AMERICAN JOURNAL OF HYPERTENSION 1
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Cardiovascular disease is the leading cause of morbidity and
mortality in the United States1 particularly among African
Americans (AAs) as compared to whites.1–3 AAs show higher
nocturnal blood pressure (BP) and a blunted decline in BP from
day to night.4–8 This attenuated decline in night-time BP relative
to daytime BP, often referred to as “nondipping,” is associated
with elevated risk for cardiovascular disease in normotensive and
hypertensive populations,9–11 and has been linked to develop-
ment of subclinical atherosclerosis,12 left ventricular hypertro-
phy,13 congestive heart failure,14 and all-cause mortality.15,16
The etiology of ethnic differences in BP is unclear; however,
differences in dietary habits have been suggested to be one pos-
sible contributor.17,18 Lifestyle modification, including diet and
exercise, is the recommended initial intervention strategy for
lowering BP.19 In particular, the DASH (Dietary Approaches
to Stop Hypertension) diet, which is rich in fruits and vegeta-
bles, low-fat dairy foods, fiber, and protein, and low in satu-
rated fat, total fat, and cholesterol, has been found efficacious
in reducing BP in hypertensive populations in a series of feed-
ing studies as well as in free-living situations.20–22 For exam-
ple, the recently completed ENCORE (Exercise and Nutrition
interventions for CardiOvasculaR hEalth) study demonstrated
a significant decline in clinic and 24-h ambulatory BP among
overweight, unmedicated outpatients with high BP randomly
assigned to 4 months of the DASH diet with or without exer-
cise and weight loss compared to usual diet controls (UCs).22
However, it remains uncertain as to whether the DASH diet
influences nocturnal BP dipping. The aim of the present study
was to determine whether the DASH diet attenuates ethnic
differences in nocturnal BP dipping in a sample of overweight,
unmedicated AA and white participants with high BP, com-
pared to participants randomized to a UC condition.
The trial’s design and methods are presented in detail else-
where.22 Briefly, the ENCORE study was a randomized trial
1Department of Psychiatry and Behavioral Sciences, Duke University Medical
Center, Durham, North Carolina, USA; 2Department of Medicine, Division of
Cardiology, University of North Carolina, Chapel Hill, North Carolina, USA;
3Present address: Robert Wood Johnson Foundation Health and Society
Scholars Program, University of California, San Francisco, California, USA.
Correspondence: Andrew Sherwood (firstname.lastname@example.org)
Received 30 November 2010; first decision 7 January 2011; accepted 30 June 2011.
© 2011 American Journal of Hypertension, Ltd
Ethnic Differences in the Effects of the DASH Diet
on Nocturnal Blood Pressure Dipping in Individuals
with High Blood Pressure
Aric A. Prather1,3, James A. Blumenthal1, Alan L. Hinderliter2 and Andrew Sherwood1
Ethnic differences in nocturnal blood pressure (BP) dipping may
contribute to the increased risk for adverse cardiovascular events
noted in African Americans (AAs). The DASH (Dietary Approaches to
Stop Hypertension) diet has been shown to be efficacious in lowering
clinic and ambulatory BP; however, the effect of the DASH diet on BP
dipping is unclear.
One hundred and eighteen men and women with high clinic BP
(systolic BP (SBP) 130–159; diastolic BP 85–99) and above ideal body
weight were randomized to a DASH diet intervention or to a usual
diet control (UC) condition. Measures of 24-h ambulatory BP were
obtained at baseline and at the end of the 4-month intervention
At baseline, AAs (n = 43) displayed blunted nocturnal SBP dipping
compared to Caucasians (CAs; n = 75) and were more likely to be
categorized as nondippers (<10% nocturnal decline in SBP, AAs:
51% vs. CAs: 27%). AAs randomized to the DASH diet intervention
showed a significant improvement in SBP dipping postintervention
compared to AAs in the UC condition (P = 0.04), whereas there was
no appreciable change in SBP dipping in CAs (P = 0.72). Following
the intervention, ethnic differences in SBP dipping were no longer
statistically significant (nondipper status: AAs: 44% vs. CAs: 32%;
P = 0.19).
Our study provides preliminary evidence suggesting that in
overweight men and women with high BP, AAs may be especially
likely to benefit from augmented SBP dipping associated with
consumption of the DASH diet.
