Am J Clin Nutr 1994 Young 1203S 12S

Plant proteins
in relation
to human
and amino acid nutrition1’2
Vernon

R Young

and

ABSTRACT

Plant

capita

supply

North

American

quirements,

and

acids

for

review

cerning
tion

amino

acid
protein

of

a list

of some

professional

and

1994;59(suppl):

quality.

Mixtures

of

plant

generally

the

fruits,

amino

acid

of

re-

plant

source
realities

con-

protein

and

human

nutri-

to the

Am

consumer.

J

C/in

Nuir

l2S.

KEY

WORDS

mentation,
score,

Amino
nutritional

timing,

acids,

requirements.

quality,

digestibility,

nitrogen,

limiting

protein,

balance,

(Table
35%

However,

there

amino

acid,

from

lysine

Far
Introduction

East,

are the predominant

constitute
tein,

a primary

essential

production.
always

supplied

intake
major

century

we
have

deletion,

will

be

to

of

encoding

value

of

way

the

that

plant

foods

have

to reduce

course
before

directly

or

grains,

risk

the

of chronic

has

the

be

amenable

been

to ef-

For

these

of plant

food

reasons
proteins

Quantitative

of major

plant

Throughout
for

history,

food

commercial
depends
Am

J Cli,z

and

at

humans
least

purposes.
on
Nutr

approximately

I 50

However,

have
species
most

20 different

1994:59(suppl):1203S-l2S.

used

of the world’s
plant
Printed

plant

spe-

cultivated

crops,
in USA.

©

of
direct

and

plants

provide

cereal

grains,

world’s

food

animal

products

of food

protein.

in per

capita

between

data

lower

the

protein

developed

example.

(Table

lysine.

is constant

levels

Indonesia.

in North

for

for

In the

3) show

estimated

ofintake
amino

across

all

mdiStates,

the

contri-

protein
as

ofthe

intake
a whole.

indispensable

acids,
age

many

that

population

sulfur

protein.
of the

United

daily

the

3 is the pattern

acids

cereals
use

threonine,

and

groups.

production
involves
protein
of plants that

and

as

benefits

legumes

foods

for

of this

aspects
of

a potential
loss
could otherwise

used

humans.

shift

for

feed

and

to

Furthermore,

in the

the

composition

increase
potential

of human

diets

diets

of plant
based

foods

and

on

plant

mainly

the protein

nutritional

sources

deserve

ad-

our

con-

sideration.

From

Massachusetts

are

613,

American

subjects

the Clinical

School

Cambridge,

2

the nutritional

of human

for

1994

much

of India

survey

which

equacy

population
which

of the

I ; ref 6). For

approach

areas

amino

health

I

3000

been

(Table

and

crops

some

have

portion

sources

groups

tion,
cies

The

availability

protein

is ‘30%
for all age
Also shown
in Table

needs

importance

and

may

by

To assess

nutrition.

capita

to the

nutritional
as a

basis,

hand,

plant

approximate

have received
considerable
attention
in recent years and this topic
was also a major focus of interest
at the Congress.
Therefore,
the

contribution

recommended

(5).

role

the

in-

either

their

protein.

discrepancies

protein

their

genes
that

per

marked

from

but

On the other

plant

amounts

un-

of

a substantial

regions

made

the

legumes,

be used to meet human
needs,
it has been a popular
view, and
one that was echoed
at the Second
International
Congress
on
Vegetarian
Nutrition,
to recommend
significant
reductions
in the

addition,

it is likely

increased

diseases

in brief,

( 1).
next

an increased

of edible

In part because
livestock
of the energy
and available

products

the

for

animal

tryptophan,

food

food

are derived

1. On a global

supply

of the

and

(essential)

have

the

regulation

will
an

of
crop

proteins

example,

its

history

turn

(2, 3). With

diets

of

and

to estimate,

in Table

consumption

bution

they

plants

by

and

and

bulk

Indeed,

indirectly,

Additionally,

to consider,

the

specifications

storage
for

energy

of human

organization
seed

(4).

the

the
that

market

in Western-type

it is pertinent

with

needs.

of genes

genetic

manipulation

in human

food

household

using,

tailored

for

foods

human

anticipated

responsible

of plant

pro-

for

of its protein

or modification

nutritional

minerals,

energy

therefore,

global

derstanding

fective

vitamins,

utilizable

in shaping
is

been

of carbon,
and

most

players
it

of solar

surprising,

the

and

Furthermore,
that

acids,

It is not

energy
been

resource

fatty

harvesters

that

difficult

are

in rural

food

grains

legumes),
nutrition,

animal
products
supply
70%
of the food
the equivalent
figure is ‘20%
for the populations

viduals

Plants

of protein
are

developing

America
whereas

acid

protein

human

cereal

2) and energy.

contribute

and

comple-

amino

supplies

are given

supplies

(including

of

legumes.

sources

protein

vegetables

context
are

65%
of the world
in particular.
account

health

cereals,

the

groups

world

animal

amounts

short

and

of concern

or

In

oil-seed

The

pro-

into

nuts.

important

cluding

of amino
This

divided
and

most

myths

issues

informed

per

discussed

requirements.

a series

nutritional

l203S-

in

are

well-balanced

between

32%

protein

human

physiological

a list

the relationship

and

of

ofthe

and

content,

and

human

with

‘65%

basis

sources

as a complete

meeting
ends

These

dietary

serve

contribute

a worldwide

Reprints

of
and

Research

Center

Science,
the

of plant
various

and Laboratory

Massachusetts

Department

of

proteins
conditions

the

we should

first

of Human

Institute
Human

in meeting

of

Nutrition,

Nutri-

Technology,
University

of

at Amherst.

not available.

Massachusetts

Society

role
under

for

Institute

Clinical

Address

correspondence

of Technology.

Nutrition

Cambridge,

to VR Young,
MA

EI8-

02142.

