Available via license: CC BY-NC-ND 4.0
Content may be subject to copyright.
A Substantial Proportion of 6- to 12-Month-Old Infants Have Calculated
Daily Absorbed Iron below Recommendations, Especially Those Who Are
Breastfed
Steven A. Abrams, MD
1
, Joel C. Hampton, MS
2
, and Kristen L. Finn, DCN, RD
3
Objective To calculate the amount of bioavailable iron consumed among 6- to 12- month-old infants considering
differences in iron bioavailability among dietary iron sources and to compare this with current recommended in-
takes.
Study design We used the Feeding Infants and Toddlers Study database of dietary intakes from 2016 and the
estimated bioavailability of dietary iron sources to evaluate the proportion of infants whose calculated total daily
absorbed iron fell below physiologic requirements, that is, the recommended amount needed to fully support
growth and erythropoiesis.
Results The calculated daily iron absorption was below the recommended amount in 54.3% of infants evaluated
ranging from 19.5% of 448 exclusively formula-fed infants, to 95.8% of 296 exclusively breastfed infants and 72.2%
of 102 mixed fed infants. The calculated mean iron absorption of 6- to 9- month-old breastfed infants was 0.27 mg/
day, far less than the estimated physiologic requirement of 0.69 mg/day. The most highly bioavailable iron, heme
iron, was <12% of the contributor to total iron absorbed in breastfed infants.
Conclusions These data indicate a need for further education and public health policies to support increased iron
intake in 6- to 12- month-old infants, emphasizing those receiving any breast milk. Exclusively formula-fed infants
are at lower risk, but rates of low absorbed iron indicate that all infants may need monitoring for clinical evidence of
low iron status. Consideration should be given to increasing the proportion of heme iron obtained from animal prod-
ucts in the diet where feasible. (J Pediatr 2020;-:1-7).
See editorial, p
Iron deficiency remains a critical global health problem.
1
In the first year of life, adequate iron stores are critical for eryth-
ropoiesis and neurocognitive development. Up until about 6 months of age, iron stores acquired prenatally along with a
small amount of iron from breast milk are adequate to meet these needs for most healthy full-term infants and as such addi-
tional iron is not needed until ³4 months of age, with the World Health Organization recommendation being 6 months of
age.
2-4
After about 6 months of age, supplemental iron is needed by full-term infants and usual dietary recommendations
suggest the primary use of iron-containing solid foods.
5
These recommendations do not fully account for the differences in the relative bioavailability of iron from nonheme iron,
including infant formula and from heme iron or from human milk and how these may affect iron status.
6
Determination of
total iron absorption has usually combined groups of infants and not separately considered breastfed, mixed fed, and
formula-fed infants.
6
Nonetheless, recommendations, including those of the Di-
etary Guidelines Advisory Committee, 2020, indicate that formula-fed infants are
not at substantial risk for low iron intake and do not consider the considerable
population of older, mixed fed infants.
7
We sought to use a well-characterized recent database that provides detailed
information on iron intake and sources to calculate the daily absorbed iron
intake from infants receiving a variety of milk and formula intakes consistent
with usual diets in the US. From this information, we determined the proportion
of infants whose diet was below the intake needed to meet calculated absorbed
From the
1
Dell Medical School at the University of Texas
at Austin, Austin, TX;
2
RTI International, Durham, NC; and
3
Nestl
e Nutrition, Arlington, VA
The Feeding Infants and Toddlers Study 2016 was
funded by Nestl
e Research, Vers-chez-les-Blanc, Lau-
sanne, Switzerland and analyses described in this pub-
lication was funded by Gerber Products Co, Nestl
e
Nutrition, Arlington, VA 22209. Nestl
e Research, in
collaboration with research partners RTI International
and subcontractor University of Minnesota, designed
and implemented the Feeding and Infants and Toddlers
Study. Data interpretation and preparation of the manu-
script was conducted by S.A. who did so without any
form of financial support for this project or his research.
S.A. and J.H. declare no conflicts of interest. S.A. does
not consult with or receive research financial support
from Nestl
e. K.F. is employed by Nestl
e Nutrition.
0022-3476/ª2020 The Author(s). Published by Elsevier Inc. This is an
open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/).
https://doi.org/10.1016/j.jpeds.2020.10.071
DRI Dietary reference intakes
EAR Estimated average requirement
FITS Feeding Infants and Toddlers Study
WIC The Special Supplemental Nutrition Program for Women, Infants, and Children
1
ORIGINAL
ARTICLES
iron requirements and to further determine the proportion
of iron in each group that came from heme iron vs nonheme
iron or breast milk.
The aims of this study were to report the iron intake distri-
bution among breastfed (only received breast milk), mixed
fed (received breast milk and infant formula), and formula-
fed (received only infant formula) 6- to 12- month-old in-
fants; report the percent of infants with iron intakes below
the estimated average requirement (EAR) by milk or formula
feeding type; calculate an estimate of the amount of absorbed
iron consumed by applying established absorption factors for
heme, nonheme, and breast milk sources of iron; estimate the
percent of infants with calculated absorbed iron intakes
below the daily absorbed iron requirement of 0.69 mg (the
physiologic requirement) used to set the dietary reference in-
takes (DRI) for this age group; and determine the contribu-
tion of heme, nonheme, and breast milk iron to total
calculated absorbed iron intake.
6
These calculations are based
on assumptions used in development of these guidelines
including using average size and growth rates for infants as
well as estimates of absorption which would be affected by in-
dividual factors including iron status.
