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Protein intake trends and conformity with the Dietary Reference Intakes in the United States: Analysis of the National Health and Nutrition Examination Survey, 2001-2014

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Background: Systematic analysis of dietary protein intake may identify demographic groups within the American population that are not meeting the Dietary Reference Intakes (DRIs). Objective: This cross-sectional study analyzed protein intake trends (2001-2014) and evaluated recent conformity to the DRIs (2011-2014) according to age, sex, and race or ethnicity in the US population. Design: Protein intakes and trends during 2-y cycles of NHANES 2001-2014 (n = 57,980; ≥2 y old) were calculated as absolute (grams per day) and relative [grams per kilogram of ideal body weight (IBW) per day] intakes and as a percentage of total energy. Sex and race or ethnicity [Asian, Hispanic, non-Hispanic black (NHB), and non-Hispanic white (NHW)] differences were determined for protein intake and percentage of the population below the Estimated Average Requirement (EAR) and Recommended Dietary Allowance, and above and below the Acceptable Macronutrient Distribution Range (AMDR). Results: Usual protein intakes (mean ± SE) averaged from 55.3 ± 0.9 (children aged 2-3 y) to 88.2 ± 1.1 g/d (adults aged 19-30 y). Protein comprised 14-16% of total energy intakes. Relative protein intakes averaged from 1.10 ± 0.01 (adults aged ≥71 y) to 3.63 ± 0.07 g · kg IBW-1 · d-1 (children aged 2-3 y), and were above the EAR in all demographic groups. Asian and Hispanic populations aged >19 y consumed more relative protein (1.32 ± 0.02 and 1.32 ± 0.02 g · kg IBW-1 · d-1, respectively) than did NHB and NHW (1.18 ± 0.01 g · kg IBW-1 · d-1). Relative protein intakes did not differ by race or ethnicity in the 2-18 y population. Adolescent (aged 14-18 y) females and older (aged ≥71 y) NHB men had the largest population percentages below the EAR (11% and 13%, respectively); <1% of any demographic group had intakes above the AMDR. Conclusions: The majority of the US population exceeds minimum recommendations for protein intake. Protein intake remains well below the upper end of the AMDR, indicating that protein intake, as a percentage of energy intake, is not excessive in the American diet. This trial was registered at www.isrctn.com as ISRCTN76534484.
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Protein intake trends and conformity with the Dietary Reference
Intakes in the United States: analysis of the National Health
and Nutrition Examination Survey, 2001–2014
Claire E Berryman,1,2Harris R Lieberman,1Victor L Fulgoni, III,3and Stefan M Pasiakos1
1Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA; 2Oak Ridge Institute for Science and Education, Belcamp,
MD; and 3Henry M Jackson Foundation, Bethesda, MD
ABSTRACT
Background: Systematic analysis of dietary protein intake may
identify demographic groups within the American population that
are not meeting the Dietary Reference Intakes (DRIs).
Objective: This cross-sectional study analyzed protein intake trends
(2001–2014) and evaluated recent conformity to the DRIs (2011–
2014) according to age, sex, and race or ethnicity in the US popula-
tion.
Design: Protein intakes and trends during 2-y cycles of NHANES
2001–2014 (n=57,980; 2 y old) were calculated as absolute
(grams per day) and relative [grams per kilogram of ideal body
weight (IBW) per day] intakes and as a percentage of total en-
ergy. Sex and race or ethnicity [Asian, Hispanic, non-Hispanic black
(NHB), and non-Hispanic white (NHW)] differences were deter-
mined for protein intake and percentage of the population below the
Estimated Average Requirement (EAR) and Recommended Dietary
Allowance, and above and below the Acceptable Macronutrient Dis-
tribution Range (AMDR).
Results: Usual protein intakes (mean ±SE) averaged from
55.3 ±0.9 (children aged 2–3 y) to 88.2 ±1.1 g/d (adults aged
19–30 y). Protein comprised 14–16% of total energy intakes. Rel-
ative protein intakes averaged from 1.10 ±0.01 (adults aged 71 y)
to 3.63 ±0.07 g ·kg IBW–1 ·d–1 (children aged 2–3 y), and were
above the EAR in all demographic groups. Asian and Hispanic pop-
ulations aged >19 y consumed more relative protein (1.32 ±0.02
and 1.32 ±0.02 g ·kg IBW–1 ·d–1, respectively) than did NHB and
NHW (1.18 ±0.01 g ·kg IBW–1 ·d–1). Relative protein intakes did
not differ by race or ethnicity in the 2–18 y population. Adolescent
(aged 14–18 y) females and older (aged 71 y) NHB men had the
largest population percentages below the EAR (11% and 13%, re-
spectively); <1% of any demographic group had intakes above the
AMDR.
Conclusions: The majority of the US population exceeds minimum
recommendations for protein intake. Protein intake remains well be-
low the upper end of the AMDR, indicating that protein intake, as a
percentage of energy intake, is not excessive in the American diet.
This trial was registered at www.isrctn.com as ISRCTN76534484.
Am J Clin Nutr 2018;108:405–413.
Keywords: NHANES, Estimated Average Requirement, Recom-
mended Dietary Allowance, Acceptable Macronutrient Distribution
Range, race and ethnicity
INTRODUCTION
Dietary protein is required for the maintenance of all body pro-
cesses, providing the structural and functional foundation to sup-
port life (1). In humans, 20 distinct amino acids function as sub-
strates for protein synthesis (1). Nine of these amino acids are
essential amino acids, which cannot be synthesized by the body
and must be acquired from the diet (1). The Dietary Reference
Intakes (DRIs) for protein, which include the Estimated Average
Requirement (EAR; children aged 1–3 y: 0.87, children aged 4–
13 y: 0.76, boys aged 14–18 y: 0.73, girls aged 14–18 y: 0.71,
adults aged 19 y: 0.66 g protein ·kg–1 ·d–1) and Recommended
Dietary Allowance (RDA; children aged 1–3 y: 1.05, children
Supported by the US Army Medical Research and Materiel Command and
the Department of Defense Center Alliance for Nutrition and Dietary Supple-
ments Research.
Supplemental Figure 1 is available from the “Supplementary data” link in
the online posting of the article and from the same link in the online table of
contents at https://academic.oup.com/ajcn/.
The opinions or assertions contained herein are the private views of the au-
thors and are not to be construed as ofcial or as reecting the views of the
Army or the Department of Defense. Any citations of commercial organiza-
tions and trade names in this report do not constitute an ofcial Department
of the Army endorsement of approval of the products or services of these
organizations.
Address correspondence to SMP (e-mail: stefan.m.pasiakos.
civ@mail.mil).
Abbreviations used: AMDR, Acceptable Macronutrient Distribution
Range; DRI, Dietary Reference Intake; EAR, Estimated Average Require-
ment; IBW, ideal body weight; NHB, non-Hispanic black; NHW, non-
Hispanic white; RDA, Recommended Dietary Allowance.
Received January 18, 2018. Accepted for publication April 4, 2018.
First published online June 21, 2018; doi: https://doi.org/10.1093/ajcn/
nqy088.
