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Corresponding author. Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, M5S 3E2, Canada. Tel.: +1 416 867 7475; fax: +1 416 867 7495.
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaDepartment of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaDivision of Endocrinology and Metabolism, St. Michael’s Hospital, Toronto, ON, CanadaLi Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, Canada
Clinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaFaculty of Medicine, University of Ottawa, Ottawa, ON, Canada
Clinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaFaculty of Medicine, University of Ottawa, Ottawa, ON, Canada
Clinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaFaculty of Medicine, University of Ottawa, Ottawa, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, Canada
Clinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaLi Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, ON, CanadaDepartment of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaDivision of Endocrinology and Metabolism, St. Michael’s Hospital, Toronto, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaDepartment of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaDivision of Endocrinology and Metabolism, St. Michael’s Hospital, Toronto, ON, CanadaLi Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, ON, Canada
Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaDivision of Endocrinology and Metabolism, St. Michael’s Hospital, Toronto, ON, CanadaLi Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, ON, Canada
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, CanadaClinical Nutrition & Risk Factor Modification Center, St. Michael’s Hospital, Toronto, ON, CanadaCollege of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada
The DASH diet has become generally accepted as a hypertension and cardiovascular risk reduction strategy.
•
The Dietary Portfolio, developed to lower LDL, also has food components that lower blood pressure (BP).
•
A previously published study of the Dietary Portfolio suggested the possibility for a BP lowering effect.
•
Thus we conducted a secondary analysis comparing a DASH (control) with a Portfolio (test) diet in relation to BP.
•
This study indicates that the Dietary Portfolio has BP and cardiovascular risk reduction potential.
Abstract
Background and aim
Compared to a DASH-type diet, an intensively applied dietary portfolio reduced diastolic blood pressure at 24 weeks as a secondary outcome in a previous study. Due to the importance of strategies to reduce blood pressure, we performed an exploratory analysis pooling data from intensively and routinely applied portfolio treatments from the same study to assess the effect over time on systolic, diastolic and mean arterial pressure (MAP), and the relation to sodium (Na+), potassium (K+), and portfolio components.
Methods and results
241 participants with hyperlipidemia, from four academic centers across Canada were randomized and completed either a DASH-type diet (control n = 82) or a dietary portfolio that included, soy protein, viscous fibers and nuts (n = 159) for 24 weeks. Fasting measures and 7-day food records were obtained at weeks 0, 12 and 24, with 24-h urines at weeks 0 and 24. The dietary portfolio reduced systolic, diastolic and mean arterial blood pressure compared to the control by 2.1 mm Hg (95% CI, 4.2 to −0.1 mm Hg) (p = 0.056), 1.8 mm Hg (CI, 3.2 to 0.4 mm Hg) (p = 0.013) and 1.9 mm Hg (CI, 3.4 to 0.4 mm Hg) (p = 0.015), respectively. Blood pressure reductions were small at 12 weeks and only reached significance at 24 weeks. Nuts, soy and viscous fiber all related negatively to change in mean arterial pressure (ρ = −0.15 to −0.17, p ≤ 0.016) as did urinary potassium (ρ = −0.25, p = 0.001), while the Na+/K+ ratio was positively associated (ρ = 0.20, p = 0.010).
Conclusions
Consumption of a cholesterol-lowering dietary portfolio also decreased blood pressure by comparison with a healthy DASH-type diet.
Group DA-SCR Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group.
] interest in using diet as the treatment for elevated blood pressure and have been the dietary approaches of choice for both hypertension and cardiovascular disease risk reduction [
An effective approach to high blood pressure control: a science advisory from the American Heart Association, the American College of Cardiology, and the Centers for Disease Control and Prevention.
2012 Update of the Canadian Cardiovascular Society guidelines for the diagnosis and treatment of dyslipidemia for the prevention of cardiovascular disease in the adult.
Statin-associated muscle symptoms: impact on statin therapy-European Atherosclerosis Society Consensus Panel Statement on Assessment, Aetiology and Management.
]. We have therefore undertaken an exploratory analysis of a previously published dietary portfolio study that focused on blood lipid changes and demonstrated a 13–14% reduction in LDL-C [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
]. That study also demonstrated a significant reduction in diastolic blood pressure on the intensive portfolio arm as a secondary outcome when compared to a DASH-type diet. The dietary portfolio promotes consumption of nuts, soy protein, plant sterols, and viscous fiber to lower serum cholesterol, but of these dietary components nuts, soy protein, and viscous fiber may also lower blood pressure [
]. In the present analysis we combined the intensively and less intensively applied dietary portfolio treatments to strengthen the power of the study. The data for these two treatments were combined since no significant differences were seen in changes in blood pressure, lipids or dietary compliance with key ingredients. We have added the 12 week data to allow the effect over time to be assessed and also added urinary measures of sodium and potassium, as indicators of dietary intake that may influence blood pressure. This diet was compared with the healthy DASH-type diet as a positive control.
