Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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Infant Growth (0–2 years)

0027 Postnatal growth is, essentially, hypertrophic: it is an

enlargement of the already existing cells rather than

the addition of new ones. The period of maximum

postnatal growth corresponds with the first year of

life. During the first 12 months of life, size increases

50%, by around 25 cm (50 versus 75–80 cm), weight

rises 200%, by around 7 kg (3.3 versus 10 kg), and

cranial circumference enlarges by 45%, which is

around 11 cm (35 versus 47 cm), relative to birth.

During the second year, there is an obvious deceler-

ation of growth: size increases by only 10–12 cm (75

versus 85–90 cm), weight rises 2.5 kg (10 versus 12–

13 kg) and cranial circumference enlarges by 2–

2.5 cm (47 versus 50 cm).

Growth during Preschool Age (3–5 years)

0028 This is the final stage of neonatal growth deceler-

ation. Growth velocity slows down and becomes

more constant; size increases by around 6–8cm

year

1

. Around the fourth year of life neonatal size

has doubled (50 versus 100 cm), weight rises 2 kg

year

1

and cranial circumference enlarges by 1 cm

year

1

. The increase is in leg length, while subcutane-

ous fat decreases. This changes the infant’s look into a

more slender, less rounded one than that of the first 2

years of life.

Growth Velocity from School Age to the Beginning

of Puberty (6–10 Years for Girls, 6–12 Years for

Boys)

0029 Growth becomes slow and steady. The increment per

year is 5–6 cm for size and 3 kg for weight. The child

has a proportionally greater increase on leg length.

Immediately before puberty, growth velocity reaches

its lowest point – 4–5 cm year

1

. Cranial circumfer-

ence growth is only 2–3 cm for this whole period.

0030 When they are 6–8 years old, most children experi-

ence a slight prepubertal or midchildhood spurt. This

mild acceleration (increment 1.5 cm year

1

) occurs

basically at the expense of leg enlargement and coin-

cides with an increase in suprarenal sexual hormone

secretion, which may provoke an increase in GH

secretion and peak (adrenarchy).

Pubertal Growth

0031 Puberty begins with activation of the hypothalamus–

pituitary–gonadal axis, by means of the coordinated

action of sex steroids, GH, insulin-like growth factor

1 (IGF-1), and thyroid hormones. It is characterized by

growth velocity and acceleration of development of

sexual organs. After the slow, steady and prolonged

growth stage which takes place in childhood, a progres-

sively accelerating stage (growth spurt) begins, which

peaks at maximum speed and then subsequently slows

down. Although all body sections take part in the

pubertal spurt, it affects trunk size to a larger extent

than lower limbs. These stages have been expressed

following a using musical system of descriptors (an-

dante, moderato, allegro, lento, lentissimo).

0032The start of acceleration in pubertal growth

happens 18–24 months earlier for girls than for

boys. In the first year, growth velocity amounts to

7 cm year

1

for boys and 6 cm year

1

for girls. During

the year of greatest growth (the peak), which happens

for girls at 11.5 + 1 and for boys at 13.5 + 1 years of

life girls gain 8–10 cm and boys 9–11 cm, mainly at

the trunk. That is, growth velocity doubles and

becomes comparable that which took place in the

second year of life. Later on, there is progressive

deceleration until adult size is reached. An important

increase in weight velocity also occurs: at the peak it

is up to 8–9 kg for boys and 7–8 kg for girls.

0033Before puberty, boys’ and girls’ size is similar. As

girls’ puberty begins earlier, they are slightly taller

and heavier when aged 11–13. The fact that boys

reach puberty 2 years later means that, when they

begin it, they are 8–10 cm higher and 6–8 kg heavier

than girls. Moreover, 2–5 cm and 2–4 kg must be

added to the previously mentioned data because of a

more intensive speed peak in boys’ case.

Final Adult Height

0034At the end of growth, which happens 2 years earlier

for girls (16 versus 18 years), boys are 10–15 cm taller

and 8–12 kg heavier than girls.

0035Once the closure of long-bone epiphysis occurs,

there is still a residual growth of 1–2 cm (no more

than 1–2% of total size) which may go on until the

25th year of life, or even longer, when all the spine

epiphyses are closed.

Growth Regulation

0036Growth is neither a constant nor regular linear pro-

cess, but it is a dynamic one with a chaotic pattern

that acts intermittently with static phases when

growth is minimal, and jumps about, therefore show-

ing a wide speed range in 1 year.