Am J Clin Nutr 2018;108:405–413. Printed in USA. © 2018 American Society for Nutrition. This work is written by (a) US Government
employee(s) and is in the public domain in the US. 405
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406 BERRYMAN ET AL.
aged 4–13 y: 0.95, boys and girls aged 14–18 y: 0.85, adults aged
19 y, 0.80 g protein ·kg–1 ·d–1), quantify specic nutrient in-
take requirements that are the basis for assessing and planning
adequate diets for individuals and populations (1). An inability
to meet the EAR or RDA for any one essential amino acid can
be detrimental, leading to a negative nitrogen balance and a loss
of functional body proteins (2–5). This is particularly important
in populations that are susceptible to loss of muscle mass and
physical function (6–9). An analysis of 2003–2004 NHANES
data showed that 7–9% of older (aged 51 y) females and 8%
of young (aged 9–18 y) females were not meeting the EAR for
protein (10). Characterization of protein intake patterns provides
information to inform both policy guidelines and nutrition coun-
seling for various demographics of the US population.
The apparent popularity of diets that are higher in protein has
increased over the past 2 decades. There has been a change from
the idea that higher-protein diets (for adults, >0.8 g protein ·kg–1
·d–1 and 35% of total energy) only benet athletes to an under-
standing of the broader health advantages. In 2015, the Food and
Health Survey reported 89% of Americans agreed with the state-
ment “it is important to get enough protein in the diet,” 81% with
“protein can help maintain muscle during aging,” and 65% with
“high protein diets can help with weight loss” (11). Protein has
been shown to promote weight loss and maintenance while pre-
serving muscle mass (12–14). Increased protein intake is associ-
ated with lower body weight, BMI, and waist circumference and
higher HDL cholesterol levels (15). In the United States, market
trends indicate that protein-containing food product sales have
grown from $600 million in 2008 to $1.1 billion in 2013
and are projected to reach $1.6 billion in 2018 (16). Whether
widespread awareness regarding the advantages of dietary pro-
tein and increased availability of protein-containing food prod-
ucts have inuenced dietary protein intake trends in the US pop-
ulation is unknown.
The current study, a systematic update to our previous work
(10), characterizes protein intake trends over the past 14 y (2001–
2014) and assesses recent (2011–2014) conformity with protein-
specic DRIs according to age, sex, race, and ethnicity in the
US population. Importantly, this study evaluates protein intake
trends and DRI conformity parameters by race and ethnicity and
in Americans aged 80 y, allowing identication of demographic
groups that may be particularly vulnerable to inadequate protein
intake.
METHODS
NHANES is a large ongoing dietary survey of a nationally
representative sample of the non-institutionalized US population.
The data are collected and released by the National Center for
Health Statistics, part of the Centers for Disease Control and Pre-
vention, every 2 y. The Research Ethics Review Board at the
National Center for Health Statistics approved the survey pro-
tocol and all participants or proxies provided written informed
consent. Detailed descriptions of the survey design and the data
collection procedures are reported elsewhere (17). The current
trial was registered with the ISRCTN registry (www.isrctn.com)
as ISRCTN76534484.
Data from NHANES 2001–2014 were used to determine mean
protein intakes during the entire period (2001–2014) and for
each 2-y cycle (2001–2002, 2003–2004, 2005–2006, 2007–2008,
2009–2010, 2011–2012, 2013–2014). The study sample included
individuals (n=57,980; aged 2 y) with complete and reli-
able dietary records using the USDA automated multiple-pass
method (Supplemental Figure 1). Pregnant or lactating females
(n=1442) and individuals consuming no calories (n=34)
were excluded. Individuals were grouped by DRI-specic age
and sex categories (1). Overall and cycle-specic protein intake
means were determined using data from the rst 24-h recall. Cy-
cle trends were evaluated using regression analyses with cycle as
the independent variable and regression coefcient (β)represent-
ing change over time.
Data from NHANES 2011–2014 (n=15,829; aged 2y)were
used to determine current protein intake by age (2–18, 19, 51,
and 71 y), sex, and race/ethnicity [Asian, non-Hispanic black
(NHB), Hispanic, and non-Hispanic white (NHW)]. Usual intake
means were derived from 2 nonconsecutive 24-h recalls, one in
person and the other via telephone, using the National Cancer
Institute method (18). Usual intake analyses were conducted sep-
arately for each ethnicity group and stratied by age and sex. The
covariates used were weekday/weekend intake day and DRI age
groups (with 2 additional groups: ages 71–79 and 80 y). Ethnic-
ity was added as a covariate for the ethnicity =all group, and sex
was added as a covariate in the analysis of children. Differences
in usual protein intake between sex and race or ethnicity groups
were evaluated using a zstatistic, with P0.01 considered sig-
nicant. Data from NHANES 2011–2014 were also used to de-
termine the percentage of the population consuming less than the
EAR, RDA, and Acceptable Macronutrient Distribution Range
(AMDR) and more than the AMDR for age, sex, and race or eth-
nicity group. Individuals with missing race or ethnicity data or
marking “Other Race” on the survey (n=652) were omitted from
the race or ethnicity-specic analyses.
Protein intake is presented 3 ways: 1) grams of protein per day,
2) grams of protein per kilogram of ideal body weight (IBW),
and 3) percentage of energy from protein. For grams of protein
per kilogram of IBW calculations, body weights were adjusted to
the nearest IBW. For example, for adults who were overweight or
obese, body weights were adjusted to a BMI (kg/m2) of 24.9, and
for adults who were underweight, body weights were adjusted to
a BMI of 18.5. For children whose weights were less than the
5th percentile for BMI for age, body weight was adjusted to 5%
of BMI for age. For children whose weights were greater than
the 85th percentile for BMI for age, body weight was adjusted to
84.9%. IBW was used, rather than actual body weight, to align
with previous work (10).
Data were analyzed using SAS version 9.2 (SAS Institute,
Cary, NC) and SUDAAN release 11.0 (Research Triangle Insti-
tute, Research Triangle Park, NC). Appropriate sample weights
were used to adjust for the complex sample design of NHANES.
Data are presented as mean ±SE, unless stated otherwise.
RESULTS
Absolute protein intake was lowest in children aged 2–3 y
(55.3 ±0.9 g/d) and highest in adults aged 19–30 y (88.2 ±1.1
g/d; Figure 1). Relative protein intake was lowest in adults aged
71 y (1.10 ±0.01 g ·kg IBW–1 ·d–1) and highest in children
aged 2–3 y (3.63 ±0.07 g ·kg IBW–1 ·d–1). Protein intake, as
a percentage of total energy intake, ranged from 14% to 16%
across all age groups. The only population to have a signicant,
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DIETARY PROTEIN INTAKE IN AMERICA 407
0
5
10
15
20
25
30
35
% total energy
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
2-3 4-8 9-13 14-18 19-30 31-50 51-70 71+
th
gi
e
wy
do
b
l
aed
igk
/
g
Years
0
10
20
30
40
50
60
70
80
90
100
g/d
A
B
C
5-20%
10-30%
10-35%
FIGURE 1 Usual protein intake (mean ±SE) by age in the US popula-
tion (NHANES, 2011–2014; n=15,829) is presented as absolute amounts
(A), percentage of total energy intake (B), and relative to ideal body weight
(C). Dotted lines represent the upper and lower bounds of the Acceptable
Macronutrient Distribution Range for protein by age group.
albeit small, increase in all estimates of protein intake from 2001
to 2014 were men aged 71 y (1.15 ±0.35 g ·d–1 ·cycle–1 ,
0.02 ±0.00 g ·kg IBW–1 ·d–1 ·cycle–1 , and 0.14% ±0.05%
total energy/cycle; Tab l e 1).
