The October break gave me a lot of time to unwind, and was a nice break from the stressful and always dreaded “IB Year 2 Semester 1”. One of the ways I decided to spend my downtime was by blogging on a social media site called Tumblr, and it was then that I came across this post:
As we were studying Oxidation and Reduction in class, I had to investigate the idea further.
A quick Google search on the statement led me to a thread on The Student Room (UK) with others also discussing their fears: was breathing ultimately killing them?
Some users showed their support and offered scientific explanations-
It made sense… I had learned from Biology class that one of the reactants required for the process of cellular respiration is Oxygen which comes from the air that we breathe. Further research led me to a report linking Oxidative Stress (essentially a deficiency of anti-oxidants) to a string of diseases including Diabetes and Arteriosclerosis (Vendemiale et al., 1999). I realized then that this was not a debate to be taken lightly, and decided to investigate the following question for my blog post: to what extent does Oxygen harm the human body?
I turned to the experts for some insight.
It turns out, Oxidation is a natural occurrence when there is exposure to air. Cut an apple and leave it out, it will undergo Oxidation and slowly change color (to brown). Leave equipment made from Iron out unprotected, and it will rust. Breathe, and your cells will decay.
Oxygen in our body reacts with our cells, and as a result, these cells undergo oxidation. As oxidation is the loss of electrons, the affected cell is chemically altered and ultimately dies. It is then replaced by fresh, new cells. According to Jeffrey Blumberg, a professor of nutrition at Tufts University in Boston, this is nothing to worry about. Blumberg dismisses any fears about oxidation by saying that it is a “natural process” that occurs “during normal cellular functions” (Davis, n.d).
However, what we do have to worry about are those cells that are unintentionally damaged in the process- Blumberg asserts that although the metabolism of oxygen in the body is “efficient”, 1% – 2% of cells will suffer this damage in the process (Davis, n.d). This damage occurs by the breaking of covalent bonds between their molecules (SucceedMonavie, 2010). As two molecules split apart, the shared electron is released and both molecules become unstable and highly reactive as a result. These unstable and highly reactive molecules are known as ‘free radicals’, and are a type of Reactive Oxygen Species (Evans & Halliwell, 1999).
- Molecules turn into unstable ‘Free Radicals’ – (SucceedMonavie, 2010)
Because of their unstable nature, ‘free radicals’ will attack healthy cells in an attempt to act as as an oxidizing agent to gain back an electron and achieve stability (SucceedMonavie, 2010). According to Blumberg, “these molecules will rob any molecule to quench that need [for an electron]”, and this makes the ‘free radicals’ potentially very dangerous (Davis, n.d). When attacked molecules are oxidized by a free-radical, the attacked molecules turn into free radicals themselves (SucceedMonavie, 2010). As 1 free-radical breaks apart a bond between 2 healthy cells to undergo reduction, 1 free-radical (if not stopped) is later responsible for the production of 2 radicals. This statistically works similar to bacteria growth, and results in a chain-reaction that produces a rapid and exponential increase in the number of ‘free radicals’ present in our body. Oxidative stress, defined as “a disturbance in the balance between the production of reactive oxygen species (free radicals) and anti-oxidant defenses” can be attributed to this chain reaction (Betteridge, 2000). It has been linked to various heart diseases and cancers, as well as to Alzheimer’s and Parkinson’s disease (Davis, n.d).
Additionally, as the ‘free radicals’ attack healthy cells around them, they may not kill the healthy cells. This can potentially lead to devastating consequences for the body. According to Blumberg, “if free radicals simply killed a cell, it wouldn’t be so bad… the body could just regenerate another one”. He instead suggests that the problem lies with damage to the cell, as this damages the DNA which leads to the mutation of the affected cell, as well as abnormal growth and reproduction of that cell- “the seed of disease” (Davis, n.d).
So oxygen is harmful to the human body? Why don’t we just stop breathing?
I realized that the initial post had been right, to a certain extent. Although Oxygen does have the potential to do damage to our bodies, it is also vital to our survival- and it certainly does not “take 80 years to kill us”. We must also remember that only 1% – 2% of metabolized Oxygen actually turns into a ‘free radical’ (Davis, n.d). Valko et al. (2007) look to Reactive Oxygen Species as being “two faced”- though these can damage cell structures, proteins, and DNA, they can simultaneously strengthen the immune system. As this strengthened immune system can then combat a host of illnesses including Oxidative Stress, the actions of Reactive Oxygen Species “re-establish” and “maintain redox balance” or “redox homeostasis” (Valko et al., 2007). Interestingly enough, there are animals out there who do not need any oxygen whatsoever to survive (Danovaro et al., 2010). For us however, oxygen is required for cell respiration to occur- if you don’t breathe, you die.
