RESEARCH
Original Research
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Whole-Grain Ready-to-Eat Oat Cereal, as Part
of a Dietary Program for Weight Loss, Reduces
Low-Density Lipoprotein Cholesterol in Adults with
Overweight and Obesity More than a Dietary
Program Including Low-Fiber Control Foods
KEVIN C. MAKI, PhD; JEANNEMARIE M. BEISEIGEL, PhD, RD; SATYA S. JONNALAGADDA, PhD, RD; CAROLYN K. GUGGER, PhD, RD;
MATTHEW S. REEVES, DO; MILDRED V. FARMER, MD; VALERIE N. KADEN; TIA M. RAINS, PhD
ABSTRACT
Objective Weight loss and consumption of viscous fibers
both lower low-density lipoprotein (LDL) cholesterol levels. We evaluated whether or not a whole-grain, readyto-eat (RTE) oat cereal containing viscous fiber, as part of
a dietary program for weight loss, lowers LDL cholesterol
levels and improves other cardiovascular disease risk
markers more than a dietary program alone.
Design Randomized, parallel-arm, controlled trial.
Subjects/setting Free-living, overweight and obese adults
(N!204, body mass index 25 to 45) with baseline LDL
cholesterol levels 130 to 200 mg/dL (3.4 to 5.2 mmol/L)
were randomized; 144 were included in the main analysis
of participants who completed the trial without significant protocol violations.
Intervention Two portions per day of whole-grain RTE oat
cereal (3 g/day oat b-glucan) or energy-matched low-fiber
K. C. Maki is chief science officer, M. S. Reeves is medical director, V. N. Kaden is a project manager, and
T. M. Rains is director of medical writing, Provident
Clinical Research, Glen Ellyn, IL, and Bloomington, IN.
J. M. Beiseigel and C. K. Gugger are senior scientists,
and S. S. Jonnalagadda is a principal scientist, General
Mills, Minneapolis, MN. M. V. Farmer is a principal
investigator, Meridien Research, St Petersburg, FL.
Address correspondence to: Kevin C. Maki, PhD, Provident Clinical Research, 489 Taft Ave, Glen Ellyn, IL
60137. E-mail: [email protected]
Manuscript accepted: July 31, 2009.
Copyright © 2010 by the American Dietetic
Association.
0002-8223/10/11002-0002$36.00/0
doi: 10.1016/j.jada.2009.10.037
© 2010 by the American Dietetic Association
foods (control), as part of a reduced energy ("500 kcal/day
deficit) dietary program that encouraged limiting consumption of foods high in energy and fat, portion control,
and regular physical activity.
Main outcome measures Fasting lipoprotein levels, waist
circumference, triceps skinfold thickness, and body
weight were measured at baseline and weeks 4, 8, 10,
and 12.
Results LDL cholesterol level was reduced significantly
more with whole-grain RTE oat cereal vs control
(#8.7$1.0 vs #4.3$1.1%, P!0.005). Total cholesterol
(#5.4$0.8 vs #2.9$0.9%, P!0.038) and non– high-density lipoprotein-cholesterol (#6.3$1.0 vs #3.3$1.1%,
P!0.046) were also lowered significantly more with
whole-grain RTE oat cereal, whereas high-density lipoprotein and triglyceride responses did not differ between groups. Weight loss was not different between
groups (#2.2$0.3 vs #1.7$0.3 kg, P!0.325), but waist
circumference decreased more (#3.3$0.4 vs #1.9$0.4
cm, P!0.012) with whole-grain RTE oat cereal. Larger
reductions in LDL, total, and non– high-density lipoprotein cholesterol levels and waist circumference were evident as early as week 4 in the whole-grain RTE oat cereal
group.
Conclusions Consumption of a whole-grain RTE oat cereal
as part of a dietary program for weight loss had favorable
effects on fasting lipid levels and waist circumference.
J Am Diet Assoc. 2010;110:205-214.
T
he benefits of diet and lifestyle modification for cardiovascular disease (CVD) risk factor management
are well documented (1,2). The National Cholesterol
Education Program Adult Treatment Panel III recommends lowering low-density lipoprotein (LDL) cholesterol
level as a primary goal for CVD prevention by achieving
Journal of the AMERICAN DIETETIC ASSOCIATION
205
and maintaining a normal body weight, maintaining regular physical activity, and restricting dietary intake of
saturated fats, trans fats, and cholesterol. In addition,
incorporation of dietary adjuncts that favorably affect
LDL cholesterol level, such as viscous fibers and plant
sterols and stanols, are recommended (2). Each of these
diet and lifestyle strategies has been shown to independently lower atherogenic lipoprotein cholesterol concentrations in individuals with hypercholesterolemia (2). For
example, weight loss has been shown to reduce LDL
cholesterol level "0.8 mg/dL (0.02 mmol/L), or "0.6%, for
each kilogram decrease in body weight (3). Viscous fibers,
such as b-glucan from oats, have also been shown to
produce cholesterol-lowering effects (4,5). Meta-analyses
show that daily intake of 3 g/d b-glucan lowers LDL
cholesterol concentrations by "5.0 mg/dL (0.13 mmol/L),
or "4%, based on the average LDL cholesterol level
among adult Americans (4,5). It has been proposed that a
meal containing such fiber increases the viscosity of stomach and intestinal contents, which may reduce absorption/reabsorption of cholesterol and bile acids, thus lowering blood cholesterol concentration, although other
mechanisms may also contribute to the observed hypocholesterolemic effect of viscous fibers (6).