Keywords: blood pressure; DASH diet; ethnicity; hypertension; nocturnal
American Journal of Hypertension, advance online publication 25 August 2011;
2 AMERICAN JOURNAL OF HYPERTENSION
DASH Diet and Blood Pressure
comparing the effects of the DASH diet with and without weight
loss. Participants were randomized to one of three conditions: (i)
the DASH diet alone (DASH-A), (ii) the DASH diet combined
with behavioral weight management (DASH-WM), and (iii) the
UC; the primary endpoint was clinic BP while other biomark-
ers of cardiovascular health, including flow mediated dilation,
baroreflex sensitivity, and insulin resistance served as secondary
endpoints. Assessments were obtained prior to randomization
and at the end of the 4-month intervention. Immediately fol-
lowing randomization, participants entered a 2-week control-
led feeding period in which they ate according to their assigned
diet. For the UC and DASH-A conditions, participants con-
sumed study meals isocalorically, whereas participants in the
DASH-WM condition consumed meals at 500-calorie-per-day
deficit to allow for weight loss of one pound per week. Following
this feeding period, participants ate their prescribed diets
on their own for the remaining 14 weeks of the study. In the
DASH-A condition participants received instruction in modify-
ing the content of their diet to meet DASH guidelines and were
instructed explicitly not to exercise or to attempt to lose weight.
DASH-A participants received weekly 30–45-min group coun-
seling on the DASH diet and were provided feedback on their
dietary adherence. Those participants in DASH-WM received
the same instruction on the DASH diet as the DASH-A group;
however, their weekly group counseling sessions also included
cognitive-behavioral weight loss strategies (e.g., self-monitoring
internal cues of satiation) as well as supervised exercise ses-
sions three times per week. Participants in the UC condition
were asked to maintain their usual dietary habits for 4 months
until they were reassessed and were told not to change their
usual exercise habits or to lose weight. On a biweekly basis, their
weight and BP were monitored and their health habits were
assessed to ensure they had not joined any exercise or weight
Participants. As described in our previous publication,22 the
study sample consisted of 144 healthy, but overweight, men
and women with above-normal BP (mean systolic BP (SBP)
130–159 or diastolic BP 85–99 mm Hg based on four separate
screening visits). Additional inclusion criteria included being
age ≥35 years, a body mass index (BMI) of 25–40 kg/m2, seden-
tary, free from any medications known to affect the cardiovas-
cular system, and any medical comorbidities that would pre-
clude safe participation in the trial. This sub-analysis is limited
to Caucasian (CA) and AAs (ethnicity defined by self-report)
for whom daytime and night-time ambulatory BP readings
were obtained at both baseline and postintervention. As noted
in the primary publication of this clinical trial, 18 participants
were missing ambulatory BP data. Additionally, night-time BP
measurements were missing from six participants. Because
the other minorities comprised such a small (n = 2) subset of
the sample, they were not included, yielding 118 participants
for this analysis. In addition, because only 9 AAs (vs. 32 CAs)
were randomized to the DASH-WM condition, DASH-WM,
and DASH-A (19 AAs vs. 19 CAs) participants were combined
together to facilitate the examination of intervention effects of
a DASH diet intervention on nocturnal BP dipping amongst
CA and AAs.
Ambulatory BP monitoring. To assess diurnal variation in BP,
participants wore an Accutracker II (Suntech Medical, Raleigh,
NC) ambulatory BP monitor over a 24-h period.23 This device
provided BP measurements four times per hour during the
waking day and two times per hour during sleep. Daytime and
night-time BP measures were differentiated by diary reported
sleep/wake times obtained concurrently. Sleep times were una-
vailable on (n = 19) participants at either baseline or postinter-
vention time points. However, in an effort to utilize all available
data, BP measurements were deemed as occurring during the
night-time if obtained between 12:00 AM and 6:00 AM.16,24
Mean daytime and night-time systolic SBP and diastolic BP
values were computed based on all valid readings during the
measurement periods. BP measurements were accompanied
by a diary entry documenting posture, activity, and location.
Nocturnal BP dipping was computed as a ratio of daytime
BP/night-time BP where a smaller ratio indicates greater
nocturnal decline in BP. The day/night BP ratio provides a
continuous measure of nocturnal decline. For descriptive
purposes, participants were also classified as a either a dipper,
defined by decrease in SBP from daytime to night-time values
of greater than or equal to 10%, or a nondipper, classified as
having less than a 10% decline in systolic BP from daytime to
night-time BP averages.
