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Should You Add NO2 Supplements to Your Stack?

L-arginine, which we’ll just call arginine, is the main ingredient in “NO2” supplements that promise to build muscle mass and power sex drive. But are they really worth the money to add to your supplement program?

It’s writing on topics like this that make me really appreciate the owner of this site. Usually, site owners want articles that try to persuade readers to buy more of a product. If you are a bodybuilder, then I’m probably going to persuade you to buy less-although it is still helpful to take supplemental arginine. But if you are an older person who has peripheral artery disease, then you really should consider taking the kinds of arginine dosages that are often recommended for bodybuilders.

Arginine Is Semi-Essential

Most amino acids are classified as essential or non-essential. Essential amino acids are required for human life and cannot be manufactured by the human body. They have to be obtained from food.

Non-essential amino acids are required for human life, but the human body can make them from the essential amino acids. They do not have to be obtained from food unless diet does not provide enough of the essential amino acids the body needs to make them.

Arginine (like glutamine) is classified as semi-essential, or conditionally essential. There are certain stages of life and health conditions in which the body cannot manufacture arginine. Infants can’t make it, and people who have inflammatory bowel disease or kidney disease can’t make arginine from other amino acids.

Older children, teens, and adults who have tissue injuries or broken bones always need more of the amino acid than the body can make from other amino acids. Athletic training to increase muscle mass requires more arginine than the body can make from other sources. Just not a lot.

Arginine and Other Amino Acids

This isn’t a chemistry lesson, but I’ll review the relationships of arginine and other amino acids briefly.

  • The kidneys can make arginine from the amino acid citrulline.
  • Citrulline can be obtained directly from the diet, or it can be manufactured in the lining of the intestine from glutamine.
  • If you take a citrulline supplement to reduce muscle inflammation after working out, it won’t work if you don’t get enough arginine from diet or supplements.
  • The body can also make citrulline from proline and ornithine and use that citrulline to make arginine but at an even higher energy cost.
  • The body can substitute citrulline for arginine in making NO (nitric oxide), but it doesn’t work as well as arginine.

And most of the processes that the body uses to make arginine also run in reverse, so that the body can make the other amino acids from excess arginine. All of these processes require a large amount of energy from glucose. Getting arginine from food or supplements reduces energy demands.

Why Everybody Needs Arginine

Arginine has two important functions in exercise physiology.

  • It is a chemical precursor of creatine, which, with water, “pumps up” muscle.
  • It is a chemical precursor of nitric oxide (NO, not NO2), which relaxes the linings of blood vessels in a manner identical to the action of the well-known erectile dysfunction treatments Viagra, Cialis, and Levitra.

Nitric oxide doesn’t just relax arterial walls in men. It also regulates blood vessel tone in infants, children, and women. And if a manufacturer is trying to sell you a “NO2” supplement, maybe they really don’t understand what arginine does. It is essential to the body’s production of NO, the nitric oxide radical, not NO2, the gas nitrogen dioxide, and not N2O, nitrous oxide, the chemical used for “laughing gas.”

Can You Get Enough Arginine from Food?

Arginine is found in meat, dairy products, eggs, fish, legumes, beans, nuts, and seeds. The food in a typical diet provides 3 to 6 grams of arginine every day. The process of digestion typically releases 90% of the arginine in food and sends it through the hepatic portal vein to the liver, but the liver only admits about half of the arginine it receives into the body. The cells in the lining of the arteries, in turn, only absorb about 0.1% of the arginine provided to them by the bloodstream unless the body also gets all the proline, glutamine, ornithine, and citrulline it needs from diet and supplements.

Shellfish, sesame seeds, and poultry are especially good sources of arginine. Two cups (280 grams) of diced roasted turkey, for instance, would contain 6 grams of arginine. But only about 5.5 grams of the 6 grams of arginine in the turkey would be released by digestion, and only about 2.7 grams of the 6 grams would be absorbed into the bloodstream, less if the body needed to make glutamine or proline out of the arginine.

In other words, arginine supplements only “work” if your body doesn’t have to break down arginine to make other amino acids. You need to be getting your basic protein needs first before you can benefit from taking arginine.