Determining Factors (Genome)

0037Growth is genetically determined by means of a poly-

genic device. Genetic influence on growth is less clear

during the prenatal period, when birth weight

depends 60% on environmental factors – basically

maternal ones – with only 40% due to genetic

influence. Nevertheless, the subsequent relationship

of adult size with inheritance represents, under

ideal health and environment conditions, 80% of

2978 GROWTH AND DEVELOPMENT

determining factors, so that environment only repre-

sents 20%. The fact that to a great extent genetic

burden defines size becomes obvious in studies on

twins. In the case of monozygotics the difference in

their adult size is just 2.5 cm, with a correlation coef-

ficient of 0.99, whilst in the case of dizygotics it is

12 cm, with a coefficient of 0.66. The variability rank

between brothers rises to 16 cm, with a coefficient of

0.55, reaching a rank of 25 cm in the general popula-

tion. Another sample of genetic influence is sexual

maturation, since the difference of menarche appear-

ance age in monozygotics is 2 months, in dizygotics is

1 year, while in the general population it is more than

1 year. The correlation between the parents’ size and

children’s adult size is 0.55 when compared to both

parents’ size, 0.45 for mother and children and 0.42

for father and children. Regarding the correlation

between birth size and adult size, this is low in the

newborns case (r ¼ 0.25–0.30), but increases rapidly

and significantly so that in the second year it is al-

ready 0.80.

Regulating Factors (Hormones and Growth

Patterns)

0038 Each cell is controlled by an enormous variety of

hormones, growth patterns, and their carrier pro-

teins. This is accomplished in different ways and by

different pathways: endocrine, paracrine, autocrine,

juxtacrine, intracrine, and neuroendocrine ones.

However, all pathways are necessary to express the

whole genetic potential of growth (Table 1).

0039 Prenatal growth regulation Hormonal regulation of

fetal growth shows important peculiarities in connec-

tion with postnatal growth. GH exerts scarce influ-

ence. In contrast, human placental lactogen (hPL)

plays a more important role. Although its structure

is similar to GH, its growth-promoting action is lower

than that of GH.

0040IGFs play an important role in regulating fetal

growth. IGF-2, with insulin-like actions, as well as

actions on fetal, placental, and uterine growth, is very

important during the fetal period. IGF-1, especially in

the last months of pregnancy, keeps a close correl-

ation with birth weight and size, as shown by serum

levels. Newborns suffering a delay in their intrauter-

ine growth show significantly lower levels at birth

and in their first year of life, especially those whose

fetal growth delay was more intense and with a lower

adjusting index. This means that IGF secretion is

sensitive to nutrient availability, particularly that of

energy and proteins. Other growth factors, such as

neural growth factor-b (NGF-b), epidermal growth

factor (EGF), and transforming growth factor-a

(TGF-a), also play a role in cell growth and differen-

tiation. Insulin has an important function, not only in

protein synthesis, but also in cell transport and use of

amino acids and glucose, in enzymatic induction, in

lipogenic activity, and in somatic growth. It also plays

a part in the regulation of IGF-1 synthesis. Thyroid

hormones, glucocorticoids, and sexual hormones

exert a bigger influence on the development of spe-

cific organs than on longitudinal growth. The role of

thyroxine in the development of the central nervous

system is to be noted (Table 2).

0041Postnatal growth regulation The role of hormones

during the postnatal period as executors of the prede-

termined genetic program for growth is a crucial one.

GH is essential for normal linear growth from the end

of the first stage of life, when the quantity of receptors

and tissular sensitivity to GH becomes evident.

tbl0001 Table 1 Modes of cellular regulation

Mode Agent Source Vehicle Target Modulators

Endocrine Hormone Gland Circulation Heterologous tissue Neurons

Hormones

Growth factors

Paracrine Growth factor Local site Diffusion Heterologous cell Hormones

Growth factors

Autocrine Growth factor Local site Diffusion Autologous cell Hormones

Growth factors

Juxtacrine Growth factor precursor Local site Cell contact Adjacent cell Proteases

Intracrine Hormone Intracellular Cytoplasm Intracellular receptor ?

Growth factor

Nutrient

Neuroendocrine Neurotransmitter Neuron Axon Heterologous tissue Hormones

Growth factor Growth factors

Neurons

Reproduced with permission from Russell WE (1997) Nutrition and the humoral regulation of growth. In: Walker AW and Watkins JB (eds) Nutrition in

Pediatrics, pp. 248–271. London: B.C. Delker Inc Publ.

GROWTH AND DEVELOPMENT 2979

During puberty, the increase in sexual hormone secre-

tion – in males this is testosterone while in females it

is estrogen – stimulate GH and IGF secretion as well

as their local action on growth cartilage. The pubertal

growth spurt is, therefore, closely connected with the

interaction of GH, IGF-1, and sexual hormones.

