Udall, JN Et Al (1984) the Tolerance and Nutritional Value

8/9/2019 Udall, JN Et Al (1984) the Tolerance and Nutritional Value

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h m erican Journal of linical N utrition40: AU G UST 1984 pp 285 292. Printed in U SA 1984 A m erican Society for Clin ical N utrition

28 5

The to le rance and nutritiona l va lue o f tw om icrofunga l foods in hum an sub jec tso n N U dall C liffo rd W Lo Vernon R Young and N evin S Scrimshaw

AB STRA CT The tolerance ofhum an subjects to tw o m icrofungal food products w as studied

in separate double blind cross over studies. A s an addition to the subjects usual diets cookies

with and w ithout 20 g of a product from u s rium gr mine r ium w ere fed to a group of 100

ind ividuals daily In a second study c upcakes w ith and w ithout 10 g of eciom yces v r iotiiw ere g iven daily to 5 individuals M ild rashes possibly related to one of the m icrofungal food

products occurred in tw o individuals fed varioti i xcept for decre se in serum cholesterol

during the gr mine r ium study no sign ificant changes were noted in I 7 serum constituents.

D uring nutritive value studies digestibility b io logical value and net protein u tilization were

calculated for the tw o m icrofungal pro teins and for m ilk. The values for m ilk w ere 95 85 and

80 respectively . The values for gr mine r ium w ere 78 84 and 65 respectively. For v r o t

corresponding figures w ere 81 67 and 54 . O n the basis oft s r s u l t s

b oth m ic ro fu ng lfoods m y be deem ed s fe for hum n consum ption t the levels testedm J lin N uir

I 984;40:285-292.

KEY W OR DS M icrofungal food , single-cell pro tein, novel food , nu tritive value

Introduction

W ith increasing pressure on the w orlds

agricultu ral and fishery resources from anexpanding population, the search for newand abundant protein sources fo r hum anconsum ption has turned to single-cell pro-teins. S tud ies of their nu tritive value in ex-perim ental and farm anim als indicate themto be a source of pro tein, com parab le tocasein , and of higher quality w ith addedm eth ion ine 1 -3 . In hum an feeding trials,how ever, bo th bacterial 4 and yeast pro-teins 5 have often been associated w ithadverse side effects. G astro intestinal sym p-tom s have been observed w hen som e m icro-

b ial pro teins w ere consum ed in am ounts aslow as 10 g/day 6 . R ashes have also been

associated w ith the consum ption of m icro-b ial pro teins 7 . M oreover, the relativelyhigh purine con ten t o f sing le-cell organ ism sresu lts in increased blood and urinary uric

acid in indiv iduals ingesting them in sign if-ican t am ounts 8 . P rocessing to reduce theR N A content so lves th is p rob lem 3, 9, 10 .

There is only one published report of theacceptability and nutritional value of a m i-crofungal food product. A novel food fromthe hyphae of the m ushroom , Polvporus

squamosus 64 produced in subm erged cu l

tu re in ulgaria has been fed to farm anim alsand hum ans w ithout adverse side effects 1 1 ).

The to lerance and nutritional value of tw o

sim ilar m icrofungal proteins fo r hum ans are

the basis of this report. B oth novel pro teins

w ere ex tensively studied in anim als beforethe hum an stud ies 12-14). There w ere nosigns oftox icity or carcinogenicity associatedw ith the use of these novel foods in experi-

m ental anim als. A nim als thrived and gainedw eight w hen fed d iets that con tained up to

40 w /w ) m icrofungal products 12- 14).

T he hum an stud ies w ere approved by the

I From the D epartm ent of Nutrition and Food Sd-

ence and the Clinical R esearch Center, M assachusettsInstitute of Technology, Cam bridge, M A 02139.

Supported in part by the N ational Institute ofHealth/General Clinical R esearch Center Grant 5M O l-RR00088-20, by Ranks Hovis M cDougall L td . H igh

W ycom be, England and by Tam pella Process Engi-neering Co, Tam pere, F inland.

