud e to th ose fo un d in th is s tud y fo r tho se 2m on ths a nd fo r v alue s a t b irth .

A w ide v aria tion o f saliva ry a-a m yla selev els b etw e e n in d iv idu als ha s be e n fou ndfo r ad u lts as w ell a s fo r in fan ts (1 5 , 17 , 18 ).U n de rs tan d in g th is v aria tio n c ou ld be use fu lin fo rm u la tin g a dv ice o n the in trod uc tio n o fs ta rc h -c on ta in in g foo ds in to the in fan t d ie t.O n ly tw o re la t ion sh ip s e xp la ine d v aria tio nsin a-a m y la se a c tiv i ty in in fan ts . A c tiv itie sw e re h ig he r in o lde r c h ild re n an d a ctiv itie sw e re h ig he r in c h ild re n w ith h igh er bo dyw e ig h ts . H ow e ve r, a ge an d w e igh t w ou ld beh ig h ly c o rre la ted in an y h ea lth y g ro up ofin fa n ts a nd the e ffe c t o f e ithe r is d iffic u l t tosep ara te . In the g rou p s tu d ie d , ag e a c co un tedfo r 4 2% of v aria tio n ob serv ed , w he rea sw e ig h t a c co un ted fo r 2 7% . F u rthe rm o re nos ign ific an t re la tio nsh ip w a s fo un d b e tw ee na-a m yla se a c tiv i ty an d eithe r a bso lu tew e ig h t o f the in fan t o r m o n th ly inc rea se inw eig h t . A g e the refo re a p pe ars to be the on lyfac to r c lo sely re la te d to the d ev elopm e n t o fa-a m yla se . H o w e ve r, the re la tio nsh ip is no ts tron g en ou gh to u se a ge a s a re lia b le m di-c ato r o f sa liva ry a-a m yla se lev els.

In flue nc e o f d ie ta ry c arb oh yd ra te o n thea-a m yla se c on ten t o f sa liv a in a du lts is un -c l e ar . Hi g h c arb oh yd rate d ie ts w e re a sso c i-a ted w ith in cre ase d a m y lo ly tic a ct iv ity insom e stu d ie s (1 9 , 2 0 ) b u t n o t in o the rs (2 ,21 a). T he in fa n ts in ve s tiga te d in th is s tud yd id no t sho w an y s ig n ific a n t po s itive re la-tio nsh ip be tw ee n sal iva ry a-a m y la se a c tiv i tya n d s ta rc h -c on ta in in g foo d in the d ie t. T h iss t u d y wo u l d s u p p o r t t h e c o n c l us i on o fD a w e s 2 2 t h a t t h er e is l ittle e v id en c e tosug ge s t tha t sa l iva ry a -a m y la se le ve ls ch a ngein resp on se to d ie ta ry c om po ne n ts.

In a de qu ate d ige s tion o f d ie tary c a rbo hy -d r a t e h a s be e n f o u n d t o b e a c a u s e o f fa i lureto th riv e an d se ve re d ia rrhe a in in fa n ts (1 ).S u c h re spo nse is in a ll c a se s a f u n c t i o n o fth e to ta l am ou n t o f c arb oh yd rate fed . D ev -iz ia e t a l (23 ) re po rte d th at 10 to 23 g ofs ta rch w a s ab so rb ed b y 1- a n d 3 -m o n th -o ldin fan ts w h en se rve d a s co ok ed flo u rs . S tarc hin th e a m o un ts o f 4 0 g /d ay o r 2 5 ta b lespo on sh as be en re po rte d to ca u se ferm en ta tived ia rrhe a (2 3 ). T h e a m oun t o f s ta rch fed d aily


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588 S E V E N H U Y S E N E T A Lto the in fa n t w ith sev ere g ro w th failu re re -p o rte d by L illib ridg e a nd T o w n e s (1 ) w a s 9 ,l7 ,an d7 0g fo r0 to l, lto2 ,an d2 to4m on ths , re spe c tive ly . T he h ig he s t lev e l o fstarc h fed in the p re sen t s tu dy w as ap p ro x i-m ately 3 2 g /da y to a 5 -m on th -o ld in fa n t.S in ce th e in trod uc tion o f s tarc h -c o n ta in ingfo od s h ad n o m e asu rab le effe ct o n g ro w th ,it se e m s th at the fe e d in g p rac tic es o f m o th ersin th is s tud y sup p lie d a m ou n ts o fs ta rch tha tca n be to le ra ted b y m ost in fa n ts . I t ha s be ensu gg es te d th at m a m m a ry am ylase m ay b eim po rta n t in ca rbo hy dra te d ige s tion o fb rea s t-fed in fan ts (6 ) a nd m ay h av e c on trib -u ted to th e to le ran c e sho w n b y the in fa n tsinves t igated.

S in c e som e in fan ts d o no t to lera team ou n ts o f starc h rec o rd ed he re in it is p ru -de n t to de la y the in tro du ction o f s tarc h -co n ta in ing foo ds in th e d ie t . C u rren t re c-om m e nd ation s , s ta tin g th at in fa n ts sh ou ldn o t re ce ive w ea n in g fo od s before 4 monthso ld , w o u ld ap pe a r to be a pp rop ria te fo r m ostin fan ts . I t se em s lik ely tha t in fan ts o f 3months or less do not produce sufficientam ou n ts o f sa liv ary a -am ylase to d ige s t e ve nsm all a m ou n ts o f s ta rc h . aR e fe re nc e s

1 . L illib ridge C B , T ow nes PL . P hys io log ic defic iencyof pancrea tic am ylase in in fan cy : a facto r in ia tro -gon ic d ia rrh ea. J P ed ia tr 1973 ;82 :2 79-8 2 .2 . G uy ton A C , ed . D iges tio n and abso rp tion in th egas tro in tes tina l tract. In : T ex tboo k o f m ed ica l ph ys-io logy . T oro n to : W B S au nders C o . 197 6 :816-19 .