The effects of combining diet and lifestyle interventions
on LDL cholesterol reduction are less well documented,
particularly in free-living conditions (7). Whole grain
ready-to-eat (RTE) oat breakfast cereal is a widely available source of viscous fiber. This study was undertaken to
evaluate if including a whole-grain RTE oat cereal as part
of a dietary program for weight loss lowers LDL cholesterol level and improves other CVD risk markers to a
greater degree than that observed with a dietary program
for weight loss alone in men and women with overweight
or obesity and hypercholesterolemia.
METHODS
Study Design
This was a randomized, controlled, parallel-arm study
conducted at two clinical research sites, Provident Clinical Research (Bloomington, IN) and Meridien Research
(St Petersburg, FL). The trial included a 1-week screening/baseline period followed by 12 weeks of treatment
during which subjects visited the clinic every 2 weeks. An
institutional review board (Quorum Review IRB, Seattle,
WA) approved the protocol before initiation of the study,
and participants provided written informed consent before any study procedures were performed.
Study Participants
Eligible participants included generally healthy, adult
men and women, aged 20 to 65 years, with body mass
index !25 and %45 and plasma LDL cholesterol level
!130 mg/dL (3.4 mmol/L) and %200 mg/dL (5.2 mmol/L).
Women of childbearing potential had to be willing to use
a medically approved form of contraception throughout
the study. Participants who smoked could not have plans
to change smoking habits during the treatment period.
Participants who reported a weight change of $4.5 kg
during the previous 2 months; use of weight loss medications within 2 months before screening or supplements,
206
February 2010 Volume 110 Number 2
programs, or meal replacement products within 2 weeks
before screening; use of drugs (within 4 weeks before
screening), supplements, or foods (within 2 weeks before
screening) known to alter lipid levels; use of fiber-containing supplements within 2 weeks before screening; or
daily consumption of oat or barley products (eg, RTE
oat-based cereals, oatmeal, or oatbran), or frequent consumption of foods rich in viscous fiber within 2 weeks of
screening were excluded from the study. Participants
with clinically significant abnormal laboratory test results (eg, triglycerides !400 mg/dL [4.5 mmol/L], glucose
!126 mg/dL [7.0 mmol/L], creatinine !1.5 mg/dL [114.4
"mol/L], and alanine aminotransferase and aspartate
aminotransferase levels !1.5 times the upper limit of
normal) or uncontrolled hypertension (systolic/diastolic
blood pressures !160/100 mm Hg); a history of cardiac,
renal, hepatic, endocrine, pulmonary, biliary, pancreatic,
gastrointestinal or neurologic disorders, or cancer in the
past 2 years; known sensitivity to any of the ingredients
in the study foods; a history of weight-reducing surgery; a
history of eating disorders or alcohol abuse; or who used
thyroid hormones (except stable dose replacement therapy) or systemic corticosteroids were also excluded from
the study.
Diet, Consumption of Study Product, and Exercise
Based on a review of diet records obtained during the
screening period, recommendations were made to decrease portion sizes, and to reduce consumption of highfat and high-energy density foods to produce a target
energy deficit of "500 kcal/day below estimated maintenance requirements, while consuming a nutritionally balanced diet. Participants followed the diet throughout the
12-week treatment period with a goal of achieving a
weight loss of "0.5 kg/week. Energy needs for weight
maintenance were calculated using the Mifflin-St Jeor
equation, adjusted for the level of physical activity at
baseline (8). In addition to the general dietary recommendations, participants were randomly assigned to consume
either two portions/day ("3 c/day) of whole-grain RTE oat
cereal (providing 3 g/day b-glucan) or low-fiber breakfast/
snack foods (eg, RTE corn cereals, white toast, plain
bagels and English muffins, pretzels, soda crackers, or
rice cakes) with a similar energy and macronutrient content (control group). Participants were instructed on how
to incorporate these foods into their reduced-energy diet
to maintain an energy deficit. The whole-grain RTE oat
cereal (Cheerios, General Mills, Minneapolis, MN) was
prepared and packaged in "40 g portions by the manufacturer. Each portion contained 1.5 g b-glucan. All participants were instructed to avoid foods rich in viscous
soluble fiber such as barley, oatmeal, and oat bran products, with the exception of the study product provided to
the whole-grain RTE oat cereal group. Participants met
with a registered dietitian biweekly to monitor and reinforce dietary changes. Participants were also encouraged
to engage in 30 to 60 minutes/day of moderate-intensity
exercise (eg, walking) on most days, as recommended by
the American College of Sports Medicine and the American Heart Association (9).