0042GH actions imply a complex interaction of factors,

including cerebral neurotransmitters and hypothal-

amic peptides; genes, receptors, and GH-carrier pro-

teins; IGFs and their receptors; carrier and inhibitor

proteins, and nutritional signs. GH exerts direct

actions on cell division, protein synthesis, lipolysis,

enzymatic induction, and the stimulation of cellular

transport of amino acids and glucose. Its effects in

promoting longitudinal growth affect growth cartil-

age directly, inducing maturation of the most undif-

ferentiated and indirect chondrocytes, facilitating the

expression of IGF-1 gene, which for its part stimu-

lates chondrocyte maturation and multiplication. The

importance of GH, GHBP (growth hormone binding

protein), IGF-1 and IGFBP-3 (insulin-like growth

factor binding protein-3) carrier proteins is notable

in the activity and function on the GH–IGF-1 axis

growth (Figure 4, Table 2).

tbl0002 Table 2 Insulin-like growth factors and binding proteins

Functions

IGF-I Fetal growth and especially postnatal one

Insulin-like actions

Important sensitivity to undernutrition

IGF-II Fetal growth

Important insulin-like actions

Limited sensitivity to undernutrition

BP-1 Transport of IGFs from vascular space

BP-2 Transport of IGFs from vascular space

BP-3 Sequesters the circulating IGF in an inactive form.

Component of 150 kDa serum IGF complex

intravascular reservoir

BP-4 Blocks IGF action in cells

BP-5 Potentiales IGF action in cells

Pituitary gland

Pit-1 dwarfs

IGHD (GH-1 defects)

Central nervous system

Serotonergic − sleep

Dopaminergic − apomorphine

α-Adrenergic −

L−dopa

β-Adrenergic

+ −

Hypothalamus

IGF-I

IGF-I receptor

Bone

IGF-IR defects

Pygmies

GHRH

GHIF

GHRH receptor

GH receptor

Liver

GHR defects

Laron dwarfs

Pygmies

Pit-1

fig0004 Figure 4 Regulation of growth hormone (GH) secretion: this is regulated by various factors. The sites of derangements responsible

for various familial disorders of the GH axis are indicated on the right. GHRH, growth hormone-releasing hormone; GHIF, growth

hormone-inhibitory factor, Pit-1, specific pituitary transacting factor; GHR, growth hormone receptor. Reproduced with permission

from Mullis PE (1998) Genetic control of growth. In: Kelmer ChJH, Savage MO, Stirling HF and Saenger P (eds) Growth disorders, pp.

39–61. Cambridge: Chapman & Hall.

2980 GROWTH AND DEVELOPMENT

0043 There is a close relationship between IGF-1 and

GH. GH, diet, and nutritional state are the main

factors regulating IGF-1 synthesis. Although the

contribution of proteins and essential amino acids is

important for IGF-1 regulation, it is essential in

accurate energy input. Liver is the most important

source of plasma IGF-1, which acts as an endocrine

factor, but many other organs and tissues also synthe-

size IGF-1 by a local action where it is synthesized or

in adjacent tissues, that is, with autocrine and para-

crine action. This suggests a diffuse biological action:

not only a metabolic but also a mitogenic one, with

effects on cell proliferation, protein synthesis, and

body enlargement processes.

0044 Thyroid hormones have a role in bone maturation,

metabolism, and central neural system (CNS) devel-

opment. Apart from their direct effect on the cartil-

age, they are necessary in adequate GH secretion and

as a complete expression of their effect on cartilage

and bone formation. They stimulate IGF-1 produc-

tion, while a lack of thyroid hormones restricts the

effects of IGF-1 on the cartilage, independent of the

effects it exerts.

0045 Insulin favors protein and hepatic glycogen synthe-

sies, as well as lipogenesis. In addition, it exerts an action

promoting mitogenic growth mediated by IGF and other

growth factors. Sexual hormones play an important role

in sexual maturation and pubertal growth, and together

with GH are responsible for the pubertal spurt. They

exert direct anabolic action and an effect modulating

GH and IGF-1 secretion and function.

0046 Peptide growth factors Quite recently a group of

messengers has been discovered inducing cell growth,

proliferation, and differentiation. Unlike classical

hormones, they are delivered in multiple cell types

and act in more locally, exerting their actions on a

wide variety of cell types or on specific tissues. Epi-

dermal growth factor (EGF) mostly acts on cells of

ectodermal origin cells and activating the mitosis of

epithelial cells, conjunctive tissue, glial cells, and

granulosum ovarian cells. Alfa transformant growth

factor (TGF-a) shows similar actions to EGF, and

shares the same membrane receptors. Platelet-derived

growth factor (PDGF) is a mitogen for many types of

mesodermic cells such as fibroblasts, smooth-muscle

cells, and glial cells. Fibroblastic growth factors

(FGF) stimulate the proliferation of cells of endo-

dermic and mesodermic origin. Together with these

growth-stimulating factors, there is an inhibitory

system, which is quite unknown so far.

Permissive, External, or Environmental Factors

0047 Nutrition is the main permissive factor, but at the

same time socioeconomic, health and psychoemotional

levels, environment, habitat, and iatrogenic factors will

make it possible or not to achieve the highest genetic

potential for growth.

0048Nutrition has a direct influence on the expression

of genes controlling growth and metabolism. It is

indispensable for the adequate function of regulating

factors and, for their part, these influence nutrient

transport and use. Most hormones and growth

factors join cell receptors and their ability to influence

the genome requires a ‘cascade’ of reactions, involv-

ing proteins, lipids, and ions as secondary messengers.