When males and females from the NHANES 2011–2014
cohort were combined for race and ethnicity analysis, Asian
and Hispanic individuals aged 2–18 y consumed signicantly
more protein (72.0 ±2.7 and 71.6 ±1.4 g/d, respectively)
than NHB individuals (64.6 ±0.7 g/d) of the same age range
(Tabl e 2 ). In terms of protein intake as a percentage of to-
tal energy, Hispanic individuals aged 2–18 y consumed more
protein (14.8% ±0.1%) than did NHB and NHW individuals
(13.9% ±0.1% and 14.2% ±0.2%, respectively), whereas Asian
individuals consumed signicantly more protein (15.9% ±0.3%)
than all 3 groups. However, there were no ethnicity or race dif-
ferences for the population aged 2–18 y when protein intake was
expressed relative to IBW.
In the sex-combined analysis for individuals aged 19 y,
Hispanic individuals consumed signicantly more protein
(89.5 ±1.3 g/d) than did Asian, NHB, and NHW individuals
during 2011–2014 (81.8 ±1.5, 81.5 ±1.0, and 82.7 ±0.6 g/d,
respectively; Tab le 2). Protein intake as a percentage of total en-
ergy intake and relative to IBW were greater for both the Asian
(17.2% ±0.2% and 1.32 ±0.02 g ·kg IBW–1 ·d–1, respec-
tively) and Hispanic (16.5% ±0.1% and 1.35 ±0.02 g ·kg
IBW–1 ·d–1, respectively) populations compared with the NHB
(15.2% ±0.1% and 1.18 ±0.01 g ·kg IBW–1 ·d–1, respectively)
and NHW (15.5% ±0.2% and 1.18 ±0.01 g ·kg IBW–1 ·d–1,
respectively) populations.
In the ethnicity and race combined analysis, no children aged
2–3 or 4–8 y fell below the EAR or RDA for protein (Tab le 3).
A greater percentage of females aged 19–30, 31–50, and
51–70 y fell below the EAR for protein (4.10–5.34%) than that of
males of the same age range (0.59–1.92%). Similarly, a greater
percentage of females aged 9–13, 14–18, 19–30, 31–50, and 51–
70 y had protein intakes below the RDA (6.92–23.36%) com-
pared with males of the same age range (2.31–11.26%). Fur-
thermore, <5% of any population had protein intakes below the
AMDR, and <1% of any population had protein intakes above
the AMDR (Tabl es 3 and 4).
When males and females were combined for race and ethnic-
ity analysis, a smaller percentage of the Asian and Hispanic pop-
ulations aged 2–18 y fell below the EAR (0.52% ±0.54% and
1.63% ±0.53%, respectively) and RDA (2.02% ±1.15% and
4.19% ±0.90%, respectively) for protein than in the NHB popu-
lation (EAR: 5.20% ±0.86%, RDA: 10.47% ±1.14%; Tab le 4,
Figure 2). Furthermore, a smaller percentage of the Asian pop-
ulation aged 2–18 y fell below the RDA for protein than in the
NHW population (7.08% ±1.58%). In individuals aged 19 y,
a smaller percentage of the Asian and Hispanic populations fell
below the EAR (1.30% ±0.44% and 1.71% ±0.53%, respec-
tively) for protein than in the NHB population (4.69% ±0.83%).
In addition, a smaller percentage of the Asian population aged
19 y fell below the EAR for protein than in the NHW popu-
lation (3.43% ±0.51%). In individuals aged 19 y, a smaller
percentage of the Asian and Hispanic populations fell below the
RDA (5.10% ±1.01% and 6.03% ±1.15%, respectively) for pro-
tein than in the NHB and NHW populations (13.43% ±1.35%
and 11.07% ±0.91%, respectively).
DISCUSSION
The current study characterized protein intake trends in the US
population (2001–2014) and evaluated recent conformity with
protein-specic DRIs (2011–2014). This report used data from
more individuals, to our knowledge, than any previous study to
quantify the percentage of the population not meeting DRI stan-
dards for protein by ethnicity and race, and in older adults aged
80 y. The current ndings indicate: 1) protein intake in the
United States has been generally stable over the past 14 y, with
the only consistent increase in protein intake during that time
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408 BERRYMAN ET AL.
TABLE 1
Trends in protein intake by age and sex from NHANES, 2001–20141
Protein intake
by sex Age, y n2001–2014 2001–2002 2003–2004 2005–2006 2007–2008 2009–2010 2011–2012 2013–2014 βSE P
Protein, g/d
Combined 2–3 3208 53.3 ±0.6 52.9 ±1.2 55.9 ±1.7 51.9 ±1.6 52.4 ±2.2 54.1 ±1.1 53.2 ±1.1 52.7 ±1.4 0.12 0.25 0.6405
4–8 6311 61.6 ±0.5 63.5 ±0.9 65.7 ±1.6 60.3 ±1.4 57.8 ±0.9 61.1 ±1.1 63.2 ±0.7 59.7 ±1.6 0.54 0.25 0.0302
Females 9–13 3333 65.0 ±0.9 64.2 ±1.8 67.2 ±2.1 66.0 ±2.6 65.9 ±2.1 63.6 ±1.9 62.6 ±3.7 66.1 ±2.1 0.24 0.46 0.6115
14–18 3430 63.9 ±0.8 63.7 ±1.6 67.0 ±1.6 64.9 ±2.0 63.1 ±2.2 64.2 ±2.2 66.4 ±2.5 58.7 ±2.2 0.65 0.38 0.0859
19– 30 3429 70.3 ±0.8 71.8 ±1.8 72.3 ±2.3 69.6 ±2.1 69.6 ±1.7 67.7 ±1.9 71.1 ±1.9 70.3 ±2.1 0.31 0.38 0.4212
31– 50 5724 70.8 ±0.6 69.5 ±1.6 68.9 ±1.7 74.7 ±1.7 69.8 ±1.5 70.3 ±1.3 69.6 ±1.6 72.9 ±1.5 0.25 0.30 0.3981