So how can we take active measures to slow down the process of Oxidation and prevent the onset of Oxidative Stress?
The initial post on Tumblr was right to a certain extent; anti-oxidants do serve this purpose. Anti-oxidants are able to stop the dangerous chain reaction by donating one of their electrons to the unstable ‘free radical’, therefore stabilizing it. They are not oxidized in the process (this is one of their properties), so all potential harm is eliminated from the body (SucceedMonavie, 2010). It is for this reason that Oxidative Stress occurs only when there is an imbalance in the amount of ‘free radicals’ and levels of anti-oxidants present in the body; if the body is lacking in anti-oxidants or abundant in ‘free radicals’, then there will not be enough anti-oxidant to stop the chain reaction from occurring. Increasing intake of anti-oxidants will prevent the sickness from developing (Davis, n.d). Some common foods high in anti-oxidants are tomatoes, carrots, tea, and citrus fruits. Fun fact relating to China- Chinese oolong tea in particular, is 40 times richer in anti-oxidants than regular green tea (Rutherford, 2011). Blumberg urges, “Sure, you can live your whole life without getting epicatechin 3-gallate, a flavonoid found in huge quantities in green tea, but if having it in your diet promotes better health, why not try it?” (Davis, n.d)
Decreasing the risk of developing ‘free radicals’ in the body can also be a preventative measure. Although my blog post focused specifically on the action of Reactive Oxygen Species, there are other types of free radicals as well. One of these is the Reactive Nitrogen Species, taken into the body by breathing in Nitric Oxide (Valko et al., 2007). This is present in polluted air, something we are very much exposed to as residents of Shanghai. Blumberg asserts that the “toxins” present in the air of a city environment cause an “oxidative burden” on the body which is, with modernization and increased industry and technology, much higher than ever before. He also labels cigarette smoke as having “active free radical generators”, and recommends quitting smoking to “preserve health” (Davis, n.d). Minimizing exposure to pollution and second-hand smoke are also important steps that can taken to do this.
Other factors that can contribute to Oxidative Stress if exposed to in excess, are X-Rays, sunlight, strenuous exercise, and alcohol (Parnes, n.d). Although X-Rays are unavoidable for medical reasons, limiting consumption of alcohol and increasing consumption of anti-oxidants when participating in strenuous exercise or gaining excessive exposure to sunlight can reduce risk of developing Oxidative Stress.
So what? Who cares? (Implications)
Living in China, a country with huge amounts of pollution, increases our risk of developing Oxidative Stress. Additionally, as the sickness has been linked to a host of diseases, preventative measure should be taken in order to minimize the risk of developing those illnesses. Awareness of risk factors of the sickness can help us take these preventative measures.
DJ, B. (2000). What is Oxidative Stress?. Metabolism: Clinical And Experimental , 49, 3-8. Retrieved October 7, 2013, from the PubMed database.
Danavaro, R., Dell’Anno, A., Pusceddu, A., Gambi, C., Heiner, I., & Kristensen, R. (2010). The First Metazoa Living in Permanently Anoxic Conditions. BMC Biology, 8(30). Retrieved October 9, 2013, from http://www.biomedcentral.com/1741-7007/8/30/abstract
Davis, J. (n.d.). How Antioxidants Work: Preventing Free Radical Damage and Oxidation. WebMD. Retrieved October 7, 2013, from http://www.webmd.com/food-recipes/features/how-antioxidants-work1
Evans, F., & Halliwell, B. (1999). Free Radicals and Hearing: Cause, Consequence, and Criteria. Annals of the New York Academy of Sciences, 884, 19-40. Retrieved October 7, 2013, from the PubMed database.
Parnes, R. (n.d.). What is an Antioxidant?. Discovery Health. Retrieved October 7, 2013, from http://health.howstuffworks.com/wellness/food-nutrition/facts/antioxidant1.htm
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SuceedMonavie. (2010, January 2). How antioxidants work. Youtube. Retrieved October 7, 2013, from https://www.youtube.com/watch?v=lG3OOXIXvxw
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Vendemiale, G., Grattagliano, I., & Altomare, E. (1999). An Update on the Role of Free Radicals and Antioxidant Defense in Human Disease. International Journal of Clinical & Laboratory Research, 29(2), 49-55. Retrieved October 6, 2013, from the PubMed database.