Study analysis · Journal of Human Hypertension · 2020
The DASH diet lowered blood pressure by about 5.5 mm Hg—but the benefit depended on time of day and sex.
In people with slightly high blood pressure, eating DASH or more fruits and veggies for 8 weeks lowered blood pressure, and DASH helped women's nighttime blood pressure more.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study looked at existing data from a diet and blood pressure study to see if different diets changed blood pressure patterns over the day. Because we don't know if people were randomly assigned to diets, we can't say the diets definitely caused the changes—only that they were linked to changes. So it's like noticing that people who ate certain foods had different blood pressure, but we can't prove the food was the reason.
What’s the bottom line?
Researchers looked at blood pressure data from a study where people ate either a control diet, a fruits-and-vegetables diet, or the DASH diet for 8 weeks. Both healthy diets lowered blood pressure compared with the control diet. The drop depended on time of day and was different for men and women.
How strong is this study?
The study used a decent number of people and measured blood pressure over 24 hours, which is good. But we only have a short summary, so we don't know important details like whether people were randomly put into diet groups or if anyone knew which diet they were on. That means we should be cautious about trusting the results too much.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
52 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=338)+16.3/20
- Follow-up+10/10
100 / 100
0 / 100
- P-valuesno p-values reported
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 538 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design cannot establish causation — the findings describe an association, not a cause. Randomization status is unknown; the abstract does not explicitly state randomized allocation. This is a secondary analysis of existing data, which cannot control for unmeasured confounding. Without full methodology, causal inference is not warranted.
COI Unknown
Could not determine conflict of interest status
No conflicts of interest or funding information were disclosed in the provided text; therefore, COI status cannot be determined.
The provided text is an abstract and lacks a conflict of interest or funding statement. No author affiliations or disclosures are present. Therefore, COI severity cannot be fully assessed; no industry funding is evident from the text.
Key takeaways
- 01
The DASH diet lowered systolic blood pressure by about 5.5 mm Hg (absolute) compared with control.
- 02
From reported averages, DASH lowered systolic BP by about 4.7 mm Hg and diastolic by about 2.7 mm Hg; fruits-and-vegetables lowered systolic by about 3.6 mm Hg and diastolic by about 2.3 mm Hg; control had no change.
- 03
Nighttime BP dropped more with DASH than fruits-and-vegetables in women, but not men.
- 04
People with higher starting BP had larger drops.
- 05
These are absolute differences in blood pressure (mm Hg), not relative risks.
- 06
A 5.5 mm Hg lower systolic BP is a modest but meaningful shift.
- 07
The study did not report absolute risk reductions for heart attacks or strokes, so we cannot say how many events were prevented.
- 08
Benefits may vary by time of day and sex.
Practical takeaways
If you have high-normal to mildly elevated blood pressure, a DASH-style or fruits-and-vegetables-rich diet may help lower BP over about 8 weeks; the abstract notes that when detected early, a dietary approach may be preferred to medication.
This is based on an abstract-only summary. Randomization, blinding, p-values, confidence intervals, and full methodology were not available. It is not medical advice; talk to a clinician before changing treatment.
low confidenceAsk your clinician whether longer ambulatory blood pressure monitoring—longer than 24 hours—might be useful, because the study recommends monitoring BP around the clock due to day-to-day variability.
The recommendation comes from the abstract, but access, cost, and clinical appropriateness vary. Full details of the monitoring protocol were not available.
low confidenceConsider that dietary effects on blood pressure may depend on time of day, sex, and baseline BP, so a personalized approach may be more useful than a one-size-fits-all plan.
The abstract reports sex and circadian differences but does not provide effect sizes, p-values, or full methods. These findings need confirmation with full-text data.
low confidenceWhy this study matters
Both DASH and fruits-and-veggies diets lowered blood pressure
In a re-analysis of the DASH feeding study, 338 adults with high-normal to mildly elevated blood pressure followed control, fruits-and-vegetables (FV), or DASH diets for 8 weeks. The control diet showed no change (131.2/83.5 to 131.0/83.6 mm Hg). FV lowered BP from 132.6/84.4 to 129.0/82.1 mm Hg (about -3.6/-2.3 mm Hg absolute). DASH lowered BP from 131.9/83.6 to 127.2/80.9 mm Hg (about -4.7/-2.7 mm Hg absolute). DASH was associated with about a 5.5 mm Hg absolute systolic reduction compared with control.
A 5.5 mm Hg lower systolic BP is a modest but meaningful shift—similar to what some lifestyle changes aim for. It suggests food patterns can move the needle for people whose BP is not yet in the hypertension range.
Timing and sex change the blood pressure story
The abstract states the decrease in BP was circadian stage-dependent and differed between men and women. Nighttime BP decreased more with DASH than with FV, and this difference was observed in women but not in men. The FV and DASH diets also had different effects on blood pressure variability (BPV).
It challenges the idea that any healthy diet works the same for everyone at every hour. Nighttime blood pressure is clinically important, and sex-specific differences could influence personalized advice.