51–70 5287 66.8 ±0.7 64.3 ±1.1 66.6 ±2.8 67.3 ±2.0 65.1 ±1.8 67.6 ±1.6 66.6 ±1.3 69.0 ±1.1 0.50 0.29 0.0902
71 2821 58.1 ±0.6 56.3 ±1.6 58.8 ±1.1 57.0 ±1.8 56.6 ±1.2 59.8 ±1.7 59.1 ±1.4 59.1 ±1.8 0.41 0.30 0.1635
80 1247 56.2 ±0.8 54.0 ±1.8 55.8 ±2.3 53.2 ±1.4 55.1 ±1.7 57.1 ±2.2 57.8 ±2.3 60.0 ±2.2 0.93 0.39 0.0203
Males 9–13 3274 78.6 ±1.1 80.2 ±3.6 82.2 ±2.7 75.0 ±2.9 81.1 ±3.7 74.2 ±1.7 78.8 ±1.5 78.3 ±2.5 0.49 0.53 0.3629
14–18 3664 97.3 ±1.5 94.5 ±3.7 97.6 ±4.3 105.4 ±3.2 92.1 ±2.1 98.5 ±4.1 90.5 ±5.3 100.8 ±4.2 0.05 0.78 0.9477
19–30 3869 106.3 ±1.2 104.4 ±4.1 108.8 ±2.5 108.2 ±3.3 104.1 ±3.2 102.7 ±3.2 105.9 ±2.4 109.5 ±3.2 0.16 0.62 0.7944
31–50 5675 105.6 ±0.8 103.1 ±2.2 105.9 ±2.1 111.1 ±2.1 104.1 ±2.5 106.5 ±2.4 107.4 ±1.9 101.2 ±1.7 0.22 0.38 0.5603
51–70 5190 91.5 ±0.8 88.4 ±2.3 88.4 ±2.2 93.1 ±2.4 91.6 ±2.5 95.1 ±1.8 90.9 ±2.5 92.0 ±1.3 0.58 0.38 0.1316
71 2765 75.8 ±0.8 74.0 ±1.4 72.3 ±2.7 76.7 ±1.6 72.6 ±2.7 73.2 ±1.9 80.7 ±1.7 79.8 ±1.8 1.15 0.35 0.0015
80 1123 71.2 ±1.1 69.4 ±2.0 67.9 ±3.0 71.7 ±1.8 69.7 ±3.2 67.2 ±2.5 76.9 ±2.6 73.8 ±3.7 1.02 0.57 0.0755
Protein, % calories
Combined 2–3 3208 14.3 ±0.1 13.9 ±0.2 14.1 ±0.3 14.2 ±0.3 14.3 ±0.3 14.6 ±0.3 14.2 ±0.2 14.7 ±0.3 0.10 0.05 0.0336
4–8 6311 13.6 ±0.1 13.5 ±0.2 13.4 ±0.2 13.3 ±0.2 13.4 ±0.2 14.1 ±0.2 13.5 ±0.1 13.8 ±0.3 0.06 0.04 0.1070
Females 9–13 3333 13.9 ±0.1 13.4 ±0.3 13.5 ±0.4 13.8 ±0.2 14.0 ±0.3 13.7 ±0.4 14.0 ±0.5 14.8 ±0.4 0.18 0.08 0.0226
14–18 3430 13.8 ±0.1 13.3 ±0.3 13.3 ±0.2 13.6 ±0.3 13.7 ±0.4 14.2 ±0.3 13.9 ±0.4 14.4 ±0.4 0.18 0.06 0.0058
19–30 3429 14.7 ±0.1 14.0 ±0.4 14.3 ±0.4 14.8 ±0.3 15.3 ±0.4 14.7 ±0.2 14.6 ±0.3 15.1 ±0.5 0.13 0.07 0.0834
31–50 5724 15.3 ±0.1 14.9 ±0.3 14.5 ±0.2 16.1 ±0.3 15.0 ±0.2 15.7 ±0.1 15.0 ±0.4 15.5 ±0.2 0.08 0.05 0.0998
51–70 5287 15.7 ±0.1 15.2 ±0.2 15.6 ±0.3 16.3 ±0.2 15.6 ±0.2 15.8 ±0.3 15.3 ±0.2 16.1 ±0.3 0.05 0.05 0.3183
71 2821 15.3 ±0.1 15.0 ±0.3 15.3 ±0.2 15.4 ±0.3 15.4 ±0.2 15.7 ±0.3 15.4 ±0.4 15.1 ±0.3 0.02 0.06 0.7136
80 1247 15.3 ±0.1 14.8 ±0.4 15.1 ±0.3 15.4 ±0.4 15.1 ±0.2 15.6 ±0.4 15.2 ±0.3 15.4 ±0.4 0.07 0.08 0.3429
Males 9–13 3274 14.2 ±0.1 13.9 ±0.3 13.9 ±0.4 13.8 ±0.3 14.5 ±0.2 14.5 ±0.3 14.3 ±0.3 14.7 ±0.3 0.13 0.06 0.0282
14–18 3664 14.8 ±0.1 13.9 ±0.4 14.2 ±0.2 14.6 ±0.3 15.3 ±0.3 14.9 ±0.3 14.9 ±0.5 16.0 ±0.4 0.30 0.07 0.0001
19–30 3869 15.4 ±0.1 14.3 ±0.4 15.0 ±0.3 15.3 ±0.3 15.4 ±0.2 15.6 ±0.3 15.5 ±0.2 16.6 ±0.5 0.29 0.08 0.0003
31–50 5675 15.7 ±0.1 15.0 ±0.3 15.0 ±0.2 15.8 ±0.2 15.7 ±0.2 16.0 ±0.3 15.8 ±0.2 16.2 ±0.2 0.20 0.05 <0.0001
51–70 5190 15.8 ±0.1 15.3 ±0.3 16.1 ±0.3 15.6 ±0.2 16.0 ±0.2 16.2 ±0.3 15.5 ±0.3 15.8 ±0.4 0.03 0.06 0.5709
71 2765 15.9 ±0.1 15.4 ±0.2 15.6 ±0.3 15.7 ±0.3 15.9 ±0.3 15.7 ±0.2 16.3 ±0.4 16.3 ±0.3 0.14 0.05 0.0089
80 1123 15.5 ±0.2 15.7 ±0.3 15.6 ±0.6 15.2 ±0.3 15.6 ±0.4 15.4 ±0.3 15.3 ±0.6 15.8 ±0.5 0.00 0.09 0.9632
Protein, g ·kg
IBW–1 ·d–1
Combined 2–3 2984 3.65 ±0.04 3.55 ±0.08 3.87 ±0.14 3.61 ±0.11 3.57 ±0.16 3.73 ±0.10 3.62 ±0.08 3.62 ±0.09 0.01 0.02 0.7632
4–8 6244 2.70 ±0.02 2.75 ±0.06 2.89 ±0.07 2.66 ±0.06 2.61 ±0.06 2.71 ±0.05 2.75 ±0.05 2.56 ±0.07 0.03 0.01 0.0242
Females 9–13 3310 1.56 ±0.02 1.53 ±0.04 1.60 ±0.06 1.56 ±0.06 1.64 ±0.06 1.51 ±0.04 1.50 ±0.09 1.61 ±0.05 0.00 0.01 0.9152
14–18 3369 1.12 ±0.02 1.13 ±0.03 1.20 ±0.03 1.14 ±0.04 1.11 ±0.05 1.10 ±0.04 1.19 ±0.04 1.01 ±0.04 0.02 0.01 0.0231
19–30 3386 1.15 ±0.01 1.18 ±0.03 1.19 ±0.05 1.15 ±0.04 1.13 ±0.02 1.10 ±0.04 1.14 ±0.03 1.15 ±0.04 0.01 0.01 0.2508
31–50 5664 1.12 ±0.01 1.11 ±0.02 1.09 ±0.03 1.19 ±0.03 1.10 ±0.03 1.12 ±0.02 1.10 ±0.03 1.15 ±0.02 0.00 0.00 0.6680
51–70 5212 1.06 ±0.01 1.02 ±0.01 1.05 ±0.04 1.06 ±0.03 1.03 ±0.03 1.08 ±0.03 1.07 ±0.02 1.11 ±0.02 0.01 0.00 0.0099
71 2687 0.98 ±0.01 0.98 ±0.02 0.98 ±0.02 0.96 ±0.03 0.95 ±0.02 1.01 ±0.03 1.00 ±0.02 1.00 ±0.03 0.01 0.01 0.2549
80 1170 0.99 ±0.01 0.98 ±0.04 0.97 ±0.04 0.92 ±0.03 0.96 ±0.04 1.00 ±0.04 1.02 ±0.03 1.04 ±0.04 0.01 0.01 0.0585
Males 9–13 3253 1.93 ±0.02 2.03 ±0.08 2.03 ±0.06 1.86 ±0.05 1.95 ±0.09 1.81 ±0.06 1.88 ±0.04 1.95 ±0.06 0.02 0.01 0.1072
14–18 3632 1.47 ±0.02 1.42 ±0.05 1.47 ±0.06 1.59 ±0.06 1.41 ±0.03 1.52 ±0.06 1.36 ±0.08 1.51 ±0.05 0.00 0.01 0.9410
19–30 3830 1.45 ±0.02 1.41 ±0.06 1.47 ±0.04 1.47 ±0.05 1.43 ±0.04 1.40 ±0.05 1.44 ±0.03 1.50 ±0.04 0.01 0.01 0.5086
31–50 5620 1.39 ±0.01 1.36 ±0.03 1.40 ±0.03 1.45 ±0.03 1.37 ±0.03 1.40 ±0.03 1.42 ±0.03 1.33 ±0.02 0.00 0.01 0.6849
51–70 5118 1.21 ±0.01 1.18 ±0.03 1.16 ±0.03 1.24 ±0.04 1.21 ±0.03 1.26 ±0.03 1.21 ±0.03 1.23 ±0.02 0.01 0.01 0.0844
71 2626 1.06 ±0.01 1.03 ±0.02 1.01 ±0.03 1.07 ±0.02 1.00 ±0.04 1.01 ±0.03 1.14 ±0.02 1.11 ±0.02 0.02 0.00 0.0017
80 1034 1.02 ±0.02 0.99 ±0.04 0.99 ±0.05 1.03 ±0.02 0.99 ±0.05 0.95 ±0.03 1.12 ±0.04 1.04 ±0.06 0.01 0.01 0.1439
