High-nitrate vegetable diet increases plasma nitrate and nitrite concentrations and reduces blood pressure in healthy women

Probably not a substantial claim: may not pass S3 (load-bearing).

Participants on the high-nitrate diet consumed a mean raw weight of 180 (SD 75) g of high-nitrate vegetables and salad daily, equivalent to approximately two 80 g portions.

“Participants on the HN diet consumed a mean raw weight of 180 (SD 75) g of HN vegetables and salad daily, equivalent to approximately two 80 g portions.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Baseline SBP and DBP of the participants were in line with current mean UK population levels for 16-24-year-old women (110 mmHg and 66 mmHg, respectively).

“Baseline SBP and DBP were in line with current mean UK population levels in 16-24-year-old women of 110 mmHg and 66 mmHg, respectively (33) .”

• cites [33]Not checked yet

  Not checked in the free run.

May combine two claims.

In our study, the HN diet resulted in a significant reduction in SBP but not DBP.

“whereas our study resulted in a significant reduction in SBP but not DBP.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The laboratory technician who carried out the analysis of plasma nitrate and nitrite concentrations was blinded to the test conditions.

“The laboratory technician who carried out the analysis of plasma nitrate and nitrite concentrations was blinded to the test conditions.”

Probably not a substantial claim: may not pass S3 (load-bearing).

One participant was excluded from the final analysis because her baseline plasma nitrite concentration lay more than 3 SD outside the group mean.

“One participant was subsequently excluded from the final analysis on the basis that her baseline plasma nitrite concentration lay >3 SD outside the group mean (Fig. 1).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

All participants were provided with a written information sheet about the study and all provided written informed consent prior to being enrolled.

“All participants were provided with a written information sheet about the study and all provided written informed consent prior to being enrolled in the study.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Each participant was tested at approximately the same time of day to avoid diurnal variation.

“Each participant was tested at approximately the same time of day to avoid diurnal variation.”

Probably not a substantial claim: may not pass S3 (load-bearing).

There was no significant difference between Control and high-nitrate diets in duration of exercise undertaken.

“Similarly, there was no significant difference between Control and HN diets in duration of exercise undertaken (Control diet: mean 4•0 (SD 2•6) h/week; HN diet: mean 4•2 (SD 2•6) h/week).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Food diaries suggested good compliance.

“Food diaries suggested good compliance.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Data analysis was performed on the remaining nineteen participants.

“Data analysis was performed on the remaining nineteen participants”

Probably not a substantial claim: may not pass S3 (load-bearing).

Five participants did not consume high-nitrate vegetables 2-3 h prior to the laboratory visit.

“Six participants consumed small portions of HN vegetables during the Control diet and five participants did not consume HN vegetables 2-3 h prior to the laboratory visit.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Ten participants were excluded or withdrew after enrolment due to personal reasons, time constraints or illness unrelated to the study, or difficulties in obtaining vascular access.

“Ten participants were excluded or withdrew after enrolment due to personal reasons, time constraints or illness unrelated to the study, or difficulties in obtaining vascular access.”

Classified as probably not a substantial claim.

A 3-week wash-out was selected in order to synchronize dietary interventions with participants' menstrual cycles.

“A 3-week wash-out was selected in order to synchronize dietary interventions with participants' menstrual cycles.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Direct measurement of nitrate content of the vegetables consumed was beyond the scope of the study.

“Direct measurement of nitrate content of the vegetables consumed was beyond the scope of the study.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Six participants consumed small portions of high-nitrate vegetables during the Control diet.

“Six participants consumed small portions of HN vegetables during the Control diet and five participants did not consume HN vegetables 2-3 h prior to the laboratory visit.”

Classified as probably not a substantial claim.

The study had a randomized, crossover design.

“The study had a randomized, crossover design (Fig. 1).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Participants were randomized using a sealed envelope technique.

“Participants were randomized using a sealed envelope technique to receive a box of HN vegetables (HN diet) for 1 week or were given written instructions to avoid HN vegetables for 1 week (Control diet)”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

No participant withdrew after allocation, such that the analysis was carried out on an intention-to-treat basis.

“No participant withdrew after allocation, such that the analysis was carried out on an intention-to-treat basis (Fig. 1).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures were approved by the local institutional Ethics Committee.

“The study was conducted according to the guidelines laid down in the Declaration of Helsinki and all procedures were approved by the local institutional Ethics Committee.”

Probably not a substantial claim: may not pass S3 (load-bearing).

There was no significant difference in body mass of participants from baseline to the end of the study period.

“There was no significant difference in body mass of participants from baseline (mean 62•7 (SD 10•3) kg) to the end of the study period (mean 62•4 (SD 10•4) kg).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Participants were not informed of the study hypothesis until the end of the study.

