Antioxidants and Oxidation: Everything you need to know..
What is the antioxidant?
Antioxidants are substances that may protect cells against free radicals, can prevent or slow damage to cells caused by free radicals. Free radicals are waste substances produced by cells as the body processes food and reacts to the environment. If the body cannot process and remove free radicals efficiently, oxidative stress can result. This can harm cells and body function. Free radicals are also known as reactive oxygen species (ROS).
The process of oxidation in the human body damages cell membranes and other structures, including cellular proteins, lipids and DNA. When oxygen is metabolised, it creates unstable molecules called ‘free radicals’, which steal electrons from other molecules, causing damage to DNA and other cells.
The body can cope with some free radicals and needs them to function effectively. Oxidative stress has been linked to heart disease, cancer, arthritis, stroke, respiratory diseases, immune deficiency, emphysema, Parkinson's disease, and other inflammatory or ischemic conditions.
Oxidation can be accelerated by stress, cigarette smoking, alcohol, sunlight, pollution and other factors.
Factors that increase the production of free radicals in the body can be internal, such as inflammation, or external, for example, pollution, UV exposure, and cigarette smoke.
Effect of free radicals:
Some conditions caused by free radicals include; deterioration of the eye lens, which may contributes to blindness, inflammation of the joints (arthritis), damage to nerve cells in the brain, which contributes to conditions such as Parkinson’s or Alzheimer’s disease, acceleration of the ageing process and increased risk of coronary heart disease, since free radicals encourage low-density lipoprotein (LDL) cholesterol to stick to artery walls.
The main reactive oxygen species (ROS) are the hydroxyl radicals (HO•) and superoxide (O2•-), peroxyl and alkoxyl radicals (RO2• and RO•), the singlet oxygen (1O2)3-5, as well as hydrogen peroxide (H2O2) and organic peroxides (ROOH).4 In addition to direct damage to molecules such as lipids, amino acids and DNA, ROS can activate enzymatic and non-enzymatic cellular responses, with the potential to modify other processes that end up interfering with gene expression.
Antioxidant benefits:
Antioxidants can combine to neutralize reactive oxygen species preventing oxidative damage to cells and tissues, that caused by potentially harmful molecules known as free radicals.
Skin aging
Solar radiation and other environmental factors responsible for oxidative phenomena, skin aging, is accompanied by the decline of the endogenous antioxidant mechanisms. In the intrinsic aging process, progressive damage to mitochondrial DNA occurs, with increased ROS production, which causes cell aging and impairs protein proliferation. In skin aging, there is a progressive accumulation of proteins, DNA and modified lipids, reinforcing the association between ROS and intrinsic aging. The most physiological protective effect against oxidative stress seems to be the support to the endogenous system, using antioxidants normally present in the skin. It is confirmed that the acute exposure of human skin to solar radiation leading to oxidation can be prevented by previous treatments with antioxidants, reducing the risk of carcinogenesis.
Cardiovascular disorders
Cardiovascular disorders or cardiovascular diseases (CVD) are major illness associated with heart and blood vessels. Reactive oxygen species (ROS), generated during excessive oxidative stress, are responsible for the pathophysiology of various cardiovascular disorders including atherosclerosis, cardiac hypertrophy, cardiomyopathy, heart failure, ischemia and myocardial infarction.
However, during excessive oxidative stress body's endogenous system fails to maintain normal physiology hence antioxidant supplementation is necessary, which could scavenge the free radicals and other toxic radicals.
Central nervous system
Antioxidants are important mediator in the central nervous system. Antioxidants, such as glutathione and ascorbate, have been shown to signal through transmitter receptors and protect against acute and chronic oxidative stress, modulating the activity of different signaling pathways.
Several authors have investigated the role of these nutrients in the brains of the young and the aged in degenerative diseases such as Alzheimer’s and Parkinson’s, and during brain aging due to adiposity- and physical inactivity-mediated metabolic disturbances, chronic inflammation, and oxidative stress.
Antioxidants types:
There are thought to be hundreds and possibly thousands of substances that can act as antioxidants. Each has its own role and can interact with others to help the body work effectively.
"Antioxidant" is not really the name of a substance, but rather it describes what a range of substances can do.
Examples of antioxidants that come from outside the body include:
vitamin A, vitamin C, vitamin E, beta-carotene, lycopene, lutein, selenium, manganese, zeaxanthin, flavonoids, flavones, catechins, polyphenols, and phytoestrogens are all types of antioxidants and phytonutrients, and they are all found in plant-based foods.
Among enzymatic antioxidants, glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD).
References:
1- An Bras Dermatol. 2017 May-Jun; 92(3): 356–362, Antioxidants in dermatology, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5514576/
2- Curr Pharm Des. 2015;21(30):4441-55, Role of Antioxidants for the Treatment of Cardiovascular Diseases: Challenges and Opportunities, https://www.ncbi.nlm.nih.gov/pubmed/26234792
3- Coron Artery Dis. 2015 Mar; 26(2): 176–183, Antioxidants and Coronary Artery Disease: From Pathophysiology to Preventive Therapy, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315737/
4- Nutrients. 2017 Nov; 9(11): 1263, Fatty Acids, Antioxidants and Physical Activity in Brain Aging, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5707735/