Methods
This is a secondary analysis of a study with methods that have been reported previously in detail [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
]. The study complies with the Declaration of Helsinki, and was approved by the ethics committees of St. Michael's Hospital and the Universities of Laval, Toronto, Manitoba, British Columbia and the Natural Health Products Directorate at Health Canada. Participant written informed consent was obtained prior to starting the study.
Participants
241 participants with hyperlipidemia (93 men and 148 postmenopausal women), >20–85 years, were recruited from 4 centres across Canada. They completed both the original study and provided 7-day diet histories at the start and end of the study period (Supplemental Fig. 1) [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
]. Those with a history of cancer or a strong family history of cancer, cardiovascular disease, untreated hypertension (blood pressure 140/90 mm Hg or greater), diabetes, renal or liver disease, or currently on lipid lowering medications were excluded.
Study protocol
In brief, a randomized controlled parallel trial was conducted, involving 3 diets; intensive portfolio (monthly visits), routine portfolio and control (one 3 month visit for both), each for a duration of 24 weeks. Blood pressure was measured at each visit 3 times and the average recorded, using a digital blood pressure monitor (Omron HEM-907XL, Omron Healthcare Inc, Vernon Hills, Illinois). Twenty-four hour urine collections were made at 3 sites at the start and end of each treatment (n = 164).
Diets
Participants were counseled at each visit by dietitians to follow weight maintaining vegetarian diets during the 6 month study period. Each participant was given a 7 day study food checklist to follow [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
]. For both the intensive and routine dietary portfolio the recommended targets were: 9.8 g of viscous fibers per 1000 kcal diet, from barley, oats, psyllium, eggplant, and okra; 22.5 g of soy protein per 1000 kcal, from components of soy milk, tofu and soy meat analogs; 22.5 g of nuts per 1000 kcal; and 0.94 g of plant sterols per 1000 kcal from a margarine enriched with plant sterol esters [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
]. The control dietary intervention emphasized avoidance of the specified core portfolio dietary components above and recommended a lacto-ovo-vegetarian DASH-type diet that focused on low saturated fat, whole grain cereals with low fat dairy, fruit and vegetables, and a reduction in red meat and snack foods [
Effects of high vs low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial.
Adherence with the dietary interventions was estimated as mean daily intakes from 7-day diet histories. For the dietary portfolio adherence was assessed based on servings of soy protein foods, nuts, viscous fiber foods, and plant sterol margarine consumed, with each contributing 25% when taken at the recommended amount (Supplemental Table 1a). For the DASH-type diet, increased servings of fruit, vegetables and low fat dairy contributed positively to the score and servings of red meat and snack foods consumed contributed negatively to the score. The number of servings, expressed as a percentage (one serving = 7.75%) were used to assess adherence based on the average DASH servings of fruit, vegetables and low fat dairy, providing a total of 12.9 servings per 2000 kcal diet (100% adherence) as recommended in a recent publication (Supplemental Table 1b) [
Effects of high vs low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial.
Blood samples were analyzed in each centre's hospital or routine laboratory, and diets were analyzed using a program based on the US Department of Agriculture data [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
The results are expressed as means [95% confidence interval (CI)]. No significant differences were observed in the original report between the intensive and routine treatments in terms of dietary compliance, or changes in body weight, blood lipids or blood pressure [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
]. Therefore the two dietary portfolios were considered here as a single treatment with 241 participants completing the study. The primary outcome was change in mean arterial pressure from baseline to week 24 in the completers. This measure combines systolic and diastolic blood pressure in the ratio 1 SBP: 2 DBP. A repeated measures mixed-effects model, using compound symmetry covariance (PROC MIXED, SAS version 9.4), was used to estimate least squares mean within and between-treatment changes for all variables. The results are presented both with and without adjustment for changes in covariates including waist, BMI, age, sex, blood pressure medication and baseline values. C-reactive protein (CRP) values were log transformed to satisfy distributional assumptions. A sensitivity analysis was conducted using generalized estimating equations (PROC GENMOD) with an exchangeable correlation structure to validate the findings obtained from the mixed-effects model. The mixed models were also run excluding participants on blood pressure medications, as well as using all participants providing at least one post-randomization measure (intention-to-treat).
Complete dietary data were only available for week 0 and week 24. Change in dietary variables was expressed as percent kilocalories for macronutrients and milligrams/1000 kilocalories for micronutrients. Both baseline and change values of the three active dietary components assessed were found to be non-normally distributed (Shapiro–Wilk p < 0.005), as a large number of participants were consuming none of the components at baseline (nuts n = 39, soy protein foods n = 128, viscous fiber foods n = 34). Therefore, Spearman correlations (PROC CORR) were used to assess the relation between the dietary intake data and changes in blood pressure using the data from all the treatments. Urinary data were treated similarly.