Hormonal control of growth is highly sensitive to

nutritional mean, so that intracellular availability of

nutrients is the last regulator of growth. Therefore,

malnutrition has important negative effects on

growth, affecting the GH–IGF axis.

0049Together with malnutrition, low socioeconomic,

and familiar educational levels, the number of chil-

dren and home characteristics have a negative added

influence on growth, not only on prenatal but also

postnatal growth. Differences in adult size are due,

to a large extent, to the growth delay accumulated

during fetal stage and during the first 3 postnatal

years, since this is not effectively made up later on.

So, in the case of those individuals short for gesta-

tional age (SGA) – mainly in symmetric factors (size,

weight, and cranial circumference within the same

percentile) – who manifest a situation of prolonged

malnutrition, their adult size is lower.

0050Any disease, especially a chronic one, interferes

with normal growth and development. The degree

affected depends on age at onset, duration, and

seriousness. A growing social phenomenon is growth

failure due to a serious emotional deprivation pro-

ducing a lower GH secretion (psychosocial growth

delay). An adverse familiar environment and ill treat-

ment are two examples of this condition.

Growth Velocity Secular Trend

0051Over the last 150 years, since the beginning of the

Industrial Revolution, growth velocity has speeded

up, producing a significant increase in average adult

size in developed countries. The existence of better

socioeconomic, hygienic, sanitary, and nutritional

conditions has had an important influence. In Spain,

the socioeconomic, sanitary, and nutritional changes

occurring in the twentieth century marked the evolu-

tion of an increase in secular growth. The situation in

1900–50 was that of a developing country nowadays.

In 1950–99 the Spanish economic miracle took place,

accompanied by a spectacular improvement in life-

style, medical care, and the availability and accessi-

bility of food of high nutritional value. During the

period 1900–55 the height of Spanish soldiers

GROWTH AND DEVELOPMENT 2981

increased only 1.7 cm (0.3 cm per decade), whereas in

1955–95, it increased by 9.2 cm (2.3 cm per decade).

A remarkable fact is that differences in adult size

among recruits from different regions over the last

40 years have significantly decreased, ranging from

4.5 cm in 1956 to just 1.6 cm in 1996. Those regions

which were less developed in 1955 showed a far

superior increase with relation to most developed

ones, as their income per capita approached the

most developed regions (Table 3).

‘Catch-Up,’‘Catch-Down,’ and Channeling

0052 Birth size reflects maternal environment rather than

fetus genotype. Thus, during the first 2 years of life

many children suffer some changes in their growth

velocity as maternal factors are progressively losing

influence and genetic forces determining postnatal

growth pattern are gaining in importance. Children

born shorter or larger than they should be according

to their genetic growth potential gradually change

their weight and size percentile upwards or down-

wards until they reach the most appropriate one,

corresponding to their genome. At this point they

standardize their growth velocity. These acceleration

and deceleration processes, occurring during the post-

natal adaptation period, are known as ‘catch-up’ and

‘catch-down,’ or ‘lag-down,’ respectively.

0053 From 2 years onwards, growth becomes quite a

steady process, following an extremely regular

pattern. It is unusual that a healthy infant changes

the channel determined by its genetic antecedants by

more than one percentile. So, from this age, size is

closely correlated with adult size. This pattern or

growth curve has been defined as ‘a guided missile’

and as a ship led along a channel, so that the infant

undergoes a ‘canalized’ growth process. ‘Channeling’

has been defined as the capacity of reverting to the

original growth curve after moving away from its

pattern because of a disease and/or malnutrition.

‘Catch-up’ is the recuperation growth, which can be

three to four times higher than average until the ori-

ginal channel is reached. The earlier and longer an

insult is, the more difficult complete recuperation of

growth becomes.

Methods for Growth Assessment

Anthropometric Study

0054The assessment of somatic growth is based on the

analysis of those changes produced in time in body

size, shape, and composition. In order to value the

most important aspects of growth, one of the most

reliable methods is the anthropometric study, that is,

the application of biomedical techniques expressing

quantitatively body shape, which is called ‘auxo-

logical anthropometry.’ The validity of the method

depends on a precise and exact measurement with an

accurate device or material and by means of a right

technique.

0055Height and size Body height measurement is the

best parameter of skeleton growth, since, unlike

weight, this is not influenced by fat or water accumu-

lation. Over the first 2 years of life, it is preferable

to measure height in the supine position. Ideally,

mechanical instruments (Harpender’s infantometer,

ranging from 300 to 940 mm) should be used to get

an exact measure. Size is used instead of height from 2

years onwards, and the chosen instrument is Harpen-

der’s stadiometer.

0056Cranial circumference This one of the most anthro-

pometric measures in children, since it is related to

intracranial volume and makes possible an estimate

of brain growth velocity. To make this measurement,

a nonextensible metal tape measure is used.

