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What is Oxidative Stress and how can we Prevent it?

You’ve probably heard the term ‘oxidative stress’ buzzing around the health and wellness community, but you may be wondering “what does it actually mean?”

In simple terms, oxidative stress is the term given to an imbalance between free radicals and the antioxidant defence system in the body. Free radicals are the unpaired electrons resulting from various internal, physiological and external, environmental processes, such as inflammation, obesity, diets rich in sugar and processed foods, exposure to radiation and cigarette smoking. Due to their uneven number of electrons, free radicals can easily interfere and react with other molecules in the body. This leads to large chain chemical reactions, known as oxidation, which can be both positive and negative in the body. Oxidation and free radicals can help fight off pathogens; therefore, reducing risk of infection. However, excessive oxidation and free radicals without the antioxidant defence to counterbalance can cause cell and tissue damage. Furthermore, this damage has been suggested to increase the risk of a variety of diseases. So to put it simply, we want to limit oxidative stress in the body!

This is where antioxidants – another word we’ve been hearing a lot of lately – come into play. The body’s natural antioxidant defence system can counteract the effects of free radicals, as antioxidants are able to donate spare electrons to stabilise the free radical, preventing oxidative stress and subsequent damage from occurring. However, when there is a build up of free radicals and oxidative stress, we often look to the diet as a method for obtaining further antioxidants and counteracting this oxidative stress.

How can oxidative stress affect the body?

When there is an imbalance in free radical activity and the body’s antioxidant activity, free radicals can begin reacting with the DNA, proteins and lipids of the body, increasing the risk of disease over time.

A review from Senoner and Dichtl (2019) concluded that free radicals and oxidative stress promote hypertension, arrhythmia, changes in the shape and size of the heart (cardiac remodelling) and the formation of atherosclerotic plaque in the arteries, which further exacerbates hypertension and may lead to cardiovascular disease.

Similar reviews suggest oxidative stress is involved in the development and progression of a variety of diseases, including type 2 diabetes, cancer, Alzheimer’s disease, Parkinson’s disease and general signs of ageing.

So, how can we prevent oxidative stress from occurring?

While avoiding some of the risk factors for free radicals and oxidative stress, such as inflammation or pollution, may be impossible, enhancing and improving the antioxidant defence system of the body through the diet can significantly reduce oxidative stress and its negative effects.

Antioxidants such as vitamin A, vitamin C, vitamin E, beta-carotene, lycopene and selenium can be found throughout many of the foods we commonly consume; however, certain foods have been suggested to have higher levels of antioxidants than others. The Carlsen et al (2010) database contains over 3100 foods, beverages, spices, herbs and supplements, tested and ranked based on total antioxidant content and free-radical scavenging abilities – or in layman’s terms – how effective these foods and other items may be for reducing and preventing oxidative stress through their antioxidant content.

Interestingly, the Carlsen et al (2010) study found that, overall, plant-based foods had significantly higher antioxidant content in comparison to animal-based foods and mixed food products. This means that fruits, vegetables, grains, legumes, nuts and seeds typically contained a higher antioxidant content in comparison to meat, fish, dairy products and eggs. The mean antioxidant content in the various plant-based foods was between 5-33x higher than that in animal-based foods! This finding suggests that a diet based primarily on plant-based foods is richer in antioxidants in comparison to a primarily animal-food based diet. This may be why diets such as the Mediterranean diet, which is rich in plant-based foods, have been associated with increased lifespan and a reduction in negative connotations of ageing, including prevalence of cardiovascular disease and type 2 diabetes.

The Carlsen et al (2010) study found that, of the day-to-day foods we may consume, foods such as herbs, spices, blackcurrants, wild strawberries, goji berries, dark chocolate, artichokes, dried apricots, kale, chillies, walnuts, pecans, sunflower seeds, tea, coffee, fruit juices, buckwheat, millet, barley and wholemeal bread were some of the most antioxidant-rich foods. Incorporating any of these foods and other plant-based foods into your diet is recommended in order to increase antioxidant intake and reduce oxidative stress in the body.

Aside from nutrition, there are several other healthy lifestyle changes you can make in order to reduce your oxidative stress and the risk of its negative health associations.

  • Exercise: While strenuous, excessive exercise (especially in individuals who do not exercise often) has been suggested to increase oxidative stress in the body, a progressive, regular exercise regime has been suggested to lead to an adaptive response in the body to this oxidative stress, finding an increase in natural antioxidant levels.
  • Sleep: Getting an ample amount of sleep and increasing time sleeping to between 7 and 9 hours per night has been suggested to improve the body’s ability to defend against oxidative stress and the production of free radicals. Research has also suggested that antioxidant levels reduce during sleep deprivation, leading to relative cell damage. During sleep recovery, these antioxidants levels improved.
  • Stop smoking: Tobacco fumes, whether directly inhaled or consumed through second-hand smoke, have been suggested to increase oxidative stress and free radical production in the body. By stopping smoking and avoiding second-hand smoke where possible, we reduce this risk.
  • Reduce alcohol intake: Likewise, consuming alcohol, especially in large quantities, increases free radical production and oxidative stress in the body. One exception to this is red wine! While the alcohol in red wine does exacerbate oxidative stress, some research has found red wine to increase blood plasma antioxidant levels due to the rich antioxidant content of red grapes. However, this research still found oxidative damage to lipids following a 4-week red wine trial.
  • Wear sun cream: Research suggests that UV radiation from the sun also increases oxidative stress in the skin cells, increasing risk of skin inflammation, premature signs of ageing and cancer development. Wearing sun cream with sufficient UV protection has been found to increase the antioxidant response and defend against oxidative stress.




Contribution from Beth Addey ANutr