I 2035

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

can

foods

on

region.

to their

L Pellett

protein

of protein

in relation
teins

Peter

protein

12045

YOUNG

TABLE

AND

1

Energy

PELLETT

TABLE

and

protein

and economic

supplies

regions

per

capita

per

day

for

selected

geographic

3

Protein

for 1989’

consumption

(female)

Energy

Animal
protein

Carbohydrate

Total
protein

and

in the United

amino

Plant
protein

Region
Developing
Far East
Middle East
Africa
Latin America
Economic
class
Least

14

Age

61

group

Meat,

protein

Plant

(nitrogen)

This

and

gld

Protein
quality

joint

II

59

81

<I

42

27

55

59

69

31

40

17

78

78

6-8y

68

33

154

227

69

35

40

12

2363

(9.89)

72

12

58

79

19-22y

65

30

183

184

72

35

39

12

65

29

68

57

35-50y

65

29

191

169

71

34

39

12

59

32

48

190

68

34

38

12

2058

(8.61)

2409

(10.08)

74

11

3417

(14.30)

53

61

104

42

3457

(14.46)

51

60

103

42

3650

(15.27)

48

73

110

34

3240

(13.56)

50

66

98

33

67

25

71

65

data

76

(reference

9

52

y

y

58

for

been

the

specific

reviewed

to plant

81

us

(8,

of some

proteins

will

9)

were

protein,

and

others

important

‘

Based

2

Ly.

on US Department

stages

and evaluated

during

from
These

defined
eggs,
data

trogen
they

meat,
were

balance
reveal

maintenance

Organization,

FAOIWHO/UNU

and milk, are
derived
largely
studies

and,

decline

of adequate

2

Relative

importance
intake

when

an age-related

TABLE
capita

in the

for

protein

of various

for different
growth
and

expressed
in dietary

food groups

lysine:

Saa,

Total plant
Cereals
Pulses, nuts, oil crops
Starchy roots
Other vegetables
Fruits
Total animal

2277 (9 526)
1385 (5 794)

weight,

in average

Percent
of energy

needs

world

Total

2710(11339)

on FAO/Agrostat

%

Protein
g

84
51

46. 1
33.7

daily

per

Percent
of protein

65
47

5

2.0

3

2

2.5

4

65 (272)

2

0.8

1

16

25.0

35

71.1

100

data (reference

100

6).

Try.

amino

acids

ditions

(histidine,

isoleucine,

threonine,

and

tyrosinc,
specific

Data

(reference

for

conditionally

taurine,
physiological

leucine,

tryptophan,

and

arginine,
pathological

of two compoindispensable
lysine,

methionine,

valine)

indispensable

glycine,
and

tryptophan.

amino

under

all con-

acids

glutamine,
conditions

(cystine,

proline)
under
and 2) the re-

and porphyrins.
accepted
that

With respect
to the first component,
it is usually
the nutritive
values
of various
food protein
sources

are to a large

extent

ability

individual

of the

determined

efficiency

with

which

in support

of an

adequate

TABLE
4
Safe protein
Age group

by the

concentration

indispensable
a given
state

source

amino

acids.

of food

protein

of nutritional

intakes

as proposed

health

and

avail-

Hence,

the

is utilized
depends

both

in 1985 by FAO/WHO/UNU’
Males

8

Females2
gprotein

. kg’

. d’

3-6mo
6-9mo

1.85
1.65

1.85
1.65

9-l2mo

1.50

1.50

l-2y

1.20

1.20

1.15

1.15

3-Sy

1.10

1.10

S-7y

1.00

7-lOy

1.00
1.00
1.00

12-14y

1.00
1.00
1.00

0.95

14-l6y

0.94

0.90

l6-l8y
Adults

0.88
0.75

0.80
0.75

l0-12y

%

141 (590)
46 ( 192)
433 (1 811)

Consumption

requirement
for dietary
protein
consists
1) the
requirement
for the nutritionally

for

6.0

(456)

threonine:

Thr.

status.

4

109

Food

acids:

amino

The
nents:

2-3

kcal(kJ)

Based

protein

sulfur

quality
as those

1989’

Energy

‘

(FAO/

age groups.
metabolic
ni-

per kg body

nutritional

by a

the World

(1 1) report

given
from

the

recently

of Agriculture

7).

quirement
for nonspecific
nitrogen
for the synthesis
of the nutritionally
dispensable
amino
acids (aspartic
acid, asparagine,
glutamic acid, alanine,
serine)
and other physiologically
important
nitrogen-containing
compounds
such as nucleic
acids,
creatine,

protein

Health
Organization,
and the United
Nations
University
WHO/UNO)
(1 1). In Table
4, the safe intakes of high
proteins,

1 1)

here.

and

Agriculture

acids.
(10,

more

presented

at various

reviewed

pro-

amino

and

of the

be

requirements

for total

for total

indispensable

by

account

acid

of the Food

of requirements

12

83

6).

to the estimates

of humans,

panel

protein

67

requirements

life cycle

Png/g

Try

75

and amino
considerations

The

Thr

(12.34)

and

relevant

Saa

(10.25)

so an abbreviated

issues

Ly

2954

2710(11.34)

has

Grain
products

2450

attention

subject

poultry.

acids2

y

‘ Adapted
from reference
1 1 . Values
are uncorrected
for nutritional
value (amino acid scores) of mixed dietary proteins for infants and children and digestibility
for all groups.
2 Safe
protein intakes for pregnant
females,
intakes in table + 6g: for
lactating
females (0-6 mo), intakes in table + 17.5 g; and for lactating
females (6 mo), intakes in table + 13 g.

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

tein

groups

Amino

fish

gid

77

phenylalanine,
our

age

73

on FAO/Agrostat

turn

various

(11.91)

>75

developed

Based

g

for

2846

2732(11.43)

Low income
Developed
Western Europe
North
America
Oceania
World
‘

%

pattern

Proteins

Total
kca! (Mi)

acid

States’

PLANT
on the

physiological

acids

and

amino

acids

This

requirements

total

nitrogen

in the source

raises

pensable

the

acids

are extensive

data

on the
summary
sources

are

the

to be

shown,
the
much lower
than

are

lower
acid

and

Given
and

amino

these

animal

protein

acid

protein

in plant

of

with
score

of foods

protein

fruits

found

survey

of the

various

acid

value

example

is the

protein

efficiency

ratio

official

use since

first proposed

cedure

does

which

proteins

(see

ref

procedure

and

( 19) on protein

in I 946

by Block

lationship

between

of their

acid
and

amino

limiting

acid

Mitchell
acid.

The

or percentage

limiting

acid

portant

issue

pattern

to be used

lating

of

scoring
was

When

Block

the

of

many

subsequent

composition
determined

amino

scoring

systems

feature

of most

before

1985,

ergy and
reference

protein
amino

requirements
acid pattern

published

showed

that

the form
needed

needed

of indispensable
only

15%

or less

this

proteins

egg

un-

led

to the

as a basis

was published,
was used for

scoring

for

acid

requirement

w35%
amino
(1 1, 22).

of their
acids

whereas

systems

report
was
studies
data

total

25 ±

3

38 ± 3

12 ± 4

37 ±

S

32 ± 4

12 ± 2

Nuts, seeds

36 ± 3

17 ± 3

Fruits

45

46 ± 17
27 ± 6
38

29 ± 7

11 ±

Animal

foods

±

12

85 ±

9

44

‘ 1±
SD. Based on data from FAO (reference
of Agriculture
(reference
13).