0057Estimate of weight and body mass Weight is not

as specific a growth measure as size, since it shows

body composition (water, fat, muscle, bones, viscera),

that is, a mixture of tissues. But weight, mainly in

infants, is a better reflection of health and nutritional

state. Precision balances must be used, not only

tbl0003 Table 3 Secular trend in Spain

Mean Height of Spanish recruits

(1956^1996)

Height (cm)

Autonomous Community

(regions) CC.AA.

1956 1996 D1956^1996

Paı

s Vasco 168.7 175.2 6.5

Catalun

a 168.6 175.0 6.2

Canarias 167.3 175.1 7.8

Baleares 167.1 174.9 7.8

Madrid 166.8 175.1 8.3

Navarra 166.8 175.6 8.8

Cantabria 166.8 174.8 8.0

Valencia 166.3 174.8 8.5

Arago

n 166.1 175.3 9.2

Asturias 165.9 174.5 8.6

La Rioja 165.3 175.0 9.7

Murcia 164.4 174.8 10.4

Castilla-Leo

n 164.3 174.8 10.5

Castilla-La Mancha 164.2 174.7 10.5

Andalucı

a 164.2 174.5 10.3

Galicia 164.2 174.0 9.8

Extremadura 164.0 174.0 10.0

Difference Between

(CC.AA.)

4.5 1.6

Spain 165.9 175.1 9.2

2982 GROWTH AND DEVELOPMENT

electronic (which are better for infants), but also

manual ones. They should be periodically balanced

and calibrated.

0058 Subcutaneous fat is a measure that correlates ad-

equately with body fat content, being higher than

weight for adiposity assessment. It is, therefore, an

important measure of nutritional state. Triceps

subcutaneous fat represents accurately limb fat, and

subscapular one shows trunk fatty deposit. The as-

sessment of the deposit of subcutaneous fat tissue

must be done with a thickness compass (Holtain

calliper).

0059 The weight (kg)/size (m

) index, or Quetelet’s

index, or body mass index (BMI) is nowadays con-

sidered the most accurate indicator of weight/size.

0060 Bone maturation The most useful way to measure

biological maturity is to estimate skeleton age. This is

because the changes bones suffer during maturation

are very similar in all individuals, and each ossifica-

tion center undergoes a series of morphological

changes which are easily identifiable. Conventionally,

an X-ray of the left hand and wrist is used to calculate

skeleton maturity simply, because there is a great

proportion of long and rounded bones in an easily

accessible area.

0061 Atlas methods assess quantitatively the maturity of

epiphyseal nuclei. The most widely used one is that

of Greulich and Pyle. Numerical methods are ahead

of atlas ones, since by transforming a simply qualita-

tive evaluation into a quantitative phenomenon, they

allow more precise assessment of the normal process

of bone maturation and pathological set of symptoms

by means of the mathematical analysis of data. The

most widely used method is that of Tanner and

Whitehouse (RUSTW2).

Adult Height Prediction

0062 Adult height prediction according to parents’ height:

genetic potential for height Since genetic constitu-

tion is the main determining growth factor, parents’

height is of special importance in their children’s

growth assessment. Each parent’s height contributes

equally to their children’s growth, so their mean

height must be a reference. Garn and Rohman,

using the data in Fels’ longitudinal studies, made

tables of mean parental height, which are useful to

predict the most probable child’s height at a deter-

mined age and final height. Tanner constructed some

graphics for 2–9-year-old children in which their

height is expressed as a percentile of the expected

standard, adjusted to mean parental height. A calcu-

lation of the expected target size based on mean

parental height (genetic growth potential) is achieved

like this:

For a boy :

Father’s heightþ mother’s height þ 13cmðÞ10  2

For a girl :

Mother’s heightþ father’s height  13cmðÞ8:5  2

Kalberg proposes a new model to estimate

target height. It is a simple linear function of

mean parents’ size (y ¼estimate of child’s height,

x ¼mean parents’ size (cm)). It is y ¼45.99 þ 0.78x

for boys, and y ¼37.85 þ0.75x for girls. This new

model gets better results than the equation of cor-

rected parental height, especially in the case of chil-

dren whose parents’ height is short.

0063Methods of adult height prediction These methods

are based on, or use, skeletal maturation, not only to

determine growth velocity but also to make a predic-

tion of adult size. The three predicting models most

widely used are:

0064Bayley-Pinneau’s method: this uses tables from

bone-age data taken from Greulich and Pyle’s

atlas. These are based on total growth percentage

achieved at different ages: there are three sub-

groups according to whether bone age is ad-

vanced, slowed, or accurate in relation to

chronological age. These tables can only be ap-

plied to bone aged over 6 years.

0065Roche, Wainer and Thissen’s method: this uses

correlation coefficients existing in different age

periods between final size and height, weight,

and bone age, according to Greulich and Pyle’s

atlas, and parental size. This method can be used

for 1–16-year-old boys and 1–4-year-old girls.

0066Tanner’s method: based on a mathematical equa-

tion relating a number of coefficients established

for each age and sex under the following param-

eters: height, bone age, according to the RUSTW2

method, and chronological age. In 1983 the

method was revised and more exact predicting

equations were proposed.