Study product diaries were collected at biweekly clinic
visits to evaluate compliance with consumption of test
product or control foods. Three-day diet records were
collected at baseline and at weeks 4 and 12 to evaluate
compliance with dietary instructions and assess dietary
changes. Diet analyses were completed using the Food
Processor Nutrition Analysis & Fitness Software (version
8.5.0, 2005, ESHA Research, Salem, OR). A physical activity score was calculated as described by Sallis and
colleagues (10) from the Stanford 7-Day Physical Activity
Recall questionnaire completed by subjects at baseline
and at weeks 4 and 12.
Anthropometric and Blood Pressure Measurements
Body weight and waist circumference were measured at
each biweekly clinic visit. Weight was measured while
participants were wearing lightweight clothing and without shoes. A nonstretch anthropometric tape was used to
measured midarm and waist circumferences. Waist circumference was measured on a horizontal plane at the
level of the iliac crest using a nonstretch anthropometric
tape at the end of a normal expiration (2). Midarm circumference and triceps skinfold thickness were measured
(an average of three measures was recorded for both) at
screening and weeks 4, 8, and 12 as described by Heyward (11). Triceps skinfold was measured using calipers
(Fabrication Enterprises, White Plains, NY).
Seated, resting blood pressure was assessed at each
biweekly clinic visit after the participant had been seated
for at least 5 minutes. Participants refrained from smoking cigarettes or ingesting caffeine during the 30 minutes
preceding the measurement. Blood pressure was measured using an automatic blood pressure device (Welch
Allyn Model 3500, Skaneateles Falls, NY). Two measurements were taken, separated by at least 2 minutes, and
averaged.
Laboratory Measurements
Clinical laboratory measurements (ie, serum chemistry,
hematology, and urinalysis) collected at screening were
conducted by Elmhurst Memorial Hospital Laboratory
(Elmhurst, IL) utilizing instruments by Beckman, Inc
(Fullerton, CA). Fasting plasma lipid profiles were collected at screening and at weeks 0, 4, 8, 10, and 12.
Cholesterol and triglyceride levels were measured using
the Beckman Coulter’s LX20 PRO (Fullerton, CA). LDL
cholesterol concentration was calculated according to the
Friedewald equation (12) as follows: LDL cholesterol!
total cholesterol– high-density lipoprotein (HDL) cholesterol–triglyceride/5. Since this equation is not valid when
triglyceride concentration is above 400 mg/dL (4.5 mmol/
L), LDL cholesterol values were not calculated in the few
instances where this occurred. High-sensitivity C-reactive protein (hs-CRP) was measured at weeks 0 and 12 on
a Siemens Medical Solutions BN II nephelometer (Deerfield, IL). A questionnaire was used to assess conditions
that could potentially confound hs-CRP concentrations
(eg, concurrent infection or injury) at the time of each
hs-CRP measurement to identify potential explanations
for unusually high values.
Statistical Analyses
Statistical analyses were conducted using SAS (version
9.1.3, 2005, SAS Institute Inc, Cary, NC). An evaluable
sample size of 128 subjects (64 per arm) was expected to
provide 80% power (two-sided #!.05) to detect a difference of 5% between groups in the percent change from
baseline in LDL cholesterol, assuming a 10% pooled standard deviation for the LDL cholesterol response. All tests
of significance, unless otherwise stated, were performed
at #!.05, two-sided. Assumptions of normality of residuals and homogeneity of variance were investigated for
each response variable. When it was determined that the
distribution was not approximated by a normal curve,
values were ranked before analysis. However, since sensitivity analyses revealed no material differences between
results for ranked and unranked analyses, means$
standard error or 95% confidence intervals are presented
for continuous variables.
Evaluations of the effects of treatment on the outcome
variables were completed on a modified intent-to-treat
(MITT) population, defined as all participants who received at least one portion of study product and provided
at least one postrandomization lipid value, as well as a
per-protocol population, a subset of MITT participants
who completed the intervention, were at least 80% compliant with study product consumption and had no major
protocol violations. All decisions regarding exclusion from
the per-protocol population were undertaken before database lock and made by individuals with no knowledge of
the study group to which the participant had been assigned. Incomplete data from participants who withdrew
early were included in the MITT analysis utilizing the
method of last observation carried forward. The value of the
previous nonbaseline visit was carried forward to subsequent visits, if missing. Only measured values were used for
the analysis of the per-protocol population. Efficacy results
are presented for the per-protocol population unless otherwise stated, and material differences between the per-protocol and MITT results are noted where applicable.
Baseline comparisons between treatment groups were
completed with the $2 test, Fisher’s exact (two-tail) tests,
or analysis of variance. Differences between and within
treatment groups in the changes or percent changes from
baseline to end-of-treatment in LDL cholesterol level,
other lipid variables, body weight, dietary, and anthropometric values were assessed by repeated measures analysis of covariance using SAS PROC MIXED. The initial
models included terms for baseline value, treatment
group, visit, research site, and treatment group by visit
and treatment group by research site interactions. Each
model was reduced in a stepwise manner until only significant (P%0.05) terms or treatment group and research
site remained. There were no significant treatment by
time interactions for lipid variables, therefore these results
are presented as means$standard error or 95% confidence
intervals for percent changes from baseline (average of values at weeks #1 and 0) to on-treatment values (average of
values collected at weeks, 4, 8, 10, and 12).