1985

that
amino

generally
acids
apparently

in

FAOIWHOIUNU

quirements

in various

2

12

12) and US Department

estimates

age groups

US authorities
(10) are shown
purposes,
if the values
given
essential

amino

adults
would

acids

for

the

are

adult,

compared

pattern

of various

evident

that

much

(per

and

by

7) with

the

including

protein

amino

acid

it should

food

required.

in cereal

of

es-

of

sources,

in these

than

needs
for children
child pattern

unit

acids

acids,

lysine

protein

per

protein

of protein)

amino

proteins

5 and

animal

re-

for adults.
acid requirement

expressed

of amino

unit

of the indispensable
in soy

and

the amounts

higher

are

Tables

(see

plant

total

value of a protein
adoption
ofthe

of a protein
(1 1) amino

which

acid

proposed

7. For amino
acid scoring
7 for the concentration
of

to the

the nutritional
In contrast,

amino

the estimates

in Table
in Table

would
underestimate
the value
When
the FAO/WHOIUNU
timates

of the

and

in relation

were adopted,
be overestimated.

is

As a result,

all

the sulfur
proteins

be

sources
amino

are

ac-

predicted

to

be in considerable
excess
of adult needs.
Thus,
all usual
food
proteins
would
readily
meet and even exceed
the requirement
for
the indispensable
amino
acids, providing
that the dietary
protein
supply
was equal to or above
the safe protein
intakes
(Table
4).
On
reason

the above
basis it would
to be further
concerned

be concluded
that
with an assessment

tional
cluded

quality
of plant proteins
that our attention
should

in adults.
It could
also
be focused
on children

fants,

particularly

because

food

sources,
possibly
increasing
UNU

plications

roles

the
of

seeking

of

far

too

taken

for

most

in-

(9,

23,

24).

low

to further

substantiate

this

for the inadequacy

and would
and

protein
formula,
there
is

FAOIWHO/

estimates

the case

to be

plant

containing

number

international

are

strengthen

approaches
both

diets

be conand in-

have

of

important

im-

to comprehensively

animal

food

protein

assources

in

nutrition.
specifics

quirements

were

from

recent

more

of this

new

previously
data

estimates
for the amino
shown
in Table
8, and
made

current

in adults
are

would

given

requirement

recommendations

for

the

acids

be

a limited

there is little
of the nutri-

fed a diet of a proprietary
strained
foods.
However,

the
(10)

(25-27)

which

the international
sess

that

national

groups

or

infants
with

amino

might

source

evidence
(I I) and

dispensable

they

protein

for example,
supplemented

The

on en-

that a single
on all ages,

adults

protein

± 10
± 10
45 ± 14

human
acid

Tryptophan

31

evidence,

proteins

which

the FAO/WHOIUNU

Threonine

64

Several

the relatively

requirements

of the amino

when

amino

infants

of pro-

of egg

nutrition,

acid

reference

proposed

that
in

im-

(1 1, 21, 22).

proposed

despite

(20)

acids

Legumes

a single

or for calcu-

or mixture

acids

human

amino

and

acid

quality

Mitchell

acid

for

critical

protein

later

indispensable

protein

or reference

amino

It was

of human

A common

and

is defined
food

of the concentra-

amino

proteins

of estimates

of the

re-

the con-

score

in a standard

nutritional

for a food

a linear
and

in the

a particularly

choice

score

as a standard.

dervalued
use

the

acid

interest.

amounts

Hence,

for assessing

procedure,

used

high

(15).

becomes

an amino

teins

amino

on the

first introduced

acid

as a proportion

Expert

is based

acid

of the

pattern

been

FAO/WHO

amino

amino

is expressed
acid

have

observed

tion
amino

human
conand oil-seed

of proteins

amino

Cereals

need,

nutritional

nutrition

who

and

same

pro-

ap-

was

value

limiting

and

this

directly

concept

(20),

amino

the

more

evaluation

This

of the

15 for

termed

the

by a recent

quality

score.

the

in widespread

be

Lysine

mg/g

ids,

the biological

concentration

would

nutri-

to assess

satisfactorily

that

nutri-

of human

of protein
used

has been

predict

protein

of an amino

source

is

plant

their

in I 9 19 ( 1 6). However,

procedures

concept

as the

of

foods

needs

been

of food

necessarily

sources’

amino

among

about

the

the topic
have

proposed
and developed.
The procedure
that was adopted

tent

is

in proteins
protein

to ask

rat bioassay

(PER),

food protein

amino

value of all plant protein
foods intended
for direct
sumption
(1 7, 18). This is particularly
so for legume

Consultation

As

threonine

content

to meeting

we introduce

nutritional

to human

Food

at a
groups

limiting

plant

relevant

approaches

One

plicable

of different

(12,

foods.

and

amounts

for

it is now

review).

Alternative

acid content

There

sulfur-containing

of amino

Hence,

proteins.

indis-

foods.

lysine
is consistently
plant-food
protein
and

extensive

Various

not

balance

composition

the

in reference

nutrition.

S
of the amino

The

proteins.

comparative

animal

in legumes

comparisons

quality.

and

6.

significance

tional

specific

by FAO/WHO/UNU

research
reviewed

we have

on human

amino

by us (9, 23, 24).

arrived

at a new,

acid

re-

However,

tentative

set of

acid needs
of adults.
These
values
are
are compared
with the I 985 estimates
for the children

It can be seen that, except
for a lower
lower lysine
content,
our proposed
adult

aged

2-5

y.

threonine
and
pattern
is quite

slightly
similar

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

tional

and

In addition,

acid

in Table

TABLE
Survey

amino
of

Sulfur
content

amino
acid
in all major

A more

the

the

limiting

compared

origin.

presented

most

lower

in cereals

animal

indispensable

concentration

purposes,
Table 5 gives the amounts
of those indispensable
amino
acids that

foods.

distinctly

the

the

amino

indispensable
concentration

in animal

acids

of

in plant

13). For present
in different
food
likely

on

12055

of interest.

question

amino

for

and

PROTEINS

1206S
TABLE

YOUNG

AND

PELLEU
TABLE

6

Protein concentration,
limiting
score for selected plant foods’

amino

acid (LAA)

score

6 (Continued)

and lysine
LAA

Protein
LAA

Protein

(amino

score
acid)