We hypothesized that current dietary practices in the US
would lead to relatively low bioavailable iron intake in
breastfed and mixed fed infants leading to a risk of inade-
quate absorbed iron.
Methods
Conducted in 2002, 2008, and 2016, Feeding Infants and Tod-
dlers Study (FITS) is a nation-wide survey examining food
intake and feeding behaviors among infants and children
<4 years of age in the US.
8,9
Data reported here are those
only from the 2016 FITS study. Trained telephone inter-
viewers obtained informed consent and detailed dietary
intake data using the multiple-pass 24-hour recall methodol-
ogy from eligible caregivers (n = 3235). A subset of caregivers
were randomly selected to complete a second 24-hour recall to
estimate usual nutrient intake distributions (n = 799). Sample
weighting methods were applied to control for bias between
the survey sample and the US population. Nutrient intakes
were calculated with systems developed by the Nutrition
Coordinating Center at the University of Minnesota. The esti-
mated breast milk volume and nutrient composition used in
FITS is consistent with the methodology used in the National
Health and Nutrition Examination Surveys and by the Insti-
tute of Medicine to develop the DRI for infants.
10,11
For
breastfed infants, an intake of 600 mL/day was assumed and
pumped milk or infant formula was subtracted.
10,12-14
Insti-
tutional review boards at the University of Minnesota, RTI In-
ternational, and Fort Hays University approved the study
methods and procedures. A detailed description of the FITS
2016 study design and methodology is available elsewhere.
15
The EAR is the amount of a nutrient whose intake is deter-
mined to meet the needs of 50% of the population.
16
For in-
fants >6 months of age, the EAR for iron of 6.9 mg/day was
established using factorial modeling, which considered the
amount of iron required for increases in tissue iron, storage
iron, and hemoglobin mass and accounting for basal iron los-
ses.
6
An absorbed iron requirement of 0.69 mg/day was deter-
mined to be adequate for 50% of the population.
6
Because
the bioavailability of iron from foods differ, absorption fac-
tors of 50% for breast milk, 20% for heme iron sources,
and 5% for nonheme iron sources were applied along with
the likelihood infants of that age would consume heme and
nonheme iron according to data from the National Health
and Nutrition Examination Survey.
6
An overall estimate of
10% absorption was then applied converting the absorbed
iron requirement of 0.69 mg/day to a total daily iron intake
requirement of 6.9 mg/day (the EAR).
6
For this analysis, only infants age 6 to 12 months (had not
reached their first birthday) who were breastfed (received
only breast milk; n = 296), mixed fed (received breast milk
and infant formula; n = 102), or formula fed (received only
infant formula; n = 448) according to the 24-hour recall
were included (n = 846). Infants who received neither infant
formula nor breast milk (ie, no milk or cow milk) on the day
of the recall were excluded (n = 56). First, iron intake distri-
butions and the percent of infants with iron intakes below the
EAR were calculated for the overall population and by milk
type (breastfed, mixed fed, and formula fed). Second, 2 regis-
tered dietitians familiar with the FITS methodology indepen-
dently reviewed the extensive list of individual foods
captured in the survey and determined if it was a heme or
nonheme source of iron. If the food title or description
included the words meat (including poultry), meat gravy,
or meat broth, it was coded as a heme iron source. Breast
milk was coded as breast milk, and all other foods were coded
as nonheme iron sources. Together, the dietitians determined
the code in the few cases where there was disagreement in the
independent assessments.
Once the food map was coded, absorption factors were
applied to the total iron content of the food consistent with
the DRI methodology as follows: 50% for breast milk, 20%
for heme iron sources, and 5% for nonheme iron sources.
6
We then calculated the total amount of iron absorbed daily
as the product of the intake and the absorption. We refer
to this as the calculated absorbed iron intake. Subsequently,
distributions and percent of infants with daily intakes below
the calculated absorbed iron requirement of 0.69 mg were
determined for the overall population and by milk type.
6
Results for 3-month increments in age (6-9 months and
9-12 months) were also calculated to capture the rapid
changes in complementary feeding practices for this age
group. Sources of calculated absorbed iron were ranked ac-
cording to contribution they made to the calculated absorbed
iron intake for the overall population by milk feeding type.
Descriptive statistics were calculated for participant char-
acteristics including race, household income, participation
in the Special Supplemental Nutrition Program for Women,
Infants, and Children (WIC), and caregiver education level.
Differences between milk feeding types in characteristics,
mean iron intakes, mean calculated absorbed iron intakes,
percent below the EAR, and percent below the absorbed
THE JOURNAL OF PEDIATRICS www.jpeds.com Volume --2020
2Abrams, Hampton, and Finn
iron requirement were calculated with unpaired ttests. A P
value of < .05 was considered statistically significant. All sta-
tistics were analyzed using the following software: SAS
(version 9, SAS Institute Inc) and SAS-callable SUDAAN
(version 11, RTI International).
Results
There were some differences in characteristics among infants
with different milk feeding types (Table I). Significantly
more breastfed infants were non-Hispanic white compared
with mixed fed and formula-fed infants. Formula-fed
infants were significantly more likely to come from lower
income households, participate in WIC, and have
caregivers with less education compared with breastfed and
mixed fed infants. Significantly, more breastfed infants
consumed nonbaby food meat on the day of the 24-hour
recall compared with mixed fed and exclusively formula-
fed infants, but differences in baby food meat consumption
were not significant. Significantly more breastfed and
mixed fed infants consumed a dietary supplement
compared with formula-fed infants, but iron supplement
use was low and differences in use between groups was not
significant.