3 Address reprin t requests to: John N U dall, M D,C lin ical R esearch Center, 50 Am es Street, M assachu-setts Institute of Technology, Cam bridge, M A 02142.

Recip ien t of a C lin ical Associate Physician Aw ard S M O l -R R 00 08 8- 20 ).

Received Septem ber 26 , 1983.A ccepted for publication February 28, 1984.


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28 6 U DA LL ET A L

C om m ittee on the U se of H um ans as Experim ental S ub jects and the Execu tive andP olicy C om m ittees of the C linical R esearchC enter of M assachusetts Institu te of Technology

M aterials and m ethods

The nature and intent of each study w as explainedthoroughly to participan ts and a consent form wassigned by each ind ividual A careful m edical histo rywas obtained follow ed by a com plete physical exam ination T he to lerance and nutritive value stud ies w ereunder the superv ision of a physician w ho was availab leto evaluate any sym ptom s that occurred Participantswere asked to keep personal diaries and to record anyunusual sym ptom s D ata from the stud ies w ere analyzed using both paired and sam ple tests 15 .

To lerance studies

ubjects A total of healthy adult vo lunteers

participated in the u s rium gr mine rium protein FGP study and 50 in the ecilom yces v riolii protein PVP study. The m ean age, w eigh t, and height ofsubjects participating in each study are show n in Tabk

tu y esign Participants in the studies rem ainedon their usual diets and went about their custom aryactiv ities during both study periods. Each study lasted67 days and fo llow ed a double-b lind cross-over design Fig I . For 30 days each, subjects ingested either acontrol food or an experim ental m icrofungal food. Thefoods w ere eaten daily at the M assachusetts Institute ofTechnology research k itchen 5 days/w k. Subjects w eregiv n r tion of either the control or the m icrofungalfood to take hom e for Saturday and Sunday.

Initial assignm ent to the control or experim entalfood period w as random . After the first 30 day period

the control or experim ental food was stopped for 1 wkbefore subjects were changed over to the alternativefood. The foods were coded in such a way that neitherthe physicians nor the subjects knew w hether a participan t w as receiving the control or the m icrofungal preparation.

iets The first study w as conducted w ith FO P pro-duced by Ranks Hovis M cDougall L td . H igh W y-

TA BLE 1

com be, England , and com m ercially available as M yco-pro tein. FG P w as produced by continuous ferm entationon a m edium of com m ercial g lucose syrup, treated toreduce the nucleic acid content and dried . The productcontains 54 . 1 p rotein N x 6 .25) by w eigh t 43.7true protein), 14 .9 fiber, 5 .8 m oisture, 6.1 ash ,and 1 .0 ether ex tract 12). The am ino acid com posi-tion of FOP is shown in Table 2 . It was fed in experi-m ental cookies each containing S g of FG P 2.7 g ofprotein) or o therwise identical cookies without theadded FO P. Subjects ate two cookies each m orn ing

between 9:00 and 10:00 AM and two cookies in theafternoon between 4:00 and 5:00 PM . Therefore, par-ticipants consum ing the experim ental cookies ingested20 g ofFG P per day .

For the second study, PV P was produced by Tam -pella Process EngineeringCom pany, Tam pere, F inland,on an energy substrate of the spen t liquor of a sulfitewood pulp ing m ill 13, 14). The product is an alm ostodorless, cream -colored powder that is 55.9 proteinby weight 4 6.2 true protein ), 28.6 n itrogen-freeextract, 8.8 crude fiber, 5 .6 ash , and 1.1 ether

extract 13 , 14). It is com m ercially available as Pekiloprotein and was not treated to reduce the nucleic acidcontent. The am ino acid com position of PV P is show nin Table 2. A com m ercial cake m ix w as used in theM assachusetts Institute ofTechnology research kitchento prepare m uffins with and w ithout 10 g of PVP 5.6g of pro tein). Subjects ate one m uffin a day.

