By Greg Arnold, DC, CSCS, December 15, 2009, abstracted from “Oral l- Supplementation Attenuates Blood Pressure Response to Cold Pressor Test in Young Men” printed online in the American Journal of Hypertension

Cardiovascular diseases (CVD), including heart disease and stroke, are the first and third leading causes of death for both men and women in the United States. They account for 1 in 3 of all U.S. deaths and are expected to cost our healthcare system $473 billion in 2009. If all major types of cardiovascular disease were eliminated, U.S. life expectancy would increase by nearly 7 years (1).

As one of the most significant risk factors for cardiovascular disease, high blood pressure increases the heart's workload, causing the heart to thicken and increasing your risk of stroke, heart attack, kidney failure and congestive heart failure (2).  As a result, blood pressure has been deemed a worldwide epidemic (3) and is estimated to cost our healthcare system $73 billion in 2009 (4).  The National Institutes of Health classify a healthy blood pressure as 120/80 mmHg or less, a blood pressure between 120/80 and 140/90 as “Prehypertension”, and 140/90 mmHg or greater as high blood pressure (5).

Now a new study (6) has found that an amino acid called l-Citrulline may help with blood pressure health.  In the study, 17 men with normal blood pressure between the ages of 21 and 23 were given either 6 grams per day of l-citrulline or placebo for 4 weeks.  During this time, half of each group underwent a test called the cold pressor test which increases blood flow of the coronary arteries and artificially increases blood pressure (7).  The other half of each group did not undergo the cold pressor test.

By the end of 4 weeks, the researchers saw no blood pressure differences between the L-Citrulline and the placebo groups not undergoing the cold pressor test.  In the cold pressor test groups, however, l-citrulline “significantly decreased” systolic blood pressure (the top number) in the arm as well as the main heart artery called the aorta compared to placebo.  Specifically, the drop in arm systolic blood pressure in the l-citrulline group was 6 mm Hg (139 to 133 mm Hg) compared to a 2 mm Hg increase (133 to 135 mm Hg) while aorta systolic blood pressure drop in the l-citruline group dropped by 4 mm Hg (121 to 117 mm Hg) while the placebo group saw a 4 mm Hg increase (114 to 118 mm Hg) at the end of 4 weeks.

Regarding a reading called “pulse pressure” which is the difference between the systolic and diastolic (the bottom number) readings, those in the l-citrulline cold pressor group had a 3 mm Hg drop in aortic pulse pressure while those in the placebo group had a 1 mm Hg increase in pulse pressure.  No significant differences were seen in the arm (brachial) pulse pressure.

The results led the researchers to conclude that “oral L-citrulline supplementation [decreases] the brachial systolic blood pressure, aortic systolic blood pressure, and aortic pulse pressure responses to CPT” in young men with normal blood pressure.

Greg Arnold is a Chiropractic Physician practicing in Danville, CA.  You can contact Dr. Arnold directly by emailing him at mailto:PitchingDoc@msn.com or visiting his web site at www.CompleteChiropracticHealthcare.com

Reference:
1. “Cardiovascular Disease at a Glance” posted on www.cdc.gov/NCCDPHP/publications/AAG/dhdsp.htm
2. “Risk Factors for Coronary Heart Disease” posted on www.americanheart.org/presenter.jhtml?identifier=4726
3. Casas JP. Homocysteine and stroke: evidence on a causal link from mendelian randomization. Lancet 2005; 365(9455): 224-232
4. “May is high blood pressure education month” posted on www.cdc.gov/features/highbloodpressure/
5. “What Is High Blood Pressure?” posted on www.nhlbi.nih.gov/health/dci/Diseases/Hbp/HBP_WhatIs.html
6. Figueroa A.  Oral l- Supplementation Attenuates Blood Pressure Response to Cold Pressor Test in Young Men.  Am J Hypertens 2009 Oct 22. [Epub ahead of print]
7. de Marchi SF.  Sympathetic stimulation using the cold pressor test increases coronary collateral flow.  SWISS MED WKLY 2001;131:351–356