Lysine
score

seed
Sesame seed
Sunflower
seed
Vegetables
Bean (green)
Broccoli
Cabbage
Carrots
Pumpkin

Cassava

Okra
Onion
Peas (green)
Pepper sweet
Potato
Spinach
Squash
Sweet potato
Taro
Tomato

%

89 (Lys)

89

0.2

75 (Aaa)

64 (Lys)

64

Avocados

2.0

82

87 (Lys)

87

12.2

48 (Lys)
49 (Lys)
33 (Lys)

48

1 .0
0.8
0.9

80 (Lys)
67 (Leu,
37 (Leu)

0.7

57 (Lys)

57

72

72

Bananas
Figs
Orange
Peach
Pear
Pineapple
Plantain
Plum

0.4
0.4

62 (Lys)
74 (Leu)

62
111

1.3

69 (Leu)

80

0.8

37 (Lys)

37

9.4
11.0
16.9
7.9
7.1
14.8
11.3
13.2
12.6
13.7
10.3
12.8

49
33

(Lys)

66 (Lys)

66

62 (Lys)

62

71
35
48
46
38
38
33

62

(Lys)
(Lys)
(Lys)
(Lys)
(Lys)
(Lys)
(Lys)

35
48
46
38
38
33

28.1

21.5
36.2
23.9
25.8
21.7

118
118
115
117
120
116
92
120

100
100
100
100

86 (Saa)
95 (Saa)
78 (Saa)

83 (Saa)
62 (Lys)
91 (Saa)

36.5

100

29.7

100

62

121
115
124

0.9
1.5

pattern
and

school

estimates
believe

recommended

by

they

are for reasons

Based
are

on the revised
given

protein

quality

ommend
The first

estimations

in Table

in human

(1 1) should

65 (Lys)

65

15.3

92 (Lys)
76 (Lys)
65 (Lys)

92
76

be the amino
acid requirement
would
be applied
to all groups

55 (Lys)
71 (Lys)

55

22.8

1.8
3.0

83 (Lys)
67 (Leu)

83

1.2

73 (Saa)

1.0

58 (Saa)

81
67

1.3
2.0

44 (Leu)
70 (Lys)
53(Leu)
85 (Saa)

0.9

77 (Lys,

2.1

91 (L.eu)

2.9

100

1.2

70(Thr)

1.7

85 (Lys)

1.5

77(Lys)
56 (Leu)

0.9

these

pre-

revised

are rational,

as we

(9, 23, 24),

the

now

acid

for

it is

of breast

reflected

be

based

the second,

requirements

evaluation
only

on

necessary

the

to

amino

acid

in Table

for

ages

2 y of

in the recommendations

dietary
rec-

or scoring,
patterns.
which
according
to

as shown

pattern
above

that

of

made

2-5

age.

com-

8, would
y, which

This

view

by the expert

is

group

65

107
47
88
129

47 (Lys)
88 (Lys)

1.2

If

elsewhere

that

nutrition

milk;

5.4

Aaa, aromatic
1 1) and refer-

(1 1) for

in adults

use of two amino
acid requirement,
pattern
would
be that for the infant,

FAO/WHO/UNU

17.7

80
69
86

Lys)

y).

of amino

8, it follows

position

100

82

nutritional
value
of different
protein
sources
would
not be affected as markedly
by the age of the consumer.
This is in contrast
to the position
adopted
in the 1985
FAO/WHO/UNU
report.

58

24.5

109

(Lys)

(2-S

discussed

58 (Lys)

100

69
66

FAOIWHOIUNU

early
school-age
children
of amino
acid requirements

20.4
14.3
3.3
8.0
14.9
14.3
41.0

53 (Aaa)
66(Lys)

‘ Lys,
lysine; Saa, sulfur amino acids; Leu, leucine;
amino acids. Based on FAO/WHOIUNU
data (reference
ences 12, 13, and 14.

to the
21.9
23.6
19.3
23.5

(continued)

71

convened

by

FAO/WHO

FAO/WHOIUNU
5 y be used

to assess

young
children,
FAO/WHO
protein
which

82

PDCAAS

acid

(mg/g

-

Leu)

77

105
105
95
85
77
64

It should

be noted
procedure,

the different
the digestibility

Amino
The

amino

acid

by the US government

acid

the

group

1985

aged

2-

in reference

adults.
purposes,

in food

to

the so-called

score

(PDCAAS),

x digestibility

protein

in 1985
pattern

is included

for differences

for ages
in this

protein

procedure
as the official

2-5

amino

y
acid

in the digestibility

sources.
We will refer
protein
foods
below.

and plant
scoring

that
the

of foods

amino

digestibility

to allow

food-protein
of plant

acid score

quality

acid content
FAO/WHO/UNU

that

for

content

protein)

Amino

-

proposed

and also
for scoring

digestibility-corrected
can be defined
as follows:
Amino

scoring

which
requirement

the protein

56

101

acid

older children,
(19) proposed,

82

70

(19),

amino

of

specifically

to

quality

appears
procedure

likely

to be adopted
for food

protein

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

Cottonseed

score

14.5
12.5
13.3

Legumes

Bean white
Bean kidney
Chick peak
Cow pea
Lentil
Lima bean
Lupine
Mungbean
Peanut
Pigeon pea
Soybean
Wing bean
Nuts and Seeds
Almond
Brazil
Cashew
Coconut
Pecan
Pistachio
Walnut

Lysine

acid)

Vegetables
Turnip
Yam
Fruits
Apples

%
Cereals
Amaranth
Barley
Buckwheat
Bulgur
Corn
Millet
Oats
Rice brown
Rice white
Rye
Sorghum
Triticale
Wheat hard
Wheat durum
Wheat flour
Spaghetti

score

(amino

PLANT
TABLE

PROTEINS

12075

7

Estimates

of amino

acid

requirements

of preschool

children,

older

Intake
Preschool’
Amino

acid

(2-S

children,

and

adults

for wt

Intake

Schoolchildren2

y)

(10-12
mg

kg body

‘

Adults’

y)

(

wt

Preschool’

18 y)

(2-S

Schoolchildren2

y)

(10-12

d

‘

by protein

mg/g

Adults’

y)