p ecim en collection Blood specim ens obtained dur-ing each of the tw o tolerance stud ies were draw n be-tween 8:00 and 9:00 AM after an overnight fast. Four25.0-m l venous b lood sam ples w ere taken from eachparticipan t during the FG P study. O ne sam ple wasobtained before and after each ofthe two study periods F ig 1 . Three venous blood sam ples w ere obtainedduring the PVP study . One sam ple w as drawn beforethe initial 30-day study period, a second sam ple afterthis period, and the third at the term ination of the

second 30-day period F ig 1 .The concentrations of 1 7 serum constituen ts w ere

m easured: g lucose S igm a Bulletin 635, S igm a Chem i-cal Co. St Louis, M O , b lood urea n itrogen B UNH yland U N-Test Reagent K it, Hyland Division Tray-

enol Laboratories, Inc. Costa M esa, CA , sodium and

potassium analyzed on an IL 443 flam e photom eter,Instrum entation Laboratory, Inc. Lexington , M A , cal-

Characteristics of subjects participating in m icrofungal feeding studies m ean and range

tu y N o sex ge t t

T k rn

Tolerance S tudiesFG P 50/F 23.7 18-59 62.0 43-86 1 67 1 53 -1 78

50/M 22.6 18-40 72.0 56-88 177 160-195PV P 25/F 25.6 18-53 61.0 45-80 160 156-178

25/M 22.2 18-30 72.0 51-97 179 160-196

Nutritive value stud iesF G P 1 3 / M 1 9 . 9 1 8 - 2 5 7 3 . 0 5 9 - 8 6 1 8 0 1 6 9- 1 87

PV P 6/M 20.3 18-22 66.0 60-75 175 163-186

a W t and ht of subjects ob tained during the physical exam ination before each study .


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D A Y

T O L E R A N C E S T U D IE S

7

O N T R O

r rJ3

O N T R O

O N T R O O N T R O

_y_

67

7

D A Y

7 F GP 6f 2W FG P M E T H 11

t {188} 6M L

M IC R O F U N G A L F O O D 8

Y

N U T R IT IV E V L U E S T U IE S

I

D Y P R O T EIN N IT R O G E N L O O D

F R EE P E R IO D L N C E S M P L E

P R I O

FIG I. Experim ental design of m icrofungal tolerance and nutritive value studies. Subjects crossed over to thealternative food con trol or experim ental after the in itial 30 days ofthe tolerance studies. Physicians and subjectsw ere not aware ofwhich food w as being taken during the 60-day periods, and assignm ent to treatm ent groups w asrandom . Each nutritive value study began w ith a protein-free day. Blood sam pling and nitrogen balance periodsa re d es ig n at ed .

TA BLE 2Representative am ino acid com positionm icrofungal products gil 6 g N of the tw o

FGP 12 PVP I3

IndispensableC ystine 0 .73 0.77Iso leucine 4 .31 4.12Leucine 6 .96 6.49Lysine 7.24 6.33M eth ionine 1.92 1.52Phenylalan ine 3.73 5.78Threonine 5 .24 4.14V aline 5 . 1 1 4.93Tyrosine 3 .4 1 3.49Tryptophan 1.83 1.88

DispensableA lanine 8 .52 5.78A rginine 6.11 6.10A spartic acid 9.80 8.09Glutam ic Acid 14.32 10.82Glycine 4.83 4.37H istadine 3.25 1.89Proline 5.38 3.81Serine 4.74 3.94

S Calculated from a protein N x 6.25 content of43 .7 g/lOO g dried product.

cium Technicon M ethod no SE-C OO 3FJ4, TechniconInstrum ent Corp , Tarry town, NY , phosphorus Tech-nicon m ethod no SE4-0004FH4 , u ric acid 16 , creat-m ine 17 , lactic acid dehydrogenase W orthing ton LPset SM 520093, W orthington Biochem ical Corp , Free-ho ld, NJ , alkaline phosphatase W orthington PN P set