“Participants were not informed of the study hypothesis until the end of the study.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Sample size calculation estimated that twenty participants were necessary to detect a significant reduction in systolic blood pressure with an α level of 5% and statistical power of 80%.

“In order to detect a significant reduction in SBP with α level of 5 % and statistical power of 80 %, it was estimated that a sample size of twenty participants was necessary.”

May combine two claims.

Our finding of no significant change in blood pressure after the Control diet is consistent with the findings of Berry et al., which demonstrated that fruit and low-nitrate vegetables do not induce blood-pressure-lowering effects.

“Therefore, our finding of no significant change of BP after the Control diet is consistent with the findings of the study by Berry et al. (30) , which demonstrated that fruit and low-nitrate vegetables do not induce BP-lowering effects.”

• cites [30]Not checked yet

  Not checked in the free run.

May combine two claims.

Both our study and that by Sobko et al. suggest that supplementation of diets with whole high-nitrate vegetables significantly affects both plasma nitrate and nitrite concentrations.

“Both our study and that by Sobko et al. (20) suggest that supplementation of diets with whole HN vegetables significantly affects both plasma nitrate and nitrite concentrations.”

• cites [20] sourceNot checked yet

  Not checked in the free run.

Classified as probably not a substantial claim. May combine two claims.

Vegetables were obtained from one supplier and the trial was completed in a 4-month period to control for environmental and agricultural variation in nitrate content.

“In order to control for this as much as possible, vegetables were obtained from one supplier (Riverford Organic Farms Ltd, Buckfastleigh, UK) and the trial was completed in a 4-month period.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Thirty healthy, adult women were enrolled and assessed for eligibility.

“Thirty healthy, adult women were enrolled and assessed for eligibility.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Polyphenols may increase generation of nitric oxide in the gastrointestinal tract and protect nitric oxide from oxidation.

“It has been proposed that polyphenols may increase generation of nitric oxide in the gastrointestinal tract and protect nitric oxide from oxidation (16) .”

• cites [16]Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The DASH diet provides more K, Mg, Ca, fibre and less total and saturated fat than a control diet.

“The DASH diet provides more K, Mg, Ca, fibre and less total and saturated fat than a control diet (35) .”

• cites [35]Not checked yet

  Not checked in the free run.

May combine two claims.

Sobko et al. reported a significant reduction in DBP of ~5 mmHg after 10 d but no change in SBP.

“Sobko et al. (20) reported a significant reduction in DBP of ~5 mmHg after 10 d but no change in SBP”

• cites [20] sourceNot checked yet

  Not checked in the free run.

The quote only partly states this claim.

Consumption of whole HN vegetables may be as effective in reducing SBP in women as other nitrate interventions.

“Our results suggest that the consumption of whole HN vegetables may be as effective in reducing SBP in women.”

May combine two claims.

The study by Sobko et al. used a different methodology, with an older population (mean age 36 (SD 10) years), Japanese HN foods (such as seaweed), and included both men and women.

“The study by Sobko et al. (20) used a different methodology, with an older population (mean age 36 (SD 10) years), Japanese HN foods (such as seaweed), and included both men and women.”

• cites [20] sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

The effect of eating two daily portions of HN vegetables on normal dietary intake was not assessed.

“The effect of eating two daily portions of HN vegetables, which can add bulk to the diet, on normal dietary intake was not assessed.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The DASH diet is not widely advised in the UK.

“but it is not widely advised in the UK (36) .”

• cites [36] sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Most of the study populations in the systematic review consisted of healthy, young men and may not be representative of the whole population.

“However, most of the study populations have consisted of healthy, young men and may not be representative of the whole population (6) .”

• cites [6] sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Hord et al. calculated that the DASH diet could provide more than 1200 mg nitrate/d (equivalent to approximately 17 mg nitrate/kg body mass per day), from eight to ten portions of fruit and vegetables, including two portions of green leafy vegetables.

“For example, Hord et al. (16) calculated that the DASH (Dietary Approaches to Stop Hypertension) diet could provide more than 1200 mg nitrate/d (equivalent to ~17 mg nitrate/kg body mass per d), from eight to ten portions of fruit and vegetables, including two portions of green leafy vegetables.”

• cites [16]Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

The DASH diet has been endorsed as an effective treatment for high BP in the USA.

“The DASH diet has been endorsed as an effective treatment for high BP in the USA (21)”

• cites [21] sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Cochrane reviews concluded there was insufficient evidence to support the use of K, Mg and Ca supplements as hypotensive agents.

“However, Cochrane reviews of the effectiveness of K, Mg and Ca supplements concluded that there was insufficient evidence to support their use as hypotensive agents (37)(38)(39) .”

• cites (37)(38)(39)Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Many other nutrients or biologically active compounds, such as polyphenols, found in both fruit and vegetables may have physiological effects.

“However, there are many other nutrients or biologically active compounds, such as polyphenols, found in both fruit and vegetables, which may have physiological effects (41) .”