The Framingham coronary heart disease and cardiovascular risk factor scores (FRS) were calculated using the variables of age, sex, systolic blood pressure, total cholesterol and HDL-C. The exclusion criteria accounted for diabetes status [
Dietary adherence, in terms of desired number of servings, was 48% on the dietary portfolio and 105% on the DASH-type control (Supplemental Table 1a–b) at week 24. A relative increase in fat intake was observed on the portfolio compared to the DASH-type control by 8% of total calories with a corresponding reduction in available carbohydrate (p < 0.0001), and related to increased nut intake. No change was seen in total protein intake, but a 30% (95% CI, 26–34%) (p < 0.0001) relative increase in vegetable protein as a proportion of total protein was observed in the portfolio group. Sodium intake remained constant but potassium was significantly higher on the control diet by 127 mg/d (CI, −242 to −12 mg/d) (p = 0.031). No difference was seen between the portfolio and control treatments in the change in body weight, BMI, or waist circumference (Table 1).
Table 1Anthropometric and serum measures of portfolio and control diets, and the between-treatment differences.
Pooled portfolio (N = 159)
DASH-type control (N = 82)
Portfolio minus DASH-type control
Baseline
Change
Baseline
Change
Difference
Pr > |t|
Adjusted‡
Pr > |t|
Weight (kg)
75 (73,77)
−1.9 (−2.4,−1.3)
*
76 (73,79)
−1.8 (−2.6,−1)
*
−0.1 (−1,0.9)
0.857
−0.1 (−0.1,0)
0.237
BMI (kg/m2)
27 (26,27)
−0.7 (−0.8,−0.5)
*
27 (26,28)
−0.7 (−0.9,−0.4)
*
0 (−0.3,0.3)
0.992
0 (−0.2,0.2)
0.838
Waist (cm)
90 (88,91)
−1 (−1.4,−0.5)
*
90 (88,93)
−1.3 (−1.9,−0.7)
*
0.4 (−0.4,1.1)
0.328
0.2 (−0.4,0.8)
0.472
TC (mmol/L)
6.5 (6.4,6.7)
−0.8 (−1.0,−0.7)
*
6.3 (6.2,6.5)
−0.2 (−0.3,0)
*
−0.7 (−0.9,−0.5)
<0.0001
−0.6 (−0.7,−0.4)
<0.0001
LDL-C (mmol/L)
4.5 (4.3,4.6)
−0.8 (−0.9,−0.7)
*
4.3 (4.1,4.4)
−0.2 (−0.3,0)
*
−0.6 (−0.8,−0.5)
<0.0001
−0.5 (−0.7,−0.4)
<0.0001
HDL (mmol/L)
1.4 (1.4,1.5)
0 (−0.1,0)
*
1.4 (1.3,1.5)
0 (−0.1,0)
0 (−0.1,0.1)
0.923
0 (−0.1,0)
0.831
TC:HDL
4.9 (4.7,5.1)
−0.5 (−0.6,−0.4)
*
4.8 (4.5,5)
0 (−0.2,0.1)
−0.5 (−0.7,−0.3)
<0.0001
−0.4 (−0.6,−0.3)
<0.0001
TG (mmol/L)
1.5 (1.4,1.6)
0 (−0.1,0.1)
1.5 (1.3,1.8)
0 (−0.1,0.1)
0 (−0.2,0.1)
0.808
0 (−0.2,0.1)
0.489
SBP (mm Hg)
120 (118, 122)
−2.5 (−3.7,−1.2)
*
118 (115, 121)
−0.4 (−2.1,1.4)
−2.1 (−4.2,0.1)
0.056
−2 (−4,0)
0.045
DBP (mm Hg)
73 (72,75)
−2.0 (−2.8,−1.2)
*
72 (70,74)
−0.2 (−1.4,0.9)
−1.8 (−3.2,−0.4)
0.013
−1.3 (−2.6,−0.1)
0.039
MAP (mm Hg)
89 (87,90)
−2.1 (−3.0,−1.3)
*
87 (85,89)
−0.3 (−1.5,1)
−1.9 (−3.4,−0.4)
0.015
−1.6 (−2.9,−0.2)
0.026
Apo-A1 (g/L)
1.6 (1.6,1.6)
0 (0,0)
1.6 (1.6,1.7)
0 (0,0)
0 (0,0)
0.926
0 (0,0)
0.988
Apo-B (g/L)
1.2 (1.2,1.3)
−0.2 (−0.2,−0.1)
*
1.2 (1.1,1.2)
0 (0,0)
−0.2 (−0.2,−0.1)
<0.0001
−0.1 (−0.2,−0.1)
<0.0001
CRP (mg/L)†
1.5 (1.3,1.8)
−0.2 (−1.0,0.5)
*
2.3 (1.1,3.4)
0.5 (−0.4,1.5)
−0.8 (−2.0,0.4)
0.007
−1.3 (−2.5,−0.2)
0.000
10 yr CHD Risk
8 (7.3,8.6)
−1.4 (−1.7,−1.1)
*
7.3 (6.4,8.2)
−0.2 (−0.6,0.2)
−1.2 (−1.7,−0.7)
<0.0001
−1 (−1.4,−0.6)
<0.0001
10 yr CVD Risk
9.9 (9.0,10.8)
−1.6 (−1.9,−1.2)
*
9.2 (8,10.4)
−0.2 (−0.7,0.3)
−1.4 (−2,−0.8)
<0.0001
−1.2 (−1.7,−0.7)
<0.0001
Data are presented as mean, confidence interval. Bold values indicate statistical significance.