Among exclusively breastfed infants in each age subcate-
gory, the mean total iron intake was significantly lower and
the percentage of infants with iron intakes below the EAR
was significantly higher compared with mixed fed and
formula-fed infants (Table II). Mixed fed infants had
significantly lower mean iron intakes and the percentage of
mixed fed infants below the EAR was significantly higher
compared with formula-fed infants. Very few exclusively
formula-fed infants had iron intakes below the EAR in
either age group.
When absorption factors were applied, mean calculated
absorbed iron intakes and the percentage of infants with
intakes below the absorbed iron requirement (0.69 mg/
day) were significantly different between all milk feeding
typesineachagegroup(Table III). The percentage of
infants below the 0.69 mg/day absorbed iron threshold
was higher than the percentage of infants with total daily
iron intakes below the EAR (from Table II)inevery
category.
Among breastfed infants, 42% of calculated absorbed iron
came from human milk, 47% from nonheme iron sources,
and 11% from heme iron sources (Figure). Among mixed
fed infants, 17% of calculated absorbed iron came from
human milk, 79% from nonheme sources, and 4% from
heme sources. Among formula-fed infants, 93% of the
calculated absorbed iron was from nonheme sources and
7% from heme sources. Although bioavailability of iron
from breast milk is high, the overall intake is low.
When the sources of calculated absorbed iron were ranked,
the grain group and milk group (human milk and infant
Table I. Characteristics by milk feeding type for
infants 6 to 12 months of age
Characteristics
Breastfed
(n = 296)
Mixed fed
(n = 102)
Formula fed
(n = 448)
Child’s sex male 55.4 (2.9) 57.8 (4.9) 52.2 (2.4)
Child first born 33.3 (2.9) 42.6 (5.1) 39.5 (2.6)
Race
Hispanic 11.9 (1.9) 13.0 (3.4) 15.5 (1.7)
Non-Hispanic white 77.9 (2.4)*
†
64.0 (4.8)*63.9 (2.3)
†
Non-Hispanic black 5.8 (1.4)
†
12.0 (3.3) 17.3 (1.8)
†
Non-Hispanic other 5.1 (1.3) 11.0 (3.1)
‡
3.4 (0.9)
‡
Income (US$)
<10 000 3.38 (1.05)
†
4.9 (2.13)
‡
10.49 (1.45)
†‡
10 000-19 999 7.43 (1.52) 4.9 (2.14)
‡
10.94 (1.47)
‡
20 000-34 999 13.18 (1.97)
†
15.69 (3.6)
‡
26.56 (2.09)
†‡
35 000-49 999 19.93 (2.32) 23.53 (4.2) 16.96 (1.77)
50 000-74 999 23.31 (2.46)
†
18.63 (3.85) 16.96 (1.77)
†
75 000-99 999 18.24 (2.25)
†
19.61 (3.93)
‡
8.93 (1.35)
†‡
100 000-149 999 11.15 (1.83) 7.84 (2.66) 6.92 (1.2)
³150 000 3.38 (1.05) 4.9 (2.14) 2.23 (0.07)
Maternal education
High school or less 14.2 (2.0)
†
16.8 (3.7)
‡
27.5 (2.1)
†‡
Some post-secondary 22.7 (2.4) 19.8 (4.0) 25.9 (2.1)
College or graduate 63.1 (2.8)
†
63.4 (4.8)
‡
46.7 (2.4)
†‡
WIC participant 25.7 (2.5)
†
33.3 (4.7)
‡
55.6 (2.3)
†‡
Meat intake
Nonbaby food 31.4 (2.7)*
†
18.6 (3.9)*21.4 (1.9)
†
Baby food 5.4 (1.3) 2.9 (1.7) 3.1 (0.8)
Supplement with iron 4.1 (1.2) 2.9 (1.7) 2.9 (0.8)
Mean volume intake (mL)
Formula n/a 443 (32) 918 (17)
Human milk 658 (74) 379 (21) n/a
Milk feeding type defined by 24-hour recalls: Breastfed = received breast milk and no infant
formula; mixed fed = received breast milk and infant formula; formula fed = received infant
formula and no breast milk.
Values are percent (standard error).
*Breastfed vs mixed fed, P< .05.
†Breastfed vs formula fed, P< .05.
‡Mixed fed vs formula fed, P< .05.
Table II. Total iron intakes (mg/d) and relationship
with feeding type (without absorption factors applied)
Feeding types No. 10th 25th Median Mean SE 75th 90th %<EAR
6-9 Months
Overall 469 4.8 7.1 10.2 11.0 0.3 14.2 18.3 23.8
Breastfed 153 0.9 1.3 2.1 2.7*
†
0.2 3.4 5.2 95.5*
†
Mixed fed 71 5.2 7.0 9.7 10.5*
‡
0.6 13.1 16.9 24.2*
‡
Formula fed 234 10.5 13.1 16.6 17.6
†‡
0.4 21.0 26.0 0.7
†‡
9-12 Months
Overall 434 6.0 8.7 12.3 13.2 0.3 16.8 21.5 14.0
Breastfed 143 2.2 3.3 5.2 6.5
†§
0.4 8.3 12.4 66.0*
†
Mixed fed 31 5.0 6.8 9.5 10.2
‡§
0.8 12.8 16.4 25.5*
‡
Formula fed 214 11.0 13.5 17.1 18.3
†‡
0.5 21.7 26.9 0.5
†‡
6-12 Months
Overall 902 5.3 7.8 11.3 12.1 0.2 15.5 20.0 18.9
Breastfed 296 1.1 1.8 3.3 4.5*
†
0.2 5.7 9.3 81.5*
†
Mixed fed 102 5.1 6.9 9.6 10.4*
‡
0.5 13.0 16.7 24.6*
‡
Formula fed 448 10.7 13.3 16.8 17.9
†‡
0.3 21.4 26.5 0.6
†‡
EAR of 6.9 mg/d.
