Demystifying Oxidative Stress

If you haven’t heard the term “oxidative stress” mentioned at least once a day in social media, supplement advertisements, and popular magazines, you might be living under a rock. (Can I join you there, by the way?) Oxidative stress is the latest fear-mongering buzzword tossed around the health and wellness community these days. It sounds scary and bad, very scientific, and hard to understand. In this article I hope to shed light and clarity on just what oxidative stress is, so you can make lifestyle choices for yourself and your loved ones based on facts, not hype.

First, the technical definition: oxidative stress is a state of imbalance between the production of free radicals and the body’s ability to counteract their damaging effects.

Where do free radicals come from?

Almost every type of cell in the body contains structures called mitochondria. These are the “powerhouses” of the cells that take in oxygen and nutrients and convert them into energy for the cell to continue living. During that process, oxygen molecules are split into single atoms with unpaired electrons. An atom with an unpaired electron is what we call a free radical.

Electrons like to be in pairs (i.e. “stable”) so free radicals scavenge the body to seek out other electrons so they can become a pair. It’s during this scavenging process (called “oxidation”) that free radicals cause damage to various types of cells.

Although free radicals are damaging, they are a normal part of life. Besides being a natural byproduct of normal cellular processes, free radicals are an important element of our immune system, destroying viruses, bacteria and damaged body cells. Free radicals are also produced during exercise, in order to help muscle cells become more receptive to insulin. However, the body also produces free radicals in response to negative impacts in the environment – such as tobacco smoke, ultraviolet rays, exposure to certain chemicals, or air pollution.

When the volume of free radicals and the amount of antioxidants are balanced, everything chugs along just fine and all is well. But when too many free radicals are produced and the body’s antioxidant production can’t keep up with neutralizing them, we get an overabundance of free radicals – otherwise known as oxidative stress. Oxidative stress, when unmanaged, can lead to oxidative damage – the real problem.

Where do antioxidants come from?

“Antioxidant” is a general term for any compound that can counteract free radicals. As just described, free radicals steal electrons from other molecules, damaging those molecules in the process. Antioxidants “neutralize” free radicals by giving up some of their own electrons.

It’s important to understand that “antioxidant” is a chemical property, not a specific nutritional element.

First, the body’s cells naturally produce certain powerful antioxidants, such as alpha lipoic acid and glutathione. Next, the foods we eat supply other antioxidants, such as vitamins C and E. Plants are full of compounds known as phytochemicals, of which many appear to also have antioxidant properties:

  • Hesperetin, found in oranges and other citrus fruits
  • Lycopene, in tomatoes
  • Lutein, found in kale
  • Flavanols in cocoa (dark chocolate!)
  • Anthocyanins in blueberries
  • Quercetin that’s in apples and onions
  • Catechins in green tea

First the stress, then the damage

Oxidative stress isn’t the real problem – oxidative damage is. Oxidative damage to cells and tissues occurs when the body is unable to keep up with and neutralize free radical production. Free radicals target fatty tissue (called “lipids”), DNA, and proteins in the body. Proteins, lipids, and DNA make up a large part of the body, so that damage can lead to a vast number of diseases over time. These include:

  • Diabetes
  • Atherosclerosis, or the hardening of the blood vessels
  • Many inflammatory conditions
  • High blood pressure and heart disease
  • Neurodegenerative diseases, such as Parkinson’s and Alzheimer’s
  • Cancer

It’s also theorized that oxidative damage contributes to aging.

Root causes of oxidative damage

Rancid Vegetable Oils

The membranes of our cells, which hold the cell together and give it form, are mostly made up of delicate fatty acids, the types and composition of which is directly influenced by what kinds of fats we eat. For example, consuming anti-inflammatory omega-3 fatty acids (ex. fish oil) is very beneficial to cell membrane structure and function. On the other hand, eating “rancid” dietary fats actually deteriorates cell membrane health, leading to oxidative damage.

So what are “rancid dietary fats”? Well, they’re in every grocery store and well-ingrained in the standard American diet. They’re industrially created vegetable oils, including canola, soybean, peanut, and safflower oils. What they all have in common is a high content of omega-6 polyunsaturated fatty acid (PUFAs for short). Omega-6 PUFAs are extremely susceptible to damage from heat and light, and when this happens, they become oxidatively damaged, becoming “rancid.”