Graphics and Limits for Normality

0067As human growth shows a strong tendency to remain

‘channeled,’ the successive points of a curve are

strongly correlated. So, the best method of assessing

growth is to measure it regularly and represent it on

standard graphics. In this sense, periodic measure-

ment of growth is a sensitive, easy and economical

indicator of the state of health and quality of life of

children and the population.

GROWTH AND DEVELOPMENT 2983

0068 Distance graphics Distance graphics are useful to

understand a specific growth situation, the height

achieved at an individual’s age or by the children of

any community, by comparison. Distance graphics

come from the study of a sample of children of differ-

ent age who are examined just once (‘cross method’).

Therefore, it is useful to assess growth, nutrition,

health or socioeconomic state, and differences and

to monitor height variations in groups or in the

whole society. In contrast, the longitudinal method

allows the follow-up of a population sample during

part or all growth periods. Each child is measured at

regular intervals of time. This method is the only one

that permits the analysis of individual circumstances

and the inflections produced in growth velocity, as

well as creating curves for growth velocity. Therefore,

it is essential for clinical analysis, diagnosis, and treat-

ment of growth disorders.

0069 To analyze variations, increments, or inflections in

the speed of children’s growth, it is necessary to have

velocity standards in velocity graphics. These can

express growth increments experienced in a specific

time interval. So, to assess velocity, height increment

is divided into the time which has passed between

two measurements. The time between two measure-

ments is more easily calculated by means of a decimal

calendar.

0070 To assess if a child is within the normal variation

limits for growth, percentiles or standard deviations

must be used. The third and 97th percentiles define

the cutting point between normal and pathological

risk, and the first and 99th percentile define patho-

logical risk. Standard deviation, calculated by means

of a score standard deviation or Z-scoring, allows one

to evaluate multiple or fraction standard deviations

of a subject separated from the average, by means of

the formula: Z ¼a x/ TD, where a ¼value to com-

pare, x ¼mean of standard group and TD ¼typical

deviation. When it is + 2 SD, the risk area starts, and

+ 3 SD would be pathology.

0071 The most widely used graphics from an inter-

national point of view are Tanner’s (longitudinal)

and those from the National Centre of Health Statis-

tics (cross ones). However, the most accurate proced-

ure will be to use individual country standards.

See also: Bone; Hormones: Adrenal Hormones; Thyroid

Hormones; Gut Hormones; Pancreatic Hormones;

Pituitary Hormones; Steroid Hormones

Further Reading

Barker DJP (2000) Fetal origins of cardiovascular and lung

disease. Marcel Dekker Inc. New York.

Baxter-Jones ADG, Cardy AH and Helms DS (1999) Influ-

ence of socioeconomic conditions on growth in infancy:

the 1921 Aberdeen birth cohort. Archives of Diseases of

Childhood 81: 5–9.

Greulich WW and Pyle SI (1971) A radiographic standard

of reference for the growing hand and wrist. Chicago:

Case Western Reserve University.

Holmes R and Soothill PW (1998) Normal fetal growth. In:

Kelmer ChJH, Savage MO, Striling HF and Saenger P

(eds) Growth disorders, pp. 143–157. Cambridge:

Chapmen & Hall.

Karlberg J (1989) A biologically-oriented mathematical

model (ICP) for human growth. Acta Paediatr 350

(suppl): 70–78.

Karlberg J and Luo ZC (2000) Foetal size to final height.

Acta Paediatr 89: 632–636.

LeRoith D (1997) Insulin-like growth factors. N Eng J Med

336: 633–640.

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2984 GROWTH AND DEVELOPMENT

GUAVAS

S Yusof, Universiti Putra Malaysia, Selangor, Malaysia

Introduction

0001 Guava has long been established in many tropical and

subtropical countries of the world, although its origin

was from Central America. Much of the interest in

guava has been due to its extremely high vitamin

content. Nutritionally, it is a healthy fruit, containing

relatively high amounts of vitamin C and total fiber.

Guava has the potential to become a commercially

important tropical fruit crop not only for processing,

but also for fresh consumption. Improved propaga-

tion techniques have produced fruits with better qual-

ity and thus increased the commercial importance of

the fruit in many countries, especially in the Far East.

Morphology and Anatomy of Fruits

0002 Guava is the most important fruit plant in the large

family, Myrtaceae, which also includes strawberry

guava, Psidium cattleianum sabine; the rose apple,

Engenia jambos; Surinam cherry, Engenia uniflora;

the mountain apple, Engenia malaccensis; the Java

plum, Engenia cumini Merr.; and the spices cinna-

mon, clove, allspice, and nutmeg. Guava is classified

under the genus Psidium which contains 150 species,

but only Psidium guajava has been exploited com-

mercially. Guava is a shrub but under high moisture

conditions can grow up to 6–9 m in height and

spread, with trunk diameters of 30 cm or more. The

trunk is short, freely branching from the base.