*Statistical comparison of means between feeding types and %<EAR between feeding types
within each age group: Breastfed vs mixed fed, P< .0001.
†Statistical comparison of means between feeding types and %<EAR between feeding types
within each age group: Breastfed vs formula fed, P< .0001.
‡Statistical comparison of means between feeding types and %<EAR between feeding types
within each age group: Mixed fed vs formula fed, P< .0001.
§Statistical comparison of means between feeding types and %<EAR between feeding types
within each age group: Breastfed vs mixed fed 9-12 months, P= .0002.
-2020 ORIGINAL ARTICLES
A Substantial Proportion of 6- to 12-Month-Old Infants Have Calculated Daily Absorbed Iron below Recommendations,
Especially Those Who Are Breastfed
3
formula) were the main contributors to total iron intake
(Table IV; available at www.jpeds.com) for all infants and
for bottom and top quartiles of calculated absorbed iron
intakes (Table V and Table VI; available at www.jpeds.
com). Infant cereal was the top source of iron among
breastfed infants, followed by human milk and meat.
Among mixed fed and formula-fed infants, infant formula
was the top source of calculated absorbed iron followed
by infant cereal. Among meat sources, chicken and
turkey were the top contributors to iron, although these
contribute relatively little heme iron. Although beef is high
in heme iron, it did not contribute ³0.01 mg/day calculated
absorbed iron to the diets of infants in any feeding type
categories and, thus, is not listed as a source of iron.
Among infants in the bottom quartile of calculated ab-
sorbed iron intakes, human milk or infant formula is the
top source contributing to the majority of iron intakes
(0.10-0.42 mg/day) (Table V). Infant cereal is the second
ranked source, but contributes only 0.02-0.04 mg/day of
iron. Among infants in the top quartile of calculated
absorbed iron, infant cereal is the top source of iron
contributing 0.45-0.62 mg/day of absorbed iron and milk is
ranked second contributing 0.10-0.65 mg of absorbed
iron daily (Table VI). Very few infants received infant
formula or human milk exclusively and did not receive any
complementary foods. Among those in the bottom quartile
of calculated absorbed iron intake, 4.0% of breastfed
infants, 1.5% of mixed fed infants, and 1.6% of formula-
fed infants received no complementary foods. All infants
in the top quartile of calculated absorbed iron intake
consumed some complementary foods in addition to
human milk or infant formula.
Discussion
We found that the calculated absorbed iron based on current
feeding patterns were below that needed to meet require-
ments for growth and erythropoiesis in a large proportion
of 6- to 12- month-old infants. This cohort included infants
who were receiving all or part of their feedings from breast
milk, as well as some infants who did not receive any breast
milk. These data further demonstrate that there is minimal
iron intake in all groups from highly bioavailable heme
iron sources and that low intakes were substantially similar
both in 6- to 9-month-old and 9- to 12-month-old infants,
indicating no trend toward increased heme iron intake after
solid food intake was well-established.
The determination of iron intake and proportion of chil-
dren meeting their estimated iron requirements have been
derived historically using what is referred to as a factorial
approach.
6
In this approach, the dietary iron intake is multi-
plied by the percentage absorbed and then, after accounting
for any excretion in urine, stool, or sweat, this amount is
compared with the amount of iron that is needed to meet
the needs of the child to provide iron for adequate erythro-
poiesis. This latter amount is determined based on the
average body growth, the amount of iron present in red blood
cells, estimated blood volume changes during growth, and
any iron that may be expected to be outside of red blood cells.
The details of this derivation have been described previously
and, although there are some uncertainties in the calcula-
tions, especially of blood volume, it is likely to reasonably
reflect the actual average daily iron need of 6- to
12-month-old infants.
6
In evaluating whether a population is meeting its intake
target for a nutrient, the key value is the EAR. This is the di-
etary intake needed, on average, to meet the needs of one-half
of all children.
10,16
It is, for iron, much lower than the better
known recommended dietary allowance, which is intended to
meet the needs of nearly all children in a given age range (as
separated by sex for older children and adolescents). It is
usual to evaluate a populations sufficiency for iron and other
nutrients using a “cut point” analysis, in which the propor-
tion of the population below the EAR is used to determine
what proportion of the population has a low intake. Howev-
er, this determination may underestimate insufficient intakes
if the assumptions in the EAR value is falsely elevated as it was
derived using calculations of absorbed iron, are higher than
are actually achieved.
16
Individual dietary guidance is usually
based on the recommended dietary allowance, but for popu-
lation studies the EAR is the appropriate value. For iron, the
recommended dietary allowance is 11 mg/day, which is
considerably higher that the EAR of 6.9 mg/day.
