Introduction
Nitric oxide is a gaseous molecule made mostly within the lining of our arteries, consisting of one atom of nitrogen (N) and one atom of oxygen (O), and abbreviated as NO. NO is an important signaling molecule that lasts only a few seconds in the blood. It is considered the body’s only known healthy free radical.
What does NO do?
NO is a chemical messenger that signals muscles in the arteries to relax, allowing the artery to expand, increasing diameter. This lowers blood pressure and improves circulation. Experts note that those suffering from atherosclerosis, diabetes or hypertension often show impaired NO pathways. Improving vascular responsiveness through NO production can reduce complications of these disease states.
NO also prompts immune cells to kill bacteria, viruses and cancer cells, and triggers brain cells to communicate.
More health benefits of nitric oxide include:
- Preventing or reversing high blood pressure, keeping arteries flexible and responsive to changes in blood pressure.
- Limiting swelling and pain of arthritis.
- Reducing the risk of diabetes and complications like kidney disease, blindness and limb amputations.
- Reducing the risk of heart disease, since it can lower inflammation, reduce formation of blood clots and prevent the buildup of fatty plaques.
- Protecting bones from osteoporosis.
- Reducing the risk of Alzheimer’s and other dementia.
- Improving sleep.
- Reversing erectile dysfunction by improving blood flow.
- Protecting the skin from sun damage.
- Enhancing athletic performance by improving oxygenation of muscle tissues and delaying fatigue.
- Improving the sense of smell.
Who is at risk for low NO?
- Premature babies with underdeveloped lungs and immune systems.
- Those with diseases such as asthma, cancer, chronic obstructive pulmonary disease, depression, dementia, diabetes, erectile dysfunction, glaucoma, heart disease, insomnia, obesity, osteoporosis, skin disease or stomach ulcers.
- Those over age 40. NO production decreases by 75% between ages 20 and 70.
Two pathways for making NO
Nitric oxide is not found in foods. Our bodies produce NO from compounds in foods via two different pathways, the L-Arginine pathway, using the amino acid L-Arginine, and the nitrate pathway, using nitrates found naturally in whole vegetables and some fruits, especially dark, leafy greens and beet root.
The L-arginine pathway efficiency decreases with age. The nitrate pathway is a safe way to produce NO as we age. Nitrate content of foods depends on several factors, including exposure to sunlight and nutrient content of soil. Content may vary depending on the geographic location where produce is grown.
- High NO producers: Kale, Swiss chard, arugula, spinach, chicory, wild radish, bok choy, beets, lettuce, cabbage, mustard greens, cauliflower, parsley, kohlrabi, carrots and broccoli.
- Medium producers: Asparagus, celery, watercress, artichoke, eggplants, strawberries, potatoes, garlic, tomatoes and melon.
- Low producers: String beans, figs, prunes, sweet potatoes, raspberries, raisins, bananas, cherries, onions, bean sprouts, chickpeas and red wine.
Dishes such as coleslaw, vegetable juice and vegetable soup are medium producers.
Are nitrates harmful?
Some studies have linked nitrates and nitrites used for meat preservation to some forms of cancer due to the production of harmful nitrosamines. Nitrosamines are formed when nitrites react with amines present in foods (cured meats and fish, cheese, oils), especially when cooked at high temperatures. The saturated fat in these foods also increases the formation of nitrosamines.
Boosting NO production
When we chew foods with nitrates, friendly oral bacteria react with saliva to convert nitrates into nitrites. In the stomach, nitrites are converted to nitric oxide, where they go into the bloodstream to meet the body’s needs. Helpful tips for producing NO include:
- Consume plenty of dark, leafy greens, beetroot, cruciferous vegetables, fruits, and raw nuts and seeds. Chew greens thoroughly until they are mostly liquid before swallowing. The nitrate pathway requires healthy oral bacteria in saliva to start the conversion of nitrates to NO.
- Choose raw or lightly steamed vegetables Cooking diminishes available nitrate content in foods.
- Antioxidants like vitamin C (found in citrus, kiwi, red peppers and broccoli) and polyphenols (found in blueberries, blackberries, raspberries, dark grapes and dark chocolate) help to preserve the nitric oxide molecule.
- Nasal humming can increase NO production 15-fold compared to quiet exhalation. Daily humming can reduce the risk of sinusitis and upper airway infections.
- Simple exercises such as squats or jumping jacks can boost NO and improve circulation of the lymphatic system, improving immunity.
- Exposure to sunlight can also increase production of NO, although the amount required is not yet determined.
Caveats
- Antibacterial mouthwash can kill healthy oral bacteria needed to reduce nitrate to nitrite, and can decrease NO-production by at least a third, up to 90%.
- Nitrate and nitrite are water-soluble and can be reduced 60%–80% by boiling or dehydrating foods.
- Kidney dialysis eliminates NO. Patients on dialysis may benefit from NO supplements.
- Blood-thinning medications may be affected by vitamin K contained in green leafy vegetables. Providers may suggest removing these foods from your diet when taking these medications. However, removing NO-producing foods seriously reduces your body’s capacity to fight disease. Instead, commit to consuming at least 1 cup of raw greens and cruciferous vegetables daily. If you are consistent with your intake, your provider can adjust your medication for the vitamin K content.
- NO lozenges and beet root powders are becoming widely available. The majority of beet products on the market do not contain any detectable nitrite or nitrate and therefore will not improve nitric oxide availability. Check to be assured these supplements are produced by reputable sources using methods that do not destroy nitrate bioavailability.
- L-arginine supplements, often used by athletes, are not recommended unless your primary care provider has determined deficiency of this amino acid. Supplements can lead to toxic overdose and increased risk of liver or kidney damage, or ischemic heart disease.
- Reputable health agencies conclude the benefits of plant foods outweigh the risk of nitrosamine production from nitrates in foods.
Best practices
- Eat at least 1 cup of dark salad greens or cruciferous vegetables every day. Raw or lightly steam these greens, rather than boiling them.
- Chew greens thoroughly, allowing the saliva to break the food down to mostly liquid before swallowing. Refrain from using antibacterial mouthwash or toothpaste, since they can reduce NO production.
- Accompany greens with a source of vitamin C such as citrus, bell pepper, broccoli or kiwifruit. Leafy greens also contain vitamin C.
- Consume foods high in polyphenol antioxidants with greens, such as dark-colored fruit (berries), red wine or grapes, and dark chocolate (65% cacao or more).
- Enjoy 1–2 ounces of raw nuts daily for L-Arginine and healthy unsaturated fats.
- Use unsaturated fats from whole foods such as nuts, seeds, avocado and olives and reduce intake of saturated fats from meat, fish, poultry, dairy and processed foods.
- Substitute plant proteins low in fat for animal proteins. Good plant-protein sources include legumes (beans, lentils, soy, split peas), select grains such as quinoa, buckwheat and amaranth, and small amounts (1 ounce per day) of raw, unsalted nuts and seeds.
- Include aerobic exercise in your daily routine. Try to get a minimum of 30 minutes of walking, bicycling or swimming per day.
- Consider humming for several minutes (100 exhales) three to four times per day to increase nasal NO production.
- Speak to your provider if you are taking blood pressure or blood-thinning medications that can be affected by NO-producing foods.
References
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