SM 5 10072 , am ylase H arleco am ylase reagent set64191, Harleco, D ivision of EM Industries Inc, Gibbs-tow n, NJ I 8 , SO O T W orthington G PT setSM S10031 , SGPT W orthing ton G PT set SM 5 10046 ,total protein Technicon m ethod no SE4-0014FC4 ,album in Technicon m ethod no SE4-0030FD4 , cho-lesterol Enzym atic serum cholesterol determ ination byB oehringer-M annheim kit, 124087, Boehringer-M ann-heim Biochem ical C o, B rookfield, CT , triglyceride W orthington trig lyceride reagent set 27977 . In addi-tion, a com plete blood count and urinalysis w ere ob-tam ed. The urine co llected on each of the b lood sam -pling days w as tested for pH, g lucose, p rotein , ketones,and white and red blood cells.

u tri t ive v lue stud ies

ubjects Thirteen healthy m ale M IT students w ererecruited for the FOP nutritive value study and six forthe PVP study Table 1 . O ne subject RS participatingin the FG P nutritive value study presented aberrantresultsand therefore was not included in the calculationof the m ean values. Since variation in his daily creati-nine excretion w as excessive, it is likely that he w as notadhering strictly to the experim ental p rotocol.

tu y esign The 48 day FG P study w as divided


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28 8 UD A LL ET AL

in to three 16-day dietary periods: FGP, cow s m ilkprotein, and FGP plus m eth ionine. Tw o dietary se-quences w ere used: FG P-cows m ilk-FG P plus m ethio-nine or the reverse Fig 1 . Subjects were enrolled inthe study in tw o phases; four in itially started the study,follow ed several weeks later by the rem aining nineind iv iduals. The PV P study lasted 1 1 days; there wasno cows m ilk period F ig 1 . Each dietary period w asbegun after a 1-day protein-free period to accelerateadaptation to the dietary period 19 . Subjects werew eighed daily.

iet The sole source of dietary pro tein during thenutritive value stud ies was either FGP, cow s m ilkprotein , or PVP. There were tw o experim ental pe-riods in the FG P study in which participan ts took eitherFG P or FO P w ith 1 methionine supplem entation.

The ingred ien ts of the liquid form ula diet used inthese studies are show n in Table 3 . The subjects con-sum ed their diets as four equal m eals at 8 to 9:00 A M ,12 noon, 5:30 to 6:30, and 9 to 10:00 PM . A vitam in

tab let w as given to each subject daily One-A-D ay tab-let, M iles Laboratory Inc. E lkhart, IN ) and one m ineraltab let and tw o choline bitartrate tablets Plus Products,Irvine, C A) were given to m eet U S National A cadem yof Sciences/N ational Research Council recom m enda-tions 20) T ab le 4 .

In the FG P study, the total protein intake during thetw o experim ental phases FGP and FO P plus m ethio-nine and the control pro tein phase cow s m ilk w as0 .30 g protein/kg body w eight/day. In the PVP study,pro tein intake w as 0.35 g protein /kg body weigh t/day.

TA BLE 3C om position ofthe liquid form ulas used in the FG Pand PV P nutritive value studies am ounts in g/day for70-kg reference m an

DietIngredient

OP ilk P V P

PVP 46.4FOP 45.7tD ried sk im m ilk 62.5Polycosef I 50.0D extri-M altose* 1 80.0 I 52.0C ornO il 130.0 130.0 115.0A vicel C ellulose)lI 3.0 5.0 5.0N aCl 1 .0 1.0 2.0C a10 O H)2 PO 41 2.0 0. 1 2.0K 2H PO 4 6.1 3.5 6 .1W ater 400.0 500 .0 450.0Lem on juice 5.0Pure vanilla 10 .0 To enhance m ixing and palatability properties,

PV P w as com bined w ith 200 m l w ater boiled for 7 m m ,cooled , and w ater replaced to 200 m l and blended withother ingred ients. FGP and sk im m ilk pow ders were

m ixed directly w ith the o ther constituents.t In the m eth ionine supplem ented FOP diet, L-m e-

thionine w as used at a level of 1.0 g/l { 174}g of FGP lOOg o f p ro te in ).