Because of concerns that dietary practice has led to lower
intakes of both iron supplements and iron-containing foods
in the US since the original calculations of the EAR were
done, we evaluated the frequency of potentially low bioavail-
able iron intake using a recent, broadly representative popu-
lation in the US. To do this, we used the same bioavailability
Table III. Total calculated absorbed iron (mg/d) and
relationship with feeding type (with absorption factors
applied)
Feeding types No. 10th 25th Median Mean SE 75th 90th % <0.69*
6-9 months
Overall 469 0.3 0.4 0.6 0.6 0.01 0.8 1.0 64.3
Breastfed 153 0.2 0.2 0.3 0.3
†‡
0.01 0.3 0.4 99.8
†‡
Mixed fed 71 0.3 0.4 0.5 0.6
†§
0.03 0.7 0.9 71.7
†§
Formula fed 234 0.6 0.7 0.9 0.9
‡§
0.02 1.1 1.3 23.4
‡§
9-12 months
Overall 434 0.4 0.6 0.7 0.8 0.02 1.0 1.2 44.3
Breastfed 143 0.3 0.3 0.4 0.5
‡{
0.01 0.5 0.7 91.3
†‡
Mixed fed 31 0.3 0.4 0.5 0.6
§{
0.04 0.7 0.9 73.2
†§
Formula fed 214 0.6 0.8 0.9 1.0
‡§
0.02 1.2 1.4 15.7
‡§
6-12 months
Overall 902 0.4 0.5 0.7 0.7 0.01 0.9 1.1 54.3
Breastfed 296 0.2 0.2 0.3 0.4
†‡
0.01 0.4 0.6 95.8
†‡
Mixed fed 102 0.3 0.4 0.5 0.6
†§
0.02 0.7 0.9 72.2
†§
Formula fed 448 0.6 0.7 0.9 1.0
‡§
0.01 1.1 1.4 19.5
‡§
*0.69 mg/d is the absorbed daily iron requirement used to establish the EAR.
†Statistical comparison between feeding types within each age group: Breastfed vs mixed fed,
P< .0001.
‡Statistical comparison between feeding types within each age group: Breastfed vs formula
fed, P< .0001.
§Statistical comparison between feeding types within each age group: Mixed fed vs formula
fed, P< .0001.
{Statistical comparison between feeding types within each age group: Breastfed vs mixed fed
9.0-11.9 months, P= .0086.
THE JOURNAL OF PEDIATRICS www.jpeds.com Volume -
4Abrams, Hampton, and Finn
estimates as were used in the original derivation, applying
them to breast milk, nonheme iron (including infant for-
mula), and heme iron. We then evaluated the total amount
of each of these in the diets of the infants and determine
the calculated daily absorbed iron.
In considering these data, and recognizing the importance
of breast milk, it is important to consider methods to assess
and respond to low overall iron intakes, especially extremely
low values. Consideration only of the proportion below the
EAR or the absorbed iron requirement misses concerns about
the proportion with very low absorbed iron. For example, the
10th percentile of daily absorbed iron was only 0.2 mg in
breastfed and 0.3 mg in mixed fed infants 6-12 months of
age. Even recognizing individual variation in absorption ca-
pacity and the possibility that lower iron status would in-
crease the proportion of absorbed iron, these values are far
below that needed for adequate erythropoiesis during rapid
growth in this age group. Iron deficiency, especially in the
first 2 years of life, may be associated with significant life-
long developmental consequences and, as such, although
this study did not specifically address markers of iron defi-
ciency, low intakes relative to requirements is of concern
related not only to hematologic measures, but also to devel-
opmental outcomes.
17
Figure. Sources of iron contributing to total calculated absorbed iron by feeding type for infants 6-12 months of age.
-2020 ORIGINAL ARTICLES
A Substantial Proportion of 6- to 12-Month-Old Infants Have Calculated Daily Absorbed Iron below Recommendations,
Especially Those Who Are Breastfed
5
The likely primary etiology of these low intakes relative to
absorbed requirements is a secular decrease in the intake of
iron from solid foods. Evaluation of the current compared
with the 2008 FITS studies showed a decrease in mean iron
intake among 6- to 12- month-old infants from 15.1 to
13.6 mg/day between 2008 and 2016.
18
During the same
time, the percentage of infants 6-12 months of age receiving
infant cereal decreased from 65% to 52%.
19
Overall, it has
been noted that, whereas in 2002 only 7% of 6- to
12- month-old FITS participants had an intake below the
EAR overall, by 2016 that value was 18%.
19-21
Of note is
that, despite the American Academy of Pediatrics recom-
mendation to provide supplemental iron to breastfed infants
beginning at 4 months of age and until solid food iron intake
is well-established, few infants in this study as well as others
receive supplemental iron (<5% in this study), which may
exacerbate the impact of low iron intakes.
22,23
The database of infants used in this analysis has been well-
described as representative of the US population, but social
and other changes, including increased food insecurity
associated with the 2020 novel coronavirus disease-2019
pandemic, may have changed feeding patterns since the study
data were collected.
24
These changes, including decreases in
WIC participation (a provider of iron food sources) and con-
cerns about use of cereals such as those related to arsenic in
rice-based infant cereals, are likely to have led to current
lower, not higher, population intakes of iron since the FITS
data were collected in 2016.
25,26
The calculations of absorbed iron are based on bioavail-
ability estimates used by the Institute of Medicine to establish
the DRI.
6
These values may not apply uniformly to all food
sources, especially for infant formulas where certain types
of formula; for example, soy formulas may have lower
bioavailability than others.
27
Intake of breast milk is difficult
to estimate precisely, but the value used is consistent with ex-
pected values in this age group and small variations would
have minimal effect on results owing to the low concentra-
tion of iron in breast milk.
Iron bioavailability is affected by a broad range of dietary
components, as well as the iron status of the infants.