How much arginine is enough arginine? Up to 20 grams of arginine a day can improve NO production in the bloodstream. You simply can’t eat enough meat, dairy products, fish, legumes, beans, nuts, and seeds to get this much arginine, without consuming massive amounts of calories and fat. You can add this amount of arginine to your stack

And why should you care about NO? Nitric oxide generated by cells in the lining of blood vessels:

  • Normalizes blood pressure.
  • Increases sexual responsiveness in women and erectile strength in men.
  • Increases circulation in the peripheral arteries.

If you have good cardiovascular health, you probably don’t need supplemental arginine to be healthy. If you have circulatory problems, you can benefit from up to 20 grams a day. But what if your goal is to build muscle?

Arginine for Muscle Building

The bottom line of scientific research into arginine is that taking arginine supplements won’t help you if you aren’t on an intensive training program, but taking 1 gram of arginine and 1 gram of ornithine a day will enhance muscle mass if you are. (See more about arginine and ornithine.)The amounts of arginine that help grow muscle are a lot less than the amounts of arginine that support cardiovascular health. The reason for this is that muscles take up a far greater percentage of available arginine than the cells in the linings of blood vessels.

Just 1 gram of arginine a day with 1 gram of ornithine a day is enough to enhance muscle gains from resistance exercise. On the other hand, taking up 15 grams of arginine a day for 15 days had no effects on marathon runners preparing for a race.

Arginine and Growth Hormone

And what about taking arginine to support the production of growth hormone? Since growth hormone is associated with muscle growth, tissue repair, mental agility, sexual prowess, and youth, increasing the secretion of growth hormone is a good thing.

But the amount of arginine needed to increase the secretion of growth hormone by about 60%, in one clinical trial, in elderly men, was huge: 250 mg per kilogram of body weight each day. For a man weighing 100 kilos (220 pounds), the daily dosage of arginine would be 25 grams or 25,000 mg. The enhanced production of growth hormone after taking arginine may simply reflect restoration to normal levels, not the production of enough growth hormone to give younger men and women a competitive advantage in sports.

So Who Should Take Arginine, and How Much?

There is good scientific evidence to suggest that younger athletes in training can benefit from taking up to 1 gram (1,000 mg) of arginine per day. If you aren’t doing strength-building exercises, there is no advantage to taking arginine if you already get the essential amino acids in your diet.

There is good scientific evidence to suggest that elderly persons with cardiovascular problems, especially peripheral arterial disease, may benefit from taking up to 20 or 25 grams (20,000 to 25,000 mg) per day. A study sponsored by Herbalife found that 5 grams of arginine (with citrulline, alpha-lipoic acid, vitamin C, vitamin E, folic acid, and taurine) was enough to increase stamina in male cyclists aged 50 to 73.

If I were training, I’d use 1 gram of arginine a day, and maybe not bother with it if I were taking creatine. If I had peripheral arterial disease, I would definitely look into taking 20-25 grams a day. And for people over 50, I would consider adding 5 grams a day for general health.

Is arginine safe? Are there people who should not take arginine?

  • People who have herpes, HIV, or solid tumors should not take arginine.
  • People who have asthma should not take more than 1 gram of arginine daily.
  • People who take blood pressure medication, anyone who uses nitroglycerine, and men who take Viagra, Levitra, or Cialis should not take arginine.
  • Don’t take arginine if you are under medical care for having had a heart attack.

When to take arginine? For best results, take just before going to bed on an empty stomach. And what about the various forms of arginine?

  • Arginine pyroglutamate is most frequently recommended for stimulation of growth hormone, especially in a product that combines it with lysine, but there is no scientifically proven advantage of using arginine in this form.
  • Arginine alpha-ketoglutarate is a salt of arginine and alpha-ketoglutaric acid. It is more completely absorbed into the bloodstream than arginine from other sources, but it is still necessary to get complete protein from other sources for this form of arginine to be beneficial. There is no science that shows it is superior for muscle growth.
  • Arginine ethyl ester is a highly soluble form of arginine. It has an intensely bitter taste, which is why it is usually stirred into orange juice. Although about 10% more of this form of arginine enters the hepatic portal vein to be transported to the liver, it behaves like any other form of arginine once it is inside the body.

All of these forms of arginine are OK. None of them gives you a big advantage over any of the others. L-arginine HCl works just as well as the more expensive versions of the product.

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