Supplements that increase nitric oxide in the body make up one of the most popular categories on the market today. They have attracted the attention of serious athletes and weightlifters seeking to enhance muscle performance and/or augment training adaptations. NO serves many useful purposes throughout the body. IThis article explores the ways in which nitric oxide and its precursors can have a positive effect not only on athletic performance but also on many aspects of good health.
Breaking Down Nitric Oxide
Nitric oxide, produced naturally by the human body, ranks among the most important molecules for blood vessel health. Nitric oxide (NO) plays a critical role in endothelial function, promoting relaxation and subsequent dilation of vascular smooth muscle, which, in turn, may favorably impact blood flow. These desirable aspects help to lower blood pressure and contribute to skeletal muscle performance/hypertrophy. Nitric oxide gets synthesized in the body by nitric-oxide-synthase-dependent and -independent pathways.
Nitric oxide supplementation may improve cardiac health. It has also been credited with enhanced exercise performance, a reduction in high blood pressure during pregnancy, help with cases of erectile dysfunction, and improved healing processes. We shall address each of these in greater detail later.
Nitric oxide exists as a gas and is produced when the amino acid arginine reacts with nitrate. As such, arginine and its partner, citrulline, often appear together in athletic-enhancing supplements because they promote nitric oxide production. While arginine can directly affect the production of NO, L-citrulline acts as an L-arginine precursor that gets further converted to NO through a reaction catalyzed by the enzyme NO synthase. In general, L-arginine supplements increase respiratory response and enhance performance during exercise, while L-citrulline (coupled with malate and other molecules) increases work capacity.
Top Performance and Health Benefits of NO Supplements
Medical professionals now recognize at least 4 key aspects in which NO supplements can have a positive effect on the body:
- Erectile dysfunction (ED): The amino acid L-citrulline may help treat erectile dysfunction by increasing the production of nitric oxide, necessary for the muscles in the penis to relax. This relaxation allows chambers inside the penis to fill with blood so it can maintain an erection.
- Decrease in muscle soreness: In a 2010 study, 41 subjects were randomly assigned to receive either 8 grams of citrulline malate or a placebo 1 hour prior to a workout in which they performed as many repetitions as possible on a flat barbell bench press. Those who received citrulline malate reported 40% less muscle soreness at 24 and 48 hours post-workout than those who took the placebo. Citrulline malate increases nitric oxide production, which increases blood flow to active muscles. In turn, citrulline malate may possibly enhance nutrient delivery and clear those naturally occurring waste products associated with muscular fatigue, such as lactate and ammonia. A later study revealed that while citrulline could diminish muscle soreness at 24 and 48 hours after intense exercise, it did not reduce soreness at 72 hours. Thus, its ability may depend on the exercise itself, the citrulline dosage, and timing.
- Lowering blood pressure: One theory regarding elevated blood pressure suggests that such individuals have an impaired ability to utilize NO effectively. Dietitians suggest that consuming a diet high in fruits and vegetables may help decrease blood pressure. Such diets contain a great deal of nitrate and flavonoids, another compound shown to help lower blood pressure and diminish the risk of diseases associated with it. Scientists believe flavonoids not only increase nitric oxide production but also decrease its breakdown, promoting higher circulating levels overall.
- Boosts exercise performance: By widening blood vessels, nitric oxide can help increase the delivery of nutrients and oxygen to working muscles during exercise, thus enhancing overall athletic performance. One study showed that NO enhanced work capacity only in untrained or newly trained individuals. Since physical activity itself boosts NO production, scientists believe that well-trained athletes already have sufficient NO and the means to utilize it effectively.
Additional but lesser-known health benefits may include the following:
- Limiting the swelling and discomfort of arthritis
- Reducing the risk of diabetes and its serious complications such as blindness, kidney failure and limb amputation
- Reducing the risk of heart disease by diminishing inflammation, reducing the formation of blood clots, and preventing the buildup of fatty plaques within the arteries
- Protecting bones from osteopenia/osteoporosis
- Reducing the risk of various dementia-type conditions, including Alzheimer’s
- Improving sleep
- Protecting the skin from sun damage
- Improving the sense of smell
Obtaining NO From Natural Sources
Fortunately for us, many delicious and readily available foods offer an abundance of nitrates, citrulline and/or arginine. Once consumed, these foods can contribute significantly to the production of nitric oxide in the body. Below we suggest some healthy options:
- Poultry: a great source of a coenzyme important in the preservation of nitric oxide in the body
- Garlic: increases the levels of enzymes involved in the synthesis of nitric oxide
- Leafy greens: loaded with nitrates that get converted to nitric oxide (beetroot, kale, spinach)
- Citrus fruits: their high levels of vitamin C increase levels of enzymes crucial to nitric oxide formation
- Nuts/seeds: offer an abundance of amino acids, which play a part in the production of nitric oxide
- Cocoa: contains flavanols, compounds that significantly boost nitric oxide levels
In addition to making prudent food choices, other simple daily movements can initiate nitric oxide production in the body. Surprisingly, simply breathing serves as one of the easiest ways to increase NO production. Types of breathing exercises that personal trainers can suggest to clients include taking meditative, slow breaths, breathing through the nose, and even humming a favorite tune. The latter actually encourages the creation of vibrations in the sinuses, releasing a surge of nitric oxide that can support circulation and oxygen delivery throughout the body.