1Values are means ±SEs. Individual protein intakes were derived from the rst of 2 nonconsecutive 24-h recalls. Body weights were adjusted to the nearest
IBW for children and adults. Cycle trends were evaluated using regression analyses with cycle as the independent variable and the regression coefcient (β)
representing change over time. P0.01 was considered signicant. IBW, ideal body weight.
being observed in men aged 71 y; 2) Asian and Hispanic popu-
lations aged 19 y have greater relative protein intake than NHB
and NHW populations of the same age, whereas there were no
race or ethnicity differences for relative protein intake in the 2–
18 y population; 3) adolescent females (14–18 y) and older NHB
men (71 y) have the greatest percentage of the population below
EAR and RDA recommendations; and 4)<1% of any population
group had protein intakes above the AMDR for protein.
The current analysis shows that protein intake has remained
largely unchanged over the past 14 y, despite widespread pub-
licity regarding protein-related health benets (11) and the in-
creased variety of protein-containing food products in the US
food supply (16). Protein intakes continue to exceed both mini-
mum population and individual protein intake requirements (i.e.,
EAR and RDA, respectively), but are far from exceeding the
AMDR. The EAR and RDA are based on the minimum intake
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DIETARY PROTEIN INTAKE IN AMERICA 409
TABLE 2
Usual protein intake by age, sex, and race or ethnicity from NHANES, 2011–20141
2–18 y 19 y 51 y 71 y
Protein intake by sex and race/ethnicity nMean ±SE nMean ±SE nMean ±SE nMean ±SE
Combined
Protein, g/d
Asian 615 72.0 ±2.7a1134 81.8 ±1.5a423 75.9 ±1.5 82 74.0 ±3.5
NHB 1601 64.6 ±0.7b2331 81.5 ±1.0a1133 75.3 ±1.8 235 64.6 ±2.3
Hispanic 1881 71.6 ±1.4a2110 89.5 ±1.3b860 80.6 ±2.1 145 69.7 ±3.3
NHW 1433 68.0 ±1.3ab 4076 82.7 ±0.6a2022 78.5 ±0.9 832 71.4 ±1.2
Protein, % calories
Asian 615 15.9 ±0.3a1134 17.2 ±0.2a423 17.3 ±0.3a82 17.7 ±0.7a
NHB 1601 13.9 ±0.1b2331 15.2 ±0.1b1133 15.6 ±0.2b235 16.1 ±0.3ab
Hispanic 1881 14.8 ±0.1c2110 16.5 ±0.1a860 16.8 ±0.2a145 17.1 ±0.4a
NHW 1433 14.2 ±0.2b4076 15.5 ±0.2b2022 15.6 ±0.2b832 15.5 ±0.2b
Protein, g ·kg IBW–1 ·d–1
Asian 602 2.29 ±0.11 1123 1.32 ±0.02a416 1.27 ±0.03a79 1.30 ±0.07a
NHB 1582 2.03 ±0.05 2299 1.18 ±0.01b1115 1.09 ±0.03b230 1.00 ±0.04b
Hispanic 1855 2.20 ±0.05 2091 1.35 ±0.02a853 1.24 ±0.03a144 1.12 ±0.05ab
NHW 1417 2.04 ±0.04 4033 1.18 ±0.01b1990 1.14 ±0.01b807 1.09 ±0.02b
Females
Protein, g/d
Asian 321 65.7 ±2.2 561 70.4 ±1.7ab 218 67.0 ±1.9 39 64.8 ±4.1
NHB 776 60.5 ±1.2 1196 69.4 ±0.9ab 575 64.8 ±1.2 114 59.8 ±2.7
Hispanic 937 64.4 ±1.7 1076 72.7 ±1.2a437 67.0 ±2.0 76 59.8 ±3.3
NHW 692 59.9 ±1.2 2040 67.4 ±0.6b1049 66.3 ±0.9 426 62.2 ±1.4
Protein, % calories
Asian 321 15.4 ±0.3a561 16.8 ±0.3a218 16.8 ±0.4a39 16.7 ±0.8ab
NHB 776 13.9 ±0.1b1196 14.8 ±0.1b575 15.3 ±0.2b114 16.0 ±0.5ab
Hispanic 937 14.7 ±0.2a1076 16.3 ±0.2a437 16.7 ±0.3a76 17.1 ±0.6a
NHW 692 13.8 ±0.3b2040 15.2 ±0.2b1049 15.4 ±0.2b426 15.1 ±0.2b
Protein, g ·kg IBW–1 ·d–1
Asian 315 2.17 ±0.12 555 1.27 ±0.03a216 1.23 ±0.03a37 1.25 ±0.09
NHB 768 1.97 ±0.05 1177 1.08 ±0.01b566 1.01 ±0.02b110 1.01 ±0.05
Hispanic 926 2.06 ±0.06 1064 1.21 ±0.02a431 1.15 ±0.03ac 75 1.04 ±0.06
NHW 685 1.88 ±0.06 2017 1.07 ±0.01b1036 1.07 ±0.01c418 1.04 ±0.02
Males
Protein, g/d
Asian 294 78.5 ±4.0ab 573 93.8 ±2.4a205 87.4 ±2.4 43 85.1 ±5.3ab
NHB 825 68.8 ±1.1a1135 95.9 ±2.4a558 87.8 ±3.4 121 71.5 ±3.6a
Hispanic 944 78.4 ±1.6b1034 106.2 ±2.3b423 95.6 ±3.1 69 84.5 ±5.0ab
NHW 741 75.6 ±1.7b2036 97.9 ±0.9a973 92.4 ±1.3 406 83.1 ±1.4b
Protein, % calories
Asian 294 16.3 ±0.4a573 17.6 ±0.4a205 17.9 ±0.5a43 19.0 ±0.9a
NHB 825 13.9 ±0.2b1135 15.6 ±0.2b558 15.8 ±0.2b121 16.4 ±0.5b
Hispanic 944 14.9 ±0.1c1034 16.8 ±0.2a423 16.9 ±0.2a69 17.2 ±0.5ab
NHW 741 14.5 ±0.2bc 2036 15.7 ±0.2b973 15.8 ±0.2b406 16.0 ±0.3b
Protein, g ·kg IBW–1 ·d–1
Asian 287 2.40 ±0.17 568 1.38 ±0.04ab 200 1.34 ±0.04a42 1.34 ±0.09a
NHB 814 2.10 ±0.07 1122 1.29 ±0.03b549 1.19 ±0.04ab 120 0.99 ±0.04b
Hispanic 929 2.33 ±0.05 1027 1.48 ±0.03a422 1.35 ±0.05ab 69 1.22 ±0.07a
NHW 732 2.21 ±0.06 2016 1.29 ±0.01b954 1.23 ±0.02b389 1.15 ±0.02a
1Values are means ±SEs. Usual protein intakes were derived from 2 nonconsecutive 24-h recalls using the National Cancer Institute method (18). Body
weights were adjusted to the nearest IBW for children and adults. Differences between race or ethnicity groups were evaluated using the zstatistic. Different
lowercase letters within an age and sex category indicate signicant differences, P0.01. IBW, ideal body weight; NHB, non-Hispanic black; NHW, non-
Hispanic white.
