Complementary Alternative Cardiovascular Medicine

Chapter 7 / Nutrachemicals and CVD 105
cholesteremia, compared with healthy individuals. Boger et al. (16) studied
aortic atherosclerosis after a high-fat–cholesterol diet in rabbits.
Rabbits given L-arginine with the diet developed fewer lesions than
those without L-arginine (control group) and fewer lesions than a third
group of rabbits who were given lovastatin with a high-fat–high-cholesterol
diet.
Endothelial dysfunction is present in individuals with hypertension
and studies have failed to show any beneficial effects of L-arginine in this
patient group (17). The postulated mechanism of endothelial dysfunction
in hypertension is an imbalance between vasodilator and vasoconstrictor
factors rather than NO substrate deficiency. Patients with
hypertension and associated left ventricular hypertrophy (LVH) may
complain of angina, despite angiographically normal epicardial coronary
arteries. In a cohort of 12 patients, Mohri et al. (18) demonstrated
that inhibition of endogenous NO production, with intracoronary N G -
monomethyl-L-arginine (L-NMMA), unmasked myocardial ischemia
(evident by decreased lactate uptake and increased lactate production in
coronary sinus sampling) during pacing-induced tachycardia. This
myocardial ischemia was reversed by intracoronary L-arginine. Therefore,
L-arginine may have a potential role as an antianginal agent in
patients with hypertension with angina, LVH, and normal epicardial
coronary arteries.
In conclusion, multiple small studies of L-arginine supplementation
have yielded favorable responses in patients with CAD and CHF. L-arginine-modulated
enhancement of endothelial function has been noted in
patients with hypercholesteremia. Vascular dysfunction in patients with
diabetes and hypertension may reflect endothelial-independent mechanisms;
hence, the role for L-arginine is not clearly evident. Of interest is
a study by Houghton and colleagues (19) that demonstrated an L-arginine-mediated
augumentation of CBF in African American men and
women when compared with matched Caucasian, suggesting a possible
target group that may benefit more than the others.
These findings must be confirmed by larger studies of longer duration
that address the effects of L-arginine in myocardial ischemia, cardiac
transplant patients, and in patients undergoing percutaneous coronary
interventions (PCI).
Trade name: R-Gene 10 (Pharmacia Corp.), L-Arginine (Twin Labs)
Adverse reactions: Nausea, abdominal cramps, and diarrhea. Additionally,
there are few anecdotal reports of recurrence of oral herpes lesion
with its supplementation.
Contraindications: Hypersensitivity, genetic disorder argininemia
Usual study dosage: 8–21 g/d