Effect of Oral Caffeine and L-Citrulline Supplementation on Arterial Function in Healthy Males

Summary

Caffeine is an exceedingly popular and consumed pharmacological agent. Although caffeine is primarily consumed from coffee and tea beverages, it is also available in other forms such as sodas, energy drinks, tablets and capsules. Nevertheless, caffeine acutely increases brachial and aortic systolic blood pressure (BP) and arterial stiffness. Arterial stiffness is an independent predictor of cardiovascular disease (CVD) and assessed through pulse wave velocity (PWV). Interestingly, previous studies have proposed that caffeine may increase aortic BP through increases in aortic PWV and augmentation index (AIx), a measurement of wave reflection. Yet, these effects were seen in middle-aged adults with treated hypertension and a wide age range. Therefore, it is imperative to consider that caffeine may cause different effects in young normotensive individuals than in older adults independently of BP levels. Importantly, oral supplementation of the amino-acid, L-citrulline has been shown to enhance the bioavailability of L-arginine levels and nitric oxide (NO) production and, therefore, improve arterial function. L-citrulline supplementation for 7 days given at 6 g/day has shown to increase NO levels while improving PWV. Previous studies by our group also demonstrated that L-citrulline supplementation reduces the BP response to cold exposure; a condition with an increased vasoconstriction. Therefore, the acute effects of caffeine on central and peripheral PWV and BP in healthy young men are yet to be fully evaluated. We hypothesized that acute caffeine intake would increase peripheral and aortic BP and PWV and that L-citrulline supplementation would attenuate the effects induced by acute caffeine ingestion.

Conditions

• Hypertension
• Healthy

Interventions

DRUG

Caffeine

A 200 mg caffeine tablet was given to subject to examine the drugs effect on arterial function.

DRUG

Placebo

A 750 mg placebo capsule (maltodextrin) was given to subjects to examine the effect of the drug on arterial function.

DIETARY_SUPPLEMENT

L-citrulline

L-citrulline was used to examine the effect of the supplement on arterial function.

Sponsors & Collaborators

• Florida State University

  lead OTHER

Principal Investigators

• Arturo Figueroa, M.D. Ph.D · Florida State University

Study Design

Allocation

RANDOMIZED

Purpose

OTHER

Masking

DOUBLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

40 Years

Sex

MALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2012-09-30

Primary Completion

2014-03-31

Completion

2014-03-31