(

18 y)

protein

-

16

Histidine

-

-

Isoleucine

31.0

28.0

10.0

28

28

13

Leucine

73.0

14.0

66

44

19

Lysine

64.0

44.0
44.0

12.0

58

44

16

27.0

22.0

13.0

25

22

17

69.0

22.0

14.0

63

22

19

37.0

28.0

7.0

34

28

9

12.5
38.0
352.0

3.3
25.0
216.0

3.5
10.0
84.0

11
35
320

9
25
216

5
13
1 11

Methionine

and

Phenylalanine

cystine

and tyrosine

Threonine

Tryptophan
Valine
Total (-histidine)
Adapted
from reference
1 1.
Based on NRC data (reference

‘
2

nutritional

value

the hybrid
in children,

value

of

maize

the

amino
maize
cultivars.

high-lysine

and this

normal

metabolic

the

by

maize

data

composition

have
calculated
prediction
is that

Bressani

of

studies

A lower

two

the
the

to that

in metabolic

(29).

obtained

of com-

is superior

with

tern for children
aged 2-5 y is set too high then this would
give
the protein
a lower numerical
value for the score than would
be

predictions

and
The

confirmed

compared

with

acid

variety

has been

as summarized

for

of protein
foods.
Because
(28) it might be worthwhile

biological

varieties

of high-

via a feeding-metabolic

study.

likely
to be the first limiting
amino
predominantly
on cereal
grains
(30)
more

accurately

the

lysine

content

requirement
pattern.
The
reference
amino
PDCAAS

predicts

protein
a high

that

products,
nutritional

of the

pattern

in addition

reference

used

(Table

9) and

biological

value

of the

high-lysine

metabolic
between

studies
the scores

ucs for the hybrid
content

of the

the

numerical
maize

is difficult
to judge.
and the metabolically
and

high-lysine

for

as derived

from

the
the

The relative
differences
derived,
biological
val-

maizes

FAOIWHOIUNU

estimates

are small.

(1 1) amino

acid

ample,

Torun

New,

Amino

amino

acid

requirement

acid

requirement
pattern

estimates

for adults

for preschool

Adult
tentative
requirement’
mg ‘kg’

pat-

TABLE 9
Indispensable

graded

isolates,

in diets

when

they

containing

amounts

of one

of two

and amino

acid score

adeof
cx-

soy-pro-

amino

acid content

of normal

and

maize

Adult
amino acid
pattern2
d’

mglg

Maize’

and

protein

Preschool
child
amino acid
pattern2
mg/g

protein

Amino

acid

High-

FAOIWHO

lysine

pattern2

acid score’

Normal

High-lysine

0.44

0.63

mg/g N

Lysine

177

256

363

Isoleucine

206

193

175

>2.00

Leucine
Sulfur amino

827

507

413

>1.00

35
65

28
66

Lysine

30

50

58

Sulfur amino acids
Aromatic
amino acids

I3
39

25
65

25
63

Threonine
Tryptophan
Valine

Threonine

IS

25

34

Leucine-Isoleucine

Tryptophan
Valine

6
20

10
35

11
35

23.

Normal

mg/g N

23
40

Based on data from reference
Adapted
from reference
1 1.

Amino
1991

children

Isoleucine
Leucine

‘

soy

of protein

8
tentative

corresponding

2

(3 1) gave

and

( 1 8), would
have
this topic in detail

If the lysine
reference

high-lysine

TABLE

source

the
soy

quate
energy
and other essential
nutrients,
are fully capable
promoting
adequate
growth
in young
infants
(17, 18). For

of 0.63

or major

flour

at

well-processed

the

sole

soy

arrive

acid

and

are the

that

is most

amino

to

to cereals,

such as isolated
soy proteins
value.
We have reviewed

concluded

lysine

that are based
to determine

lysine maize
was also reported
(29). However,
whether
any significance
should
be given to the difference
between
the value for
score

have

acid

Because

acid in diets
it is important

Aromatic

2

Adapted
Adapted

3

Corrected

‘

erence

acids

amino

proteins.

acids

1 88

188

156

>

505

502

394

>

213

199

213

35
292

78

68

298

219

4.01

from reference
from reference
for

digestibility,

2.63

>

2.36

0.98
>1.00

I .00
I .00

>1.00
> I .00

0.89

0.83

I .00

> I .00

>1.00

>1.00

>1.00

>1.00

29.
19.
assuming

a value

of

0.89

relative

to

ref-

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

human

mon
hybrid
and high-lysine
PDCAAS
for these different

-

10).

quality
evaluation
and quality
control
we have argued
in favor of this policy
to briefly
compare
some
based on the PDCAAS.
In Table
9 we compare

8-12

l208S

YOUNG

tein

isolates

to children

energy
malnutrition
with those obtained
tation

who

and
using

had

isolated

depending

soy

on the

from

earlier

data

protein

showed

tested

specific

was

criterion

used

107%

value

that

of milk,

for comparison.

particularly

Hence,

the protein
nutritional
value
of the well-processed
isolated
soy
proteins
so far examined
in young
children
is essentially
cquivalent

to that

of milk

protein.

Results
of studies
on the nutritional
protein
products
in adults
have also
( I 7, 1 8). In summary.
the
protein
(Supro-620,
Ralston
an analysis
adults,

of the

> 80%

digestibility
comparable

isolate

higher

carried

out

when

than

dren and
‘ ‘human’

children

and

growing

rats.

cereal

(97%)

and

was

effectively
in combination
overall
quality
of the total

various
value of

assay

soy

assay

professionals

of poor

metabolic

data

quality.

as well
Clearly

reveal

are deficient

proteins,

be

that

they

as consumers

the

more

of potentially

mainly

in lysine.

soy protein.

can

be and

that

soy

of protein,

This

mdi-

can be used

a cereal
that
acids results

or amino

to a discussion

of plant

acid,

foods.

hu-

types (Types
I, II, III, and IV) as shown
Type I is an example
where
no protein

are of high

nu-

is achieved.

For

high

with most cereal grains to improve
the
protein
intake.
A combination
of soy

direct

recent,

are able to
of ade-

the soybean
is low in
peanut
and sesame

in particular,

is high in lysine,
with
concentration
of s-amino

concept

can

example,

this

occurs

the

contains
a
in a nutrimixture

complementation
Various

is

nutritional

re-

are combined.
into one of four

in Figure
1.
complementary

with

is

effect

combinations

of

pea-

value.

Parenthetically,
others

the

question

emerges

( 17,

1 8),

of the

here.