Branches are pliable and hence are rarely broken

by winds. Leaves are usually opposite and simple,

arranged in pairs; oblong or oval in shape measuring

about 10–18 cm in length; smooth on the upper sur-

face but finely pubescent on the undersurface and

prominently veined. Flowers occur singly or in clus-

ters of two to three at the leaf axils of current and

preceding growth. The flowers are bisexual or called

perfect flowers. They are white in color, 2.5–3.5 cm in

diameter, with four or five petals, numerous stamens,

and one style. Flowers open between 5 and 7 a.m.,

depending upon the cultivar and morning tempera-

tures. The tubular calyx encases the bud and splits

into four or five segments at anthesis. The ovary is

inferior with four or five carpels, each containing

numerous ovules in axile placentation. The flowers

can be self-pollinated, but cross-pollination takes

place most frequently, aided by bees and pollen-

carrying insects. After fertilization, the flowers will

develop into mature fruits.

0003Botanically, the fruit is a berry or capsule. It is a

many-seeded berry, varying in size from 2.5 to 10 cm

in diameter and from 50 to 500 g in weight. The shape

of the fruit can be globose, ovoid, elongated, or pear-

shaped. The color of the skin of some varieties may

turn yellow when ripe; the flesh color may be pink,

salmon, white, or yellow. Skin texture may be smooth

or rough. The inner walls of the carpels are fleshy and

of varying thickness and seeds are embedded in the

pulp. The fruits may have thick flesh with only a

few seeds in a small center cavity, or thin flesh with

numerous seeds embedded in a large mass of pulp.

The seeds are small, bony, kidney-shaped, flattened,

light yellow or yellowish brown, measuring about

3–5 mm long by 2–3 mm wide. It occupies about

1.6–4.4% of the weight of fruit. Fruit growth follows

a simple sigmoid curve and pulp growth parallels

total fruit growth. The days from anthesis to harvest

can vary from about 120 to over 220 days, depending

upon temperature during fruit development. The vari-

ation between different cultivars can be up to 60 days.

Cultivars

0004Guavas can be classified into three types depending on

their end use, namely the dessert type, the processing

type, and those suitable for both dessert and process-

ing (Table 1). In India a low-acid dessert cultivar, such

as Allahabad Safeda an ‘apple color,’ with white flesh

was developed. South Africa’s Malherbe and Fan

Ratief are mild, sweet, dessert types, with light pink

color. They are also suitable for canning as halved

fruit. For processing, Beaumont, Ka Hua Kula, and

Waiakea are recommended in Hawaii. Beaumont was

the first processing cultivar introduced to Hawaiian

industry and was the only recommended processing

guava until the introduction of Ka Hua Kula. Beau-

mont produces fruits ranging from 145 to 235 g, aver-

aging about 170 g. Fruits are mildly acid with total

titratable acidity ranging from less than 1.0% during

the summer to about 1.25% in winter. Soluble solids

range from about 7% in winter to 10% during

summer. Fruit characteristics of Ka Hua Kula are simi-

lar, with a slightly stronger pink color and somewhat

higher acidity. Both varieties are good yielders,

exceeding 227 kg tree

1

year

1

. Florida has developed

both dessert and processing cultivars of excellent qual-

ity. Ruby, Supreme and the hybrid Ruby  Supreme,

are excellent dessert types. Pink Acid and Patillo are

GUAVAS 2985

two acid cultivars with dark pink color suitable for

processing. Other varieties that have been developed

in various countries are as shown in Table 1.

0005 Certain guava cultivars exhibit a change of skin

color from green to yellow during ripening, whereas

in others the color remains green and this is depend-

ent on the cultivar. The flesh color may change from

white to either creamy white, yellowish pink, deep

pink, or salmon-red upon ripening. The presence of

carotenoids, lycopene, and b-carotene may influence

the intensity of the flesh color of ripe fruit. Fruit

texture may differ between cultivars and it varies

with position of the tissue. For example, the Beau-

mont cultivar is significantly softer when ripe, and its

firmness decreases more rapidly during ripening than

that of the Vietnamese guava. Irrespective of the

cultivar type, outer mesocarp tissue of the fruit is

consistently firmer than inner mesocarp tissue.

Fruiting Cycle

0006 The fruiting peaks can deviate with prevailing

weather conditions and cultural practices. Since

flowers are produced on new growth, factors that

stimulate new growth, such as irrigation, fertiliza-

tion, pruning, and defoliation stimulate flowering.

The practice of pruning, fertilizing, and irrigation at

the end of harvest is essential. Pruning is repeated

every 8–9 months. Initial flowering after pruning

occurs in about 5–6 weeks. Defoliation can be accom-

plished using urea plus ethephon and a detergent.

Following defoliation, new leaves appear in about

3–4 weeks, with a peak of flowering occurring 9–12

weeks after defoliation. This is followed by fruit set

and a peak of abscission of young fruit. The percent-

age fruit abscission is correlated with number of

fruitlets set per tree. In Hawaii, a small harvest

peak occurs between April and November.

