Abstract
Objectives: Dietary nitrate supplementation increases nitric oxide (NO) bioavailability and reduces blood pressure (BP). Individual differences in these responses are suspected but have not yet been investigated using robust designs, e.g., replicate crossover trials, and appropriate statistical models. We examined the within-individual consistency of the effects of dietary nitrate supplementation on NO biomarkers and blood pressure, and quantified inter-individual response differences.
Methods: Fifteen healthy men (age: 27 (5), BMI: 24 (4) kg/m2) visited the laboratory on four occasions. Two visits involved consumption of 140 ml nitrate-rich beetroot juice and two involved consumption of 140 ml nitrate-depleted beetroot juice. Plasma nitrate and nitrite concentrations were measured 2.5 hours post-supplementation, and BP was measured prior to and 2.5 hours post-supplementation. Correlations between replicates were quantified for the placebo-adjusted post-supplementation plasma nitrate and nitrite concentrations and pre-to-post supplementation changes in BP. Within-participant linear mixed models were used to quantify individual response heterogeneity via participant-condition interactions.
Results: Consumption of nitrate-rich beetroot juice elevated plasma nitrate and nitrite concentrations and reduced systolic (-7 mmHg, 95% CI = -3 to -11 mmHg, p=0.001) and diastolic (-6 mmHg, 95% CI = -2 to -9 mmHg, p=0.003) BP versus placebo. Moderate-to-large positive correlations were observed between the two replicates of placebo-adjusted responses to nitrate supplementation for plasma nitrate (r=0.91) and nitrite (r=0.55) concentrations as well as for systolic BP (r=0.80) (all p< 0.05). Significant participant-condition interactions were present for plasma nitrate and nitrite concentrations and systolic BP (p< 0.02).
Conclusions: In this seminal study involving a replicate crossover design, we have shown that effects of dietary nitrate supplementation on NO biomarkers and systolic blood pressure show good consistency within individuals, with reproducible inter-individual differences in these responses. The causes of this inter-individual variation deserve investigation.
Methods: Fifteen healthy men (age: 27 (5), BMI: 24 (4) kg/m2) visited the laboratory on four occasions. Two visits involved consumption of 140 ml nitrate-rich beetroot juice and two involved consumption of 140 ml nitrate-depleted beetroot juice. Plasma nitrate and nitrite concentrations were measured 2.5 hours post-supplementation, and BP was measured prior to and 2.5 hours post-supplementation. Correlations between replicates were quantified for the placebo-adjusted post-supplementation plasma nitrate and nitrite concentrations and pre-to-post supplementation changes in BP. Within-participant linear mixed models were used to quantify individual response heterogeneity via participant-condition interactions.
Results: Consumption of nitrate-rich beetroot juice elevated plasma nitrate and nitrite concentrations and reduced systolic (-7 mmHg, 95% CI = -3 to -11 mmHg, p=0.001) and diastolic (-6 mmHg, 95% CI = -2 to -9 mmHg, p=0.003) BP versus placebo. Moderate-to-large positive correlations were observed between the two replicates of placebo-adjusted responses to nitrate supplementation for plasma nitrate (r=0.91) and nitrite (r=0.55) concentrations as well as for systolic BP (r=0.80) (all p< 0.05). Significant participant-condition interactions were present for plasma nitrate and nitrite concentrations and systolic BP (p< 0.02).
Conclusions: In this seminal study involving a replicate crossover design, we have shown that effects of dietary nitrate supplementation on NO biomarkers and systolic blood pressure show good consistency within individuals, with reproducible inter-individual differences in these responses. The causes of this inter-individual variation deserve investigation.
Original language | English |
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Article number | 103634 |
Journal | Current Developments in Nutrition |
Volume | 8 |
Issue number | Supplement 2 |
DOIs | |
Publication status | Published - Jul 2024 |