From

methionine

our

need

for

own

studies

supplementation

methioninc

sup-

and

of soy

those

of

proteins

consumed
as isolates
for meeting
nitrogen
at physiologically
imsupplementation
of

soy-based

be desirable,

infant

the

methioninc

soy

protein

formulas

may,

however,

FAO

requirements
acid,

value

of proteins

Provided

that

proteins

has

a great

data

on the amino

(or

advantage
can

acid

the

and

of the

data.
of the

selected

human

the

nutritional

is made

first
nu-

this

B. Corn

0

I

availability

of

the

with

such

foods

and

for a wide

range

of situations,

nutritional

quality

of the diet

comwith
and

A. Corn
B. Soy Flour

of

vegetable

B. Beef Protein

I

60I

40I

20I

0

20

40

60

80

100

A.1008O

10080

I

60

I

40

20

I

0

20

40

60

80

100

I

0

% PROTEIN DISTRIBUTION IN DIET

differences
and

A. Soy Protein

view.

and

Important

Type .&

a pattern,
food

issues

Complementation

I

0

B. 0
Additional

I

Type III

indispensable

conclusion
made
by this group
pattern
of essential
amino
acid

of individual

I

require-

for the digestibility

methods
of improving
it’ ‘ remains
valid.
In addition,
the recent
recommendations
made by FAOIWHO
( 19) are entirely
consiswith

A. Pssmt
.14

protein,

for assessing

by comparison,

content

be appraised

to evaluation

basis

for meeting

an adjustment

acids in the protein),
the
the concept
of a desirable

respect

although

assay
report

(2 1 ), who

as an official

ments.

ingested

from rat PER
since the 1957

committee

scoring

tritional

binations

Type if

required
to achieve
high utilization
of
modest
( 1 8, 32) and is considerably
lower

appears

protein

amino
‘ ‘that

Type I

addition

than would
have been predicted
More than 30 y have passed
or amino

PROTEIN COMPLEMENTATION

is

clearly
unnecessary
in adults.
Soy proteins,
or concentrates,
are excellent
sole sources
and all amino
acid needs when consumed
portant
intakes
of total protein.
Methionine

tent

may

although
cottonseed,

by some
arc

concentra-

children

complementation;
the protein
quality
of
than that for either
protein
source
alone.

pertinent

for chil-

grains

which
good

This

seriously

isolate

protein,
relatively
tional
greater

consid-

However,

foods

For example.
amino
acids,

oil-seed

latter

The

severe
malnutrition
if given
on plant food sources.
Thus,

sponses
are observed
when
two dietary
proteins
These
have been classified
by Bressani
et al (33)

plementation

of

nutritional
quality.
sulfur-containing
and

was

contain.

children.

and function.
of plant
protein

that

healthy

the PER

they

in appropriate
amounts
and combinations
essential
nutrients
required
for maintenance

flour,

adults

of the

plant foods,
supply
the

cates

from

The

quality

and

true

for

findings
in these
that the protein

be predicted

infants

The

high

that

adults.
Perhaps
the discrepancy
between
‘ ‘rat’
‘
and
data also explains
why there appears
to be a lingering

held

tritional

in

would

the nutritional
‘

proteins

tested

what

in rapidly

underestimates

from the
observation

for

protein.

was

of egg
high

acids

animal

timing

of ingestion

among
origin

and
are

the

of proteins

between
concentrations

food

FIG
products
of proteins

of

logical
sources.

1 . Four
value

types

of response,

or protein

quality,

arising

reference

33.

Adapted

from

assessed
from

in terms

of an

mixing

of two

index
food

of bioprotein

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

soy

man

value

of the soy isolate
was also
with that for egg proteins.

erably

view

data,

nutritional

amino

thrive
on as well as recover
from
well-formulated
diets based entirely

quate health
Mixtures

nutritional
value
of an isolated
soy
Purina
Co. St. Louis,
MO), based on

Of particular
importance
metabolic
studies,
was the
this

quality
of specific
soybeen reviewed
previously

nitrogen-balance

of the

indispensable

tion of protein
and the quality
of the protein
in some
foods
of
vegetable
origin
may be too low to make
them adequate,
sole
sources
of proteins
when
consumed
in their traditional
manner,

responses
Interpre-

that the nutritive
86-

PELLETT
and

protein-

compared
nitrogen-balance
milk as the reference
protein.

of the nitrogen-balance

of the

recovered

AND

PLANT
TABLE

10

Digestibilities

of different

sources

of food

protein

in humans’

True
digestibility

Reference

relative
proteins

%

%

97#{247}32

100

to

Milk,

±
94 ±

cheese

95

Meat, fish
Plant proteins
Maize
Polished
rice
Whole wheat
Oatmeal
Beans
Maize, beans
Indian rice diet
Brazilian

mixed

100

78

82

88
96

93

to ingest

or whether

it is sufficient

a significant

at different
meals
as long
exceeds
the recommended

implication

90

tenance

82
82
81

There
definitive

that

these

amounts

it is not

must

at least

proteins

of protein
reover moderate

in one

each

and every
that

daily

indispensable
requirement;

nutritional

or of specific

amino
it is

state.

we can consult
of consumption

to make
of comple-

L-amino

acid

supplements

or more

amino

acids.

rats suggested
with its limiting

of the supplement
(35-38).
of diets supplemented
with

1 1.

2#{247}

or

intake over a number
of days
of intake
would
allow
main-

database
that
on the timing

are deficient

in rapidly
growing
tation of a protein

100

meets

in adults,

of each
physiological

protein

is a limited
conclusion

that

daily intake
intakes.

be consumed

essential,

sufficient
for the average
this level. This pattern
of an adequate

mentary

teins

meal,

amounts

Although
protein
and amino
acid requirements
expressed
as daily rates (of intake)
there is no

Therefore,

apparently
to achieve

90

at each

in variable

(1 1), estimates
that persist

needs

intakes
of protein,
or presumably
acid, must equal or exceed
the

93

of protein

protein

as the average
or safe protein

to FAO/WHOIUNU
refer to metabolic

periods
of time.
are conventionally
day.

amount

to consume

that delaying
amino
acid

for

Earlier

a

pro-

work

the supplemenreduces
the value

Similarly,
the frequency
lysine
in growing
pigs

of feeding
affects
the

overall
efficiency
of utilization
of dietary
protein
(39, 40). There
are few data available
from human
studies
to assess
the signifinut and
and

corn,

where

quantitatively

each

of the protein

similar

lysine

sources

deficiency

ficient
in other amino
acids. Type II response
combinations
are made of two protein
sources
limiting
amino
and cottonseed
cottonseed

overall

less

inadequate

type of response
effect
because

nutritive

of the best
of response

cance

a common

are both

also

de-

is observed
when
that have the same

acid, but in quantitatively
different
amounts.
Corn
flour, for example,
are both limiting
in lysine but

is relatively

The third
plementary

have

and

value

than

of the protein

mixture;

a true comeffect
on the

the protein

quality

mix exceeds
that of each component
alone. This type
occurs
when
one of the protein
sources
has a con-

siderably
higher
concentration
of the most limiting
amino
acid
in the other protein.
An example
of this response,
based on studies in children
(33),
is observed
when
corn
and soy flour are
mixed

so that

remainder
Finally,
sources

60%

from
the
have

of the protein

soya
Type

intake

protein.
IV response

a common

amino

comes

occurs

acid

from

corn

when

deficiency.