R o s s L a b or a to r ie s C o lu m b u s O HM en d Jo hn so n L ab ora to ries E va ns ville IN

D onated by FM C C orporation, Food and Phar-m aceutical Products D iv ision, Philadelphia, PA .

TA BLE 4Ingredien ts of vitam in and m ineral supplem ents g ivenduring the nutritive value studies

One-a-D ay tablet 1 each day)Vitam in A 5000 IU

Vitam in E 15 IUVitam in C 60 m gFolic acid 0.4 m gThiam in 1 .5 m gRiboflavin 1.7 m gN iacin 20 m gV itam in B 2 m gV itam in B12 6 gV itam in D 400 IUPantothenic acid 10 m gIron elem ental) 18 m gC alcium 100 m gPhosphorous 100 m gIodine 150 m EqM agnesium 100 m gCopper 2 m gZinc 15 m g

Trace m ineral capsule 1 each day)M gO 398 m g M gCuC l2 . 2 H 2O 2 m g CuM nSO 4.H2O 1.66 m g M nN a2 M oO 4 .2H 2O 0.083 m g M oCr SO 4)3 1 5 H 2O 0. 168 m g CrN a2SeO3 0.100 m g SeAISO 4.12H 2O 1.61 m gAlK I 0 .29 ng I

Choline bitartrate 2 each day) 250 m g choline/tablet

Energy need w as determ ined for each subject accord-ing to d ietary h istory and an estim ation ofdaily activity .This procedure had been fo llow ed previously, usuallywithout the need to adjust energy intake during theconduct of 60- to 80-day studies. A dditional energyin take was provided when necessary by protein -freebiscuits, desserts, and soft d rinks.

p ecim en co llection Four venous blood sam plesw ere taken during the FG P study. The first tw o weredraw n just before and after the first 16-day period. Theother tw o were obtained at the beginning and end ofthe third dietary period Figure 1 . Tw o venous bloodsam ples w ere obtained during the PVP balance study ,at the beginning and at the end of the 1 1-day period .A ll sam ples w ere draw n betw een 8:00 and 9:00 Mafter an overn ight fast. The sam e blood tests w ereperform ed asdescribed for the tolerance studies. A urinespecim en for routine urinalysis was also obtained oneach ofthe blood sam pling days.

A 24-h urine sam ple w as taken 1 w k before each

m icrofungal study for determ ination of urea nitrogen,uric acid, and creatin ine 21 . In addition , com plete 24-h urine and fecal collections were m ade throughout thestudy and tested for the sam e constituen ts 21 . Daringthe FG P study, fecal sam ples w ere co llected and pre-pared as pooled sam ples for the last 10 days ofeach 16-day period F ig I . For the PVP study , fecal sam pleswere collected for the last 7 days of the 1 1-day period.


5/8

M IC RO FU N GA L FOO D 28 9

A fecal m arker carm ine dye w as used to define thecollection periods 22 . A liquots of the experim entaldiets and of the pooled fecal sam ples w ere taken fortotal nitrogen analysis.

A ssessm ent of protein quality param eters w as m ade

according to conventional procedures 23, 24 . Thus,total urinary and fecal nitrogen losses were correctedfor m etabolic urinary and fecal nitrogen and subtractedfrom ingested nitrogen. Digestib ility w as the percen tageof ingested nitrogen absorbed, biological value the per-cen tage of absorbed nitrogen retained, and net proteinu tilization the percentage of ingested nitrogen retained.

Results

o le r n ce siu d ie s

O ne hundred ind ividuals consum ed contro l and m icrofungal p rotein contain ingcookies during the FO P study. N one of these

indiv iduals had any gastroin testinal reactions or skin rashes that cou ld be ascribedto ingesting the experim ental m aterial. M inor com plain ts recorded in the d iaries ofseveral indiv iduals but no t m entioned to thestaff w ere judged to be unrelated to them aterial ingested .