Possible differences in response by sex were investigated. Because no material differences were observed,
results are not presented separately for men and women.
Exploratory analyses were conducted to assess whether
differences between groups in responses for LDL cholesterol level and waist circumference remained significant
after adjusting for weight changes during the treatment
period. In addition, to assess responses early in the treatFebruary 2010 ● Journal of the AMERICAN DIETETIC ASSOCIATION
207
ment period, exploratory analyses were conducted on
lipid level and waist circumference responses at week 4.
RESULTS
Participant Characteristics
The disposition of all study participants is presented in
Figure 1. Six hundred eleven individuals were screened
and 204 were randomized to treatment (whole-grain RTE
oat cereal n!101, control n!103). One hundred seventythree participants (whole-grain RTE oat cereal n!86,
control n!87) were included in the MITT population. Of
these, 144 participants (whole-grain RTE oat cereal
n!77, control n!67) were included in the per-protocol
population. A greater percentage of subjects in the wholgrain RTE oat cereal group completed the trial (79.2%)
compared with the control group (70.9%), although this
difference was not statistically significant (P!0.225).
Baseline demographic and anthropometric characteristics for the per-protocol sample are presented for both
treatment groups in Table 1. Demographic and anthropometric characteristics were not significantly different
between groups. The majority of participants were women
(78.4%) of non-Hispanic white ethnicity (86.1%), with a
mean age of 48.8 years. Mean body mass index was "32
and the mean waist circumference was "105 cm.
Study Product Compliance
At the end of treatment, mean$standard error compliance, based on participant interview, measurement of
unused cereal servings, and review of study product diaries was 96.8%$0.6% of expected servings of study foods
for the whole-grain RTE oat cereal group and 95.7%$
0.7% for the control group (P!0.202).
Dietary Intake and Physical Activity
Both groups reduced their energy intakes during the
study. The control group showed a larger reduction in
reported energy intake at week 4 (P!0.009), but no significant difference between groups was present at week
12 (Table 2). Both total dietary fiber and soluble dietary
fiber intakes increased significantly more in the wholegrain RTE oat cereal vs the control group (P%0.001 for
both). The control group showed modest reductions in
total dietary fiber consumption during the treatment period, and the value at week 4 was significantly lower than
that at baseline (P!0.004). However, this appears to be
attributable to a reduction in energy intake because
mean daily dietary fiber consumption per 1,000 kcal of
energy increased from 8.2$0.4 g at baseline to 8.7$0.4 g
at week 4 (P!0.203 vs baseline) and 9.1$0.4 g at week 12
(P!0.040 vs baseline). Increases in total and soluble fiber
intakes in the whole-grain RTE cereal group compared to
the control group were consistent with those expected
based on the composition of the study cereal. The percentage of total daily energy intake from carbohydrate was
greater at week 12 in the whole-grain RTE oat cereal
group than in the control group (P!0.017). Intakes of
potassium, calcium, magnesium, phosphorus, and vitamin D were all increased at weeks 4 and 12 in the wholegrain RTE oat cereal vs the control group (P%0.001 for
208
February 2010 Volume 110 Number 2
all). There were no statistically significant differences
between the two groups in any other major nutrient parameters at the end of treatment (Table 2).
Both groups increased physical activity to a similar
degree. At baseline, the mean activity scores above resting were 118.4$7.6 (whole-grain RTE oat cereal) and
118.3$10.0 (control) metabolic equivalent hours. During
the treatment period, physical activity scores increased
by 9.1%$4% and 15%$5.2% (P!0.710), in the wholegrain RTE oat cereal and control groups, respectively.
Body Weight and Anthropometric Variables
Both groups lost weight during the study and weight loss
was not significantly different between groups at the
end-of-treatment (whole-grain RTE oat cereal, #2.2$0.3
kg vs control, #1.7$0.3 kg; P!0.325). Waist circumference decreased significantly more with whole-grain RTE
oat cereal compared with control (#3.3$0.4 cm vs #1.9$
0.4 cm, P!0.012) (Figure 2). Differences between treatment groups for waist circumference responses remained
statistically significant after adjustment for change in
body weight, suggesting that these effects could not be
accounted for entirely by weight loss. Triceps skinfold
thickness and midarm circumference changes did not
differ significantly between groups (data not shown).
Plasma Lipid Levels, hs-CRP, and Blood Pressures
LDL cholesterol level during the treatment period was
reduced significantly more with whole-grain RTE oat cereal than control (#8.7%$1% vs #4.3%$1.1%, P!
0.005); similar results were observed for total cholesterol
(#5.4%$0.8% vs #2.9%$0.9%, P!0.038) and non-HDL
cholesterol (#6.3%$1% vs #3.3%$1.1%, P!0.046) (Figure 3). The difference in LDL cholesterol level remained
significant after adjusting for the change in body weight.