Higher baseline BP predicted larger reductions
Study participants who had a higher BP during the reference stage were more likely to decrease their BP to a larger extent after the 8-week dietary intervention. The abstract does not report exact correlation numbers or p-values.
This suggests the people who need BP lowering most may respond most to dietary changes, which is a hopeful and motivating message.
Blood pressure variability matters—and may need longer monitoring
FV and DASH had different effects on blood pressure variability. The abstract recommends monitoring BP around the clock for longer than 24 hours and individualizing dietary or other interventions because of large day-to-day variability in both normotensive and hypertensive people.
A single clinic reading can miss important patterns. This points toward more personalized and continuous blood pressure tracking.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Researchers looked at blood pressure data from a study where people ate either a control diet, a fruits-and-vegetables diet, or the DASH diet for 8 weeks. Both healthy diets lowered blood pressure compared with the control diet. The drop depended on time of day and was different for men and women.
Research results
The DASH diet lowered systolic blood pressure by about 5.5 mm Hg (absolute) compared with control. From reported averages, DASH lowered systolic BP by about 4.7 mm Hg and diastolic by about 2.7 mm Hg; fruits-and-vegetables lowered systolic by about 3.6 mm Hg and diastolic by about 2.3 mm Hg; control had no change. Nighttime BP dropped more with DASH than fruits-and-vegetables in women, but not men. People with higher starting BP had larger drops.
What this means - more context
These are absolute differences in blood pressure (mm Hg), not relative risks. A 5.5 mm Hg lower systolic BP is a modest but meaningful shift. The study did not report absolute risk reductions for heart attacks or strokes, so we cannot say how many events were prevented. Benefits may vary by time of day and sex.
To compare the effect of three diets (control, fruits-and-vegetables, DASH) on the circadian rhythm of blood pressure using ambulatory BP monitoring data from the DASH study re-analyzed chronobiologically.
In adults with high-normal to mildly elevated blood pressure, both fruits-and-vegetables (FV) and DASH diets were associated with absolute reductions in systolic and diastolic BP over 8 weeks compared with a control diet that showed no change. DASH lowered systolic BP by about 5.5 mm Hg (absolute) compared with control. The decrease was circadian stage-dependent and differed by sex; nighttime BP decreased more with DASH than FV in women but not men. Higher baseline BP predicted larger reductions. FV and DASH had different effects on blood pressure variability.
Methods Used
Re-analysis of ambulatory BP monitoring data from the DASH randomized controlled feeding study. Participants followed control (N=112), fruits-and-vegetables (N=113), or DASH (N=113) diets for 8 weeks. Chronobiologic/cosinor analysis was used. Methodology details not fully available in abstract.
Main Finding
Both FV and DASH diets lowered BP compared with control. DASH lowered systolic BP by about 5.5 mm Hg (absolute) compared with control; reported mean changes were DASH: about −4.7/−2.7 mm Hg, FV: about −3.6/−2.3 mm Hg, control: no change. The decrease was circadian stage-dependent and differed between men and women. Nighttime BP decreased more with DASH than FV in women but not men. Higher baseline BP predicted larger reductions. Effects on BPV differed. Absolute risk not applicable (continuous BP outcome); no relative risks reported.
Confidence Level
Limited - based on abstract only, full methodology not available. No p-values, confidence intervals, or randomization/blinding details in abstract; re-analysis of RCT data.
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •Abstract-only summary; no p-values, confidence intervals, or effect sizes beyond BP means
- •Randomization and blinding not specified in abstract
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Practical Takeaways
If you have high-normal to mildly elevated blood pressure, a DASH-style or fruits-and-vegetables-rich diet may help lower BP over about 8 weeks; the abstract notes that when detected early, a dietary approach may be preferred to medication.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 538 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Lower probability
on the GRADE evidence scale
This study looked at existing data from a diet and blood pressure study to see if different diets changed blood pressure patterns over the day. Because we don't know if people were randomly assigned to diets, we can't say the diets definitely caused the changes—only that they were linked to changes. So it's like noticing that people who ate certain foods had different blood pressure, but we can't prove the food was the reason.
Strengths
- Controlled design with a control diet group
- Relatively large sample size (N=338)
- Ambulatory blood pressure monitoring (ABPM) used
Weaknesses
- Full methodology not available - based on abstract only
- Randomization status not explicitly stated - cannot confirm RCT design
- Blinding status unknown
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Researchers looked at blood pressure data from a study where people ate either a control diet, a fruits-and-vegetables diet, or the DASH diet for 8 weeks. Both healthy diets lowered blood pressure compared with the control diet. The drop depended on time of day and was different for men and women.
Research results
The DASH diet lowered systolic blood pressure by about 5.5 mm Hg (absolute) compared with control. From reported averages, DASH lowered systolic BP by about 4.7 mm Hg and diastolic by about 2.7 mm Hg; fruits-and-vegetables lowered systolic by about 3.6 mm Hg and diastolic by about 2.3 mm Hg; control had no change. Nighttime BP dropped more with DASH than fruits-and-vegetables in women, but not men. People with higher starting BP had larger drops.