28
We
have chosen not to attempt such a detailed analysis of for-
mula types or different iron sources within the nonheme
iron category, because the data do not permit this analysis
to be done reliably. Small variability in bioavailability factors
for solid foods would not likely have a large effect on diets in
infants of this age, for whom small amounts of solid foods are
given. New practices, including delayed cord clamping, may
affect the iron requirements in this age group and require
further investigation. Additionally, results represent those
based on average size and growth rates of infants and cannot
be used to predict individual infant requirements. Finally,
FITS use reported dietary intake from caregivers, which has
inherent limitations.
29
Although it may be thought that low iron intakes and ab-
sorbed iron most likely only affects lower income families,
this is not necessarily the case in the US. Higher rates of
breastfeeding in upper socioeconomic status families, as
well as the effectiveness of the WIC program in providing in-
fant formula and iron-containing solid foods might lead to
lower iron intakes among higher income compared with
lower income families. Among 6- to 12-month-old infants,
WIC participants had a significantly lower percentage below
the EAR for iron (12.6%) than both lower income (25.6%)
and higher income (34%) non-WIC participants.
30
Regard-
less of the etiology, these data demonstrate that all children
need to have consideration of iron intake regardless of socio-
economic status. Those choosing not to provide iron in solid
foods should have emphasis given on consideration of
supplements.
Pediatricians counseling families should be aware that the
possibility of low iron intake exists for all families, regardless
of whether the infant is formula fed or breastfed, although
this possibility is much higher in infants fed breast milk.
This finding may have consequences for long-term outcomes
of the infant. Although it is accurate that the absorption of
iron from breast milk, especially in older infants, is high, it
should be understood that even with a 50% absorption effi-
ciency, the daily intake of iron from breast milk (about
0.2 mg/day) can only meet about 15%-20% of the overall
need for iron of the older breastfed infant.
31-33
Further
research is needed to define the frequency of iron deficiency
in this age group, especially in mixed-fed or exclusively
breast-fed infants.
These data support the current recommendations for
routine monitoring of all older infants for evidence of anemia
using a hemoglobin measurement. Consideration should be
given to additional monitoring, not part of current recom-
mendations, for early evidence of iron deficiency without
anemia, such as using a serum ferritin, especially in infants
who are partially or fully breastfed.
3
Education, both on an
individual and a general population level, about the impor-
tance of solid food intake such as cereals containing iron
and the provision of heme iron for families that include
meat in their diet are critical, as are considerations of using
supplemental iron when dietary iron intake is low.
34
Intro-
duction of meat can safely be done in 6- to 12- month-old in-
fants and has been demonstrated to be effective on a global
basis.
35
The recent Dietary Guidelines for Americans Advisory
Committee concluded in considering diets in the first
24 months that “Every bite counts.”
7
Our data are consis-
tent with this finding related to the value of iron contain-
ing solid foods and the need to understand the significant
risk of a low iron intake in the diets of 6- to 12- month-old
infants. n
We thank Susan Pac of Nestl
e Nutrition for her contribution and assis-
tance with data coding and Brian Kineman of Nestl
e Nutrition for
methodological assistance.
Submitted for publication Sep 4, 2020; last revision received Oct 20, 2020;
accepted Oct 28, 2020.
Reprint requests: Steven A. Abrams, MD, Dell Pediatric Research Institute,
1400 Barbara Jorden Blvd., Austin TX 78723. E-mail: sabrams@austin.utexas.
edu
THE JOURNAL OF PEDIATRICS www.jpeds.com Volume -
6Abrams, Hampton, and Finn
References
1. Kassebaum NJ, Jasrasaria R, Naghavi M, Wulf SK, Johns N, Lozano R,
et al. A systematic analysis of global anemia burden from 1990 to
2010. Blood 2014;123:615-24.
2. World Health Organization. Daily iron supplementation in infants and
children guideline. 2016. www.who.int/nutrition/publications/micronu
trients/guidelines/daily_iron_supp_childrens/en/. Accessed November
18, 2020.
3. Baker RD, Greer FR, Committee on Nutrition American Academy of P.
Diagnosis and prevention of iron deficiency and iron-deficiency anemia in
infants and young children (0-3 years of age). Pediatrics 2010;126:1040-50.
4. Ziegler EE, Nelson SE, Jeter JM. Iron stores of breastfed infants during
the first year of life. Nutrients 2014;6:2023-34.
5. Dewey K, Harrison M. Feeding infants and children from birth to 24
months: summarizing existing guidance. The National Academies
Collection. Washington (DC): National Institutes of Health; 2020.
6. Institute of Medicine. Dietary reference intakes for vitamin A, vitamin K,
arsenic, boron, chromium, copper, iodine, iron, manganese, molybde-
num, nickel, silicon, vanadium, and zinc. Washington (DC): National
Academies Press; 2001.
7. Dietary Guidelines Advisory Committee. Scientific report of the 2020
Dietary Guidelines Advisory Committee: advisory report to the Secretary
of Agriculture and the Secretary of the Health and Human Services.
Washinton (DC): Department of Agriculture. Washington; 2020.
8. Briefel RR, Kalb LM, Condon E, Deming DM, Clusen NA, Fox MK, et al.
The Feeding Infants and Toddlers Study 2008: study design and
methods. J Am Diet Assoc 2010;110:S16-26.
9. Devaney B, Kalb L, Briefel R, Zavitsky-Novak T, Clusen N, Ziegler P.
Feeding Infants and Toddlers Study: overview of the study design. J
Am Diet Assoc 2004;104:s8-13.