The difference between the whole-grain RTE oat cereal
group and the control group in LDL cholesterol level
responses was evident as early as week 4 (#10.7%$1.3%
vs #6.2%$1.6%, P!0.027). Significantly larger reductions in total cholesterol (#7.9%$1.1% vs #3.8%$1.1%,
P!0.010) and non-HDL cholesterol levels (#9%$1.3% vs
#4.3%$1.3%, P!0.009) were also apparent as early as
week 4 in the whole-grain RTE oat cereal group vs the
control group. The lack of a treatment by time interaction
indicated that the difference in response between groups
did not vary over time. There were no significant differences between groups in HDL cholesterol, triglyceride, or
hs-CRP responses.
Systolic blood pressure was higher in the whole-grain
RTE oat cereal group vs control at baseline (127.2$1.2 vs
122.6$1.3 mm Hg, P!0.010), but diastolic pressures
were similar (79.4$0.9 vs 78.3$1.0 mm Hg, P!0.446). At
week 12, there was no difference between groups in the
change from baseline in systolic or diastolic blood pressures.
MITT Analyses
The per-protocol population analysis was presented
to show the magnitude of the effect in subjects who
completed the full treatment period without any major
protocol violations. Results for the MITT analyses are
Figure 1. Participant disposition in a study to determine if a whole-grain, ready-to-eat (WG-RTE) oat cereal containing viscous fiber, as part of a
dietary program for weight loss, improves cardiovascular disease risk markers more than a dietary program alone. MITT!modified intent-to-treat.
PP!per protocol. ET!early termination. *Other reasons included medication change (n!1), work schedule change (n!1), and study product too
filling (n!1).
February 2010 ● Journal of the AMERICAN DIETETIC ASSOCIATION
209
Table 1. Baseline demographic and anthropometric characteristics of adult participants in a
study to determine if a whole-grain, ready-to-eat (WG-RTE) oat cereal containing viscous
fiber, as part of a dietary program for weight loss, improves cardiovascular disease risk
markers more than a dietary program alone
Characteristic
Sex
Male
Female
Race/ethnicity
Non-Hispanic white
African American
Hispanic
Other
Age (y)
Weight (kg)
Height (cm)
Body mass index
Waist circumference (cm)
Midarm circumference (cm)
Triceps skinfold thickness (mm)
Total cholesterol (mg/dL)a
Low-density lipoprotein
cholesterol (mg/dL)a
High-density lipoprotein
cholesterol (mg/dL)a
Non-high-density lipoprotein
cholesterol (mg/dL)a
Triglyceride (mg/dL)b
Control
(n!67)
WG-RTE oat
cereal (n!77)
P between
groups
4™™™™™™™™™™ n ™™™™™™™™™™3
12
55
19
58
0.325
55
69
5
6
4
1
3
1
4™™ mean$standard error ™™3
47.5$1.3
50.1$1.1
87.6$1.8
88.7$1.9
164.7$0.9
166.2$1.1
32.2$0.6
32.0$0.5
105.2$1.5
104.5$1.3
35.2$0.4
34.9$0.4
44.1$1.1
41.8$0.9
228.7$3.2
232.0$2.4
0.389
154.7$2.4
155.4$2.1
0.819
47.8$1.4
47.8$1.3
0.846
180.9$2.8
131.3$6.8
184.3$2.4
145.9$7.8
0.377
0.190
0.121
0.666
0.319
0.707
0.735
0.692
0.091
0.414
a
To convert mg/dL cholesterol to mmol/L, multiply mg/dL by 0.026. To convert mmol/L cholesterol to mg/dL, multiply
mmol/L by 38.7. Cholesterol of 193 mg/dL!5.00 mmol/L.
b
To convert mg/dL triglyceride to mmol/L, multiply mg/dL by 0.0113. To convert mmol/L triglyceride to mg/dL, multiply
mmol/L by 88.6. Triglyceride of 159 mg/dL!1.80 mmol/L.
NOTE: Information from this table is available online at www.adajournal.org as part of a PowerPoint presentation.
generally consistent with results for the per-protocol
analyses, particularly with respect to favorable effects of
the whole-grain RTE oat cereal vs control on LDL cholesterol level (#8%$0.9% vs #4.9%$1%, P!0.018) and
waist circumference (#3.1 vs 1.9 cm, P!0.021). However,
differences in total cholesterol (#5.2%$0.8% vs #3.4%$
0.8%, P!0.073) and non-HDL cholesterol (#5.9%$0.9%
vs #4.1%$1%, P!0.130) responses did not reach statistical significance between the whole-grain RTE oat cereal
and control groups. Like the per-protocol analyses, the
MITT analyses showed no significant difference in weight
loss between groups at the end of treatment (whole-grain
RTE oat cereal, #2.0$0.3 kg vs control #1.6$0.3 kg;
P!0.249).
itis, and pharyngitis. Most adverse events were mild and
not related to consumption of the study product. Adverse
events considered at least possibly related to the study
product included nausea (two whole-grain RTE oat cereal
subjects), flatulence (two whole-grain RTE oat cereal participants), and gastroenteritis and gastroesophageal reflux (one control participant each). One participant in the
control group experienced a serious adverse event (vomiting) that resolved and did not result in discontinuation
from the trial. Adverse events that resulted in discontinuation of study participation included an infectious cyst
and spinal stenosis (reported by one control participant
each). Neither of these events was considered to be related to the study protocol.