All post intervention estimates are least squares means. Model is mixed with repeated measures, using compound symmetry as a covariance structure.
There was no significant difference in the number of people taking blood pressure medications by treatment (Fisher's exact test, p = 0.235). In the portfolio and control diet groups, 28 (18%) and 20 (24%) participants, respectively, were taking blood pressure medications. No changes were observed in use of blood pressure medications throughout the study. Using completer data from 12 to 24 weeks in the unadjusted model for the primary analysis; systolic, diastolic, and mean arterial pressure were reduced on the portfolio diet by 2.5 mm Hg (CI, 3.7 to 1.2 mm Hg) (p < 0.001), 2.0 mm Hg (CI, 2.8 to 1.2 mm Hg) (p < 0.001), and 2.1 mm Hg (CI, 3.0 to 1.3 mm Hg) (p < 0.001), respectively, (Fig. 1) with no significant changes on the control diet, resulting in relative reductions in blood pressure on the dietary portfolio: systolic 2.1 mm Hg (CI, 4.2 to −0.1 mm Hg) (p = 0.056); diastolic, 1.8 mm Hg (CI, 3.2 to 0.4 mm Hg) (p = 0.013); and mean arterial pressure, 1.9 mm Hg (CI, 3.4 to 0.4 mm Hg) (p = 0.015) (Table 1). A sensitivity analysis using generalized estimating equations for the reduction in systolic blood pressure values were significant at 2.1 mm Hg (CI, 4.1 to 0.1 mm Hg) (p = 0.040).
Figure 1Changes in systolic (A), diastolic (B), and mean arterial pressure (MAP) (C) in portfolio and control diets at weeks 0, 12, and 24. * represents significance at P<0.05.
After including baseline, waist circumference, BMI, age, sex, and blood pressure medication as covariates in the repeated measures (weeks 12 and 24) model, the significance of relative reductions were maintained (Table 1).
Using all available data from the original study participants (n = 345) showed similar treatment differences and significance levels to those reported for the completer data. The fully adjusted model showed reductions in systolic blood pressure, 1.3 mm Hg (CI, 2.5 to 0.2) p = 0.025, diastolic blood pressure, 0.9 mm Hg (CI, 1.7 to 0.2) p = 0.015, and mean arterial pressure 1.1 mm Hg (CI, 1.9 to 0.3) p = 0.01. Similarly, elimination of those on blood pressure medications also confirmed these treatment differences in blood pressure (reductions in systolic blood pressure, 2.6 mm Hg, (CI, 4.7 to 0.5) p = 0.009, diastolic blood pressure, 1.5 mm Hg, (CI, 2.9 to 0.2) p = 0.027, mean arterial pressure 1.9 mm Hg (CI, 3.3 to 0.5) p = 0.009).
Framingham cardiovascular risk score
A corresponding relative reduction was seen on the portfolio in 10-year cardiovascular risk scores for both coronary heart disease and cardiovascular disease 1.2% (CI, 1.7 to 0.7%, p < 0.001) and 1.4% (CI, 2.0 to 0.8%, p < 0.001) respectively. This risk reduction was in turn contributed to by the relative reduction in total cholesterol of 0.7 mmol/L (CI, 0.9 to 0.5 mmol/L) (p < 0.001) on the portfolio with no change in HDL-C. There were also corresponding reductions in both apolipoprotein-B [0.2 g/L (CI, 0.2 to 0.1 g/L), p < 0.001] and log CRP concentrations [0.3 mg/L (CI, 0.4 to 0.1 mg/L), log CRP p = 0.007] (Table 1). The servings of dietary portfolio foods were also related to reductions in CHD and CVD risk (Table 2).
Table 2Change in dietary variables versus change in blood pressure, CHD, and CVD risk.