W ith one exception no significant

changes w ere observed in blood tests perfo rm ed before and at the end of the controland experim ental FO P feed ings. The exception w as serum cholestero l that decreasedsignificantly during the 30 day FO P periodfrom a prefeed ing m ean value of 188 m g/d l

to a postfeeding m ean value of I m g d l p 0.001 .

A ll but tw o of the 50 subjects com pletedthe 67-day PV P study . O ne indiv idual a 5

yr-old w om an, com plained of severe head-aches after 2 1 days of consum ing m uffins.These headaches continued for 4 days andthen subsided spontaneously . A fter the 7-day m uffin-free interval she w as started onthe other m uffins. This tim e she com plainedofabdom inal d iscom fort and nausea w ithina day and her com plain ts con tinued for 2w k. A t th is tim e she w as dropped from the

study. The relationsh ip of her sym ptom s to

the tw o dietary phases w as know n only aftershe stopped eating the m uffins and the studycode w as broken. It turned out that the firstphase w as the con trol and the second theexperim ental period .

A nother fem ale sub ject noted m inorrashes on her righ t elbow , low er leg , and

buttocks on the 1 5 th day of w hat laterproved to be the experim ental period . T hesew ere described by the exam in ing physician

as sm all, nonpruritic , evanescent m acules.

B y the nex t m orning they had d isappeared .The rash reappeared on the 20 th day , and 3

days later she w as told to d iscontinue takingthe m uffins. The cu taneous reaction clearedafter 1 w k. She w as started on the m uffins

again and com pleted the 30-day trial. O nthe 30 th day she developed sm all, p ru ritic ,m acu lopapular lesions on her left forearm ,right shou lder, and right calf. A t her requestshe w as dropped from the study before the

cross-over to the con tro l m uffin .A t the end of the PV P to lerance trial, all

the d iaries w ere co llected and it w as notedthat som e ind ividuals had recorded m inor

sym ptom s that they had not reported to theresearch dietician or physician . F ifteen ofthe 50 sub jects m entioned m ild, transien t

gastroin testinal sym ptom s nausea andbloating during one of the tw o 30-day pe-

nods. O nly six of these w ere receiv ing theexperim ental m uffins at the tim e the corn-plaint w as no ted in the diary . Sym ptom s

w ere recorded as early as the 1st day and aslate as the 30 th day of the study periods.

A nalysis o f b lood and urine sam ples ob-tam ed before and after the first feeding pe-riod and at the end of the second periodshow ed that all values rem ained w ith in nor-m al lim its fo r each of the 50 subjects.

N u tritive va lue stud ies

G P The w eights of the sub jects re

m ained relatively constan t during the study

The m ean w eigh t SD of subjects onthe 1st day of the F G P milk and FO P plusm ethionine periods w ere 69 .9 8 7 7 1 2

8 1 7 8 7 4 re sp ec tiv ely T he m eanweight SD of subjects on the last dayofeach study period w as 70 .5 8.7 72.3 8 6 an d 7 7 7 .4 respectively. D uring thefirst d ietary period tw o subjects w ere

dropped from the study ; one on the 5th dayand the o ther on the 1 lth day for reasonsnot directly related to ingestion ofFG P. O ne

of these indiv iduals had an acu te in fection;the other sub ject asked to d iscontinue participation because of the dem anding regim en. The rem ain ing 1 1 subjects com pleted


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U D ALL ET A L

TAB LE 6BU N m g N /100 m l ofyoung m en in the FGPnutritive value study

TA BLE 7

Estim ates ofthe nutritive value of PV P in young adultm en

TA BLE 5Estim ates of the nutritive value of FG P in young adult

a Digestibility.

t B iological value. N et protein utilization .For calculation of B V and NPU , obligatory urine

and fecal N losses w ere taken to be 37.2 and 8.8 m g N/kg body w t/day 35 .

29 0

the first, second , and third study periodsw ith no significant com plaints.