Adverse Events
The frequencies of adverse events of any type (whether or
not related to the study products) were similar for both
the whole-grain RTE oat cereal and control groups (59.8%
vs 52.4%, P!0.321). The most common adverse events in
both groups were upper respiratory tract infection, sinus-
DISCUSSION
The results of this study show that, when consumed as
part of a dietary program for weight loss, whole-grain
RTE oat cereal (containing 3 g oat b-glucan) lowered LDL
cholesterol levels in men and women with hypercholesterolemia and overweight or obesity significantly more
210
February 2010 Volume 110 Number 2
Table 2. Diet compositions in a study to determine if a whole-grain, ready-to-eat (WG-RTE)
oat cereal containing viscous fiber, as part of a dietary program for weight loss, improves
cardiovascular disease risk markers more than a dietary program alone, by timepoint and
treatment group
Variable
Energy (kcal/d)
Baseline
Week 4
Week 12
Carbohydrate (% energy)
Baseline
Week 4
Week 12
Protein (% energy)
Baseline
Week 4
Week 12
Total fat (% energy)
Baseline
Week 4
Week 12
Cholesterol (mg/d)
Baseline
Week 4
Week 12
Saturated fatty acids (% energy)
Baseline
Week 4
Week 12
Monounsaturated fatty acids (% energy)
Baseline
Week 4
Week 12
Polyunsaturated fatty acids (% energy)
Baseline
Week 4
Week 12
Dietary fiber (g/d)
Baseline
Week 4
Week 12
Soluble dietary fiber (g/d)
Baseline
Week 4
Week 12
Sodium (mg/d)
Baseline
Week 4
Week 12
Potassium (mg/d)
Baseline
Week 4
Week 12
Calcium (mg/d)
Baseline
Week 4
Week 12
Magnesium (mg/d)
Baseline
Week 4
Week 12
Phosphorus (mg/d)
Baseline
Week 4
Week 12
Vitamin D ("g/d)
Baseline
Week 4
Week 12
Control (n!67)
WG-RTE oat cereal (n!77)
P between groups
4™™™™™™™™ mean$standard error ™™™™™™™™3
1,853$70
1,395$44***
1,443$45***
1,939$97
1,563$50***
1,529$44***
0.690
0.009
0.256
45.6$1.2
49.8$1.0***
49.8$1.0***
44.8$0.9
50.6$0.9***
52.2$0.9***
0.660
0.625
0.017
17.9$0.6
20.0$0.6**
20.1$0.6**
18.2$0.5
20.1$0.5**
19.7$0.5*
0.330
0.971
0.623
35.6$0.8
30.0$0.8***
29.8$0.7***
36.9$0.8
30.4$0.9***
29.6$0.8***
0.297
0.697
0.718
263.7$13.5
191.3$10.0***
202.4$12.4***
288.0$15.4
185.0$10.4***
189.5$12.5***
0.470
0.414
0.138
11.9$0.3
9.4$0.4***
9.5$0.3***
12.6$0.4
9.7$0.3***
9.5$0.3***
0.203
0.680
0.805
9.3$0.4
8.3$0.4
8.3$0.3*
9.4$0.4
8.9$0.4
8.4$0.4*
0.901
0.464
0.652
4.5$0.2
4.1$0.2
4.3$0.2
4.6$0.2
4.9$0.2
4.4$0.2
0.718
0.003
0.798
14.8$0.8
11.8$0.6**
12.7$0.6
15.8$1.0
21.0$0.5***
21.7$0.5***
0.612
%0.001
%0.001
1.4$0.1
1.2$0.1
1.4$0.1
1.4$0.1
4.4$0.1***
4.5$0.1***
0.979
%0.001
%0.001
2,937.0$133.3
2,527.8$105.1*
2,570.0$105.1*
3,203.3$166.9
2,829.5$114.3*
2,773.3$94.5**
0.352
0.106
0.344
1,849.8$73.7
1,637.3$59.7
1,788.5$66.6
2,201.8$192.5
2,328.4$75.9
2,385.7$85.3
0.141
%0.001
%0.001
651.2$31.8
600.9$32.8
612.0$36.3
783.2$47.4
1,042.3$36.1***
1,015.1$56.9***
0.060
%0.001
%0.001
175.7$8.1
147.5$5.4*
162.9$5.2
192.5$12.8
258.1$7.1***
257.7$8.1***
0.124
%0.001
%0.001
878.5$39.4
744.1$30.0*
814.0$34.8
937.1$46.4
1,154.0$39.1***
1,151.3$45.8***
0.123
%0.001
%0.001
2.9$1.3
2.3$0.3
2.6$0.5
2.0$0.2
5.5$0.3***
5.7$0.5***
0.467
%0.001
%0.001
*Within group difference from baseline, P%0.05.
