Nitric oxide, or nitrogen oxide, also known as nitrogen monoxide, is a molecule with chemical formula NO. In humans, nitric oxide is an important cellular signalling molecule involved in many physiological and pathological processes. It is a powerful vasodilator with a short half-life of a few seconds in the blood.
There are two ways that the body produces nitric oxide. The enzymatic pathway involves the enzyme nitric oxide synthase, which converts the amino acid L-arginine into nitric oxide and another molecule called L-citrulline. Non-enzymatic production of nitric oxide can occur through the reduction of inorganic nitrite.
The small intestine’s epithelial cells convert glutamine and glutamate to citrulline, which is then transported to the kidneys. The kidneys extract citrulline and convert it to arginine, which is then released into the bloodstream. Arginine can also be synthesised from citrulline in other cells, especially when nitric oxide synthase is active.
L-arginine is a direct precursor for nitric oxide synthesis, while L-citrulline is converted into L-arginine in the body, which then contributes to nitric oxide production. Also, when ingested, dietary nitrates are converted to nitrites, and then further reduced to nitric oxide.
Low levels of nitric oxide production are important in protecting organs such as the liver from ischemic damage.
Nitric oxide is a key vertebrate biological messenger, playing a role in a variety of biological processes. It is a known bio product in almost all type of organisms, ranging from bacteria to plants, fungi, and animal cells.
The vasodilating antihypertensive drug minoxidil contains a nitric oxide moiety and may act as a nitric oxide agonist. Similarly, Sildenafil citrate, popularly known by the trade name Viagra, stimulates erections primarily by enhancing signalling through the nitric oxide pathway in the penis.
Nitric oxide increases the flow of blood to the heart and inhibits the process of atherosclerosis (build-up of plaque on the walls of the arteries). The body produces the majority of nitric oxide in the skin cells lining the walls of the blood vessels. The nitric oxide gas stimulates blood vessels to dilate, prevents fats and cholesterol from depositing on blood vessel walls and inhibits the aggregation of platelets within vessels and reduces the risk of heart disease.
Nitric oxide, working in tandem with arginine, is very effective in the treatment of colds, dementia, high blood pressure, heart disease and erectile dysfunction by enhancing the capacity to dilate blood vessels and increase the flow of blood.
People with atherosclerosis, diabetes, or hypertension often show impaired nitric oxide pathways.
The production of nitric oxide is elevated in populations living at high altitudes, which helps these people avoid hypoxia by aiding in pulmonary vasculature vasodilation. Nitro-glycerine and amyl nitrite serve as vasodilators because they are converted to nitric oxide in the body.
NOTE: A high salt intake was demonstrated to lower nitric oxide production in patients with high blood pressure.
Watermelon is rich in the amino acid L-citrulline that is one of the best natural compounds to increase the production of nitric oxide, proven by many studies. Co-enzyme Q10 also boosts the production of nitric oxide.
Natural foods required for the body to produce nitric oxide
Foods rich in arginine, citrulline, coenzyme Q10 and nitrates are required for the body to produce nitric oxide, and the following shows the highest sources of each one.
Natural sources of arginine in alphabetical order
- Seaweed
- Sesame seeds
- Shellfish
- Soya beans
- Sunflower seeds
- Peanuts
- Pheasant
- Pumpkin seeds
- Spirulina
- Tofu
- Walnuts
Natural sources of citrulline in alphabetical order
- Butternut squash
- Cucumber
- Kidney beans
- Melon
- Oily fish
- Organ meats
- Peanuts
- Pumpkin including seeds
- Rabbit
- Soya beans
- Venison
- Watermelon
Highest sources of coenzyme Q10 in micrograms per 100 grams
Natural sources of nitrates in alphabetical order
NOTE: Saturated fats reduce nitric oxide levels in the body in the following foods:
- Meat & dairy products
- Processed foods
- Fried foods
- Cooking oils
- Palm oil in processed foods
Related subjects
- A-Z of nutrients
- Blood and vein disorders
- Dementia
- Diabetes
- Erectile dysfunction
- Heart disorders
- High blood pressure
- Obesity
- Sports nutrition