The resu lts of the calculations of digesti-bility, b iological value, and net pro tein u ti-lization are sum m arized in Table Them ean digestib ility b io log ical value and netp rotein utilization for the group of 10 m div iduals taking 0.30 g of FO P per kg bodyw eight/day w ere 78 84 and6 respectively

The m ean digestibility bio log ical value andnet p ro tein utilization for the group of 10indiv iduals on 0 30 g /kg/day of the skimm ilk form ula w ere9 8 and 80 respectively . The d ifferences in digestibility andnet pro tein utilization w ere statistically sign ifican t by paired test n lysis p 0.001but the b iological values w ere sim ilar. A salso show n in Table m eth ion ine supple-

m entation did no t affect digestibility butresulted in sign ifican tly im proved b iologicalvalue and net pro tein utilization p 0 05

W ith the excep tion of the B U N , all blood

and urinalysis tests rem ained norm al duringthe three phases of study. T he B U N de-creased sign ifican tly Tab le 6 in all th reed ietary periods p 0 00 1 com pared w ithinitial v alues

V F ive of the six sub jects com pleted

the day nitrogen balance study and there

m en

Subject

Protein

FO P

t Ut

lk

B N P U

F G Phioni

{ 49}V NPU

V D

E A

R C

K D

M C

R M

D R

W R

W i

D D

8

7 9

5 7

7 8

7 8

7 5

9

7 3

95

69

83

7

74

75

9 9

8

9

87

52

89

6 6

85

4 2

59

77

6

82

6 4

4 9

6

9

98

87

94

92

88

97

99

9 3

9 8

9 3

7 4

99

8

8

93

62

7 7

85

96

8

7

9

7

82

9

62

76

7 9 7 8 5

8 3 9

6 3 9 5 7

7 8 9 4 7 3

8 9 9 8

8 9 2 7 5

7 8 8 2 6 4

8 2 9 7 4

9 5 5 5

8 9 6 7 8

e n

79 9 7

7 6

Subject nit ialvalue

inal v lu

P M Ik G P

methionine

V D 1 5 0 6 0 4 0 4 0EA 16 0 4 0 8 0 2 0RC 17 0 5 0 4 0 5 0K D 14 0 6 0 3 0 7 0M C 16 0 7 0 8 0 4 0RM 16 0 4 0 6 0 4 0D R 11 0 5 0 7 0 4 0W R 19 0 5 0 4 0 3 0W i 1 3 0 6 0 6 0 6 0D D 14 0 4 0 6 0 6 0

M ean 15 1 5 2 5 6 4 5SD 2 2 1 0 1 8 1 5

Subject D t PU

SL 87 55 48

D B 8 7 56

E H 86 79 68

A N 77 37 9

JK 78 93 73

C C 7 6 6 9 5

M ean 8 67 54SD 5 9 6

a Digestibility

t B io lo gical valueet pro tein utilization

V alues calculated on 3 day sam ple.For calculation of B V and NPU obligatory urine

and fecal N losses w ere taken to be 37.2 and 8 .8 m g N /kg o y w t/day 35 .

w ere no sign ifican t changes in body w eights

of these subjects during the study in terval.The w eigh ts S D on the 1st and last dayofthe study w ere 66 4 5 7 and6 8 9

kg, respectively. O ne subject C C , becauseof nausea, asked to term inate the study onthe 9th day. T he o ther five subjects corn-p leted the entire study , and none of therem ain ing ind iv iduals com plained of anysym ptom s to the superv ising physician or

d ietician . T w o subjects, how ever, recordedin their diaries that they had occasional m ildnausea.

A s can be no ted in Table 7, the m eandigestib ility , b iological value, and net pro-tein utilization w ere 8 1, 67, and 54 , respec-tively; values no t sign ifican tly d ifferen t from


7/8

M IC RO FU N GA L FO O D 291

those of FO P. H ow ever bo th b iologicalvalue and net pro tein utilization of PV Pw ere significantly low er p 2 an d

0 05 respectively by tw o s m ple testw hen com pared to FO P supplem ented w ith

methionine.M ean serum B U N in blood obtained be

fore the start o f the PV P nutritive valuestudy w as 1 2.8 m g N /tO O m l and the finalB U N w as 6.2 m g N / 1 00 m l p 1 e nserum uric cid of sub jects before the studywas l .2mg/l00ml SD)and9.2 4 m g m l at com pletion of the study p

0 .001). The other initial blood and urinetests w ere not significantly different fromfinal v alues.