Weight and electrolyte assessment. Body weight was deter-
mined by a calibrated digital scale (Detecto; Cardinal Scale
Manufacturing, Webb City, MO). Sodium (Na+) and potas-
sium (K+) intake were estimated from urinary excretion dur-
ing a 24-h period.25 In addition, an estimation of glomerular
filtration rate was calculated using a modified MDRD equa-
tion.26 Differences in glomerular filtration rate have been pro-
posed to explain variation in BP and BP dipping.27
Statistical analyses. All analyses were performed using SPSS
for Windows (version 17.0; SPSS, Chicago, IL). Comparisons
of baseline characteristics were carried out using independent
t-test and χ2 statistics. The effect of intervention was evalu-
ated using general linear model functions. Separate models
were estimated for each outcome. The fixed factor predictor
variables in each model were an intervention indicator vari-
able (DASH intervention vs. UC) and ethnicity (CA vs. AA).
Covariates in each model included the corresponding preinter-
vention value of the outcome, age, gender, BMI, and posture (%
time upright). To test whether the effects of the intervention on
nocturnal BP dipping varies by ethnicity, we tested the inter-
action between intervention and ethnicity. This study was not
powered to detect interactions; however, we evaluated it and
provide the associated P value. In exploratory subgroup analy-
ses by ethnicity, we computed separate linear models to further
explore intervention effects on nocturnal BP dipping. Finally,
because intervention effects on weight and 24-h urinary excre-
tion of Na+ and K+ could give rise to changes in nocturnal BP
AMERICAN JOURNAL OF HYPERTENSION 3
DASH Diet and Blood Pressure
dipping, separate analyses adjusting for change in BMI and
change in electrolyte excretion were computed to determine
whether intervention effects on BP dipping were independent
of these changes.
Demographic characteristics and ambulatory BP averages for
CA and AAs are presented in Table 1. In this sample AAs were
more likely to be female and younger relative to CAs (P’s <
0.01). In addition, AAs displayed less nocturnal SBP dipping
(t (116) = −2.51, P = 0.01) and were more likely to be charac-
terized as a nondipper when compared to CAs (χ2 (1) = 7.15,
P = 0.007). Baseline ethnic differences in day/night SBP ratio
remained significant after adjusting for age, gender, BMI, and
posture (F (1, 112) = 8.07, P < 0.01). AAs also displayed greater
24-h urinary excretion of Na+ and a higher estimated glomer-
ular filtration rate as compared to CAs (P’s < 0.05).
Table 2 displays baseline demographic characteristics and
BP measurements by intervention condition (DASH interven-
tion vs. controls). There were no significant baseline differ-
ences between conditions with the exception of higher average
daytime SBP among those randomized to the UC condition
compared to assigned to DASH interventions (t (116) = 2.63,
P = 0.01). Conversely, ethnic differences were observed when
looking within condition: specifically, AAs in the DASH inter-
vention condition had a greater proportion of females, had a
higher BMI, and were younger than the CAs assigned to that
condition. In addition, AAs in the DASH intervention had a
lower day/night SBP ratio and thus a greater proportion of SBP
nondippers (P’s < 0.05). AAs had a higher 24-h urinary excre-
tion of Na+ compared to CAs in UC condition.
effect of dash intervention on BP dipping
Table 3 displays postintervention and intervention-related
changes in ambulatory BP by dietary intervention and eth-
nicity. As reported previously,22 participants randomized
to a DASH diet intervention showed a significant decline in
ambulatory BP compared to those in the UC condition, which
remained statistically significant after adjusting for baseline
levels of ambulatory BP, age, gender, BMI, and posture (P’s <
0.05). In addition, there was a trend suggesting DASH inter-
vention to be associated with improvements in day/night SBP
ratio (F (1, 113) = 3.13, P = 0.08). Participants meeting crite-
ria for high-normal BP or obesity randomized to the DASH
intervention showed similar changes in BP dipping observed
in hypertensive and nonobese individuals, respectively.
