4 Supplements You Can Take That Increase Oxygen

Four supplements with meaningful research behind them can influence how your body takes in, transports, or uses oxygen: iron, beetroot juice (dietary nitrate), cordyceps, and Rhodiola rosea. None of them work like breathing from an oxygen tank, and the mechanisms vary widely. Some boost the blood’s capacity to carry oxygen, others help muscles extract it more efficiently or protect oxygen saturation at altitude. The strength of evidence differs for each, and in several cases what works for one person does nothing for another.

Iron

Iron is the most straightforward of the four because the biology is well understood. Your red blood cells use iron to build hemoglobin, the protein that physically binds oxygen in the lungs and ferries it to every tissue in the body. When iron stores drop, hemoglobin production slows, fewer oxygen molecules hitch a ride per unit of blood, and your muscles and brain feel it. Fatigue, breathlessness during exertion, and poor exercise tolerance are classic signs.

The evidence for supplementation is strong but conditional: it works best when your iron stores are genuinely low. A study of iron-deficient female athletes found that two months of iron supplementation significantly improved body iron status and increased maximal oxygen uptake, but only in those who had progressed to actual iron deficiency anemia. Athletes who were iron-depleted without anemia saw their iron markers improve but did not get a measurable bump in oxygen uptake.¹ If your iron levels are already normal, extra iron will not push oxygen-carrying capacity any higher.

This matters because iron is not harmless in excess. It generates free radicals by cycling between its two chemical forms, and while the body’s regulatory systems handle normal levels of iron without trouble, pathological overload can cause damage.² The practical takeaway: get your ferritin and hemoglobin checked before supplementing. If you are deficient, iron is one of the most reliable ways to improve oxygen delivery. If you are not, supplementing is all risk and no reward.

Beetroot Juice and Dietary Nitrate

Beetroot juice has become the darling of endurance sports, and the reason is nitric oxide. Beetroot is rich in inorganic nitrate, which your body converts into nitric oxide, a molecule that widens blood vessels and improves how efficiently muscles use the oxygen they receive. As a source of nitrate, beetroot provides a natural way to increase nitric oxide availability and has emerged as a strategy for managing conditions linked to low nitric oxide, including high blood pressure and poor blood vessel function.³

The oxygen angle is specific. Beetroot juice does not put more oxygen into your blood. Instead, it appears to lower the amount of oxygen your body needs for the same amount of work. One study found that whole-body oxygen consumption dropped by about 3% during cycling at a fixed intensity after beetroot juice supplementation, though the researchers confirmed this was not due to any change in how mitochondria themselves functioned.⁴ The body simply needed less oxygen to produce the same output. That distinction is important: “increasing oxygen” here means getting more out of each breath, not getting more oxygen into the bloodstream.

There is a significant catch involving fitness level. Among well-trained cyclists, multiple days of high-dose beetroot juice supplementation did not alter exercise efficiency, oxygen uptake speed, or muscle oxygen use during either normal or low-oxygen conditions.⁵ A randomized crossover trial in healthy men also found that beetroot juice did not improve forearm oxygen delivery, blood flow, or exercise tolerance during progressive exercise, despite increasing the arteriovenous oxygen difference at certain intensities.⁶

The pattern across the research is consistent: beetroot juice tends to help recreational and moderately trained exercisers more than elite athletes. The explanation usually offered is that highly trained individuals already have well-optimized nitric oxide pathways, so the extra nudge from dietary nitrate has diminishing returns. If you are a casual runner, swimmer, or gym-goer, beetroot juice before a hard session may let you work at the same pace while using slightly less oxygen. If you are already at the sharp end of competitive sport, the benefit is likely negligible.

