What Is Oxidative Stress and How Does Nutrition Help?

What oxidative stress actually is

A free radical is an atom or molecule with an unpaired electron.¹ That unpaired electron makes the molecule unstable and reactive. It will attack nearby molecules, trying to steal an electron to become stable again. In doing so, it damages the molecule it attacks.

Your cells generate free radicals constantly as a byproduct of normal metabolism. Mitochondria produce them when they convert glucose into ATP. Immune cells produce them when they kill bacteria. UV exposure generates them in your skin. Inflammation generates them. Some free radical production is normal and even necessary. It's part of how cells signal each other.

But when free radical production exceeds your body's capacity to neutralise them, oxidative stress occurs. The excess free radicals damage the very molecules that cells depend on. Lipid peroxidation damages cell membranes. Protein oxidation damages enzymes. Oxidative damage to DNA can cause mutations that lead to cancer.

Modern life accelerates free radical production. Chronic inflammation from processed food and stress. Excessive exercise without adequate recovery. Air pollution. Blue light exposure. All of these drive oxidative stress. Your antioxidant defences haven't evolved for this much exposure.

Why it accelerates ageing and disease

Oxidative stress is a major driver of ageing. When free radicals damage proteins, your cells have to spend energy replacing them. When they damage mitochondrial DNA, mitochondria function less efficiently. When they damage telomeres, cells lose the ability to divide. Over years and decades, this accumulated damage drives cellular ageing.

Chronic oxidative stress is also involved in virtually every age-related disease. Cardiovascular disease, neurodegeneration, cancer, diabetes, arthritis. In each case, oxidative stress is part of the mechanism that drives disease progression.

This isn't to say free radicals are purely bad. They have signalling functions. But the problem is balance. When antioxidant defences are overwhelmed, the damage cascades. A single burst of oxidative stress can initiate a chain reaction of cellular damage that takes days to repair.

Oxidative stress isn't about having free radicals. It's about the balance between free radical production and your antioxidant defences. When defences are strong, free radicals are neutralised before they damage cellular components.

Your body's antioxidant defences

Your body doesn't rely on vitamin E or vitamin C to handle oxidative stress. Those are helpful, but they're minor players. The heavy lifting is done by your own antioxidant enzymes, particularly three: superoxide dismutase (SOD), catalase, and glutathione peroxidase.

SOD converts the superoxide free radical, one of the most destructive, into hydrogen peroxide and oxygen. Catalase then converts hydrogen peroxide into water and oxygen, neutralising it harmlessly. Glutathione peroxidase uses the tripeptide glutathione to neutralise various free radicals and lipid peroxides.

These three enzymes form a coordinated defence system. If any one of them is impaired, free radicals accumulate faster. If all three are robust, your cells can tolerate significant oxidative insult without damage.

Your body produces these enzymes in proportion to the oxidative stress it faces. In response to exercise, for example, mitochondria produce more free radicals, and your cells respond by upregulating SOD and catalase production. This is why moderate exercise is protective. It stimulates antioxidant defence adaptation.

But this adaptive capacity has limits. Chronic overproduction of free radicals (from excessive inflammation, air pollution, overtraining without recovery) can overwhelm adaptation. The antioxidant defences are maximally activated and still can't keep up.

How nutrition supports these defences

Your antioxidant enzymes are proteins. They require specific minerals as cofactors to function. SOD requires copper, zinc, and manganese. Catalase requires iron. Glutathione peroxidase requires selenium. Without these minerals, these enzymes can't be assembled or function properly.

Additionally, glutathione synthesis requires adequate glycine, glutamate, and cysteine. If your amino acid status is poor, or if your methylation status is poor (which affects cysteine availability), glutathione production drops. And glutathione is central to your entire antioxidant system. It doesn't just neutralise free radicals. It regenerates other antioxidants so they can be used again.

Organ meats are extraordinarily rich in both the minerals and amino acids that support antioxidant defences. Beef liver contains roughly 6 milligrams of copper per 100 grams, far more than muscle meat. It's rich in iron, zinc, and selenium. Oysters are famously high in zinc and copper. Kidney is rich in selenium.

Bone broth, made from connective tissue and bones, provides glycine in abundance, supporting glutathione synthesis. It also provides minerals like magnesium and calcium that serve as cofactors for antioxidant enzymes.