Dietary variable
Systolic blood pressure (SBP)
Diastolic blood pressure (DBP)
Mean arterial pressure (MAP)
Coronary heart disease (CHD) risk
Cardiovascular disease (CVD) risk
ρ
p-value
ρ
p-value
ρ
p-value
ρ
p-value
ρ
p-value
Total calories (kcal)
0.04
0.56
−0.04
0.54
−0.01
0.94
−0.04
0.51
−0.02
0.81
Protein (%)
−0.09
0.19
0.02
0.79
−0.03
0.67
−0.08
0.24
−0.06
0.36
Soy protein (%)
−0.09
0.15
−0.19
0.003
−0.16
0.015
−0.31
<0.0001
−0.31
<0.0001
Fat (%)
−0.07
0.28
−0.10
0.14
−0.09
0.15
−0.25
0.000
−0.22
0.001
SFA (%)
0.10
0.11
0.12
0.07
0.12
0.06
0.16
0.014
0.18
0.005
MUFA (%)
−0.13
0.038
−0.14
0.025
−0.15
0.017
−0.27
<0.0001
−0.26
<0.0001
PUFA (%)
−0.14
0.030
−0.18
0.006
−0.18
0.006
−0.30
<0.0001
−0.30
<0.0001
Cholesterol (mg/1000 kcal)
0.04
0.58
0.11
0.10
0.08
0.24
0.14
0.026
0.16
0.012
Alcohol (%)
0.02
0.81
0.07
0.31
0.04
0.52
0.01
0.88
0.00
0.99
Net CHO (%)
0.10
0.11
0.08
0.24
0.10
0.11
0.27
<0.0001
0.25
<0.0001
Total fiber (g/1000 kcal)
−0.08
0.23
−0.15
0.016
−0.13
0.045
−0.19
0.004
0.21
0.001
Viscous fiber (g/1000 kcal)
−0.14
0.034
−0.17
0.010
−0.17
0.009
−0.33
<0.0001
−0.35
<0.0001
Nuts (g/1000 kcal)
−0.11
0.09
−0.16
0.011
−0.15
0.016
−0.31
<0.0001
−0.31
<0.0001
Plant sterols (g/1000 kcal)
−0.06
0.39
−0.12
0.07
−0.11
0.10
−0.21
0.001
−0.24
0.000
Na+ (mg/1000 kcal)
0.05
0.45
0.09
0.18
0.08
0.22
0.08
0.22
0.09
0.16
K+ (mg/1000 kcal)
−0.10
0.13
−0.03
0.61
0.07
0.31
0.04
0.58
−0.04
0.58
Na+/K+
0.14
0.032
0.10
0.14
0.12
0.06
0.06
0.36
0.11
0.09
Portfolio
Adherence
−0.11
0.08
−0.18
0.006
−0.16
0.011
−0.32
<0.0001
−0.34
<0.0001
DASH
Adherence
−0.08
0.24
−0.03
0.66
−0.05
0.44
0.09
0.16
0.05
0.46
Data presented are Spearman correlations. Bold values indicate statistical significance.
Key components of the dietary portfolio compared to DASH-type control
On the dietary portfolio treatment differences included relative increases in intake of nuts [17 g/1000 kcal/d (CI, 15–20 g/1000 kcal/d)], soy protein [3.4% (CI, 2.8–3.9%) equivalent to 13.6 g/1000 kcal/d], and viscous fibers [4.6 g/1000 kcal (CI, 3.8–5.3 g/1000 kcal)] compared to the control group (Supplemental Table 3).
Using spearman correlations, and pooling test and control treatments, change in dietary portfolio adherence was related significantly to change in diastolic (ρ = −0.18, p = 0.006) and mean arterial pressure (ρ = −0.16, p = 0.011). No significant associations were seen with DASH adherence. Change in all three key dietary portfolio components were also significantly related to reductions in mean arterial pressure: nuts (ρ = −0.15, p = 0.016), soy (ρ = −0.16, p = 0.015), and viscous fiber (ρ = −0.17, p = 0.009), similar associations were seen for systolic and diastolic blood pressures (Table 2). Among participants on the DASH-type control diet, no significant correlations were seen between portfolio adherence and blood pressure outcomes; however, DASH adherence showed significant negative correlations with systolic (ρ = −0.35, P = 0.001), diastolic (ρ = −0.24, P = 0.033) and mean arterial pressure (ρ = −0.30, P = 0.005). No associations were seen between adherence to either diet and blood pressure amongst participants on the dietary portfolio diet (Supplemental Table 4).
Dietary Na+, K+, and Na+/K+ ratio
Treatment differences included a relative reduction in dietary potassium on the portfolio due to an absolute increase in dietary potassium intake on the control diet [127 mg/1000 kcals (CI, −242 to −12 mg/1000 kcals), p = 0.031] with no changes in dietary sodium. Further there was no association between the change in dietary potassium, sodium, or the sodium to potassium ratio with any blood pressure measure. However baseline dietary potassium and the Na+/K+ ratios, but not sodium, were significantly related to baseline mean arterial pressure (ρ = −0.19, n = 241, p = 0.004, and ρ = 0.19, n = 241, p = 0.004; and ρ = 0.08, n = 241, p = 0.195) respectively. Similar associations were seen for systolic and diastolic blood pressure.
Urine Na+ and K+: relation to diet and blood pressure
Creatinine adjusted urinary potassium output increased on the DASH-type control relative to the portfolio [0.9 (CI 1.6 to 0.2) p = 0.016] in keeping with the dietary increase (Supplementary Table 3). As anticipated urinary measures were significantly correlated with dietary measures: sodium (baseline ρ = 0.29, p < 0.001), potassium (baseline ρ = 0.42, week 24 ρ = 0.45, and change ρ = 0.33, all p < 0.001), as well as dietary protein intake compared to urinary urea output (baseline ρ = 0.27, p < 0.001, and change ρ = 0.17 p = 0.028).