The very process by which industrial vegetable oils are made exposes omega-6 PUFAs to heat, metals, and other chemicals. Worse yet, the damage doesn’t stop there – when we cook with vegetable oils, we oxidize them even further.

The story gets worse from here. When unsaturated fats in industrial vegetable oils are oxidized, they produce substances called ALEs (advanced lipid oxidation end products). ALEs are absorbed from the gut into the bloodstream, where they activate an inflammatory response that generates various toxic compounds. They also become part of the cell membranes, making them more permeable and subject to damage. ALE’s also damage and thereby deplete the body’s stores of antioxidant vitamins A, C, and E.

The combination of inflammation and antioxidant depletion caused by the consumption of industrial vegetable oils propagates a chain reaction of oxidative damage in the body.

Just be aware that omega-6 itself is not the problem – it’s the way omega-6 fatty acids are handled during processing and cooking that damage them and make them pro-inflammatory. Fresh, whole foods high in omega 6, such as poultry, avocados, and nuts, are part of a healthy diet.

Antioxidant insufficiency

Antioxidants are best obtained from a whole-food, nutrient-dense diet rather than supplements. In fact, numerous studies have shown that antioxidant supplements have no benefit and may even cause harm.

Furthermore, naturally occurring antioxidants in foods are packed with cofactors and enzymes that make them more effective and better absorbed than synthetic ones. Other compounds in antioxidant-rich whole foods produce effects that can’t be replicated with a synthetic, isolated antioxidant supplement.

What to do: To increase antioxidant levels, eat plenty of colorful fruits and vegetables. Grass-fed meats are also an excellent source of antioxidants, including vitamin E, glutathione, and the antioxidant enzyme superoxide dismutase.

Lifestyle and environmental factors

Not surprisingly, many aspects of our lifestyle and our environment have been shown to lead to oxidative damage. These include:

  • Cigarette smoking
  • Environmental toxin exposure – particulate air pollution in urban areas and mold and biotoxins in water-damaged buildings promotes oxidative stress by depleting antioxidant reserves. Also, BPA plastics, pesticides, and heavy metals all contribute to excess free radical production.
  • Lack of sleep
  • Physiological stress
  • Chronic infections – such as gingivitis, H. pylori, and hepatitis C
  • Lack of physical exercise – although regular physical activity induces the production of free radicals in the short term, it actually increases antioxidant production over the long term.

Key takeaways

Eat an antioxidant-rich, whole-foods diet. This includes plenty of colorful fruits and vegetables. Grass-fed meats are also an excellent source of antioxidants, including vitamin E, glutathione, and the antioxidant enzyme superoxide dismutase.

Avoid processed, packaged foods and get rid of any canola, soybean, safflower, sunflower, peanut, or grapeseed oil in your kitchen. Replace them with anti-inflammatory fats found in extra virgin olive oil and coconut oil.

Include other sources of healthy fats in your diet, such as avocados, wild-caught seafood, and sprouted or lightly roasted nuts and seeds.

Don’t take antioxidant supplements, no matter how miraculous the claims their proponents make. Instead, get your antioxidants from their natural food sources.

Get plenty of sleep, and exercise regularly. Both have many additional health benefits besides fighting free radical production.

Find a daily stress-reduction practice that you enjoy. Meditation, yoga, spending time in nature, and taking “technology breaks” all help alleviate chronic stress.  [Read:  Meditation is for Everyone. Also check out the great website .]

Laurie Kelly, CPT, CES is a Fitness and Nutrition Coach who works with clients virtually to help them transform their health and fitness. She takes a holistic approach to her clients’ wellness through strength training, cardiovascular exercise, real life/behavior-based nutrition strategies and recovery techniques. She’ll work with you one-on-one to help you live a healthy and active life and achieve your unique fitness goals. Contact her here or follow her blog at

Selected References:

Kresser, Chris. What Really Causes Oxidative Damage? 14 June 2018

Harvard Health Publishing. Understanding antioxidants. Harvard Medical School.

Everything You Should Know About Oxidative Stress.

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