10. Institute of Medicine. Dietary reference intakes for energy, carbohydrate,
fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington
(DC): The National Academies Press; 2005.
11. Ahluwalia N, Herrick KA, Rossen LM, Rhodes D, Kit B, Moshfegh A,
et al. Usual nutrient intakes of US infants and toddlers generally meet
or exceed Dietary Reference Intakes: findings from NHANES 2009-
2012. Am J Clin Nutr 2016;104:1167-74.
12. Dewey KG, Finley DA, Lonnerdal B. Breast milk volume and composi-
tion during late lactation (7-20 months). J Pediatr Gastroenterol Nutr
1984;3:713-20.
13. Dewey KG, Lonnerdal B. Milk and nutrient intake of breast-fed infants
from 1 to 6 months: relation to growth and fatness. J Pediatr Gastroen-
terol Nutr 1983;2:497-506.
14. Kent JC, Mitoulas L, Cox DB, Owens RA, Hartmann PE. Breast volume
and milk production during extended lactation in women. Exp Physiol
1999;84:435-47.
15. Anater AS, Catellier DJ, Levine BA, Krotki KP, Jacquier EF, Eldridge AL,
et al. The Feeding Infants and Toddlers Study (FITS) 2016: study design
and methods. J Nutr 2018;148:1516S-24S.
16. Institute of Medicine. DRI dietary reference intakes: applications in di-
etary assessment. Washington (DC): National Academies Press; 2000.
17. Lozoff B, Georgieff MK. Iron deficiency and brain development. Semin
Pediatr Neurol 2006;13:158-65.
18. Eldridge AL, Catellier DJ, Hampton JC, Dwyer JT, Bailey RL. Trends in
mean nutrient intakes of US infants, toddlers, and young children from 3
Feeding Infants and Toddlers Studies (FITS). J Nutr 2019;149:1230-7.
19. Duffy EW, Kay MC, Jacquier E, Catellier D, Hampton J, Anater AS, et al.
Trends in food consumption patterns of US infants and toddlers from
Feeding Infants and Toddlers Studies (FITS) in 2002, 2008, 2016. Nutri-
ents 2019;11.
20. Fox MK, Pac S, Devaney B, Jankowski L. Feeding Infants and Toddlers
Study: what foods are infants and toddlers eating? J Am Diet Assoc
2004;104:s22-30.
21. Bailey RL, Catellier DJ, Jun S, Dwyer JT, Jacquier EF, Anater AS, et al.
Total usual nutrient intakes of US children (under 48 months): findings
from the Feeding Infants and Toddlers Study (FITS) 2016. J Nutr
2018;148:1557S-66S.
22. American Academy of Pediatrics Committee on Nutrition. In:
Kleinman REGF, ed. Pediatric nutrition. 8th ed. Itasca (IL): American
Academy of Pediatrics; 2019.
23. Gahche JJ, Herrick KA, Potischman N, Bailey RL, Ahluwalia N,
Dwyer JT. Dietary supplement use among infants and toddlers aged
<24 months in the United States, NHANES 2007-2014. J Nutr
2019;149:314-22.
24. Abrams SA, Avalos A, Gray M, Hawthorne M. High level of food insecu-
rity among families with children seeking routine care at federally qual-
ified health centers during the coronavirus disease 2019 pandemic.
J Pediatr X 2020;4:100044.
25. American Academy of Pediatrics. AAP welcomes FDA announcement
on limiting arsenic in infant rice cereal 2016. www.fda.gov/regulatory-
information/search-fda-guidance-documents/draft-guidance-industry-
action-level-inorganic-arsenic-rice-cereals-infants. Accessed November
18, 2020.
26. National WIC Association. Winter 2019 WIC research to practice 2019.
www.nwica.org/winter-2019-wic-research-to-practice. Accessed November
18, 2020.
27. Hurrell RF, Davidsson L, Reddy M, Kastenmayer P, Cook JD. A compar-
ison of iron absorption in adults and infants consuming identical infant
formulas. Br J Nutr 1998;79:31-6.
28. Lonnerdal B. Development of iron homeostasis in infants and young
children. Am J Clin Nutr 2017;106:1575S-80S.
29. Wu X, Jackson RT, Khan SA, Ahuja J, Pehrsson PR. Human milk
nutrient composition in the United States: current knowledge, chal-
lenges, and research needs. Curr Dev Nutr 2018;2:nzy025.
30. Guthrie JF, Catellier DJ, Jacquier EF, Eldridge AL, Johnson WL,
Lutes AC, et al. WIC and non-WIC Infants and Children Differ in Usage
of Some WIC-Provided Foods. J Nutr 2018;148:1547S-56S.
31. Domellof M, Cohen RJ, Dewey KG, Hernell O, Rivera LL, Lonnerdal B.
Iron supplementation of breast-fed Honduran and Swedish infants from
4 to 9 months of age. J Pediatr 2001;138:679-87.
32. Domellof M, Lonnerdal B, Abrams SA, Hernell O. Iron absorption in
breast-fed infants: effects of age, iron status, iron supplements, and com-
plementary foods. Am J Clin Nutr 2002;76:198-204.
33. Abrams SA, Wen J, Stuff JE. Absorption of calcium, zinc, and iron from
breast milk by five- to seven-month-old infants. Pediatr Res 1997;41:
384-90.
34. Krebs NF. Food based complementary feeding strategies for
breastfed infants: what’s the evidence that it matters? Nutr Today
2014;49:271-7.