• cites [41] sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Food diaries were not analysed for total intakes of macro- and micronutrients from all foods eaten.

“Food diaries were used to analyse consumption of vegetables and fruit on both diets, but they were not analysed for total intakes of macro-and micronutrients from all foods eaten.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Sobko et al. estimated that a traditional Japanese diet, including vegetables, mushrooms and seaweed, could provide five times the Acceptable Daily Intake, as it could theoretically contain 18.8 mg nitrate/kg body mass per day (1109 mg nitrate/d).

“Sobko et al. (20) estimated that a traditional Japanese diet, including vegetables, mushrooms and seaweed, could provide five times the ADI, as it could theoretically contain 18•8 mg nitrate/kg body mass per d (1109 mg nitrate/d).”

• cites [20] sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

There is a lack of evidence to promote the use of antioxidant supplements, which have been associated with increased mortality.

“In addition, there is a lack of evidence to promote the use of antioxidant supplements, which have been associated with increased mortality (40) .”

• cites [40] sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Overall energy intake was not significantly affected.

“suggesting that overall energy intake was not significantly affected.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

He and MacGregor estimated that reducing BP by 5 mmHg could result in a reduction in stroke death in the UK by 23 %, equating to 13 700 deaths prevented per year.

“He and MacGregor (42) estimated that reducing BP by 5 mmHg could result in a reduction in stroke death in the UK by 23 %, which could equate to 13 700 deaths prevented per year.”

• cites [42] sourceNot checked yet

  Not checked in the free run.

May combine two claims.

A population-wide BP reduction would save lives, prevent significant disabilities, and represent a major cost saving to health services.

“Not only would this BP reduction save lives and prevent significant disabilities, it would also represent a major cost saving to health services.”

Classified as probably not a substantial claim. May combine two claims.

The study recruited participants having a 28 d menstrual cycle, with testing timetabled so that participants would be at the same stage of their cycle for both the HN and Control diets.

“The current study design relied on recruitment of participants having a 28 d menstrual cycle, with testing timetabled such that the participants would be at the same stage of their cycle for both the HN and Control diets.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Stroke costs the National Health Service £3 billion per year, with a wider economic cost of £8 billion per year.

“Stroke costs the National Health Service £3 billion per year, with a wider economic cost of £8 billion per year (43) .”

• cites [43]Not checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

Nitrate intake was estimated based on self-reported vegetable consumption and indirect estimation of nitrate content of vegetables, which may vary according to factors such as crop variety, season and light conditions.

“A potential limitation in dietary control was that nitrate intake was estimated based on self-reported vegetable consumption and indirect estimation of nitrate content of vegetables, which may vary according to factors such as crop variety, season and light conditions.”

Classified as probably not a substantial claim. May combine two claims.

Participants were given HN vegetables to consume in the experimental arm but asked to maintain their normal diet during the control arm.

“The possibility of a 'placebo effect' should be considered because participants were given HN vegetables to consume in the experimental arm but asked to maintain their normal diet during the control arm.”

Classified as probably not a substantial claim.

BP is known to vary during the menstrual cycle.

“BP is known to vary during the menstrual cycle (8) .”

• cites [8]Not checked yet

  Not checked in the free run.

May combine two claims.

Participants were blind to the purpose of the study; they were not informed that the vegetables were high in inorganic nitrate or that this might influence BP.

“However, participants were blind to the purpose of the study, i.e. they were not informed that the vegetables they were given were high in inorganic nitrate or that this might influence BP.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The acute effect was measured as participants were requested to eat vegetables on the final day 2-3 h before testing.

“It could be argued, however, that the acute effect was measured as participants were requested to eat vegetables on the final day 2-3 h before testing.”

Classified as probably not a substantial claim. May combine two claims.

Incorporating the intervention into current health advice to eat at least '5 A Day' could result in a population-wide reduction of BP, reduce morbidity and mortality from stroke, and reduce costs for health-care services.

“This simple intervention could be incorporated into current health advice to eat at least '5 A Day', which could result in a population-wide reduction of BP, reduce morbidity and mortality from stroke, and reduce costs for health-care services.”

May combine two claims.

The statistical power of the present data was 64 %, lower than the 80 % predicted in the sample size calculation.

“However, this meant that the statistical power of the present data (64 %) was somewhat lower than that predicted (80 %) in the sample size calculation based on a previous study (n 20) (29) .”

• cites [29] sourceNot checked yet

  Not checked in the free run.

Probably not a substantial claim: may not pass S3 (load-bearing).

One participant allocated to the HN group was excluded because a measurement lay >3 SD beyond the group mean.

“Finally, one of the participants allocated to the HN group was excluded following analyses of primary outcome variables based on the criterion that a measurement lay >3 SD beyond the group mean.”