Can L-Arginine increase your risk of heart attack even if you have not already had a heart attack?

I've read that if you have had a heart attack, taking L-Arginine supplements will increase your chances of having and dying from another heart attack. But what about people who have not yet had a heart attack, but have the precursors of a heart attack, such as high cholesterol, hardening of the arteries, high blood pressure, etc.? Does supplementing with L-Arginine increase their risk also?
To answer Scottsdalehigh64's question, I've read on several websites that L-Arginine supplementation helps with circulation problems, which I think I have. Also, as you mentioned, I do eat well, exercise, etc.

Written By Evie Neumann

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  • Doctor J February 3, 2009, 4:51 am

    Below you will find links to a couple of scientific papers on this subject.

    There is a large body of scientific evidence that L-Arginine supplementation has potentially positive benefits in patients with cardiovascular disease. L-Arginine is the precursor for the synthesis of Nitric Oxide by the three enzymes called Nitric Oxide Synthase (NOS). Endothelial NOS (eNOS) is the form of the enzyme that produces Nitric Oxide in the lining of the arteries (the endothelium) where it is VITAL for vascular health and prevention of cardiovascular diseases.

    As the attached links indicate, the level of ADMA – Asymmetric Dimethylarginine in the patient may determine whether or not L-Arginine supplements are beneficial.

    The one scientific paper that reported a possible increased risk of heart attack in patients supplemented with L-Arginine was a terribly done and poorly reported (dishonest) study that has been completely "debunked" (1) by one of the world's leading researchers in this field – Louis Ignarro, M.D. (recipient of the Nobel Prize in 1998 for his research on Nitric Oxide). One BAD study does not make "truth".

    It is also important to understand that the cofactor for NOS is tetrahydrobiopterin (BH4), and levels of this cofactor can impact the ability of the enzyme to convert L-Arginine to Nitric Oxide. Numerous studies indicate that maintaining the high levels of BH4 needed in the body to make Nitric Oxide requires adequate amounts of Vitamin C and Folate – and, supplementation of these micronutrients can significantly affect endothelial health and Nitric Oxide production.$=relatedarticles&logdbfrom=pubmed

    Best wishes and good luck.

    p.s. one additional point: vegetable proteins (e.g. soy) are high in Arginine content (meat proteins are much lower). Thus, Vegetarians "naturally" have a higher intake of L-Arginine than meat eaters. It is interesting that Vegetarians have a much lower risk of cardiovascular disease than meat eaters, and some researchers have hypothesized that this difference in amino acid content of the diets may be a factor.