Vitamin E and C do play a supporting role. Vitamin E protects cell membranes from lipid peroxidation. Vitamin C helps regenerate vitamin E. But they're best thought of as supporting actors. The main defence is your own antioxidant enzyme system, and that depends on minerals and amino acids.

Your body's antioxidant defences don't come from supplements. They come from your own enzymes, which require copper, zinc, manganese, iron, and selenium as cofactors. Organ meats and bone broth provide these in abundance.

Modern oxidative stressors you can control

Understanding oxidative stress in isolation isn't helpful if you're not addressing the sources. Your antioxidant defences are powerful, but they're finite. If you're chronically driving free radical production through modifiable behaviours, supplements and nutrients are playing defence whilst you create offence.

Processed food is one of the largest drivers. Refined carbohydrates spike blood sugar, driving free radical production in response to elevated glucose. Seed oils, unstable at high temperatures, oxidise during cooking and create oxidative stress when you eat them. Excess alcohol drives free radical production. Chronic sleep deprivation impairs your antioxidant enzyme production, creating a downward spiral.

Over-exercise without adequate recovery is another surprise culprit. Moderate exercise upregulates antioxidant defences. Excessive exercise without sufficient recovery overwhelms them. You create more free radicals than your system can handle. This is why athletes often show signs of accelerated ageing if they're training hard without attention to recovery, sleep, and nutrient density.

Chronic stress elevates cortisol, which drives inflammation and oxidative stress. Air pollution, particularly fine particulate matter, triggers oxidative stress directly in your lungs and throughout your body. Blue light exposure from screens, especially late in the day, impairs mitochondrial function and increases free radical production.

Nutrition supports your antioxidant defences. But so does sleep, stress management, avoiding seed oils, and moderating exercise intensity relative to recovery.

Practical implementation

Knowing the mechanism is useful only if it translates to action. Here's a practical hierarchy. First, reduce the drivers of oxidative stress. Cut processed food. Replace seed oils with butter, coconut oil, or animal fats that are stable at high heat. Prioritise sleep. Manage stress through whatever works for you, walks, breath work, community, practice.

Second, eat nose-to-tail. Organ meats aren't a supplement. They're food. Beef liver once or twice per week provides copper, zinc, iron, and selenium in quantities that synthetic supplements struggle to match. The cofactors work synergistically. You're not isolating single nutrients. You're eating the entire mineral complex that evolution designed.

Third, include bone broth or collagen peptides for glycine, or ensure you're eating gelatinous cuts, bone-in meats, slow-cooked stews, cartilage-rich offal. Glycine is fundamental to glutathione synthesis, and it's rare in muscle meat. It concentrates in connective tissue.

Fourth, don't neglect the minerals themselves. If you're not eating organ meats regularly, consider targeted supplementation with zinc and selenium particularly. These are difficult to get consistently from plant sources. A single brazil nut provides substantial selenium, but consistency is the issue. Organs provide it reliably.

The bottom line

Oxidative stress is a fundamental driver of ageing and disease, but it's preventable and manageable. Your body has sophisticated antioxidant defences built on three main enzymes: SOD, catalase, and glutathione peroxidase.² These defences require specific minerals and amino acids to function.

Rather than chasing antioxidant supplements, prioritise the nutrients that enable your own antioxidant systems. Eat organ meats for copper, zinc, iron, and selenium.³ Drink bone broth for glycine and mineral cofactors. Ensure adequate protein for amino acid building blocks. Manage stress and inflammation, which drive free radical production.

Moderate exercise, adequate sleep, and a stable stress load also support your antioxidant adaptation. These are the foundations. Superimposed on that foundation, targeted supplementation with specific minerals might help. But nutrition is the base. Get that right, and your cells can handle oxidative stress the way they evolved to.

References

1. 1. Sies H. Oxidative stress: a concept in redox biology and medicine. Redox Biol. 2015. PMC4309843.
2. 2. Ighodaro OM, Akinloye OA. First line defence antioxidants — superoxide dismutase, catalase, and glutathione peroxidase. Alex J Med. 2018. sciencedirect.com.
3. 3. NIH Office of Dietary Supplements. Selenium fact sheet. ods.od.nih.gov/factsheets/Selenium-HealthProfessional.