Next, we examined whether changes in day/night SBP ratio
varied by ethnicity. The interaction between intervention and
ethnicity was below statistical significance (F (1, 109) = 1.97,
P = 0.16). However, because this study was underpowered to
detect interaction effects, in exploratory analyses we examined
pre/post differences in ambulatory BP in AAs and CAs sepa-
rately. We found that AAs randomly assigned to a DASH diet
table 1 | Baseline characteristics of the study sample
Caucasian (n = 75) African American (n = 43)
Age (years) 54.49.7 49.17.7 0.002
Gender (% female)
32.43.7 33.44.1 0.19
% obese (BMI ≥30) 72%— 76.7%—0.57
Education (>high school) 68.0%— 70.0%—0.84
Income (>$50 K/year) 66.7%— 60.4%—0.50
% High-normal blood pressure 17.3%— 9.3%—0.23
Daytime SBP (mm Hg)
Daytime DBP (mm Hg)
84.4 7.985.6 10.00.49
Night-time SBP (mm Hg)123.216.0 126.915.40.23
Night-time DBP (mm Hg) 71.69.074.810.4 0.08
Daytime/Night-time SBP1.16 0.1 1.120.1 0.01
Daytime/Night-time DBP 1.190.1 126.96.36.199
% SBP nondipper26.7%—51.2%— 0.01
% SBP reverse dipper (<0% dip) 5.3%—9.3%— 0.41
% SBP extreme dipper (>20% dip)
Na+ urinary excretion (mmol/24 h)
K+ urinary excretion (mmol/24 h)
Estimated glomerular filtration rate (ml/min per 1.73 m2)a
95.8 45.4 122.742.30.002
37.2 15.8 36.311.9 0.74
77.9 12.485.9 15.1 0.003
BMI, body mass index; DBP, diastolic blood pressure; SBP, systolic blood pressure.
aCaucasian n = 72, African Americans n = 40.
4 AMERICAN JOURNAL OF HYPERTENSION
DASH Diet and Blood Pressure
intervention showed a greater improvement in SBP dipping
when compared to AAs in the UC condition after adjusting
for baseline levels of SBP dipping (F (1, 40) = 4.39, P = 0.04)
independent of age, gender, BMI, and posture (F (1, 36) = 4.58,
P = 0.04). However, no differences were observed for CAs
randomized to DASH vs. UC (F (1, 68) = 0.13, P = 0.72).
table 3 | Postintervention and intervention-related changes by dietary intervention and ethnicity
DASH condition Usual control
Caucasian (n = 51) African Americans (n = 28) Caucasian (n = 24) African Americans (n = 15)
Mean s.d. Means.d. Mean s.d.Mean s.d.
Daytime SBP (mm Hg)*132.6 13.7133.4 12.7 147.014.3 137.9**12.7
Δ Daytime SBP (mm Hg)
−7.2 12.7−5.7 13.3−0.4 12.6−5.7 10.1
Daytime DBP (mm Hg)* 79.57.882.1 11.087.1 8.5 85.28.0
Δ Daytime DBP (mmHg) −4.27.7 −2.4 188.8.131.52−2.57.2
Night-time SBP (mmHg)*115.615.5 118.616.6128.213.4 126.0 11.4
Δ Night-time SBP (mmHg)*−6.5 10.9−8.818.62.5184.108.40.206
Night-time DBP (mmHg)* 67.88.771.611.8 73.48.975.3 8.9
Δ Night-time DBP (mmHg)* −3.56.4−2.6 12.51.1 7.3−0.5 6.9
Day/Night SBP ratio 1.16 0.11 1.130.091.15 0.091.100.08
Δ Day/Night SBP ratio 0.00.11 0.040.10−0.030.15−0.06 0.09
Day/Night DBP ratio 220.127.116.11 0.11 18.104.22.168 0.09
Δ Day/Night DBP ratio 0.00.11 0.010.140.0 0.12−0.03 0.11
BMI30.1 3.833.3** 3.833.64.14 31.43.9
Δ BMI* −2.0 1.8−1.0** 1.9 0.40.9−0.1**0.6
% SBP nondipper
Na+ urinary excretion (mmol/24 h)*
ΔNa+ urinary excretion (mmol/24 h)*
K+ urinary excretion (mmol/24 h)*
ΔK+ urinary excretion (mmol/24 h)
65.8 33.1 116.0**55.2112.8 53.2120.7 36.0
−29.5 34.80.30** 53.715.6 34.0 −14.9**43.1
48.520.5 47.0 18.341.719.040.510.4
11.3 18.5 11.0 16.87.516.11.1 15.8
BMI, body mass index; DASH, Dietary Approaches to Stop Hypertension; DBP, diastolic blood pressure; SBP, systolic blood pressure; UC, usual diet control.
*P < 0.05 DASH condition vs. UC; **P < 0.05 when compared to Caucasians within condition.
table 2 | Baseline characteristics by dietary intervention and ethnicity
DASH treatmentUsual control
Caucasian (n = 51) African Americans (n = 28)Caucasian (n = 24)African Americans (n = 15)
Mean s.d.Mean s.d.Mean s.d. Mean s.d.
