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Evaluating the impact of short-term nitrate-rich dietary supplementation on endothelial function in COPD: A randomized crossover study.

  • 2024-10
  • Respiratory medicine 232
    • Fernanda Beatriz Costa Delacoste
    • Cassia da Luz Goulart
    • Augusto Baumhardt Guidoti
    • Patrick Türck
    • Bruna Eibel
    • Maria Claudia Irigoyen
    • Cintia Laura Pereira de Araujo
    • Pedro Dal Lago

Study Design

Type
Randomized Controlled Trial (RCT)
Population
subjects with COPD
Methods
randomized crossover study, three series of supplementation: (1) l-arginine, (2) dehydrated beetroot, and (3) a placebo that appeared like the other supplements
Blinding
Double-blind
Duration
14 days

Aim

This study aimed to investigate the acute effects of dietary nitrate ingestion through l-arginine supplementation or dehydrated beet consumption on endothelial function in chronic obstructive pulmonary disease (COPD) patients. The secondary outcome was to analyze arterial stiffness, plasma nitrate, and nitrate/protein concentration.

Methods

In this randomized crossover study, subjects with COPD underwent three series of supplementation: (1) l-arginine, (2) dehydrated beetroot, and (3) a placebo that appeared like the other supplements. Each intervention lasted 14 days, with a 7-day washout period between series. Participants underwent endothelial function assessment using flow-mediated dilatation (FMD), and plasma nitrate levels were measured at the end of each supplementation series.

Results

Seventeen subjects (twelve male) completed the study protocol. Only five subjects presented endothelial dysfunction (RHI ≤0.51) at baseline. The mean baseline characteristics included age 66.5 ± 9.4 years, BMI 27.5 ± 4.5 kg/m2, FEV1, 0.79 (0.67-1.06) L. There were no differences (p > 0.05) between the groups or from pre-to post-interventions for RHI and arterial stiffness index (AIx) values, as well as parameters of endothelium-dependent vasodilation, such as blood flow velocity (BFV), shear stress, shear rate, FMD (mm), and FMD%. There was also no differences (p > 0.05) between the groups or from pre-to post-interventions plasma nitrate levels.

Conclusions

Acute dietary supplementation with nitrates, at the doses provided, did not show a significant improvement in endothelial function assessed by FMD, EndoPAT, or plasma nitrate levels in COPD. These findings suggest that a higher dose or prolonged supplementation might be required to achieve a therapeutic effect.

Research Insights

  • L-Arginine→Improved Vascular Endothelial Function

    There were no differences (p > 0.05) between the groups or from pre-to post-interventions for RHI and arterial stiffness index (AIx) values, as well as parameters of endothelium-dependent vasodilation, such as blood flow velocity (BFV), shear stress, shear rate, FMD (mm), and FMD%.

    Effect
    Neutral
    Effect size
    Small
    Dose
    not stated
  • L-Arginine→Increased Nitrate Level

    There was also no differences (p > 0.05) between the groups or from pre-to post-interventions plasma nitrate levels.

    Effect
    Neutral
    Effect size
    Small
    Dose
    not stated
  • L-Arginine→Reduced Arterial Stiffness

    There were no differences (p > 0.05) between the groups or from pre-to post-interventions for RHI and arterial stiffness index (AIx) values...

    Effect
    Neutral
    Effect size
    Small
    Dose
    not stated
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