Nitric oxide supplements have been popular among gym-goers and bodybuilders for many years, and the general population has taken an interest in these products for their purported heart-health benefits. Naturally, dietary nitrate supplements like beetroot powder are proliferating in supermarkets and online retailers.
So, why all the buzz about dietary nitrates? Well, along with nitric-oxide-boosting amino acids like L-arginine and L-citrulline, dietary nitrates are essential for proper blood flow and cardiovascular function. More specifically, nitrates can help lower blood pressure levels by dilating blood vessels (via a complementary amino-acid-independent mechanism that increases nitric oxide production).
As such, dietary nitrates prove helpful in heart health applications and the realm of athletic performance. They also confer plausible synergy with traditional pre-workout nitric oxide boosters like L-citrulline.
But there's some finer detail we have to consider regarding nitric oxide production and how the body regulates blood flow and blood pressure. High levels of nitric oxide aren't necessarily optimal, and the body has compensatory mechanisms to reduce nitric oxide levels if necessary. Read on and we'll break down the intricacies of blood flow, nitric oxide, and nitrate supplements.
Nitric oxide (•NO) is an atypical neurotransmitter, free radical, and promiscuous vasodilator that plays a central role in vascular tone and inflammatory response . Being a small lipophilic molecule, nitric oxide interacts with diverse intracellular and extracellular targets depending on the surrounding chemical milieu. However, the hemodynamic effects of nitric oxide (and its molecular precursors) remain the focus of this article.
As more people seek natural alternatives to increase nitric oxide production and lower blood pressure levels, nitrates have garnered considerable attention alongside the classical "NO boosters" L-arginine and L-citrulline.
Since nitric oxide is a gas, it is not found in food. Rather, the body synthesizes it endogenously via two distinct pathways:
The amino acid L-arginine is an essential precursor of nitric oxide, but dietary nitrates provide a complementary mechanism to form nitric oxide in the body. In fact, these two pathways feed off one another in a cyclical fashion to maintain levels of nitric oxide within a healthy physiological range ; when nitrate intake increases, nitric oxide synthase activity decreases and vice versa.
The sections below briefly summarize how the body produces nitric oxide from either arginine or nitrates.
The amino acid L-arginine is the primary substrate of the enzyme nitric oxide synthase (NOS). This enzyme has three distinct isoforms that are tissue-specific:
Each of these enzyme isoforms catalyzes the conversion of L-arginine to L-citrulline, which produces nitric oxide as a byproduct. L-citrulline can then be recycled back to L-arginine to produce more nitric oxide on demand.
Arginine is the main ingredient in countless pre-workout powders and supplements designed to boost nitric oxide levels. However, L-citrulline is arguably the superior choice since it is not metabolized by the liver like arginine is . Instead, supplemental L-citrulline passes to the kidneys, serving as a reservoir of L-arginine and, by extension, nitric oxide.
As a complementary pathway to the classical L-arginine-dependent mechanism, the body is capable of producing nitric oxide via its major biological end-products: nitrate (NO3-) and nitrite (NO2-). Reductase enzymes and bacteria found in the oral mucosa help reduce nitrate to nitrite, which is then further reduced to nitric oxide (especially under acidic conditions).
The low pH environment of the stomach favors nitrite reduction to nitric oxide, and research suggests that vitamin C (ascorbic acid) — an acidifying agent and antioxidant — bolsters this conversion .
Nitric oxide levels directly influence hemodynamics and cardiovascular health by regulating blood pressure, blood flow, and redox reactions. In general, as dietary nitrate intake increases, the body produces more nitric oxide and blood pressure drops (thereby facilitating blood flow); the converse is also true.
Hence, many people presume that higher levels of nitric oxide are inherently better for health and athletic performance. Still, as with just about any chemical, there is a threshold where "good" turns to "bad." Depending on the oxidant capacity of nearby cells, nitric oxide can thwart or induce oxidative stress . For example, nitric oxide can react with superoxide to create peroxynitrite, a potent pro-oxidant that damages DNA and cell membranes .
Fortunately, the amount of nitrate and nitrites that would have to be consumed to incur nitric oxide toxicity is virtually unobtainable through diet alone. Recent evidence questions whether we should recommend daily intake limits for nitrate and nitrite, which are currently set at 7 mg/kg body weight and 0.12 mg/kg body weight per day, respectively . The so-called Dietary Approaches to Stop Hypertension (DASH) diet is suggested to provide upwards of four times more than the acceptable daily intake of dietary nitrate for a 70-kg (~154-lb) adult.
Eating plenty of nitrate-rich vegetables (e.g. leafy greens and sugar beets) is a great way to support your heart health and increase nitric oxide levels. Unfortunately, a good proportion of nitrates found in the modern Western diet derive from added sodium nitrate/sodium nitrite used in processed meats. Sodium nitrate and sodium nitrite are frequently used as food additives in deli meat to preserve freshness and prevent bacteria from forming. Sodium nitrite is a known precursor of carcinogenic N-nitroso compounds .
In the same sense that monosodium glutamate is a source of glutamate, sodium nitrate is a source of nitrate. Controversy persists over the adverse health effects of consuming cured meats in large amounts, but current empirical evidence favors limiting their intake whenever possible .
The good news is there are plenty of wholesome "nitric oxide foods" that provide naturally occurring dietary nitrate. Here are ten of the best foods to eat to increase nitrate intake:
The vast majority of research on beetroot and cardiovascular function uses beetroot juice as the primary intervention . It's important to note that beetroot juice is not the same as beetroot powder you find at the supermarket or online. Beetroot juice used in studies is typically enriched with nitrate and provides considerably more than you would get from multiple doses of beetroot powder.
Considering that fresh beets provide about 25 mg of nitrate per 100 g, it's doubtful that a standard 4-gram serving of beetroot powder will yield physiologically relevant doses of nitrate . It's also unclear if the blood-pressure-lowering benefits of beetroot juice are solely due to nitrate or other bioactive compounds in sugar beets .
Given the dual-faceted nature of nitric oxide production and a lack of standardization with beetroot powder, the upcoming Transparent Labs Pump formula contains ample doses of reliable NO boosters like vitamin C, arginine nitrate, and L-citrulline. These ingredients provide robust increases in blood flow, exercise performance, and muscle pumps during training. For those that desire cardiovascular-specific health benefits, check out the Transparent Labs Cardio formula.
These supplements are designed to boost nitric oxide levels and improve blood flow but with distinguishing features suited to their respective applications. And importantly, each provides clinical doses of evidence-based active ingredients and fully transparent labels so you know exactly what you're getting.