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Effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes.

Free radical biology & medicine
July 1, 2013
Mark Gilchrist et al. (6 authors)
Journal ArticleRandomized Controlled TrialResearch Support, Non-U.S. Gov'tHuman StudyClinical
Study Details

Study Goal

The researchers sought to determine if dietary nitrate supplementation via beetroot juice would lower blood pressure, improve endothelial function, and enhance insulin sensitivity in individuals with type 2 diabetes.

Results Summary

The study found that beetroot juice supplementation increased plasma nitrite and nitrate concentrations but did not lower blood pressure, improve endothelial function, or enhance insulin sensitivity in individuals with type 2 diabetes. No significant changes were observed in any of the measured outcomes compared to placebo.

Population

27 patients with type 2 diabetes (age 67.2±4.9 years, 18 male).

Effective Dosage

250ml beetroot juice daily (containing 7.5mmol nitrate).

Duration

2 weeks.

Interactions

None mentioned.

Extracted Claims (15)
InterventionDirectionEndpointPopulationDosageImpactClaim #
Diets rich in green, leafy vegetables
decrease
blood pressure (BP)
-
-
have been shown to lower
#1
Diets rich in green, leafy vegetables
decrease
risk of cardiovascular disease
-
-
reduce
#2
Dietary nitrate supplementation
decrease
BP
healthy humans
-
has previously been shown to lower
#3
Dietary nitrate supplementation
increase
endothelial function
healthy humans
-
improve
#4
supplementing dietary nitrate with beetroot juice
decrease
BP
individuals with type 2 diabetes (T2DM)
-
will lower
#5
supplementing dietary nitrate with beetroot juice
increase
endothelial function
individuals with type 2 diabetes (T2DM)
-
improve
#6
supplementing dietary nitrate with beetroot juice
increase
insulin sensitivity
individuals with type 2 diabetes (T2DM)
-
improve
#7
beetroot juice
no change
mean ambulatory systolic BP
patients with type 2 diabetes
134.6±8.4mmHg versus 135.1±7.8mmHg (mean±SD), placebo vs active-mean difference of -0.5mmHg (placebo-active), p=0.737 (95% CI -3.9 to 2.8)
was unchanged
#8
beetroot juice
no change
macrovascular endothelial function
patients with type 2 diabetes
-
no changes
#9
beetroot juice
no change
microvascular endothelial function
patients with type 2 diabetes
-
no changes
#10
beetroot juice
no change
insulin sensitivity
patients with type 2 diabetes
-
no changes
#11
Supplementation of the diet with 7.5mmol of nitrate per day for 2 weeks
increase
plasma nitrite and nitrate concentration
individuals with T2DM
-
caused an increase
#12
Supplementation of the diet with 7.5mmol of nitrate per day for 2 weeks
no change
BP
individuals with T2DM
-
did not lower
#13
Supplementation of the diet with 7.5mmol of nitrate per day for 2 weeks
no change
endothelial function
individuals with T2DM
-
did not improve
#14
Supplementation of the diet with 7.5mmol of nitrate per day for 2 weeks
no change
insulin sensitivity
individuals with T2DM
-
did not improve
#15
Abstract

Diets rich in green, leafy vegetables have been shown to lower blood pressure (BP) and reduce the risk of cardiovascular disease. Green, leafy vegetables and beetroot are particularly rich in inorganic nitrate. Dietary nitrate supplementation, via sequential reduction to nitrite and NO, has previously been shown to lower BP and improve endothelial function in healthy humans. We sought to determine if supplementing dietary nitrate with beetroot juice, a rich source of nitrate, will lower BP and improve endothelial function and insulin sensitivity in individuals with type 2 diabetes (T2DM). Twenty-seven patients, age 67.2±4.9 years (18 male), were recruited for a double-blind, randomized, placebo-controlled crossover trial. Participants were randomized to begin, in either order, a 2-week period of supplementation with 250ml beetroot juice daily (active) or 250ml nitrate-depleted beetroot juice (placebo). At the conclusion of each intervention period 24-h ambulatory blood pressure monitoring, tests of macro- and microvascular endothelial function, and a hyperinsulinemic isoglycemic clamp were performed. After 2 weeks administration of beetroot juice mean ambulatory systolic BP was unchanged: 134.6±8.4mmHg versus 135.1±7.8mmHg (mean±SD), placebo vs active-mean difference of -0.5mmHg (placebo-active), p=0.737 (95% CI -3.9 to 2.8). There were no changes in macrovascular or microvascular endothelial function or insulin sensitivity. Supplementation of the diet with 7.5mmol of nitrate per day for 2 weeks caused an increase in plasma nitrite and nitrate concentration, but did not lower BP, improve endothelial function, or improve insulin sensitivity in individuals with T2DM.

Medical Subject Headings (MeSH)
AgedBeta vulgarisBlood PressureCardiovascular DiseasesDiabetes Mellitus, Type 2Dietary SupplementsEndotheliumFemaleHumansInsulin ResistanceMaleMiddle AgedNitratesNitric OxideNitritesVegetables
Study Links
Quality Scores
Safety90
Efficacy20/10
Quality85/10
Citation Metrics
Total Citations189
Citations/Year15.8
Relative Citation Ratio7.23
NIH Percentile96.2%
Research Impact Scores
APT Score0.95
Weight Score1.85
Normalized Score0.61
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