textured

proteins

sponse

and

beef

protein

follow

relationships

have

been

bioassay
studies.
However,
the more
from human
studies
with soy and other
of

knowledge

reason

concept

us to understand

for

of plant
discussing

a higher
of some

this

type

the need

to ingest

acid

patterns.

different

determined

limited
legumes
in

of re-

and

evaluate

foods
acid

from

rat

results
available
confirm
the ap-

human

protein
amino

the question
of timing
There
is some concern,

or within
the same
tional
value
from
amino

general

combinations

introduce
proteins.
about

this

helps

effective

similar

fect

two

nutrition.
how

can

This

bean

diet

complementation

This

concern

mentation.
tention.
a diet
and

to the question

conditions

lysine

is most

likely

predominantly
that

lysine.

The

size

of this

in the amount

of Bergstrom
(providing

50 g bovine

requirement
within

of lysine

for lysine

3 h. Hence,

could
higher

free-lysine

serum
may

be ingested

some

acid

We conclude
profile at each
of total protein

mixture

in this

hours

derived
of

of the

a relatively

later than

buffer
from
the

soy

the

and

on the data

meal

adult

lysine

daily
pool
content

a complemenprotein)

the low lysine

combined

of

acute

intracellular
low

(eg,

would

quality

both
Based

60%

protein

in the muscle

nutritional

albumin)

in

is a sizeable

that after a protein-rich

with

lysine-containing
pool

(43).

acid

particularly

to changes,

be deposited

a protein

acids,

ingested

con-

it is of interest

there

amino

et al (44), we calculate

time

this

amino

(30),

musculature

responds

at

it is not

to support

grains

of free

pool

living

at the same

to be the limiting

skeletal
space

given
commu-

meals over the course
benefits
of compledata

on cereal

in the

was

of healthy

ef-

to a maize-

personal

proteins

physiological

distributed

vulgaris

D Wilson,

complementary

metabolism
Our studies
utilization

was

the supplement

and

for usual

in the intracellular

high.

extend

when

are also

relevance

pool

plant

also

less

There

based

the

may

of Phaseolus

h (R Bressani

6

pig

different

the supplementary

that separation
of the proteins
among
of a day would
still permit
the nutritional

amino

meal, to achieve
maximum
benefit
and nutriproteins
with different,
but complementary,

somewhat

intake

and

Overall,

time,

protein
However,

to consume

of the

at the same

daily

of the addition

of rat and

profoundly

of protein
subjects
(41).
dietary
protein

(42).

>

of ingestion
of complementary
at least at the consumer
level,
proteins

characteristics
with human
that overall
the

nication,
1992).
We believe
that

tary,
is to

relevance

of the

meals

of

necessary

the

in view

whether

was

intervals

(maize)

nutritionally

be achieved.

However,

or three

in children

chronic,

nutritional

plicability

was

Because

com-

(34).

These

Our

the

findings.

be questioned

qualitative
and quantative
in rats and pigs compared
in human
adults
showed

protein

protein

the highest
value
is the one containing
of the deficient
amino
acid. Combinations

soy

and

both

The

ponent
giving
concentration

can

among

is corn.

(Type III) demonstrates
there
is a synergistic

of these

studies

digestion
meals

and

the

content
of maize.
would

be

that it is not necessary
to balance
the amino
acid
meal, especially
under conditions
where intakes
substantially
exceed minimum
physiological
re-

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

89

diet

reference

100

3

85±6
88 ± 4
86 ± 5
86 ± 7
78
78
77

Filipino mixed diet
US mixed diet
Adapted
from
SD.

3

of the need

According
quirements

proteins

Egg

1

Digestibility
reference

12095

PROTEINS

YOUNG

1210S
TABLE
Plant

AND

PELLET!’

II
proteins

in human

nutrition:

myths

and realities

Myth
I ) Plant

proteins

are

‘

‘incomplete’

Reality
(ie

‘

lack

specific

amino

acids)

1 ) Usual

dietary

food

2)

proteins

Plant

are not as

‘

‘good’

‘

as animal

Proteins from different
plant foods must be consumed
together
the same meal to achieve high nutritional
value
4 ) Animal bioassay
procedures
are satisfactory
indexes of the
human nutritional
value of food proteins
5) Plant proteins are not well digested

7) Plant proteins
value

are

are not sufficient

‘

‘imbalanced’

to achieve

in

3 ) Proteins

do not

balance
Animal

4)

diet

their nutritional

can

digestibility

can

Protein

favorable
cluding

content

alone;

several

other

the digestibility

source
may not be
of its amino
acid

nat-

of preparation
or processing.
Although
the effects
of procon protein
quality
and availability
will not be reviewed

here,

this

plant

foods

products
from the

factor

deserves

attention

for

humans.

For

of processes
seed. Such

cient

recovery

tended

for

their

palatability

marily

in bread,

processing
essing
and

conditions,

enhanced

and

drying,

and
that

such
have

treatments,

are

Cereals

cooked

or processed

use

For example,

widely

to an extent

components
in the food and factors
ration of heating,
and the presence
ing in water generally
or dry heating
reduces

improves
protein

draw
broad
generalizations
processing
and preparation

recover
favor

the oil
the effi-

legumes
is used

may
the

such as the temperature,
or absence
of moisture.

protein
quality.
concerning
conditions

quality,
Hence,
the
on

the

can
but

numerous

produce
the

be created

this

is not

preparation:

by inappropriate
a practical

problem

More basic work is needed
that occur in proteins
under

or cooking,

of these

their

ill effects

that

may

cause

or has devised

compounds

results

toxic

possible

lase
fere

compounds

immediate
undesirable

in the

from

un-

to eliminate
plant
foods

and

of

procor less-

factors),

but they

the health
problem
are eaten
more
fre-

longer
periods
of time.
in various
legume-seed

metabolic

Often

inactivation,

(antinutritional

reduced
if novel

means

others.

destruction,

compounds

may not be sufficiently
entirely,
particularly

Examples
protein

physiologic

of some of
sources
and

significance

are:

amy-

inhibitors,
which
are found
in most legumes
and may interwith starch
digestion;
cyanogen.
which
is found
in lima

beans
and may cause
respiratory
failure:
and
arc phenolic
compounds
found
in most legumes
less
digestible
complexes
(45).
In products
mercially

available

these

factors

clinical
problems.
Nevertheless,
in the course
of developing
new
protein,
sorghum

for example,
(46).

