What Is Nitric Oxide?

blood pressure lowering effect of nitric oxide

Nitric oxide (NO) is a gas that acts as a signalling molecule, or messenger, within the body. It’s also referred to as an endothelium-derived relaxing factor (EDRF) due to its role in dilating blood vessels, lowering blood pressure and increasing blood flow.

While nitric oxide is mainly found within blood vessel linings, it’s also present in the kidneys, platelet cells, heart muscle cells and in some brain and peripheral nerve cells.

What does nitric oxide do?

Within the circulation, nitric oxide regulates blood flow, blood vessel dilation and platelet clumping, to lower blood pressure, reduce the risk of unwanted blood clots, and protect against hardening and furring up of the arteries (atherosclerosis). Impaired production of nitric oxide or a reduced ability to respond to its effects (endothelial dysfunction) are an underlying cause of high blood pressure and cardiovascular disease.

As a gas, nitric oxide diffuses easily across and between cell membranes, but it only survives for a few seconds before reacting with other molecules. Anything that enhances nitric oxide production, increases its bioavailability, reduces its breakdown or allows cells to respond to it better will have a blood pressure lowering effect. Nitric oxide is therefore one of the most important targets for preventing and treating hypertension, heart attack and stroke.

What foods have nitric oxide?

As nitric oxide is a gas, it quickly evaporates so is not present in food in significant amounts. However, some foods, such as beetroot, contain nitrates which are converted into nitrites by bacteria (Veillonella and Actinomyces species) that live in your mouth, mainly on your tongue. When you swallow these food-derived nitrites, they are rapidly absorbed into your circulation and are converted into nitric oxide (NO). When eating beetroot or drinking beetroot juice, hold it in your mouth for as long as possible to maximise nitrite production.

You can also increase nitric oxide production by increasing your intake of foods that supply the amino acid, l-arginine, the main building block for making nitric oxide. Vitamin B3 is also needed for this reaction.

What foods contain l-arginine?

L-arginine is a semi-essential amino acid that your cells can make from other amino acids (eg citrulline, glutamine, glutamate, proline, ornithine) but l-arginine is often in short supply and then becomes essential in the diet.

L-arginine is found in protein-rich foods such as nuts, seeds, egg yolk, red meat and beans. It is also found in beetroot, onions, grapes, rice and coconut water.

L-arginine supplements are also available and are a popular alternative to Viagra and other erectile dysfunction drugs that work via nitric oxide dilation of peripheral blood vessels.

What foods activate nitric oxide?

Some foods contain antioxidants, especially polyphenols, which stimulate nitric oxide production and increase its bioavailability. Following a Mediterranean style diet, or a DASH diet, naturally boost the bioavailability of nitric oxide, and the list of foods with the greatest beneficial effects reads like a dream menu – fruits, vegetables, dark chocolate, nuts, olive oil, black and green tea as well as red wine.

These foods all help to dilate arteries and lower blood pressure through effects on nitric oxide – especially pomegranate juice, globe artichoke, apples, cacao, blackberries, blueberries, strawberries, black grapes, red peppers, black beans, kidney beans, soy beans, red onions, cherries, tomatoes, garlic and pumpkin seeds.

Some milk peptides (amino acid chains) found in dairy products, such as lactoferrin, appear to increase the activity of genes encoding proteins involved in nitric oxide, and some whey proteins have been found to improve blood flow through coronary arteries.

The antioxidant effect of vitamin E on blood vessel linings is believed to increase the release of nitric oxide, which has a powerful ability to dilate blood vessels and lower blood pressure. Vitamin E is found in vegetable oils (especially wheatgerm oil), avocado, wholegrain cereals, nuts and seeds.

Vitamin C also improves blood vessel dilation by restoring nitric oxide activity in people with hypertension, and by regenerating vitamin E. Vitamin C is found in most fruit and vegetables, especially berries, blackcurrants, guava, kiwi fruit, citrus, mango, bell peppers and green leaves.

Which herbal medicines work via nitric oxide?

Many herbal medicines used to treat high blood pressure work at least partly through effects on nitric oxide, including cinnamon, Cannabidiol CBD oil, Ginkgo biloba, hawthorn, pine bark extracts, ginseng, turmeric and spirulina.

How else can you stimulate nitric oxide release?

Exercise is one of the best ways to increase the activity of enzymes that release nitric oxide – one reason why your blood vessels dilate and you get a post-exercise glow.

Some therapies also stimulate nitric oxide release, such as the Buteyko method of breathing, and magnetic therapy. Interestingly, prolonged blue light exposure may also lower blood pressure by enhancing the natural release of nitric oxide in the skin.

Make the effort to naturally increase your nitric oxide production through these diet and lifestyle changes, and your blood pressure readings are likely to improve.

Image credit: ulada/shutterstock


About Dr Sarah Brewer

QUORA EXPERT - TOP WRITER 2018 Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a master's degree in nutritional medicine from the University of Surrey. Sarah is a registered Medical Doctor, a registered Nutritionist and a registered Nutritional Therapist. She is an award winning author of over 60 popular self-help books and a columnist for Prima magazine.

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