of protein necessary to prevent deciency (i.e., negative nitro-
gen balance) in 50% of the population and 97.5% of individ-
uals, respectively (1); however, consuming protein above these
minimum requirements may provide health benets (19). Ad-
equate protein is critical for growth and development in chil-
dren and adolescents (1), with some evidence suggesting that
higher-protein intake (19.9% compared with 16.8% of total en-
ergy) in this age group (5–18 y) may improve waist circumfer-
ence and LDL cholesterol concentrations (20). Higher-protein
diets, particularly in the context of low dietary acid loads,
have been positively associated with bone circumference, con-
tent, and strength in children and adolescents (21). In adults,
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410 BERRYMAN ET AL.
TABLE 3
Percentage of the population above and below DRI standards for protein by age and sex from NHANES 2011–20141
Age, y Sex nBelow EAR, % Below RDA, % Below AMDR, % Above AMDR, %
2–3 Combined 790 0.00 ±0.00 0.00 ±0.01 0.00 ±0.00 0.96 ±0.45
4–8 Combined 1808 0.00 ±0.01 0.04 ±0.03 2.57 ±1.40 0.00 ±0.00
9–13 Female 829 1.83 ±0.59 6.92 ±1.40*1.92 ±1.22 0.00 ±0.00
14–18 Female 760 11.48 ±2.26 23.36 ±2.88*1.12 ±0.93 0.00 ±0.00
19–30 Female 984 4.51 ±0.66*14.01 ±1.34*2.07 ±0.58 0.00 ±0.00
31–50 Female 1683 4.10 ±0.74*13.23 ±1.41*1.40 ±0.47 0.00 ±0.00
51–70 Female 1637 5.34 ±0.68*15.59 ±1.07*1.03 ±0.35 0.00 ±0.00
71 Female 650 6.87 ±1.12 19.21 ±2.11 1.54 ±0.45 0.00 ±0.00
80 Female 271 5.68 ±1.19 16.74 ±2.47 1.27 ±0.42 0.00 ±0.00
9–13 Male 838 0.51 ±0.20 2.31 ±0.67 1.10 ±0.61 0.00 ±0.00
14–18 Male 776 5.32 ±1.20 11.26 ±1.85 0.65 ±0.52 0.00 ±0.00
19–30 Male 1103 0.59 ±0.20 2.75 ±0.62 0.60 ±0.25 0.00 ±0.00
31–50 Male 1620 1.01 ±0.27 4.27 ±0.71 0.59 ±0.22 0.00 ±0.00
51–70 Male 1536 1.92 ±0.53 7.17 ±1.23 0.62 ±0.24 0.00 ±0.00
71 Male 634 4.48 ±0.84 13.17 ±1.33 0.47 ±0.25 0.00 ±0.00
80 Male 258 5.90 ±1.58 16.86 ±2.85 1.00 ±0.39 0.00 ±0.00
1Values are means ±SEs. *Signicant difference from males of the same age based on the zstatistic, P0.01. AMDR, Acceptable
Macronutrient Distribution Range; DRI, Dietary Reference Intake; EAR, Estimated Average Requirement; RDA, Recommended Dietary
Allowance.
higher-protein diets promote maintenance of bone mass and in-
tegrity (22–24), preservation and enhancement of muscle mass
and function in response to a variety of conditions (e.g., exercise,
weight loss, and aging) (13,25–27), and postabsorptive and post-
prandial glycemic regulation (28–31).
The AMDR, which is a designated range of intake for
each macronutrient as a percentage of total energy intake at a
level determined to both prevent deciency and minimize the
likelihood of developing chronic diseases (1),maybeamore
appropriate benchmark of optimal protein intake (children
aged 1–3 y: 5–20%, children/adolescents aged 4–18 y: 10–30%,
adults aged 19 y: 10–35% of total energy intake) (19). In the
current analysis, protein comprised 14–16% of total energy intake
for all age groups (ethnicity and race combined analyses, Figure
1), with <1% of any population group consuming protein above
the AMDR. In adults (19 y), current protein intakes (15–16%
of total energy intake) are 19 percentage points below the upper
end of the AMDR for protein (i.e., 35% of total energy intake),
indicating protein consumption, as a percentage of total energy
intake, is not excessive in the American diet. Asian males aged
71 y had the greatest percentage protein intake, at 19% of total
energy, which is still well below the upper end of the AMDR.
Population-wide dietary guidelines and individual dietary ad-
vice can safely recommend moderate increases in protein con-
sumption to optimize health, with minimal risk of exceeding the
AMDR.
The only population to have a consistent, albeit small, change
in protein intake over the past 14 y were men aged 71 y. Protein
intake increased in this group by 1.15 g/d, 0.02 g ·kg IBW–1
·d–1, and 0.14% of total energy every 2 y cycle from 2001
to 2014. Despite the increase, 4% of this demographic did not
meet the EAR for protein and 13% had usual intakes that did
not meet the RDA. Furthermore, 7% of females aged 71 y
did not meet the EAR for protein and 19% had usual intakes that
did not meet the RDA. Adequate protein intake is especially im-
portant in this demographic because aging individuals are at risk
for sarcopenia, muscle wasting, and frailty (32), all of which are
exacerbated by inadequate protein intake (33). Consuming an ad-
ditional 10–35 g/d of protein improves muscle protein synthesis
(34), physical strength and function (35,36), and lean body mass
(34–36) in older adults. Higher-protein diets (1.0–1.2 g ·kg–1 ·
d–1) are advised for older individuals to ensure consumption of
25–30 g protein/meal, which has been shown to produce an an-
abolic stimulus similar to that observed in younger individuals
(37–39). Dietary interventions to increase protein intake in this
age group may improve age-related morbidity.
