More Than Just Air: Should Oxygen Be Called a Nutrient?

The essential substance we can’t live without — and why nutrition science may be overdue for a rethink.

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From a young age, we learn that nutrients include carbohydrates, proteins, fats, vitamins, and minerals. These are the basic parts of food that keep us alive. But there is one substance we constantly take in that is essential for all these nutrients to work, yet it is rarely considered a nutrient: oxygen.

If we don’t have oxygen, we lose consciousness in seconds and can die within minutes. Oxygen is just as important as food or water, but it usually isn’t included in definitions of nutrition. This raises an important question: should oxygen be considered a nutrient? And if so, why has it been left out for so long?

Why Oxygen Hasn’t Been Classified as a Nutrient

The exclusion of oxygen from nutrition science is largely historical rather than biological. Nutrition developed as a discipline focused on diet, digestion, and substances absorbed through the gastrointestinal tract. Oxygen enters the body through the lungs, not the mouth, and this single difference has shaped how it is categorized. So, it seems, the means of entering the body was the defining factor here.

Another reason is that oxygen is readily available to most people at sea level. Nutrition science has usually focused on nutrients that are scarce or missing, such as in scurvy, rickets, or iron-deficiency anemia, where not having enough of a nutrient causes disease. Oxygen deficiency is less obvious in normal situations.

Oxygen also lacks a recommended daily allowance. Breathing is automatic, tightly regulated by the nervous system, and adjusted moment to moment according to metabolic demand. Because oxygen intake does not require conscious planning, it has been treated as background physiology rather than nutrition.

What Defines a Nutrient?

If we set tradition aside, the usual definitions of a nutrient actually fit oxygen very well. Dictionaries and biology books say nutrients are things needed for life and growth. Oxygen clearly fits this description.

On the cellular level, oxygen acts just like a nutrient. It’s taken in, moved around, delivered, and used in important chemical reactions. Hemoglobin carries oxygen in the blood, just as lipoproteins carry fats or transferrin carries iron. The main difference, as indicated, is how it gets into the body.

Water is a good example to compare. Everyone agrees water is a nutrient, even though it has no calories and doesn’t need to be digested. Like water, we need oxygen all the time to survive. The only real difference is that we breathe in oxygen rather than drink it.

The Central Role of Oxygen

Oxygen’s most important job is energy production. In the mitochondria, oxygen is the last step in a process called oxidative phosphorylation, which lets cells make adenosine triphosphate (ATP). ATP powers everything in the body, from moving muscles to thinking.

If there isn’t enough oxygen, cells have to switch to an alternative way of producing energy, which results in much less energy and creates byproducts like lactate. So, oxygen decides if our bodies can use the nutrients we eat. Even the best diet can’t keep us healthy without enough oxygen.

What Happens When Oxygen Is Limited?

Even though oxygen is usually easy to get, some conditions make it harder for the body to get enough. High altitude, lung and heart diseases, sleep apnea, severe obesity, and some cancers can all lower how much oxygen reaches our tissues.

When oxygen levels fall, cells activate complex survival responses mediated by hypoxia-inducible factors. These molecular systems alter gene expression, shift metabolism toward anaerobic pathways, and conserve energy. While lifesaving in the short term, chronic low oxygen contributes to inflammation, insulin resistance, impaired wound healing, and progression of cardiovascular and metabolic disease.

For example, in obesity, growing fat tissue can get too big for its blood supply, causing a lack of oxygen in those areas. This low oxygen sets off inflammation that is linked to insulin resistance and type 2 diabetes. So, not having enough oxygen can be just as serious as missing vitamins or minerals.

Arguments Against Using Oxygen as a Nutrient

There are reasonable objections to labeling oxygen a nutrient. Nutrition science serves practical purposes such as dietary guidance and public health policy. Oxygen intake can’t be meaningfully modified through diet, and for most people, it doesn’t require monitoring.

There’s also a risk of confusion. Oxygen therapy is already a medical treatment, especially in emergencies and for chronic lung problems. Some physicians think calling oxygen a nutrient could blur the line between diet advice and medical care.

Oxygen can also be toxic. Excess oxygen promotes the formation of reactive oxygen species, which damage cells and tissues. Premature infants exposed to high oxygen concentrations, for example, are at risk of retinal injury and blindness. As with some vitamins and minerals, the dose matters.

Why Reconsidering Oxygen Matters

Even if oxygen isn't listed on a nutrition label, treating it as a nutrient has real benefits. It helps us see how breathing, metabolism, and diet all work together. Being active helps the body deliver and use oxygen more effectively, making it easier to use nutrients well. Air quality, smoking, indoor pollution, and occupational exposures directly affect oxygen availability at the tissue level. And framing oxygen as a nutrient highlights these influences within overall health.

From a medical perspective, treating oxygen as a nutrient underscores the importance of delivering sufficient oxygen in chronic diseases. Problems like anemia, lung disease, heart failure, and sleep disorders all make it harder for the body to move oxygen, which means other nutrients don’t work as well.

So What's the Story?

Oxygen has largely been excluded from nutrition science because of tradition, not because it doesn’t meet the biological definition of a nutrient. It’s essential for life, always needed, and key to energy production and staying healthy.

Whether we officially call oxygen a nutrient or not, understanding its role alongside food and water gives us a fuller view of health. Nutrition is about what we eat and what we breathe, and how well our bodies use both.

What will dietary science do regarding oxygen’s place in their discipline in the future? It’s an intriguing question because oxygen must be included in the total guidance for everyone, whether they are patients or healthy individuals.