Cordyceps

Cordyceps is a genus of parasitic fungi with a long history in traditional Chinese medicine, often marketed with dramatic claims about oxygen and stamina. The modern research is thinner than the marketing suggests, but a few trials show genuinely interesting results. In a study of healthy young adults, three weeks of supplementation with Cordyceps militaris led to a significant improvement in maximal oxygen uptake, with the supplement group gaining roughly 4.8 ml per kilogram per minute over the placebo group. Time to exhaustion during high-intensity exercise also improved, by about 70 seconds after three weeks.⁷

The proposed mechanism relates to cellular energy production. An animal study found that Cordyceps militaris extract elevated levels of a key energy-sensing enzyme and showed trends toward increased ATP and other energy markers, though most of those changes did not reach statistical significance except at one particular dose.⁸ The idea is that if cells produce energy more efficiently, they can do more with the oxygen they receive.

A few caveats are worth noting. Most positive cordyceps studies are small, and the species matters: Cordyceps militaris (which can be cultivated) has more human trial data than the wild Cordyceps sinensis, which is extremely expensive and often adulterated. Supplement labels do not always make the distinction clear, and what ends up in the capsule varies widely across brands. If you want to try cordyceps, look for products specifying Cordyceps militaris with some form of third-party testing.

Rhodiola Rosea

Rhodiola rosea and its close relative Rhodiola crenulata have been used for centuries in high-altitude regions of Central Asia and Tibet, where the ability to maintain oxygen saturation under thin air is a matter of daily survival. Modern research has investigated whether the traditional use holds up, and the results are mixed but lean positive for altitude-specific situations.

A systematic review and meta-analysis of Rhodiola crenulata extract found that it significantly improved blood oxygen saturation levels compared to placebo, with a mean difference of about 7 percentage points. It also improved partial pressure of oxygen in arterial blood in one randomized trial. However, the researchers cautioned that high heterogeneity and risk of bias among the included studies prevent a firm conclusion.⁹ A separate controlled study found that pretreatment with Rhodiola crenulata extract significantly restored oxygen saturation that had been reduced by hypoxia exposure, and also protected cognitive function, including working memory and executive functioning, from altitude-related decline.¹⁰

Not every study agrees. One earlier trial found no effect of Rhodiola on hypoxemia during controlled hypoxia exposure, with oxygen saturation dropping similarly in both the supplement and control groups.¹¹ This inconsistency tracks with the meta-analysis’s warning about study quality. Researchers think Rhodiola may work partly by stabilizing a protein called HIF-1α, which cells use to sense and respond to low oxygen. Computational analysis has identified several Rhodiola compounds that could interact with the pathway that degrades this protein, potentially keeping the body’s oxygen-response machinery active for longer under stress.¹²

The bottom line on Rhodiola is that it looks most promising for people heading to high altitude or dealing with temporary low-oxygen environments. At sea level during a normal workout, the evidence for an oxygen benefit is much weaker. If you are planning a trek above 3,000 meters, starting Rhodiola a week or two before ascent is a reasonable hedge, but it should not replace gradual acclimatization or prescription options like acetazolamide when altitude sickness risk is high.

Why Your Mouth Bacteria Matter for Nitrate Supplements

An underappreciated piece of the beetroot story involves your oral microbiome. Dietary nitrate does not convert to nitric oxide on its own. After you swallow nitrate, your salivary glands concentrate it and secrete it back into the mouth, where specific bacteria on your tongue reduce it to nitrite. That nitrite is then swallowed again and eventually converted to nitric oxide in the stomach and bloodstream. This enterosalivary pathway is the bottleneck for every nitrate-based supplement’s effectiveness.

Research has shown that the balance of nitrite-generating versus nitrite-depleting bacteria in the mouth is associated with differences in cardiometabolic risk, suggesting these microbes play a functional role in the nitric oxide supply chain.¹³ And studies examining the effect of antibacterial mouthwash have found that wiping out oral bacteria reduces the conversion of nitrate to nitrite and, in some cases, raises blood pressure in otherwise healthy people.¹⁴

The practical implication is straightforward: if you are using beetroot juice or a nitrate supplement, using strong antiseptic mouthwash around the same time may blunt the benefit. This is the kind of interaction that rarely appears on supplement labels but can meaningfully affect whether you get results.