Discussion

The tw o m icrofungal foods stud ied w erew ell to lerated. N one of the 1 1 3 individualsw ho consum ed the FO P product had even a

suggestion ofan adverse reaction . Tw o of 56sub jects taking P V P had m ild sym ptom sthat m ay have been due to the supplem ent.A dverse reactions to accepted foods havebeen estim ated to occur in 1 to 4 o f thepopulation 25). Therefore, w e conclude thatthe tw o m icrofungal p roducts w e stud ied arew ell tolerated and that the likelihood of ad-verse reactions to these products is no greater

than w ith m any com m on foods.

There w ere changes in several serum com -ponen ts noted during the to lerance and nu-tritive value studies. C holestero l decreasedslightly but significan tly during the FO P tol-erance study although not during the P V Ptolerance study. A nim als fed FO P have a

decrease in serum cholesterol 26-29). Th iseffect m ay resu lt w hen cholestero l excretedas bile acids in to the sm all intestine is ad-sorbed to the FO P, blocking reabsorp tion ofthe b ile acid and decreasing the cholesterolpoo l 26).

N ineteen subjects w ere m onitored m oreclosely bu t fo r shorter periods oftim e during

the nu tritive value studies. B U N decreasedin the F O P and PV P nutritive value studiesas expected because, by design, the ind ivid -

uals participating in these studies w ere all innegative n itrogen balance.

Serum uric acid increased significantlyw ith the in take ofthe PV P during the nutri-

tive value study from an initial value of

m g/dl to a final value of9.2 m g/d l. This justexceeds the upper lim it fo r the norm al adultm ale 3.9 to 9 .0 m g/dl). P V P contains 8nucleic acid. U nlike the FO P it is not nucleic

acid reduced . Therefore, a 70-g referencesub ject consum ing 0.35 g of P V P bodyw eight/day w ould ingest 24 .5 g of PV P/dayw hich is 8 nucleic acid. That individuals

daily in take of nucleic acid w ould be 2 .0 g /day , the m axim um recom m ended daily in-

take of nucleic acid 30).T he daily consum ption of add itional nu-

cleic acid by subjects during the FO P nutri-tive value study w as m uch less, and as antic-ipated, d id not significantly increase serumuric acid. These results confirm the need toreduce the nucleic acid content of m icrofun-

gal pro teins, ifthey are to be used as a m ajorpro tein source in hum an diets. It is no tnecessary, how ever, if they are to be used as

a food additive, as long as the add itionaldaily nucleic acid from th is source does notexceed 2.0 g 30). This lim it w ill m ain tainserum levels of uric acid w ith in acceptab lelim its for norm al sub jects and m in im ize the

risk of deposition of urate crystals in k id -neys, jo in ts, and other tissues.

The d igestib ility of both m icrofungalp roducts w as approx im ately 83 that o fcasein . This low er value m ay be due to thepoorly d igestib le cell w alls 3 1 The digesti-

b ility values are sim ilar to those ob tained byothers fo r yeast, bacterial, and algal p roteins 2 , 3, 32, 33 . The bio log ical value and netprotein utilization data fo r bo th m icrofungalfoods are also sim ilar to those ob tained byothers in hum an balance stud ies of m icro-

b ial p roteins 2, 3, 32-34 .The results of these stud ies ind icate that

bo th m icrofungal foods are accep tab le andnutritious for hum an diets. F O P can be used

as a m ajor protein source in the form tested .P vP is suitab le as a food add itive, but as am ajor protein source it w ould need to beprocessed to reduce the nucleic acid conten t.

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Documents

Udall, JN Et Al (1984) the Tolerance and Nutritional Value