Age (years)55.1 10.049.88.4 52.9 9.647.96.5
Gender (% female)
32.1 3.634.4*3.933.2 3.831.5 4.0
Daytime SBP (mm Hg)140.1 12.9 139.112.2147.411.7 143.712.5
Daytime DBP (mm Hg)83.7 8.3 84.5 9.985.9 6.987.6 10.1
Night-time SBP (mm Hg)
122.117.5 127.5 14.8 125.712.3125.7 17.0
Night-time DBP (mm Hg)71.2 9.574.210.0 72.3 8.175.9 11.3
Daytime/Night-time SBP ratio22.214.171.124* 0.071.180.111.150.11
Daytime/Night-time DBP ratio 126.96.36.199.091.20 0.12 1.170.13
% SBP nondipper
Na+ urinary excretion (mmol/24 h)
K+ urinary excretion (mmol/24 h)
Estimated GFR (ml/min per 1.73 m2)
29.4% 60.7%* 20.8%33.3%
95.3 45.0115.8 44.696.847.1 135.7* 35.7
37.312.136.0 17.034.211.439.4 13.6
76.712.2 86.6*17.080.4 12.684.511.1
BMI, body mass index; DASH, Dietary Approaches to Stop Hypertension; DBP, diastolic blood pressure; GFR, glomerular filtration rate; SBP, systolic blood pressure.
*P < 0.05 when compared to Caucasians within condition.
AMERICAN JOURNAL OF HYPERTENSION 5
DASH Diet and Blood Pressure
Consequently, at the end of 4 months of intervention with
the DASH diet, AAs were no longer significantly different
from CAs on this measure of nocturnal SBP dipping (F (1,
112) = 1.67, P = 0.20). Moreover, as a whole sample, differ-
ences in proportion of nondippers postintervention by ethnic-
ity were no longer statistically significant (44% of AAs vs. 32%
of CAs; χ2 (1) = 1.75, P = 0.19).
the role of BMi and 24-h urinary electrolyte excretion
It is possible that intervention-related changes in BMI, Na+,
and K+ excretion may account for the reduction of ethnic
differences in day/night SBP and proportion of nondippers
postintervention. Consistent with our prior report,22 the
DASH diet intervention was associated with a greater reduc-
tion in BMI relative to the UC group (F (1, 115) = 34.25, P <
0.001). However, when change in BMI was treated as a cov-
ariate in evaluating intervention-related changes in day/night
SBP ratio separately in AAs and CAs, AAs in the DASH inter-
vention continued to display a significant increase in day/
night SBP ratio compared to AAs in the UC condition (F (1,
36) = 4.34, P = 0.04).
Participants in the DASH diet intervention displayed
a greater reduction in 24-h urinary Na+ excretion (F (1,
115) = 12.00, P < 0.01) and a significant increase in 24-h uri-
nary K+ excretion (F (1, 115) = 3.83, P = 0.05) compared to UC
controls. However, when compared across conditions, AAs in
the DASH intervention showed little change in 24-h excretion
of Na+ (t (41) = 0.94, P = 0.35) and only a marginal increase
in K+ as compared to AAs in the UC control condition (t
(41) = 1.87, P = 0.07). Nevertheless, separate models were
computed to test whether change in Na+ or K+ accounted for
improvements in SBP dipping among AAs. In this regard, AAs
in the DASH intervention continued to display a significant
improvement in SBP dipping relative to AAs in the UC condi-
tion after adjustment for change in Na+ urinary excretion (F
(1, 39) = 4.12, P = 0.05). In contrast, when change in 24-h uri-
nary K+ excretion is included as a covariate, AAs randomized
to the DASH intervention no longer differed statistically from
AAs in the UC control (F (1, 39) = 2.99, P = 0.09).
A growing literature demonstrates AAs to be at substantially
greater risk for cardiovascular morbidity and mortality com-
pared to CAs.1–3 While the mechanisms underlying this dis-
parity have yet to be fully elucidated, ethnic differences in
nocturnal BP dipping may be an important contributory fac-
tor. In the present study, at preintervention baseline, noctur-
nal SBP dipping was significantly blunted in AAs relative to
CAs, a finding that is consistent with several cross-sectional
investigations.4,6,8,28,29 In exploratory subgroup analyses, this
study revealed that AAs randomized to the DASH interven-
tion, with or without caloric restriction, displayed marked
improvement in nocturnal SBP dipping relative to AAs in
the UC condition. In contrast, CA participants derived com-
paratively little intervention-related benefit in BP dipping.