A sizable percentage of the population aged 14–18 y, particu-
larly females, did not meet the EAR for protein (11% of females,
5% of males) and had usual intakes that did not meet the current
RDA (23% of females, 11% of males). Compared with our previ-
ous analysis (NHANES 2003–2004), in which 8% of females and
<3% of males did not meet the EAR, the current ndings indi-
cate a slight increase in those not meeting the EAR for both males
and females (10). More independence in making food choices and
the high prevalence of dieting in this age group, particularly in
females, may contribute to the occurrence of inadequate protein
intake. In a cohort of adolescents (n=2287; aged 13–16 y),
55–58% of females and 22–29% of males reported dieting in the
past year (40). In another study (41), dietary intake was assessed
in preadolescence (11 y) and then again in adolescence (15.5 y);
it was reported that during adolescence, females (n=643) con-
sumed less meat and dairy, whereas males (n=589) ate less
dairy but more meat. Adequate dietary protein remains important
for growth and development in this demographic (14–18 y), de-
spite slowed growth rates after puberty (42). An emphasis on nu-
trition education, particularly related to choosing lower-energy,
nutrient-dense foods, may benet this population.
In the current study, we found no race or ethnicity differences
in relative protein intake for the population aged 2–18 y. However,
relative protein intake in the population aged 19 y was greater
for Asian and Hispanic individuals (1.32 and 1.35 g protein ·
kg ·IBW–1 ·d–1, respectively) than NHB and NHW individuals
(1.18 g protein ·kg ·IBW–1 ·d–1 for both). Ethnic and racial dis-
parities were particularly evident in 71-y-old NHB men who
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DIETARY PROTEIN INTAKE IN AMERICA 411
TABLE 4
Percentage of the population above and below DRI standards for protein by age, sex, and race/ethnicity from NHANES, 2011–20141
Age, sex, and race/ethnicity nBelow EAR, % Below RDA, % Below AMDR, % Above AMDR, %
2–18 y
Combined
Asian 602 0.52 ±0.54a2.02 ±1.15a0.27 ±0.51 0.63 ±0.36
NHB 1582 5.20 ±0.86b10.47 ±1.14b0.47 ±0.74 0.01 ±0.02
Hispanic 1855 1.63 ±0.53a4.19 ±0.90ac 0.05 ±0.07 0.02 ±0.02
NHW 1417 3.05 ±1.03ab 7.08 ±1.58bc 3.10 ±1.88 0.21 ±0.10
Females
Asian 315 0.80 ±0.74a2.92 ±1.65a0.37 ±0.64 0.50 ±0.37
NHB 768 6.15 ±1.11b12.41 ±1.48b0.51 ±0.75 0.02 ±0.02
Hispanic 926 2.52 ±0.72a6.32 ±1.30ac 0.04 ±0.08 0.01 ±0.02
NHW 685 4.34 ±1.51ab 10.11 ±2.20bc 4.19 ±2.60 0.13 ±0.06
Males
Asian 287 0.34 ±0.44a1.19 ±0.94a0.18 ±0.39 0.65 ±0.44
NHB 814 4.34 ±0.82b8.72 ±1.26b0.47 ±0.73 0.01 ±0.02
Hispanic 929 0.97 ±0.35a2.47 ±0.67a0.03 ±0.07 0.02 ±0.02
NHW 732 1.54 ±0.62a3.86 ±1.09a2.10 ±1.17 0.25 ±0.17
19 y
Combined
Asian 1123 1.30 ±0.44a5.10 ±1.01a0.12 ±0.22a0.01 ±0.01
NHB 2299 4.69 ±0.83b13.43 ±1.35b1.02 ±0.43ab 0.00 ±0.00
Hispanic 2091 1.71 ±0.53ac 6.03 ±1.15a0.45 ±0.21ab 0.00 ±0.00
NHW 4033 3.43 ±0.51bc 11.07 ±0.91b1.38 ±0.40b0.00 ±0.00
Females
Asian 555 1.87 ±0.60a6.76 ±1.29a0.10 ±0.26a0.00 ±0.00
NHB 1177 6.08 ±1.33b17.33 ±2.06b0.95 ±0.65ab 0.00 ±0.00
Hispanic 1064 2.49 ±0.96ab 8.86 ±2.06a0.42 ±0.28ab 0.00 ±0.00
NHW 2017 5.38 ±0.78b16.23 ±1.35b2.18 ±0.68b0.00 ±0.00
Males
Asian 568 0.68 ±0.52 3.45 ±1.44ab 0.17 ±0.23 0.02 ±0.02
NHB 1122 2.87 ±0.85 8.61 ±1.64a1.16 ±0.61 0.00 ±0.00
Hispanic 1027 0.88 ±0.33 3.35 ±0.79b0.51 ±0.31 0.00 ±0.01
NHW 2016 1.53 ±0.61 5.85 ±1.36ab 0.55 ±0.27 0.00 ±0.00
51 y
Combined
Asian 416 1.92 ±0.67a6.84 ±1.55a0.09 ±0.25a0.01 ±0.01
NHB 1115 7.15 ±1.14b18.96 ±1.90b0.69 ±0.30ab 0.00 ±0.00
Hispanic 853 2.85 ±0.91a9.18 ±1.96ac 0.33 ±0.20ab 0.00 ±0.01
NHW 1990 4.03 ±0.69ab 12.58 ±1.25c1.22 ±0.33b0.00 ±0.00
Females
Asian 216 2.45 ±0.94a8.83 ±1.95a0.09 ±0.32 0.00 ±0.00
NHB 566 8.93 ±1.62b23.39 ±2.43b0.44 ±0.40 0.00 ±0.00
Hispanic 431 4.01 ±1.42ab 12.45 ±2.87ac 0.30 ±0.26 0.00 ±0.00
NHW 1036 5.38 ±0.89ab 16.34 ±1.59bc 1.80 ±0.59 0.00 ±0.00
Males
Asian 200 1.02 ±0.66a4.40 ±1.85a0.15 ±0.22 0.01 ±0.04
NHB 549 5.05 ±1.30b13.32 ±2.24b0.92 ±0.56 0.00 ±0.00
Hispanic 422 1.85 ±0.79ab 6.06 ±1.72ab 0.44 ±0.31 0.00 ±0.01
NHW 954 2.26 ±0.91ab 8.10 ±1.83ab 0.56 ±0.26 0.00 ±0.00
71 y
Combined
Asian 79 1.43 ±1.19a5.40 ±3.34a0.07 ±0.20a0.01 ±0.07
NHB 230 11.12 ±2.46b26.39 ±4.21b0.42 ±0.23ab 0.00 ±0.00
Hispanic 144 5.91 ±2.19ab 16.39 ±4.38ab 0.18 ±0.20a0.00 ±0.01
NHW 807 5.47 ±0.98b16.13 ±1.79b1.53 ±0.43b0.00 ±0.00
Females
Asian 37 2.22 ±1.68 7.26 ±4.38 0.05 ±0.40a0.00 ±0.01
NHB 110 9.08 ±3.10 24.07 ±5.49 0.18 ±0.27a0.00 ±0.00
Hispanic 75 7.66 ±2.89 20.92 ±5.67 0.18 ±0.22a0.00 ±0.01
NHW 418 6.94 ±1.37 19.67 ±2.53 2.30 ±0.68b0.00 ±0.00
Males
Asian 42 1.02 ±0.75a4.17 ±2.22a0.06 ±0.10 0.04 ±0.09
NHB 120 13.22 ±3.23b29.43 ±4.90b0.53 ±0.48 0.00 ±0.00
Hispanic 69 3.55 ±2.13ab 10.59 ±4.58ac 0.40 ±0.26 0.01 ±0.02
NHW 389 3.68 ±1.10a11.84 ±1.97c0.38 ±0.26 0.00 ±0.00
1Values are mean ±SE. Differences between race or ethnicity groups were evaluated using the zstatistic. Different lowercase
letters within an age and sex category indicate signicant differences, P0.01. AMDR, Acceptable Macronutrient Distribution Range;
DRI, Dietary Reference Intake; EAR, Estimated Average Requirement NHB, non-Hispanic black; NHW, non-Hispanic white; RDA,
Recommended Dietary Allowance.