How to Recognize NO Deficiency
While not often discussed in the literature, the risk of nitric oxide deficiency increases with age. This has to do with the older body’s inability to produce nitric oxide naturally. Some of these symptoms, while also having other potential causes, seem noteworthy:
- Depression: Low levels of nitric oxide affect blood circulation, causing not only high blood pressure but also potentially leading to chronic PTSD. Nitric oxide helps reduce depression and stress by lessening inflammation.
- Poor vision: The fluid in the eyes, located in the frontal region, regulates whether intraocular pressure increases or decreases. The proper flow of this fluid is determined to a certain extent by the nitric oxide that carries it. If this fluid does not drain properly from the eye, intraocular pressure increases, causing decreased vision.
- Fatigue: Low nitric oxide levels can decrease the body’s natural energy at the cellular level. This results from reduced circulation, which limits the delivery of oxygen and nutrients the body needs. This can lead to chronic fatigue.
- Hypertension: Nitric oxide regulates blood pressure, preventing cardiac problems such as stroke and heart attacks. A lack thereof may potentiate these problems.
- Memory loss: Brain diseases such as dementia arise in part due to reduced blood flow to the brain. Low blood pressure resulting from decreased nitric oxide levels may cause cognitive decline.
As an interesting footnote, overuse of antibacterial mouthwash can kill the specific healthy oral bacteria needed to reduce nitrate to nitrite, thereby decreasing nitric oxide production by as much as 90%.
Negative Side Effects of Excess NO
Just as we outline the risks of too little nitric oxide in the body, we must also list possible hazards associated with its overconsumption.
Studies have shown that ingesting more than 9 grams per day of supplemental arginine may lead to nausea and/or diarrhea. More than 9 grams of supplemental citrulline taken in a single day — or 6 grams per day over the course of 14 days — may elicit stomach/intestinal discomfort.
While we acknowledge the abundant health benefits of foods containing antioxidants, consuming large amounts (in excess of 2,000 milligrams of vitamin C in one day) can also lead to nausea, diarrhea, and stomach pains.
As with any supplement, we must include what occurs naturally in the foods we choose in the total daily consumption. Sometimes food sources provide sufficient quantities, and excessive supplementation can tip the scales toward toxicity or discomfort.
NO and its Nobel Assets
As a free radical, nitric oxide was originally classified as a harmful pollutant. However, even as an important signaling molecule, NO remarkably lasts only a mere few seconds in the blood. In 1992, nitric oxide received the title of “molecule of the year,” due to its beneficial role in human physiology. In 1998, three scientists jointly earned the Nobel Prize in Physiology or Medicine for discovering the nitric oxide molecule. The Nobel Prize Committee referred to nitric oxide as “the most important molecule in the body”, in spite of its existence as a free radical.
Confusion often ensues when individuals mistakenly believe that nitric oxide is the same as nitrous oxide. “Nitric oxide is a short-lived gas molecule made from nitrogen and oxygen that your body naturally produces,” says Jacqueline Danielle Fryer, a registered dietitian specializing in sports nutrition at Banner Sports Medicine Scottsdale. This differs vastly from nitrous oxide, commonly referred to as “laughing gas”.
Supplement – Prescription Interactions and Contraindications
Just as nitric oxide precursors can build up and cause intestinal discomfort, L-arginine supplements can have negative interactions with some commonly taken prescription drugs.
If an individual regularly takes blood pressure medication for any number of health conditions, an excess of L-arginine may cause blood pressure to plummet to a dangerously low level. Similarly, for individuals living with diabetes and on daily medication, the possibility exists of L-arginine supplements lowering blood sugar levels too substantially.
As we age, many individuals find themselves needing blood thinners for various health conditions. As a vasodilator, L-arginine may increase bruising and bleeding when combined with blood-thinning medications.
Another consideration comes with the use of diuretics to combat swelling. Use of L-arginine in this case may cause blood potassium levels to rise precipitously, posing a risk to the kidneys.
As with any supplements, personal trainers might remind clients to check with their personal physician before starting a new regimen, especially if they currently take prescription medications.
NO Cannot Take the Place of Hard Work
Today’s society often seems overeager to find a “quick fix” for any problem or challenge. However, supplementation does not fit that bill. “Nitric oxide makes hard work feel easier, it is like upgrading the plumbing system for your muscles,” says Michael Baah, a celebrity personal trainer, strength coach, and qualified exercise oncology specialist.
Since nitric oxide production improves blood flow and oxygen delivery, “muscles receive nutrients faster and clear waste products more effectively,” Baah says. These factors, ideally, then contribute to improved endurance, reduced fatigue, and keener performance.
Even given all those endorsements and accolades, personal trainer Sam Laurence accurately points out that nitric oxide supplements ought not serve as a replacement for doing the work. “Nitric oxide is more of a supportive tool rather than a primary driver of strength or endurance gains,” Laurence says. “While the effects can be noticeable, they’re often modest unless paired with structured training and nutrition.”
As with so many aspects of good health and athletic performance, timing can make a critical difference. Supplement timing may differ by individual and by the specific supplement chosen. Baah says if an individual supplements with nitrates, he might wish to consume them 2-3 hours prior to an athletic event. “This is when plasma nitrate peaks,” he says. In the case of supplemental citrulline, Baah feels 40-60 minutes pre-workout will suffice, as “this allows conversion to arginine (building blocks for protein) in time for the session.”
We can boost nitric oxide production within the body in a variety of ways. Whether one chooses to take supplements, eat different foods, or learn slow, meditative breathing, the potential to improve overall health and gain a competitive athletic edge seems easily within reach.
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