3 . Z opp i G , A nd reo tti G , Pa jno-Ferra ra F , N ja i D M ,G ab urro D . E x ocrine p ancreas fun ction in prem a-tu re and fu ll term neona tes. Ped ia tr R es 1972 ;6:880-6.

3a. Husband J H usband P. Malhinson CN. Gastricemptying of sta rch m ea ls i n t he n ew bo rn . L anue t1970 ;2 :290-2 .

4 . H adorn B , Z op p i G , Shm erling D H , Prad er A ,M cIn ty re I, A n derson C M . Q uan tita tive assessm en tof exocr ine p an cr ea ti c f un ct io n i n i nf an ts a nd c hi l-dren . J P ed iatr 196 8 ;73 :39 .

5 . A g unod M , Y am agu ch i N , L opez R , L uhby A L ,G la ss G BJ . C orre lative study of hyd roch lo ric ac id ,

peps in and in trins ic facto r secretion in new bornsand in fan ts . A m J D ig D is 19 69 ;l4 :400-1 4 .

6 . H eitlinger L A , L ee P C , D illon W P , L eben tha l E .M am m ary am ylase : a po ss ib le a lte rna te pa thw ayof carbo hydra te d igestion in in fancy . Ped ia tr R esl983 ;17 :15-18 .

7 . M ason S . Som e aspec ts o f gas tr ic func tion in thenew b orn . A rch D is C h ild l962 ;37 :3 87-9 1 .

8 . Y ounosza i M K . G astro in tes tin al func tio n d uringin fancy . In : F om o n SJ , ed . In fan t nu trition . T o-ron to : W B Sau nders C o . 1 974 :95-108 .

9 . N utrition C anada . N a tion al su rvey . O ttaw a: H ea lthP ro tec tio n B ranch , H ea lth and W elfa re C anad a,1970.

9 a. D ev iz ia B , C iccim arra F , D ec icco N , A urricch ioS . D ig es tib ility o f sta rches in in fan ts and ch ild ren .J Ped ia tr 197 5;86 :50-5 .

10 . D aw es C . T he chem is try an d ph ysio log y o f sa liva .In : S haw JH , Sw eeney E A , C appu cino C C , M elle rSM , eds . T ex tbook of o ra l b io logy . T o ron to : W BSaund ers C o. 1978 :593-6 16 .

1 1 . Je lliffe D B . T he assessm en t o fthe nu tritiona l s tatu so fthe com m un ity . G en ev a : W H O , 1966 .12 . B ern fe ld P . A m ylases, a and fi In : C o low ick SD ,K ap lan N O , ed s. M etho ds of enzym o lo gy . N ewY ork , N Y : A cad em ic P ress , 195 5 :149-5 8 .

13 . S trum eyer D H . A m odified s ta rch fo r u se in am y-lase assays . A na l B iochem 1967 ;l9 :61 -71 .

14 . L ow ry O H , R oseb rough N J , Farr A L R anda ll R J .P ro te in m easurem en t w ith the Fo lin phen o l re -ag en t. J B io l C hem 195 1 ;1 93 :265-75 .

15 . B e llav ia SL , M o reno J , Sanz E , P icas E J , B lancoA . ct-A m ylase ac tiv ity o f hum an neon ate and ad u ltsaliva.Arch O ra l B io l l97 9 ;24 : 1 17-21 .

16. Dahlqvist A. A method for the determination ofamylase i n i nte st in al c ont en t. S ca nd J C li n La bI nv es t 1 96 2;1 4: 14 5- 51 .

1 7 . R o ss ite r M A , B arrow m an JA , D and A , W hartonB A . A m ylase con ten t o f m ixed s a li v a i n ch i ld ren .A cta Paed ia tr Scand 1974 ;6 3 :389-92 .18. Asset PJ Taylor F. A normal paediatric amylaserang e. A rch D is C hild l979 ;5 5 :236-8 .

19. Squires BT. Human salivary a mylase secretion inr e l at i o n t o d i e t. J P hys io l 1952 ; 11 9 :153-6 .

2 0. W es ley -H ad aj ia B Pi gn on H . E ffe ct of t he d ie t i nW est A frica on hu man s al iv ar y a my la se a ct iv it y.A rch O ra l B io l 197 2;17 :l4 l5 -20 .

21. Lieberman IS G ah ag an H , Yalich G Walden B.S aliv ary a my las e a ct iv it yi n S am oa n m ig ra nt s. E co lFo od N utr 1977 ;6 :107 .

2la. Behall KM. Kelsay JK Holden JM Clark WM.A m y lase and p ro te in i n s al iv a a ft er l oa d doses o fd i f fe ren t dietary carboh ydra tes. A m J C lin N utrl973 ;26 : 17-2 2.

22 . D aw es C . E ffec ts o f d ie t on sa liva ry secre tio n andc om po si ti on . J D en t R es l 97 0; 49 : 1 26 3- 72 .

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