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412 BERRYMAN ET AL.
0
5
10
15
RAEwoleB%
Sex Combined
Asian NHB Hispanic NHW
0
5
10
15
RAEwoleB%
Females
0
5
10
15
2-18 y 19+ y 51+ y 71+ y
RAEw
o
l
e
B%
Males
a
b
a
ab
ab
b
a
a
b
a
a
a
b
ac
bc
a
b
b
ab
a
b
a
ab
a
b
a
ab
ab
b
ab
ab
a
b
ab
b
a
a
ab
b
a
A
B
C
FIGURE 2 Percentage of the population (mean ±SE) below the EAR
for protein intake by race or ethnicity and age (NHANES, 2011–2014;
n=15,177) in both sexes (A), females (B), and males (C). Differences be-
tween race or ethnicity groups were evaluated using the zstatistic. Different
lowercase letters within an age and sex category indicate signicant differ-
ences, P0.01. EAR, Estimated Average Requirement; NHB, non-Hispanic
black; NHW, non-Hispanic white.
consumed less protein (0.99 ±0.04 g ·kg IBW–1 ·d–1)than
Asian, Hispanic, and NHW men (1.15 ±0.02 g ·kg IBW–1
·d–1) of the same age group and had a disproportionately higher
population percentage falling below the EAR (13%) and not
meeting the RDA (29%) for protein. The reason for this disparity
is unclear, but does not seem related to food insecurity. Based
on ndings from one systematic review (43), total protein in-
take was unaffected by food insecurity in adults and children.
However, food insecurity may adversely affect intake of specic
protein foods, such as dairy products (43). Future analyses should
evaluate specic food groups and patterns to characterize differ-
ences in both quantity and quality of protein intake by race and
ethnicity.
The strengths of the current analysis include the large sam-
ple size, comprehensive nature of the NHANES database, and
protein intake comparisons by race and ethnicity. However, de-
spite total sample size, analyses for several ethnicities (i.e., Asian
and Hispanic) and older (i.e., 71 y) population groups may be
limited by demographic-specic sample sizes. In addition, the
current analysis does not assess source-specic protein intake. On
average, Americans meet or exceed guidelines for total protein in-
take; however, source-specic protein intake is below guidelines
for dairy (all age groups except 1–3 y) and seafood, and only
meets or falls below guidelines for nuts, seeds, soy products, and
legumes (44).
The majority of the US population is meeting or exceeding
minimum population recommendations for protein intake. Di-
etary protein intake remains well below the upper end of the
AMDR, indicating current protein consumption is within rec-
ommended ranges and not excessive. Finally, a considerable
percentage of adolescent females (14–18 y) and older adults
(71 y), particularly older NHB males, fall below the EAR and
RDA. Targeted interventions and education may be necessary to
ensure these demographic groups are, at the very least, meeting
minimum protein recommendations and, ideally, consuming pro-
tein at levels to optimize health.
The authors’ responsibilities were as follows—CEB and SMP: wrote the
manuscript; VLF: analyzed the data; SMP: had primary responsibility for the
nal content; and all authors: designed the research, conducted the research,
and read and approved the nal manuscript. VLF performs consulting and
database analyses for various food and beverage companies and related enti-
ties as Senior Vice President of Nutrition Impact; the remaining authors had
no conicts of interest related to the study.
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Background: Overweight and obese older people face a high risk of muscle loss and impaired physical function, which may contribute to sarcopenic obesity. Resistance exercise training (RET) has a beneficial effect on muscle protein synthesis and can be augmented by protein supplementation (PS). However, whether body weight affects the augmentation of muscular and functional performance in response to PS in older people undergoing RET remains unclear. Objective: This study was conducted to identify the effects of PS on the body composition and physical function of older people undergoing RET. Design: We performed a comprehensive search of online databases to identify randomized controlled trials (RCTs) reporting the efficacy of PS for lean mass gain, strength gain, and physical mobility improvements in older people undergoing RET. Results: We included 17 RCTs; the overall mean ± SD age and body mass index (BMI; in kg/m²) in these RCTs were 73.4 ± 8.1 y and 29.7 ± 5.5, respectively. The participants had substantially greater lean mass and leg strength gains when PS and RET were used than with RET alone, with the standard mean differences (SMDs) being 0.58 (95% CI: 0.32, 0.84) and 0.69 (95% CI: 0.39, 0.98), respectively. The subgroup of studies with a mean BMI ≥30 exhibited substantially greater lean mass (SMD: 0.53; 95% CI: 0.19, 0.87) and leg strength (SMD: 0.88; 95% CI: 0.42, 1.34) gains in response to PS. The subgroup of studies with a mean BMI <30 also exhibited relevant gains in response to PS. Conclusions: Compared with RET alone, PS combined with RET may have a stronger effect in preventing aging-related muscle mass attenuation and leg strength loss in older people, which was found in studies with a mean BMI ≥30 and in studies with a mean BMI <30. Clinicians could use nutrition supplement and exercise strategies, especially PS plus RET, to effectively improve the physical activity and health status of all older patients.
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Context: The impact of dietary protein on body composition changes after older adults purposefully lose weight requires systematic evaluation OBJECTIVE: : This systematic review and meta-analysis assessed the effects of protein intake (<25% vs ≥25% of energy intake or 1.0 g/kg/d) on energy restriction-induced changes in body mass, lean mass, and fat mass in adults older than 50 years. Data sources: PubMed, Cochrane, Scopus, and Google Scholar were searched using the keywords "dietary proteins," "body composition," "skeletal muscle," and "muscle strength." Study selection: Two researchers independently screened 1542 abstracts. Data extraction: Information was extracted from 24 articles. Data synthesis: Twenty randomized control trials met the inclusion criteria. Conclusion: Older adults retained more lean mass and lost more fat mass during weight loss when consuming higher protein diets.