L-Arginine
The Heart's Best Friend

L-arginine is one of the 20 amino acids required by the human body.  It is not considered an essential nutrient in adults since with proper metabolism; the body will make all that it needs from food.  

It is a different story with infants in that they are unable to produce arginine.  Thus this particular amino acid is referred to as conditionally essential depending on the age and health of the individual.  

In general arginine does not have to be supplemented but there are conditions that tend to demand more of this particular amino acid and thus puts greater demand on the body for its synthesis.   

Burns, trauma, surgery and severe bacterial infections known as sepsis all rev up the demand for L-arginine.

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No shortage of Food Sources

Food sources include all meats and dairy products.  That's a broad category but beef, pork, poultry, wild game and most all seafood including shellfish are all good sources of L-arginine. 

The plant world offers ample sources as well with nuts, seeds, wheat germ, flour, buckwheat, oatmeal, chickpeas, soybeans and many more are also rich sources.  There is really no excuse for not getting adequate amounts of this important amino acid from the most common foods.

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A Nitric Oxide Precursor

There are indications that L-arginine may help erectile dysfunction (ED) but if so, it does it in a round-about way by acting as a precursor for nitrous oxide.  Just as it sounds, in biochemistry a "precursor" is a substance that must be present to produce another chemical compound. 

Judging from all the TV commercials for ED drugs, one might conclude that every post-puberty male in the country has a problem "getting it up".   

Nitrous oxide tends to relax the blood vessels and make them more amenable to expanding thus allowing blood to flow more efficiently.  ED aside, the association between L-arginine and nitric oxide should indicate a benefit for the mitigation of cardiovascular disease including heart attacks, cholesterol build-up, stroke and even ED. 

Maybe this amino acid could put the final nail in the coffin for Viagra, Cialis and Levitra; then we wouldn't have to be subjected to all those inane, suggestive commercials.  Just think, we guys could all take arginine and we might just "be ready when the moment is right".  You never know!

The Maestro of Nitric Oxide

It is impossible to discuss arginine without getting deeply involved in nitric oxide.  In considering nitric oxide, one name consistently comes to the forefront, Dr. Louis Ignarro, Nobel Prize winner in medicine and the world's leading authority on the benefits of nitric oxide and L-arginine. 

Embedded here is a series of three interviews with Dr. Ignarro, presented by the American Health Journal.  Each video is about 9 minutes long and combined they give the viewer more information on arginine and nitric oxide's benefits for cardiovascular disease than anyone could hope for.

Dr. Ignarro is the author of the book "NO More Heart Disease" which is a play on words since "NO" is the chemical formula for nitric oxide.   Coincidence?  Nope, don't believe in them.  Click on the image of the books jacket below to review it.

Nitric Oxide, Part 1, from the American Health Journal - 8:58 min.


Dr. Ignarro on Nitrous Oxide, Part 2


Dr. Ignarro on Nitrous Oxide, Part 3


Clinical Trials

Clinical trials involving L-arginine are plentiful and reading through them could keep someone busy for a very long time. The website http://ClinicalTrials.gov is the go-to place to find out what trials are underway or being planned for almost any condition. It is a very valuable service from the National Institutes of Health.

When this site was recently searched, 296 studies were listed.  Many are currently recruiting test subjects, many have concluded recruitment and are underway, some were terminated, many have been completed and have the results summarized on the government website.

Just to illustrate, number 69 on the list of recently completed trials is titled, "Watermelon supplementation and arterial stiffness". 

The recommended intervention to treating blood pressure (BP) in overweight and obese individuals is lifestyle modifications and not drug therapy.  L-arginine is believed to lower BP in these people and as we have seen, it is a substrate for endothelial NO production.

Recently, L-citrulline has been proven to be more effective than L-arginine for improving circulation NO since it is not degraded by enzymatic degradation. 

So what does watermelon have to do with anything?  It turns out that watermelon is one of the few natural foods rich in L-citrulline, another amino acid that is very efficiently transformed into L-arginine in humans. 

In this very small study, a dietary supplement of watermelon extract was used to see if it actually reduced arterial stiffness and endothelial dysfunction thus lowering blood pressure.  The study was just completed in August 2011 and the results have not been evaluated for publication yet.  Stay tuned. 

An interesting exercise would be to go to the NIH website, pick a couple of completed trials and see what happened.

If you took the time to watch Dr. Ignarro's interviews in the videos above, the conclusions of many trials should be a foregone conclusion.

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What Should an Arginine Supplement
Look Like?

Since arginine is considered to be nonessential, there is no recommended daily intake or tolerable upper limit.  Nevertheless, depending on one's health condition and the reasons for taking arginine, the therapeutic range considered safe goes from 400 mg all the way up to 6,000 mg (6 grams).

A typical arginine supplement comes in 1000 mg tablets with instructions for adults to take one to three tablets daily preferably with a meal.  There are numerous brands available in the popular drug stores as well as online.

The product shown above right is a combination of L-arginine and L-citrulline from Source Naturals in 120, 1000 mg tablets.  Of the many products offered, this combination formula looks like it should be a very effective precursor for the production nitric oxide in the body.  Click on its image to buy it or read more.  

Anyone wondering what the "L" in L-arginine stands for, it is "levo" which is Latin for "left" and describes the direction of rotation of its structure.  

There is a "D" version which is a mirror image and rotates to the right; the D is for "dextro", Latin for "right".  The "L" version is most compatible for human consumption and is the only type recommended. 

Many brands of L-arginine will be described as being "free form" which means that it does not have to be digested; it goes directly into the blood for distribution throughout the body.  Other forms are available as di-peptides, tri-peptides and hydrolysates any of which may be used in hospitals for various therapeutic applications. 

For normal dietary supplemental usage, free form arginine is considered the best.

As supplements go, it is not particularly expensive and can be purchased online for $7 to $10 for 1000 mg tablets in quantities of 50 per container.  

Natures Bounty brand L-arginine can be purchased in-store at Walgreens for around $12.99 but frequently they have a "buy one, get one free" on many of their dietary supplements.

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Interactions and Cautions

There are a few cautions to observe and some interactions between arginine and other drugs or supplements but no known interactions with food.

It should not be taken in combination with meds for high blood pressure or meds for increasing blood flow to the heart.  Care should be exercised if taking it with Viagra in that a drop in blood pressure could result. 

Using it with xylitol could inhibit the pancreas from releasing glucagon which kicks in when blood sugar levels get too low.
 
A few more cautions are that with allergies and asthma it could cause an allergic reaction and make swelling in the airways worse.  It could also make herpes worse since there is evidence that herpes needs arginine to multiply. 

It should not be taken during the two weeks prior to surgery in that it could lower the blood pressure and complicate the procedure. 

If one already has low blood pressure, taking arginine could make it even lower and in older people, taking arginine after a recent heart attack may even cause death.

These interactions and cautions were taken from the MedLine Plus page on L-arginine. It has a good overall summary of this valuable amino acid.



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