**Within group difference from baseline, P%0.01.
***Within group difference from baseline, P%0.001.
February 2010 ● Journal of the AMERICAN DIETETIC ASSOCIATION
211
Figure 2. Mean change from baseline in waist circumference for
subjects in the whole-grain ready-to-eat (WG-RTE) oat cereal vs control
groups from baseline through the end of a study (week 12) to determine if a WG-RTE oat cereal containing viscous fiber, as part of a
dietary program for weight loss, improves cardiovascular disease risk
markers more than a dietary program alone. Values to the right of week
12 data are means (95% confidence interval). Statistical tests were
performed for weeks 4 and 12 only. NOTE: Information from this figure
is available online at www.adajournal.org as part of a PowerPoint
presentation.
than a dietary program for weight loss that included
low-fiber control foods. During the treatment period, LDL
cholesterol level was reduced by 8.7% in the whole-grain
RTE oat cereal group, whereas the control group showed
a reduction in LDL cholesterol of 4.3% and a significant
difference in LDL cholesterol response was evident as
early as week 4 (#10.7% vs #6.3%).
Saltzman and colleagues (13) observed significantly
greater reductions in LDL cholesterol in subjects consuming a hypocaloric diet (1,000 kcal/day deficit) including
"80 g whole oats/day (#23.2 mg/dL or "20%) vs no oats
(#7.7 mg/dL, "6%) for 6 weeks. In that study, body
weight loss was "4.0 kg during the treatment period for
both groups, with a tightly controlled dietary regimen
where all meals were provided to participants under supervision in the clinic. The incremental effects of the
whole-grain RTE cereal on LDL cholesterol reduction in
our study are consistent with those from prior trials conducted in free-living people during weight maintenance
(4,5,14). For example, both Karmally and colleagues (14)
and Johnston and colleagues (15) provided a whole-grain
RTE oat cereal containing 3 g b-glucan as part of a weight
maintenance diet for 6 weeks to overweight subjects with
elevated LDL cholesterol levels. These trials showed reductions of 4.2% to 5.3% in LDL cholesterol and 3.8% to
4.5% in total cholesterol relative to the control condition
associated with whole-grain RTE consumption. In another study (16), a whole-grain RTE oat bran cereal (25 g
oat bran/day containing "3.5 g b-glucan) reduced LDL
cholesterol level by 8.5% from baseline over 2 weeks in
participants with hypercholesterolemia following a
weight maintenance diet.
The decline in LDL cholesterol level in both groups was
somewhat larger at week 4 than at the end of the treatment period, possibly due to somewhat greater negative
212
February 2010 Volume 110 Number 2
Figure 3. Mean change from baseline to end-of-treatment for lowdensity lipoprotein cholesterol (LDL-C), non– high-density lipoprotein
cholesterol (non-HDL-C), and total cholesterol (total-C) level for subjects in a study to determine if a whole-grain, ready-to-eat (WG-RTE)
oat cereal containing viscous fiber, as part of a dietary program for
weight loss, improves cardiovascular disease risk markers more than
a dietary program alone. Because there was no treatment by time
interaction, responses are based on average of values collected at
weeks 4, 8, 10, and 12. Values below bars are means (95% confidence
interval). NOTE: Information from this figure is available online at
www.adajournal.org as part of a PowerPoint presentation.
energy balance early in the intervention (3). Nevertheless, the difference between treatment groups was consistent throughout the treatment period. The mean difference of 4.4% in LDL cholesterol response between the
control and whole-grain RTE oat cereal groups represents
a difference of "1.4% per gram of additional soluble dietary fiber intake in the whole-grain RTE cereal group,
which is in agreement with results from other studies on
viscous soluble dietary fiber during weight maintenance
(4,5). The incremental reduction of LDL cholesterol level
attributed to the whole-grain RTE oat cereal consumption in our trial may be extrapolated to a meaningful CVD
risk reduction based on results from population studies
suggesting that each 1% reduction in LDL cholesterol
level is associated with a reduction of as much as 3% in
CVD event risk, if maintained over an extended period
(17,18). Results from previous studies with viscous dietary fibers have shown that their effects on LDL cholesterol level are maintained over extended periods with
continued consumption, with no evidence of attenuation
of the effects during daily consumption for at least 1 year
(19-21). In our study whole-grain RTE oat cereal was the
main source of viscous dietary fiber during the treatment
period. Daily consumption of whole-grain RTE oat cereal
is practical for extended periods, although cereal consumption could also be combined with other dietary
sources of viscous fibers (eg, prunes and other fruits,
barley, and legumes) to add variety.