However unlike the dietary measures, urinary changes in potassium correlated inversely with changes in systolic (ρ = −0.25, p = 0.001), diastolic (ρ = −0.23, p = 0.004), and mean arterial pressure (ρ = −0.25, p = 0.001); while the Na+/K+ ratio related positively to changes in: systolic (ρ = 0.21, p = 0.007), diastolic (ρ = 0.17, p = 0.026), and mean arterial pressure (ρ = 0.20, p = 0.010). Changes in urinary sodium did not relate to changes in blood pressure, possibly due to the lack of significant change in dietary sodium intake and urinary sodium output.
Discussion
This exploratory analysis indicated that consumption of the dietary portfolio lowers blood pressure when compared with a healthy DASH-type diet emphasizing low fat dairy, fruit and vegetables, whole grains, reduced meat intake and elimination of snack foods. The modest effect at 2 mm Hg was therefore in addition to what would be expected from DASH-type diets that have produced 10 mm Hg blood pressure reductions in study participants with an initial mean systolic blood pressure of 130 mm Hg [
Effects of high vs low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial.
]. This blood pressure reduction, combined with the effect of the dietary portfolio in the blood lipid profile, resulted in a significant reduction in the cardiovascular disease risk score. Despite excellent compliance of over 100%, the DASH-type diet nevertheless failed to reduce blood pressure probably because the baseline therapeutic diet of the participants already had many of the DASH diet features (already over 60% compliance) and blood pressure was already low at 119/73 mm Hg. Nevertheless increased compliance to the DASH diet components on the control was still associated with reduced blood pressure.
For cardiovascular risk reduction, the Canadian Cardiovascular Society has promoted use of the DASH and Mediterranean diets, as well as the dietary portfolio, also recommended for statin intolerance by the European Atherosclerosis Society, based on its cholesterol lowering potential. The American Heart Association/American College of Cardiology guidelines recommend the DASH diet [
2012 Update of the Canadian Cardiovascular Society guidelines for the diagnosis and treatment of dyslipidemia for the prevention of cardiovascular disease in the adult.
Statin-associated muscle symptoms: impact on statin therapy-European Atherosclerosis Society Consensus Panel Statement on Assessment, Aetiology and Management.
2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
]. The present study demonstrates a blood pressure advantage of increasing vegetable fat and protein, in keeping with blood pressure and cardiovascular advantages from other studies [
Effects of high vs low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial.
Consumption of 30 g of mixed nuts (walnuts, almonds and hazelnuts) as part of a Mediterranean diet was associated with a significant 0.65 mm Hg reduction in diastolic blood pressure possibly related to the monounsaturated fat content [
]. The mean nut intake in the present study was ∼36 g/d. Similarly soy protein has been shown in a number of studies and through a meta-analysis to lower blood pressure [
Konjac-mannan (glucomannan) improves glycemia and other associated risk factors for coronary heart disease in type 2 diabetes. A randomized controlled metabolic trial.
Group DA-SCR Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group.
2014 Dietary salt fact sheet of the World Hypertension League, International Society of Hypertension, Pan American Health Organization Technical Advisory Group on Cardiovascular Disease Prevention through Dietary Salt Reduction, the World Health Organization Collaborating Centre on Population Salt Reduction, and World Action on Salt & Health.
Committee on the Consequences of Sodium Reduction in P, Food, nutrition B, board on Population H, Public health P and Institute of M.
in: Strom B.L. Yaktine A.L. Oria M. Sodium intake in populations: assessment of evidence. National Academies Press (US) Copyright 2013 by the National Academy of Sciences. All rights reserved.,
Washington (DC)2013
]. Our data pose the question of whether foods that have both blood pressure and lipid lowering properties could be permitted to contain more salt to improve palatability than less cardiovascular protective foods. Thus, the present dietary portfolio that reduced systolic blood pressure by 2.5 mm Hg across the dietary period, also reduced total-cholesterol:HDL-C by 10–11% providing a reduction in CVD Framingham risk score of 1.6% per 10 years. Addition of an extra 500 mg of sodium to that diet would be predicted to increase systolic blood pressure by only 1.22 mm Hg [
Group DA-SCR Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group.
] but would lessen the reduction in the FRS by only 0.2% still leaving a benefit of 1.4% reduced CVD risk per 10 years.
The study weakness includes the fact that blood pressure was not the primary outcome; the present analysis was therefore a secondary, exploratory analysis with all the limitations that post hoc analyses involve. 24-hour ambulatory blood pressure may have provided a better reflection of the effect of the dietary interventions [
]. In addition baseline blood pressure was low at 119/73 mm Hg making further reductions difficult and thus likely underestimating the true blood pressure lowering effect [
Group DA-SCR Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group.
