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Dec 13, 2021
6 min read

Oxidative stress: causes, effects, prevention

Oxidative stress occurs when there’s an imbalance between free radicals and the body’s ability to fight them with antioxidants—leading to cell damage and contributing to diseases like atherosclerosis, cancer, diabetes, and kidney disease. You can keep levels of oxidative stress low by avoiding triggers of oxidative stress like ultraviolet radiation, cigarette smoke, and alcohol and by supporting your body’s antioxidant defense system.

Disclaimer

If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Think back to a time when you were in school, and your teacher said, “Time to break off into groups!” Do you remember the chaotic hustle that followed as you tried to find your friends to make sure you weren’t left standing alone, stressed, without a group? 

Your body experiences something called oxidative stress when it’s faced with a somewhat similar situation. Let’s dive more into this analogy so you can get a better understanding of what oxidative stress is, what causes it, and how you can prevent it. 

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What is oxidative stress?

Oxidative stress occurs when there’s an imbalance between free radicals and the body’s ability to fight them with antioxidants (more on that later). In order to understand this concept, we first have to explain what free radicals are. 

Free radicals are molecules that contain oxygen (most of the time) and have an odd number of electrons, making them unstable and destructive (Lobo, 2010). Using our group analogy above, just like you may feel stress being left without a partner or group, molecules in your body don’t like it when their electrons are unpaired. 

But they don’t suck it up and do the group projects with one less participant. They go scavenging to seek out and bind electrons from other groups (i.e., molecules), causing a negative chain of events along the way. In the body, that process of reacting with other molecules can damage our cells. 

To counter the potential damage from these free radicals, the body relies on antioxidants—molecules that can donate an electron to a raging free radical and neutralize it. And to go back to our analogy one last time, antioxidants are groups that either give or take a member, so nobody is alone. 

Oxidative stress risk factors

Some free radicals are formed naturally when you breathe, digest food, or when your body turns the food you eat into energy. This is normal and healthy. However, other exposures and lifestyle factors can also increase the formation of free radicals, including (Sharifi-Rad, 2020; Pizzino, 2017):

  • Ultraviolet radiation from sun exposure or tanning beds
  • Cigarette smoking and secondhand exposure
  • Alcohol
  • Pollutants
  • Drugs, chemicals, and pesticides
  • Too little or too much exercise (overtraining)
  • Diets high in sugar or fat (Poljsak, 2011)

What’s the role of oxidative stress in health and disease? 

When there are more free radicals than antioxidants, the free radicals can damage things like DNA, fatty tissues, and proteins in the body (Sharifi-Rad, 2020). 

Over time, uncontrolled oxidative stress may contribute to (Pizzino, 2017; Sharifi-Rad, 2020):

  • Atherosclerosis, or the hardening of the blood vessels (this can lead to cardiovascular disease)
  • Inflammatory disorders like Rheumatoid Arthritis
  • Kidney disease
  • Cancer
  • Diabetes
  • Neurodegenerative diseases like Parkinson’s disease and Alzheimer’s disease
  • Speeding up the aging process (Tan, 2018)

How do you prevent and reduce oxidative stress?

The body defends against free radicals through its antioxidant system. Antioxidants are compounds that fight free radicals by preventing or slowing the chain of events that leads to oxidative stress. 

Before jumping into this, it’s important to understand that increasing your intake of antioxidants—in your diet or supplements—isn’t enough to outweigh the impacts of free radicals. 

In other words: antioxidants are not a free radical hall pass. Smoking, alcohol, and processed foods still increase the risk of certain diseases (like cancer and cardiovascular disease), even if you eat antioxidant-rich foods.       

Here’s what you can do to ward off oxidative stress: 

Eat an antioxidant-rich diet

Support your body’s antioxidant defense mechanisms by eating foods rich in antioxidants. These dietary antioxidants include (Sharifi-Rad, 2020): 

  • Vitamin C: citrus fruits, bell peppers, strawberries, spinach
  • Vitamin E: nuts, seeds, broccoli, fatty fish 
  • Phytonutrients (beneficial plant compounds like flavonoids and carotenoids)
  • Flavonoids: green tea, cocoa, turmeric
  • Carotenoids: red, orange, and yellow fruits and vegetables 
  • Zinc: oysters, crab, pumpkin seeds
  • Selenium: Brazil nuts, tuna, sardines 

Studies indicate that plant-based diets are linked to lower levels of oxidative damage and inflammation, which helps reduce the risk for chronic disease. For example, the Mediterranean diet—rich in fruits and vegetables—can reduce DNA damage and is anti-inflammatory, whereas Western diets—high in refined carbohydrates, saturated fats, and salt—promote inflammation (Aleksandrova, 2021). 

With that said, while research shows that antioxidant-rich diets (like the Mediterranean diet) can protect against oxidative stress and inflammation, antioxidant supplements don’t appear to have the same effect (Sharifi-Rad, 2020). 

Wear sunscreen

Ultraviolet radiation from the sun (sunburns) increases oxidative stress in skin cells. This can lead to skin cancer (de Jager, 2017). The American Academy of Dermatology recommends that you use sunscreen (SPF 30 or higher) every day if you will be outside, and reapply every two hours if you’re out in the sun for an extended time (AAD, n.d.)