Consequently, at postintervention ambulatory BP assess-
ments, AAs no longer differed from CAs with respect to noc-
turnal SBP dipping.
The efficacy of DASH diet in reducing clinic, 24-h ambulatory
BP, and mortality among patients with hypertension has been
demonstrated previously.20–22,30 However, few studies have
examined the effect of the DASH diet on nocturnal BP dipping.
In one such study, Moore et al.24 showed significant declines in
daytime and night-time SBP in a sample of healthy community
volunteers randomized to an 8-week combination diet (rich in
fruits and vegetables and low-fat dairy foods) vs. a control diet;
however, this study failed to detect a statistically significant
interaction between intervention and ethnicity. Interestingly,
in a subgroup analyses, minorities randomized to the combina-
tion intervention, 90% of whom were AA, displayed significant
declines in 24-h, daytime, and night-time BP compared to AAs
in the control condition. Conversely, CAs failed to show statis-
tically significant intervention-related changes in ambulatory
BP. Similarly, a sub-analysis of the original DASH diet feeding
trial has shown evidence of ethnicity moderating the BP low-
ering benefits associated with the DASH diet.31 In this regard,
AAs randomized to the DASH combination diet showed a
greater reduction in clinic SBP compared to CAs, an effect that
was most marked in participants with hypertension.31 In the
present study, we observed a trend for an intervention effect on
nocturnal BP dipping (P = 0.08). And while this study was not
powered to detect an interaction between ethnicity and inter-
vention condition, the fact that the sub-analyses revealed that
AAs randomized to the DASH intervention showed a greater
improvement in SBP dipping when compared to AAs in the
UC condition provides intriguing, albeit preliminary, evidence
that the DASH intervention may confer a particular benefit for
AAs. That said, interpretation of this modest, preliminary find-
ing should be made cautiously.
The mechanisms that give rise to ethnic differences in BP
dipping remain to be elucidated; however, environmental (e.g.,
socioeconomic disparities8), physiologic (e.g., elevated auto-
nomic activation32), and behavioral (e.g., sleep disturbance28)
factors appear to play a role. Dietary sodium and potassium
intake also may be important.33 In a prior report,22 we noted
that our DASH dietary intervention was associated with a
reduction in sodium intake and increase in potassium intake;
however, other DASH studies have failed to find this asso-
ciation.20 In the present study, relative to CAs, AAs displayed
greater baseline sodium intake, as assessed by 24-h urinary
excretion, which remained high at postintervention. Moreover,
change in sodium intake from baseline to postintervention did
not account for differences in SBP dipping between AAs in the
DASH intervention compared to those in the UC condition.
Conversely, change in potassium intake did attenuate observed
differences in intervention-related improvements in SBP dip-
ping among AAs. While evidence supporting a link between
potassium intake and BP dipping is limited, a prior study found
a positive correlation between the magnitude of decline in SBP
during sleep and urinary potassium excretion.13 Further inves-
tigation into the role of potassium in BP dipping, particularly
among overweight AAs with high BP is warranted.
6 AMERICAN JOURNAL OF HYPERTENSION
DASH Diet and Blood Pressure
The present findings should be interpreted in the context of
several limitations. First, the effects were modest and derived
from a relatively small sample of highly motivated participants.
Second, because this study was not designed to examine eth-
nic differences specifically, few AAs were randomized to the
DASH-WM condition. Consequently, we were unable to assess
the relative impact of DASH-A compared to DASH-WM on
BP dipping. The heterogeneity of the DASH condition in this
sub-analysis (DASH-A and DASH-WM) is particularly rele-
vant when considering differences in weight loss. As expected,
participants in the DASH intervention showed a greater
decrease in BMI relative to those in the UC; however, in sub-
group analyses, adjustment for change in BMI had little effect
on improvements observed in AAs in nocturnal SBP dipping.
In summary, this study replicates prior research showing
baseline ethnic disparities in nocturnal BP dipping, with AAs
evidencing blunted BP dipping compared to CAs with high
BP. This study also provides preliminary evidence suggesting
that the DASH diet intervention may improve SBP dipping in
overweight AAs with high BP, which in turn, lessens ethnic
differences in nocturnal BP dipping. Future research exploring
the mechanisms by which the DASH diet affects nocturnal BP
dipping in both CAs and AAs is warranted.
Acknowledgments: We thank Michael A. Babyak for statistical support in the
preparation of this manuscript.
Disclosure: The authors declared no conflict of interest.
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