What this means - more context
These are absolute differences in blood pressure (mm Hg), not relative risks. A 5.5 mm Hg lower systolic BP is a modest but meaningful shift. The study did not report absolute risk reductions for heart attacks or strokes, so we cannot say how many events were prevented. Benefits may vary by time of day and sex.
To compare the effect of three diets (control, fruits-and-vegetables, DASH) on the circadian rhythm of blood pressure using ambulatory BP monitoring data from the DASH study re-analyzed chronobiologically.
In adults with high-normal to mildly elevated blood pressure, both fruits-and-vegetables (FV) and DASH diets were associated with absolute reductions in systolic and diastolic BP over 8 weeks compared with a control diet that showed no change. DASH lowered systolic BP by about 5.5 mm Hg (absolute) compared with control. The decrease was circadian stage-dependent and differed by sex; nighttime BP decreased more with DASH than FV in women but not men. Higher baseline BP predicted larger reductions. FV and DASH had different effects on blood pressure variability.
Methods Used
Re-analysis of ambulatory BP monitoring data from the DASH randomized controlled feeding study. Participants followed control (N=112), fruits-and-vegetables (N=113), or DASH (N=113) diets for 8 weeks. Chronobiologic/cosinor analysis was used. Methodology details not fully available in abstract.
Main Finding
Both FV and DASH diets lowered BP compared with control. DASH lowered systolic BP by about 5.5 mm Hg (absolute) compared with control; reported mean changes were DASH: about −4.7/−2.7 mm Hg, FV: about −3.6/−2.3 mm Hg, control: no change. The decrease was circadian stage-dependent and differed between men and women. Nighttime BP decreased more with DASH than FV in women but not men. Higher baseline BP predicted larger reductions. Effects on BPV differed. Absolute risk not applicable (continuous BP outcome); no relative risks reported.
Confidence Level
Limited - based on abstract only, full methodology not available. No p-values, confidence intervals, or randomization/blinding details in abstract; re-analysis of RCT data.
Study Flags
Red Flags
- •Full text not available - methodology details cannot be verified
- •Abstract-only summary; no p-values, confidence intervals, or effect sizes beyond BP means
- •Randomization and blinding not specified in abstract
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Practical Takeaways
If you have high-normal to mildly elevated blood pressure, a DASH-style or fruits-and-vegetables-rich diet may help lower BP over about 8 weeks; the abstract notes that when detected early, a dietary approach may be preferred to medication.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 538 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Human RCT
Subject
Lower probability
on the GRADE evidence scale
This study looked at existing data from a diet and blood pressure study to see if different diets changed blood pressure patterns over the day. Because we don't know if people were randomly assigned to diets, we can't say the diets definitely caused the changes—only that they were linked to changes. So it's like noticing that people who ate certain foods had different blood pressure, but we can't prove the food was the reason.
Strengths
- Controlled design with a control diet group
- Relatively large sample size (N=338)
- Ambulatory blood pressure monitoring (ABPM) used
Weaknesses
- Full methodology not available - based on abstract only
- Randomization status not explicitly stated - cannot confirm RCT design
- Blinding status unknown
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
The study used a decent number of people and measured blood pressure over 24 hours, which is good. But we only have a short summary, so we don't know important details like whether people were randomly put into diet groups or if anyone knew which diet they were on. That means we should be cautious about trusting the results too much.
0 / 100
- COI disclosureconflicts of interest not disclosed
- Data availabilitydata not shared
- Code availabilitycode not shared
52 / 100
- Randomizationrandomization unclear
- Blindingblinding unclear
- Control group+15/15
- Sample size (n=338)+16.3/20
- Follow-up+10/10
100 / 100
0 / 100
- P-valuesno p-values reported
- Effect sizeno effect size reported
- Confidence intervalsno confidence intervals
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 538 / 100
Probability of being correct
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
This design cannot establish causation — the findings describe an association, not a cause. Randomization status is unknown; the abstract does not explicitly state randomized allocation. This is a secondary analysis of existing data, which cannot control for unmeasured confounding. Without full methodology, causal inference is not warranted.
COI Unknown
Could not determine conflict of interest status
No conflicts of interest or funding information were disclosed in the provided text; therefore, COI status cannot be determined.
The provided text is an abstract and lacks a conflict of interest or funding statement. No author affiliations or disclosures are present. Therefore, COI severity cannot be fully assessed; no industry funding is evident from the text.
Standing
Who’s using this study?
The videos and claims on this site that lean on this study, and the researchers who wrote it.
1 video from Dr Brad Stanfield cite this study, drawing 1 claim from it.
- Very strong evidence
Randomized or controlled trials support this claim, alongside consistent supporting evidence.
Evidence
Authored by
2 researchersIf this is your work, this is how we attribute it on Fit Body Science. Fatimatou Saka is listed as the lead author.