Don’t smoke and avoid exposure to smoke

Smoking cigarettes is a known producer of free radicals and oxidative stress that is directly linked to the development of lung cancer. Secondhand smoke also exposes you to the same toxins. Avoiding smoke and secondhand exposure to it reduces your chances of oxidative stress and chronic disease (Walser, 2008). 

Engage in physical activity 

Intense exercise can trigger free radical production and oxidative stress. However, regular exercise is linked with lower levels of inflammation and chronic disease. It’s recommended to get at least 150 minutes of moderate-intensity exercise in a week to promote health. For competitive athletes that often train at high volumes, remember to take rest days to help your body recover (HHS, 2018; Sallam, 2016). 

Be mindful of alcohol consumption

When alcohol is broken down in the liver, molecules are formed that are then converted to free radicals. So increased alcohol consumption means increased free radical formation. Try to keep your alcohol intake at a low to moderate level. Moderate alcohol consumption is defined as two drinks a day for men and one for women (Wu, 2003).

Oxidative stress is a balancing act

We’re exposed to things that lead to oxidative stress daily. Prolonged and high levels of oxidative stress can damage our cells, including our DNA. And while oxidative stress is a balancing act, the equation isn’t as simple as increased antioxidants decrease free radicals, equaling less oxidative stress. 

Free radical production and oxidative stress are influenced by so many lifestyle habits, including diet, exposure to toxins and chemicals, sunlight, smoking, and exercise. Reducing oxidative stress and the risk of diseases associated with it requires a holistic approach across all of your daily habits so that you can address supporting your body’s antioxidant defenses while minimizing your exposure to free radical triggers. 

References

  1. Aleksandrova, K., Koelman, L., & Rodrigues, C. E. (2021). Dietary patterns and biomarkers of oxidative stress and inflammation: A systematic review of observational and intervention studies. Redox Biology, 42, 101869. doi: 10.1016/j.redox.2021.101869. Retrieved from https://pubmed.ncbi.nlm.nih.gov/33541846/ 
  2. American Academy of Dermatology (AAD). Sunscreen FAQs. Retrieved Dec. 13, 2021 from https://www.aad.org/public/everyday-care/sun-protection/sunscreen-patients/sunscreen-faqs 
  3. de Jager, T. L., Cockrell, A. E., & Du Plessis, S. S. (2017). Ultraviolet Light Induced Generation of Reactive Oxygen Species. Advances in Experimental Medicine and Biology, 996, 15–23. doi: 10.1007/978-3-319-56017-5_2. Retrieved from https://pubmed.ncbi.nlm.nih.gov/29124687/
  4. Guerra, K. C., Zafar, N., & Crane, J. S. (2021). Skin Cancer Prevention. [Updated 2021, Aug 14]. In: StatPearls [Internet]. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30137812/
  5. Lobo, V., Patil, A., Phatak, A., & Chandra, N. (2010). Free radicals, antioxidants and functional foods: Impact on human health. Pharmacognosy Reviews, 4(8), 118–126. doi: 10.4103/0973-7847.70902. Retrieved from https://pubmed.ncbi.nlm.nih.gov/22228951/
  6. Pizzino, G., Irrera, N., Cucinotta, M., Pallio, G., Mannino, F., Arcoraci, V., et al. (2017). Oxidative Stress: Harms and Benefits for Human Health. Oxidative Medicine and Cellular Longevity, 2017, 8416763. doi: 10.1155/2017/8416763. Retrieved from https://pubmed.ncbi.nlm.nih.gov/28819546/
  7. Sallam, N. & Laher, I. (2016). Exercise Modulates Oxidative Stress and Inflammation in Aging and Cardiovascular Diseases. Oxidative Medicine and Cellular Longevity, 2016, 7239639. doi: 10.1155/2016/7239639. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30137812/ 
  8. Sharifi-Rad, M., Anil Kumar, N. V., Zucca, P., Varoni, E. M., Dini, L., Panzarini, E., et al. (2020). Lifestyle, oxidative stress, and antioxidants: Back and forth in the pathophysiology of chronic diseases. Frontiers in Physiology, 11. doi: 10.3389/fphys.2020.00694. Retrieved from https://www.frontiersin.org/articles/10.3389/fphys.2020.00694/full
  9. Tan, B. L., Norhaizan, M. E., Liew, W. P., & Sulaiman Rahman, H. (2018). Antioxidant and Oxidative Stress: A Mutual Interplay in Age-Related Diseases. Frontiers in Pharmacology, 9, 1162. doi: 10.3389/fphar.2018.01162. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30405405/
  10. U.S Department of Health and Human Services (HHS). (2018). Physical Activity Guidelines for Americans 2nd Edition. Retrieved Nov. 27, 202, from https://health.gov/sites/default/files/2019-09/Physical_Activity_Guidelines_2nd_edition.pdf
  11. Walser, T., Cui, X., Yanagawa, J., Lee, J. M., Heinrich, E., Lee, G., et al. (2008). Smoking and lung cancer: the role of inflammation. Proceedings of the American Thoracic Society, 5(8), 811–815. doi: 10.1513/pats.200809-100TH. Retrieved from https://pubmed.ncbi.nlm.nih.gov/19017734/
  12. Wu, D. & Cederbaum, A. I. (2003). Alcohol, oxidative stress, and free radical damage. Alcohol Research & Health: The Journal of the National Institute on Alcohol Abuse and Alcoholism, 27(4), 277–284. Retrieved from https://pubmed.ncbi.nlm.nih.gov/15540798/