]. Good adherence to a DASH-type diet at baseline (65–68%) further limited demonstration of blood pressure lowering of both portfolio and DASH-type control treatments and illustrated the ease of compliance with the DASH diet. The dietary portfolio was only complied with by 48%, which limits the effect that could potentially be expected. Nevertheless, 14% LDL-C reduction was still observed at this compliance level [
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
]. The colinearity of the active ingredients by the design of the diets made it difficult to undertake multiple regression. The sodium effect could have been explored with two levels of sodium intake as was demonstrated in the DASH diet [
Group DA-SCR Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group.
The strength of the study was the demonstration in centres across the continent that healthy food components may create diets that address many risks factors, including blood pressure, blood lipids, and inflammatory biomarkers as part of a broad based cardiovascular disease risk reduction strategy.
We conclude that a dietary portfolio emphasizing cholesterol lowering foods also reduces blood pressure. Overall, plant based diets, notably the PREDIMED diet, emphasizing foods higher in protein, oil, and fiber have been associated with reduced cardiovascular disease and stroke [
] further supporting the use of plant foods for the reduction of blood pressure. Future studies could usefully compare the effects of the dietary portfolio with the DASH diet in moderately hypertensive participants with blood pressure as the primary outcome.
Funding
This work was supported by the CRCE of the Federal Government of Canada (Drs Jenkins, Jones, and Lamarche), Canadian Institutes for Health Research, Advanced Foods & Materials Canada Net, Loblaw Brands Ltd, Solae (St. Louis, Missouri), and Unilever (Vlaardingen, the Netherlands, and Toronto, Ontario, Canada). Unilever Research and Development provided the donation of margarines used in the study and Can-Oat Milling, a division of Viterra Inc (Portage la Prairie, Manitoba, Canada), provided the generous donation of HiFi medium oat bran used for the study breads and funding for freezer acquisition. St. Michael's Hospital Foundation provided funding for the production of the study booklet. Funding organizations and sponsors played no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; or the preparation, review, or approval of the manuscript.
Conflicts of interest
D.J.A.J. has received research grants from Saskatchewan Pulse Growers, the Agricultural Bioproducts Innovation Program through the Pulse Research Network, the Advanced Foods and Material Network, Loblaw Companies Ltd., Unilever, Barilla, the Almond Board of California, Agriculture and Agri-food Canada, Pulse Canada, Kellogg's Company, Canada, Quaker Oats, Canada, Procter & Gamble Technical Centre Ltd., Bayer Consumer Care, Springfield, NJ, Pepsi/Quaker, International Nut & Dried Fruit (INC), Soy Foods Association of North America, the Coca-Cola Company (investigator initiated, unrestricted grant), Solae, Haine Celestial, the Sanitarium Company, Orafti, the International Tree Nut Council Nutrition Research and Education Foundation, the Peanut Institute, the Canola and Flax Councils of Canada, the CCC, the CIHR, the Canada Foundation for Innovation and the Ontario Research Fund. He has been on the speaker's panel, served on the scientific advisory board and/or received travel support and/or honoraria from the Almond Board of California, Canadian Agriculture Policy Institute, Loblaw Companies Ltd, the Griffin Hospital for the development of the NuVal scoring system, the Coca-Cola Company, EPICURE, Danone, Saskatchewan Pulse Growers, Sanitarium Company, Orafti, the Almond Board of California, the American Peanut Council, the International Tree Nut Council Nutrition Research and Education Foundation, the Peanut Institute, Herbalife International, Pacific Health Laboratories, Nutritional Fundamental for Health, Barilla, Metagenics, Bayer Consumer Care, Unilever Canada and Netherlands, Solae, Kellogg, Quaker Oats, Procter & Gamble, the Coca-Cola Company, the Griffin Hospital, Abbott Laboratories, the Canola Council of Canada, Dean Foods, the California Strawberry Commission, Haine Celestial, PepsiCo, the Alpro Foundation, Pioneer Hi-Bred International, DuPont Nutrition and Health, Spherix Consulting and WhiteWave Foods, the Advanced Foods and Material Network, the Canola and Flax Councils of Canada, the Nutritional Fundamentals for Health, Agri-Culture and Agri-Food Canada, the Canadian Agri-Food Policy Institute, Pulse Canada, the Saskatchewan Pulse Growers, the Soy Foods Association of North America, the Nutrition Foundation of Italy (NFI), Nutra-Source Diagnostics, the McDougall Program, the Toronto Knowledge Translation Group (St. Michael's Hospital), the Canadian College of Naturopathic Medicine, The Hospital for Sick Children, the Canadian Nutrition Society (CNS), the American Society of Nutrition (ASN), Arizona State University, Paolo Sorbini Foundation and the Institute of Nutrition, Metabolism and Diabetes. He received an honorarium from the US Department of Agriculture to present the 2013 W.O. Atwater Memorial Lecture. He received the 2013 Award for Excellence in Research from the International Nut and Dried Fruit Council. He received funding and travel support from the Canadian Society of Endocrinology and Metabolism to produce mini cases for the CDA. He is a member of the ICQC. D.J.A.J's wife is a director and partner of Glycemic Index Laboratories, Toronto, Ontario, Canada, and his sister received funding from the St. Michael's Hospital Foundation to develop a dietary portfolio cookbook. His two daughters have two portfolio books planned.