0007Guava plant grows best in warm areas with abun-

dant moisture. The ideal rainfall pattern for guava is

alternating dry and wet conditions. The optimum

temperature is reported to be between 23 and 28



Temperatures lower than 23



C and higher than 27



during flowering would reduce fruit set significantly.

Chemical Composition

0008The chemical composition of guava fruits is shown in

Table 2. As in most fruits, moisture constitutes a

fairly large portion of guava fruit (85%); the energy

content is relatively high (230 kJ); the protein and

fat contents are low (0.3% and 0.1%, respectively).

Carbohydrates are the principal nonaqueous constitu-

ents of guava. Of the total carbohydrates (15%),

5.82 g are the sugars fructose, glucose, and sucrose.

tbl0002Table 2 Proximate composition of common guava, with seeds

removed

Units Amount in 100 g edible portion

Proximate

Moisture % 85

Energy kJ 230

Protein g 0.3

Fat g 0.1

Carbohydrate g 15

Fiber g 2.4

Ash g 0.5

Minerals

Calcium mg 15

Phosphorus mg 16

Iron mg 0.3

Potassium mg 292

Sodium mg 6

Vitamins

Vitamin A IU 109

Thiamin mg 0.06

Riboflavin mg 0.06

Niacin mg 1.3

Ascorbic acid mg 190

tbl0001 Table 1 Characteristics of some guava varieties and their use

Variety Origin Size

Shape Flesh color Seeds Acidity

Use

Vietnamese

Vietnam Large Ovoid White Few Low Dessert

Allahabad Safeda India Medim Round White Few Low Dessert

Fan Ratief South Africa Medium Light pink Medium Medium Dual purpose

Lucknow-49 India Large Round White Few, soft Low Dessert

Beaumont Hawaii Large Ovoid Pink Medium High Processing

Ka Hua Kula (097) Hawaii Large Ovoid Pink Few High Processing

Hong Kong Pink Hawaii Medium Pink Few Low Dessert

Ruby x Supreme Florida Large Ovoid White Few Low Dessert

11–56 Australia Medium Conical Pink Medium High Processing

11–56 (T3) Australia Medium Round Strong red-pink Low-medium Medium Dual purpose

Small, <100 g; medium, 100–200 g; large,>200 g.

Low, <0.5% anhydrous citric acid equivalent; medium, 0.5–1% anhydrous citric acid equivalent; high, >1.0% anhydrous citric acid equivalent.

Adapted from Batten (1983).

Yusof S (1989) Characteristics and potential use of guava (Psidium guajava L.) for processing and storage. PhD thesis. Universiti Putra Malaysia.

Serdang, Selangor, Malaysia.

2986 GUAVAS

Fructose is the predominant sugar, constituting about

58.9%, followed by glucose (35.7%), and sucrose

(5.3%). During development and maturation the

sugars increase gradually and then decrease in over-

ripe fruits (Figure 1). The fiber and ash contents are

considered high, with values of 2.4 and 0.5 g respect-

ively. Refer to individual nutrients .

Nutritional Value

0009 Guava is an excellent source of ascorbic acid (Table 3).

It is mainly located in the skin and a slightly lower

concentration is found in the flesh. The content of

ascorbic acid, which is also cultivar-dependent, varies

from as low as 60–100 mg 100 g

1

in some cultivars

to about 200–300 mg 100 g

1

, or to even higher levels

(800–1000 mg 100 g

1

) in other cultivars. Ascorbic

acid level generally increases with ripening, and also

with decreasing depth of the mesocarp tissue. The

fruit has an appreciable amount of minerals such as

calcium, phosphorus, iron, potassium, and sodium as

well as vitamins like vitamin A, thiamin, riboflavin,

and niacin. (See Vitamins: Overview.)

tbl0003Table 3 Ascorbic acid content of several guava varieties

Location Variety Ascorbic acid (mg 100 g

1

)

Florida Red Cattley 29.1

Florida Yellow Cattley 39.1

Florida Common Cattley 23–486

Hawaii Red or white Cattley 25–50

Hawaii Common 96–306

California Common 50–352

Puerto Rico Common 202–442

India Country 299

India Hill 11–19

Australia Large Yellow 110

Adapted from Jagtiani J, Chan H Jr and Sakai W (1988) Guavas. In: Tr o p i c a l

Fruits Processing, pp. 9–43. New York: Academic Press.

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.8

2.2

2.4

2.6

579

No. of weeks

Sugar content (%)

13 15 1711

fig0001 Figure 1 Sugar content of Vietnamese fruits during development and maturation. Circles, fructose; squares, glucose; triangles,

sucrose. From S Yusof (1989) Characteristics and potential use of guava (Psidium guajava L.) for processing and storage. PhD thesis.

Universiti Putra Malaysia. Serdang, Selangor, Malaysia.

GUAVAS 2987