Near Misses and Honorable Mentions

Two other supplements come up frequently in oxygen conversations and deserve a quick look, even though the evidence does not quite justify putting them in the top four.

L-citrulline is an amino acid that the body converts into arginine and then into nitric oxide, similar in downstream effect to beetroot but through a different entry point. One trial found that short-term citrulline supplementation improved how quickly oxygen uptake ramped up during severe exercise and increased exercise tolerance in healthy adults.¹⁵ In hypertensive postmenopausal women, citrulline improved muscle oxygenation and blood flow during handgrip exercise.¹⁶ But not all studies agree: a trial testing a single 6-gram dose of citrulline found it increased nitric oxide bioavailability by about 19% yet failed to improve respiratory performance or inspiratory muscle oxygenation.¹⁷ Citrulline is promising, especially for older adults or people with cardiovascular issues, but the oxygen-specific evidence is still patchy.

Coenzyme Q10 (CoQ10) plays a role in the mitochondrial electron transport chain, where oxygen is ultimately consumed to produce energy. It shuttles electrons between the protein complexes that drive this process.¹⁸ In cells that are deficient in CoQ10, supplementation partially restored the activity of these complexes, but only partially, and the study used isolated neurons rather than exercising humans.¹⁹ CoQ10 may help people with genuine deficiency states or mitochondrial dysfunction, but for a healthy person looking to boost oxygen use during exercise, the evidence is not there yet.

How to Tell If a Supplement Is Actually Working

Many people who try these supplements reach for a pulse oximeter or smartwatch to check their blood oxygen saturation. This approach has limits. A validation study comparing a dedicated finger pulse oximeter and an Apple Watch Series 7 during controlled drops in oxygen found that both devices tended to overestimate oxygen saturation. The dedicated oximeter fell within an acceptable error range only about half the time, and the smartwatch managed it about a third of the time. Both devices became less accurate at lower saturation levels.²⁰

This means that if you are a healthy person sitting at sea level, your oxygen saturation is already in the high 90s, and consumer devices are not sensitive enough to detect the subtle shifts that supplements might cause. You are more likely to see noise than signal. Better markers of whether a supplement is working include exercise performance, perceived effort during familiar workouts, or, for iron specifically, lab tests showing ferritin and hemoglobin changes. Chasing a number on a wrist gadget is likely to lead you astray.

When Supplements Can Work Against You During Training

There is an irony in the supplement-for-oxygen space that rarely gets mentioned. Your body adapts to exercise partly by sensing the stress of oxygen depletion and ramping up its internal defenses, including building more mitochondria. Some evidence from animal studies shows that daily antioxidant supplementation during an exercise training program prevented the expected increases in mitochondrial biogenesis markers and mitochondrial protein levels in muscle.²¹ The supplements essentially mopped up the molecular signals that told muscles to get stronger.

This does not apply to every supplement discussed in this article. Iron, for example, is replenishing a deficiency, not blunting a stress signal. Beetroot juice works through a nitric oxide pathway that is separate from the antioxidant question. But if you are stacking a long list of supplements that includes high-dose vitamins C and E alongside your beetroot and cordyceps, you may be dulling the very training stimulus you are trying to enhance. More is not always better when the goal is long-term aerobic improvement rather than a one-day performance boost.

Beetroot Juice and Sleep Oxygenation in Lung Disease

One of the more unexpected findings in the nitrate literature comes from a study of people with chronic obstructive pulmonary disease (COPD). These patients often experience drops in blood oxygen during sleep, which contributes to poor sleep quality and daytime fatigue. The study found that beetroot juice extended the time that oxygen saturation stayed elevated above waking-after-sleep-onset levels by 43% compared to placebo.²² This suggests that dietary nitrate’s vasodilatory effects may have value beyond exercise, helping maintain oxygen levels during the passive, uncontrolled setting of sleep in people whose lungs are compromised. It is a small study and not a treatment recommendation, but it points toward uses of nitrate supplementation that go well beyond the running-track context most people associate with beetroot juice.