35. Krebs NF, Mazariegos M, Chomba E, Sami N, Pasha O, Tshefu A,
et al. Randomized controlled trial of meat compared with
multimicronutrient-fortified cereal in infants and toddlers with high
stunting rates in diverse settings. Am J Clin Nutr 2012;96:840-7.
-2020 ORIGINAL ARTICLES
A Substantial Proportion of 6- to 12-Month-Old Infants Have Calculated Daily Absorbed Iron below Recommendations,
Especially Those Who Are Breastfed
7
Table IV. Ranked food sources of calculated absorbed iron by feeding type for infants 6 -12 months of age in the total
population*
Ranks Breastfed (n = 296) Iron (mg) Mixed fed (n = 102) Iron (mg) Formula fed (n = 448) Iron (mg)
1 Grains 0.21 Milk 0.27 Milk 0.52
Infant cereal 0.16 Infant formula 0.21 Infant formula 0.52
Family cereal 0.03 Human milk 0.06
Baby finger foods 0.01
2 Milk 0.10 Grains 0.26 Grains 0.32
Human milk 0.10 Infant cereal 0.23 Infant cereal 0.26
Family cereal 0.01 Family cereal 0.03
Baby finger foods 0.01 Baby finger foods 0.01
3 Meat/Proteins 0.04 Vegetables 0.02 Mixed dishes 0.05
Meat 0.03 Baby food vegetable 0.02 Chicken and vegetable 0.01
Chicken/turkey 0.01 Pasta dishes 0.01
Nonmeat 0.01 Baby food dinners 0.01
4 Mixed dishes 0.03 Meat/protein 0.02 Meat/protein 0.02
Baby food dinners 0.01 Meat 0.01 Meat 0.02
Chicken/turkey 0.01 Chicken/turkey 0.01
Nonmeat 0.01
Egg 0.01
5 Vegetables 0.02 Fruit 0.02 Fruit 0.02
Baby food vegetable 0.01 Baby food fruit 0.01 Baby food fruit 0.01
Nonbaby vegetable 0.01
*May not add up to 100% because only items contributing ³0.01 mg iron per capita are reported.
Table V. Ranked food sources of calculated absorbed iron by feeding type for infants 6 -12 months of age in the bottom
quartile of absorbed iron intake (£25th%ile)*
Ranks Breastfed (n = 140) Iron (mg) Mixed fed (n = 30) Iron (mg) Formula fed (n = 151) Iron (mg)
1 Milk 0.10 Milk 0.18 Milk 0.42
Human milk 0.10 Infant formula 0.11 Infant formula 0.42
Human milk 0.07
2 Grains 0.02 Grains 0.02 Grains 0.08
Infant cereal 0.01 Infant cereal 0.01 Infant cereal 0.04
Baby finger foods 0.01 Baby finger foods 0.01 Family cereal 0.02
Baby finger foods 0.01
3 Vegetables 0.01 Vegetables 0.02 Fruit 0.02
Baby food vegetable 0.01 Baby food vegetable 0.02 Baby food 0.01
4 Fruit 0.01 Fruit 0.01 Mixed dishes 0.02
Baby food 0.01 Baby food dinners 0.01
5 Meat/protein 0.01 Mixed dishes 0.01 Meat/protein 0.02
Meat 0.01 Soup 0.01 Meat 0.01
Chicken/turkey 0.01
*May not add up to 100% because only items contributing ³0.01 mg iron per capita are reported.
THE JOURNAL OF PEDIATRICS www.jpeds.com Volume -
7.e1 Abrams, Hampton, and Finn
Table VI. Ranked food sources of calculated absorbed iron by feeding type for infants 6 -12 months of age in the top
quartile of absorbed iron intake (‡75th percentile)
Ranks Breastfed (n = 90) Iron (mg) Mixed fed (n = 27) Iron (mg) Formula fed (n = 123) Iron (mg)
1 Grains 0.54 Grains 0.64 Grains 0.73
Infant cereal 0.45 Infant cereal 0.62 Infant cereal 0.62
Family cereal 0.06 Family cereal 0.01 Family cereal 0.08
Baby finger foods 0.02 Baby finger foods 0.01 Baby finger foods 0.02
Pasta/rice 0.01
2 Milk 0.10 Milk 0.35 Milk 0.65
Human milk 0.10 Infant formula 0.29 Infant formula 0.64
Human milk 0.05
3 Meat/protein 0.07 Meat/protein 0.03 Mixed dishes 0.09
Meat 0.05 Meat 0.01 Pasta dishes 0.03
Chicken/turkey 0.03 Fish/shellfish 0.01 Baby food dinners 0.03
Hotdog/cold cut 0.01 Chicken and vegetable 0.02
Unspecified 0.01 Beef and vegetable 0.01
4 Mixed dishes 0.06 Vegetables 0.03 Meat/protein 0.04
Baby food dinners 0.02 Baby food vegetable 0.03 Meat 0.04
Beef and vegetable 0.01 Chicken/turkey 0.02
Pork and vegetable 0.01 Hot dog/cold cut 0.01
Pasta dishes 0.01 Sausage 0.01
Soup 0.01
5 Vegetables 0.03 Fruit 0.02 Vegetables 0.03
Baby food vegetable 0.01 Baby food vegetable 0.02
Nonbaby vegetable 0.01
*May not add up to 100% because only items contributing ³0.01 mg iron per capita are reported.
-2020 ORIGINAL ARTICLES
A Substantial Proportion of 6- to 12-Month-Old Infants Have Calculated Daily Absorbed Iron below Recommendations,
Especially Those Who Are Breastfed
7.e2