In our study, waist circumference was reduced significantly more (by "1.5 cm) in the whole-grain RTE oat
cereal group than in the control group. Excess abdominal
adiposity is strongly associated with metabolic disturbances such as insulin resistance and hypertriglyceride-
mia (22). Consumption of whole grains has been associated with smaller waist circumference in population
studies (23-25). In addition, Katcher and colleagues (26)
reported a significantly larger reduction in the percentage of body fat in the abdominal area in a group assigned
to receive all of their grain servings from whole grains
during a 12-week period of energy restriction ("500 kcal/
day), compared with a group assigned to avoid whole
grains. Additional studies, particularly those using imaging methods to quantify changes in abdominal visceral
and subcutaneous fat, are needed to clarify the clinical
implications of the finding of the larger reduction in waist
circumference associated with whole-grain RTE oat cereal consumption observed herein.
Notable improvements in intakes of several dietary
components were observed with whole-grain RTE oat cereal consumption in our study, including an increase from
baseline in consumption of total dietary fiber ("6 g/day),
calcium (231 mg/day), magnesium (63 mg/day), potassium (175 mg/day), and vitamin D (3.7 "g/day), whereas
intakes of these nutrients did not improve in the control
group. These differences may be attributable to the increased consumption of some dietary components from
the whole-grain RTE cereal (eg, fiber), as well as milk,
which was frequently consumed with the cereal, as well
as to the influences of displacing other foods with the
study foods. Improvements in calcium, phosphorus and
vitamin D intakes were likely secondary to increased
milk consumption and micronutrient fortification of the
whole-grain RTE oat cereal. Total dietary fiber intake
increased to "21 g/day in the whole-grain RTE oat cereal
group, which falls within the range of 20 to 35 g fiber/day
recommended by the Institute of Medicine (27). Thus, the
inclusion of viscous fiber-containing foods, such as wholegrain RTE oat cereal, as part of a reduced-energy diet
may be advantageous for helping meet some nutrition
recommendations.
No significant effect of whole-grain RTE oat cereal consumption was observed on blood pressure at the end of
treatment in our study. Behall and colleagues (28) reported that blood pressure was significantly reduced in
adults with mildly elevated cholesterol levels fed a diet
rich in whole grains. Other studies have shown inconsistent effects of whole grain oat cereal or b-glucan consumption on blood pressure, with some suggesting benefits and others finding no effect (29-31). Thus, the
influence of whole-grain RTE oat cereal consumption on
blood pressure remains uncertain.
A limitation of the study is that average weight loss
was small, so the additive effects of a whole-grain RTE
oat cereal on changes in LDL cholesterol level with
greater quantities of weight-loss could not be assessed.
Meta-analyses suggest that each kilogram reduction in
body weight is associated with a decrease of "0.8 mg/dL
(0.02 mmol/L) in LDL cholesterol levels (3). The loss of
body weight in our study among participants in the control group was "1.7 kg, which would have been expected
to produce a reduction of only "1.4 mg/dL (0.04 mmol/L)
in LDL cholesterol. The actual reduction observed was
larger (6.3 mg/dL or 0.16 mmol/L), suggesting that other
factors may have contributed to this effect. Physical activity increased from baseline in both treatment groups to
a similar degree; however, increased physical activity is
not generally associated with reduced LDL cholesterol
level and therefore is likely not a contributor to the lipid
outcomes in our study (32). The effects of negative energy
balance and lower intakes of saturated fat and cholesterol
on LDL cholesterol level reduction are well established
and may explain, at least in part, the larger than predicted reduction in LDL cholesterol level observed in the
control group (3).
CONCLUSIONS
Dietary recommendations to achieve and maintain a favorable blood lipid profile include loss of excess body
weight and consumption of viscous dietary fibers. The
results of this study demonstrate that consumption of a
whole-grain RTE oat cereal was associated with favorable
effects on blood lipid levels and waist circumference when
consumed as part of a dietary program for weight loss by
men and women with overweight and obesity. In addition, the whole-grain RTE oat cereal group had more
favorable reported intakes of several dietary components,
including vitamin D, calcium, magnesium, and potassium. These findings suggest that incorporation of a
whole-grain RTE oat cereal into a dietary program for
weight loss may be an effective strategy to improve lipid
levels and diet quality, beyond that of a dietary program
containing low-fiber control foods, in men and women
with overweight and obesity.
STATEMENT OF POTENTIAL CONFLICT OF INTEREST:
K. C. Maki, V. N. Kaden, and T. M. Rains are employees
of Provident Clinical Research. These employees received
research grant support from General Mills to conduct the
study. M. V. Farmer is an employee at Meridien Research
and received research grant support from General Mills.
J. M. Beiseigel, C. K. Gugger, and S. S. Jonnalagadda are
employees of General Mills.
FUNDING/SUPPORT: This trial was funded by General Mills Bell Institute of Health and Nutrition, Minneapolis, MN.
ACKNOWLEDGEMENTS: The authors thank the
study participants, Stephanie DeCoeur, RN; John R. Ferrante, MS, RD, LD; Emily Beal, RD, CD; Morgan Fleck,
MS, RD; Donna Wilder, MS, MT (ASCP); Yolanda Cartwright, PhD, RD; and Sharyl K. Leinen, MBA, RD for
their assistance with this study.
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