C.W.C.K. has received honoraria from the Almond Board of California, the International Tree Nut Council Nutrition Research & Education Foundation, Barilla, and Unilever Canada. C.W.C.K. has been on the speaker's panel for the Almond Board of California; and has received research grants from Loblaws, Unilever, Barilla, and the Almond Board of California. B.L. and P.C, have received research grants from the Dairy Farmers of Canada, Dairy Australia. B.L. has received research funding from the Danone Institute, Agri- Food and Agriculture Cluster on Canola in partnership with the Canola Council of Canada, Flax 2015, Dow Agro- Sciences, and Atrium Innovations and honoraria from Unilever, Danone, and the Dairy Farmers of Canada. B.L. is Chair in Nutrition and Cardiovascular Health, supported in part by Provigo/Loblaws. S.K.N. has received research support from the Canadian Institutes of Health Research (CIHR), Ontario Graduate Scholarship (OGS), and the Canadian Foundation for Dietetic Research for work on clinical trials assessing the effect of nut intake on health outcomes. S.K.N. is also a clinical research dietitian at Glycemic Index Laboratories, Inc. R.S. is funded by a CIHR Postdoctoral Fellowship Award and has received research support from the CIHR, the Calorie Control Council, the Canadian Foundation for Dietetic Research and the Coca-Cola Company (investigator initiated, unrestricted grant). R.S. has served as an external resource person to WHO's Nutrition Guidelines Advisory Group and received travel support from WHO to attend group meetings. J.L.S. has received research support from the Calorie Control Council, the Coca-Cola Company (investigator initiated, unrestricted grant), Pulse Canada, and the International Tree Nut Council Nutrition Research and Education Foundation. J.L.S. has received travel funding, speaker fees or honoraria from the American Heart Association, the American Society for Nutrition, the National Institute of Diabetes and Digestive and Kidney Diseases, the Canadian Diabetes Association, the Canadian Nutrition Society, the Calorie Control Council, the Diabetes and Nutrition Study Group of the European Association for the Study of Diabetes, the International Life Sciences Institute North America, the International Life Sciences Institute Brazil, the University of South Carolina, the University of Alabama at Birmingham, the Canadian Sugar Institute, Oldways Preservation Trust, the Nutrition Foundation of Italy, Abbott Laboratories, Pulse Canada, Dr. Pepper Snapple Group and the Coca-Cola Company. J.L.S. is on the Clinical Practice Guidelines Expert Committee for Nutrition Therapy of both the Canadian Diabetes Association and the European Association for the Study of Diabetes, and he is on the American Society for Nutrition writing panel for a scientific statement on the metabolic and nutritional effects of fructose, sucrose and high-fructose corn syrup. J.L.S. is a member of the Carbohydrate Quality Consortium and an unpaid scientific advisor for the Food, Nutrition and Safety Program of the International Life Science Institute North America. His wife is an employee of Unilever Canada. No competing interests were declared by CI, KS, PG, CP, DF, AM, VHJ, LSA, BB, RJ, PC, VR, JF, and LL.
Appendix A. Supplementary data
The following are the supplementary data related to this article:
Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group.
An effective approach to high blood pressure control: a science advisory from the American Heart Association, the American College of Cardiology, and the Centers for Disease Control and Prevention.
2012 Update of the Canadian Cardiovascular Society guidelines for the diagnosis and treatment of dyslipidemia for the prevention of cardiovascular disease in the adult.
Statin-associated muscle symptoms: impact on statin therapy-European Atherosclerosis Society Consensus Panel Statement on Assessment, Aetiology and Management.
Effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary advice on serum lipids in hyperlipidemia: a randomized controlled trial.
Effects of high vs low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial.
2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines.
Konjac-mannan (glucomannan) improves glycemia and other associated risk factors for coronary heart disease in type 2 diabetes. A randomized controlled metabolic trial.
2014 Dietary salt fact sheet of the World Hypertension League, International Society of Hypertension, Pan American Health Organization Technical Advisory Group on Cardiovascular Disease Prevention through Dietary Salt Reduction, the World Health Organization Collaborating Centre on Population Salt Reduction, and World Action on Salt & Health.
Committee on the Consequences of Sodium Reduction in P, Food, nutrition B, board on Population H, Public health P and Institute of M.
in: Strom B.L. Yaktine A.L. Oria M. Sodium intake in populations: assessment of evidence. National Academies Press (US) Copyright 2013 by the National Academy of Sciences. All rights reserved.,
Washington (DC)2013
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