If you’ve ever browsed the supplement shelves of your local health food store, you may have encountered l-arginine. This amino acid is found in proteins you may consume on a regular basis. Nuts and seeds, for example, are great sources of l-arginine. So are meats, poultry, fish, legumes like soybeans or chickpeas and seaweed. Do you also need to take it as a supplement? Such a recommendation is controversial.
Can L-Arginine Help the Heart?
Q. Dr. Louis Ignarro is a Distinguished Professor of Pharmacology at UCLA. He was awarded the Nobel Prize in Medicine in 1998 for his work on nitric oxide. He has written a book, No More Heart Disease, in which he describes the use of l-arginine, which is converted into nitric oxide in the body.
I was fortunate to attend pharmacy college with him at Columbia University. Several years ago, I called him to see if his research has changed. In response, he assured me that it has not.
I have been taking l-arginine for 10 years and my blood pressure is excellent. He told me he is taking it himself with similar results. (I am 78 years young.)
The Importance of Nitric Oxide:
A. Thank you for reminding us of Dr. Ignarro’s contributions. Nitric oxide is indeed important in controlling blood pressure. A number of natural substances such as beet juice and cocoa flavonoids act through this mechanism.
A placebo-controlled trial found that people who took a combination of l-arginine and B vitamins had more flexible blood vessels and lower blood pressure (European Journal of Nutrition, March 2018). The daily dose was 2.4 g l-arginine, 3 mg vitamin B6, 0.4 mg folic acid and 2 mcg vitamin B12. The volunteers took this German product (Telcor Arginin plus) two tablets twice daily for three months.
They saw a modest drop in systolic blood pressure, about 6 mm Hg. Nonetheless, this change was statistically significant and comparable to the effect of many blood pressure medicines.
An earlier meta-analysis of 11 randomized controlled trials found a similar effect (American Heart Journal, Dec. 2011). In addition, l-arginine lowered systolic blood pressure by approximately 6 mm Hg in these studies as well. Doses ranged from 4 to 24 grams/day, considerably more than in the more recent German research.
Side Effects of L-Arginine Supplementation:
Before people embark on a daily supplement program, they should know the risks. While l-arginine is not toxic, it does have a few side effects. For one thing, individuals taking this supplement daily may develop insulin resistance (Life Sciences, Dec. 15, 2017).
L-arginine, taken as a supplement, can also increase inflammation in the presence of malaria infection (Tohoku Journal of Experimental Medicine, May 2015). People who suffer frequent cold sores often report that avoiding foods rich in l-arginine (and presumably supplements, too) help them heal faster. Many individuals find that doses of 10 grams or more result in digestive distress and diarrhea.
Some scientists recommend l-citrulline supplements instead of l-arginine (Nutrients, July 19, 2018). People who take l-citrulline absorb it better.
According to the scientists,
“its supplementation is therefore more effective at increasing l-arginine levels and NO [nitric oxide] synthesis.”