Summary

puffing,
as a result

on

humans

food

do not
they
and

as in the case

pose

tannins,
which
and may form
that
are comany

nutritional

or

are important
to consider
improved
sources
of plant
of new

varieties

and

uses

of

and

conclusions

proc-

heating,

depends

for

and

pri-

Thermal

However,

of the protein

in-

to enhance

short-time

microwave

that

be

foods.

adopted.

value

of

may

wheat

high-temperature,

as extrusion,
been

assessment
flours

and

breakfast-cereal-type

the nutritive

or reduced

protein.

acceptance.

pasta,

methods

spray

of such

feeding

oil-seed

to economically
do not necessarily

of high-quality
human

in an overall

example,

designed
processes

that

foods
eliminating

quently
and over
the factors
present

in their

the

but they may

quality

to source

imbalances

contain

of vegetable

utilization

proteins

time,

physiological
and clinical
responses
when
eaten.
indiminished
digestibility.
Man has learned
to avoid those

essing,

the

ural form is lower
than that of animal
proteins.
Table
10 summarizes
results
for the digestibility
in human
subjects
of various
plant
sources
and of diets based
on mixed
plant-food
sources.
Plant proteins
are often consumed
only after undergoing
some
degree
essing

plants

ening

affect

according

supplementation,

of

can

same

be high

possible
acid

which
is frequently
critical
in the
farm livestock,
is the digestibility
and individual
amino
acids.

factors

proteins.
An important
factor,
feeding
of simple-stomached
and availability
of the protein
In general,

as’ailabilirs’

of a dietary
protein
from a determination

vary

nutritional

of plant
proteins

In this
proteins

be either

brief

protein

the

duBoil-

whereas
toasting
it is difficult
to
effects
of various
proteins
and the

brief

review

in relation
consideration

protein

within
protein

component

we

to human

have

highlighted

the

value

nutrition.

We

of the contribution

made

by plant

of diets

a worldwide

the United
States.
We
and for indispensable

protein
on

then discussed
amino
acids

of plant

began
basis

with

proteins
and

a
to

also

the requirements
for
in humans
at various

ages, together
with a short survey
of the amino
acid composition
of different
plant-food
protein
sources.
There
is a large variation
in the contribution
made by plant proteins
to the availability
and
intake

of total

dietary

protein

among

populations

both

within

the

Downloaded from ajcn.nutrition.org by guest on January 14, 2014

proteins.
Many

The nutritional
value
predicted
with precision

mixture
animal

these conditions
and their nutritional
effects
to develop.
in the
long-term,
optimum
procedures
for the utilization
of plant food

ulations.
acid

protein

specific

acids

at the

individual
amino acids of plant foods.
on the chemical
and physical
changes

emphasis
on amino
acid balance
at each
in the context
of usual diets in healthy
pop-

amino

complete:

amino

6 ) The intakes and balance of intakes of indispensable
amino
acids
and nitrogen are crucial and can be adequately
met from plant
or plant and animal sources
7) There is no evidence
that amino
acid imbalances
per se are

quirements.
Consumption
of complementary
proteins
at different
meals over the course
of the day should
assure
the achievement
of an adequate
state of nitrogen
(protein)
retention
and utilization.

and

are

in specific

to be consumed

plant

important:

digestibility

need

5 ) Digestibility

amino

Therefore,
an undue
meal is inappropriate

of proteins

be low

over a day is of greater importance
bioassay
procedures
can be useful

underestimate

an adequate

and this limits

‘

may

2 ) Quality depends on the source and dietary
proteins:
can be equivalent
to high-quality

proteins

3)

6 ) Plant proteins alone
(protein intake)

combinations

proteins

technically

advanced

developing

regions.

regions
It can

amino

acid

composition

plant

proteins

are

diets
well

worldwide
be limiting,

cereals,
total

for

lysine

plant

between

these

considerations

food

protein

of the

wheat,

are

the

such

modest

as legumes

sources

that

content

can

acids

serve
that

as a complete

effectively

and

meet

of

might
where

source
amounts

or animal

and
of the

lysine

predominant

However,

of the

of higher-

proteins,

favorable
impact
on the protein
(30). Overall
it can be concluded

proteins

of amino

major

determinant

supply.

foods

and
diets

and

from

(29, 30). This indispensable
amino
acid
or marginal,
in diets of some countries

energy

protein

a major
of such

of the

a major

example,

dietary

of the world
be shown

can

well-balanced

source

physiological

re-

quirements.

We present
plant

in Table

proteins

a reference
sider
issue

11 a list of myths

in human
to amino

nutrition.

acid

imbalance

in any detail earlier,
to be an important
interesting

largely
problem

experimental

(no.

in children
protein
(49).

intakes,

as supplied

concerning

included

7) that

in this

data

have

defined

the

nature

imbalances
(48)
of an imbalance

sorghum

in regions

and

and the unhave been

during
amino
acid supplementation
However,
the suggestion
that
by

list

we did not con-

because
we do not consider
this
in practice
(47). Considerable

mechanisms
of dietary
amino
acid
toward
physiological
consequences
observed
dietary

have

high

of India,

trials of
leucine
might

be

etiologically
significant
in the pellagra
that exists
in these areas
(50) has not been substantiated
by considerable
additional
investigation

(47).

Thus,

be at all concerned
amino

acid

our usual
for

supply

diets.

meeting

needs

amino

is from

nitrogen
and

wants

the

that
acid

consumers

diet,

From
they

that

standpoint

as a desirable

and indispensable

amino

(Table

no. 6).

acids

need

to

the dietary

can be fully
the

serve

11, reality

when

proteins

proteins

requirements.

do not

imbalances

plant-food

of plant

of a healthful

for carrying
our

conclude

Mixtures

human

composition

we
about

make

up

ganization.

17.

21.

to meet both

vice. Food
Hyattsville,
no 1-1.)

Nutrition

Division,

intakes
in individuals
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Human

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26.

Zello

GA,

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Ball

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