Antioxidants: Meaning, Classification, Health Benefits & Risks

Antioxidants are compounds that can protect cells from the damaging effects of free radicals. Free Radicals are unstable molecules that can cause cellular damage and contribute to the development of various diseases. They are chemical substances that impede or slow the damage to cells mainly caused by free radicals.

• Some examples of antioxidants include Vitamin C, Vitamin E, and beta-carotene. 

• Antioxidants can be found in a variety of foods, such as fruits, vegetables, and nuts, and can also be taken as supplements.
• It is important to consume a variety of antioxidant-rich foods as part of a healthy diet to help protect against the harmful effects of free radicals.

Antioxidants Meaning

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The meaning of antioxidant is derived from two words- “anti” (Greek origin) which means against the action, and “oxidation” (English origin) meaning substance or organic compound with oxidising nature. Thus, antioxidants are defined as the “substances that delay, control or inhibit the oxidation and deterioration of food”. ​

The health benefits of antioxidants are diverse and some of them are also known for their anti-ageing properties. The examples of antioxidant rich foods for youthful and evergreen skin include- Green tea, gooseberry (amla), blueberries, beetroot, papaya, avocadoes, etc. 

• Antioxidants are found in fruits, vegetables, and other plant-based, whole foods. 
• Ascorbic acid and tartaric acid are antioxidants that act as food preservatives that are used to extend the shelf life of foods.
• Carotenoids, lupin, flavinoids, tocopherols (vitamin E derivatives), vitamin C, are some of the examples of effective antioxidants. 
• They protect against oxidation and free radical damage. 

Classification of Antioxidants

The presence of antioxidants in the low concentration can hinder the process of substrate oxidation. Overall, the classification of antioxidants are done in two important ways: enzymatic and non-enzymatic actions. Some major sources of antioxidant rich foods include dark chocolate, nuts, and high nutritional value foods and vegetables such as broccoli, carrots, spinach, berries, cherries, etc. 

Antioxidants based on Mechanism of Action

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Antioxidants are substances that are best known to neutralize free radicals in the human body. There are several free radicals that play a pivotal role in cancer, heart diseases and relevant other diseases as well. 

Antioxidant substances act via numerous chemical mechanisms, three of them are hydrogen atom transfer (HAT), single electron transfer (SET) and the capability used in chelating transition metals.

• Antioxidants in low concentration are best known to hinder the oxidation of several oxidizable biomolecules, some of the instances include lipids and proteins in meat items. 
• It generously contributes to helping improve the shelf life of items by acting as a protection against degradation due to oxidation.
• Antioxidants act as radical scavengers. 
• Some of the major instances of antioxidants that play a vital role in scavenging free radicals are phenolic compounds, ligands, flavonoids and phenolic acids. 
• It also reacts with transition metals to further form complexes and avoid the catalytic effect of metals in the oxidation mechanism.

Natural Antioxidants

Plants are best known to be an active source that supplies human body with several valuable bioactive compounds. Various plant products are considered as sources that provide natural antioxidants to humans.

• Natural antioxidants are commonly phenolics that elementally happen to exist in every part of a plant. 
• It can include fruits, vegetables, nuts, seeds, leaves, roots, and even barks. 
• There has been an extraordinary study based on pivoting upon the usage of natural antioxidants for effectively preserving meat and meat products.
• It has significantly reflected on a massive scale of consumption of phenolics or phenolic extracts. 

Here are some natural antioxidants:

• Allium Sulphur Compounds: Leeks, Garlic.
• Anthocyanins: Grapes and Berries.
• Beta-Carotene: Pumpkin, Mangoes, Spinach and Parsley.
• Catechins: Coffee and Tea.
• Copper: Fish, Lean Meat, Milk and Nuts.
• Cryptoxanthin: Red Capsicum, Pumpkin

Among the large scale distinctions of phenolic compounds, flavonoids are the most broadly investigated class of polyphenols, in close connection to their antioxidant and biological activities.

Synthetic Antioxidants

Synthetic antioxidants have a very wide usage in chemistry, medicine and the field of food industries. These substances are best known to introduce a range of new chemical groups that help improve cellular action or generally help them to be available to cell sites.

However, there are known synthetic antioxidants which are witnessed to exhibit  high reactivity toward reactive oxygen species. It further contributes in reflecting only selective protection in only some tissues.

• There is a massive production of synthetic antioxidants that help in the stabilization procedure of non-food items, including plastics and polymers. 
• Their usage in food, however, tends to produce several emerging issues like the toxicology of lipid oxidation products and the toxicology involved in antioxidants.
• The use of synthetic antioxidants, however, should be limited to a certain amount due to several potential health risks it is known to generate. 
• The search for natural antioxidants is considered to be a healthy alternative against synthetic antioxidants in the biological sphere.

Advantages of Antioxidants

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The advantages of Antioxidants are as follows:

• Antioxidants are widely known to shield against cell damage that free radicals often cause. This event is particularly claimed as oxidative stress.
• It also helps improve the digestive function in the human body.
• Antioxidants are also best known to enhance the immune function in the human body.
• Some of the other benefits it includes relate to Skin health, Blood sugar stability, Cardiovascular health and prostate health in the human body.

Health Benefits of Antioxidants

In particular, antioxidants of different types are known to affect our bodies positively. For example, beta-carotene has positively tweaked the health benefits for eyes, and the skin of humans. Lycopene, on the other hand, is best known to improve prostate health and largely contributes to lessening the signs of BPH.

Antioxidants Health Risks

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Free radicals are present everywhere around the body of human beings. It is also present inside the body of human beings. 

• Reactive oxygen species are one of the types of antioxidants present in humans. 
• Antioxidants protect the human body against the deterioration by the free radicals.
• On the other hand, the synthetic antioxidants should be under proper guidance as they may cause potential health hazards. 
• Natural Antioxidants are the safe alternatives to the synthetic products present in the food industry. 

Things to Remember

• Antioxidants are used to prevent or hinder the damage to cells that are elementally caused by free radicals.
• Antioxidants can be classified into two major types namely Natural Antioxidants and Synthetic Antioxidants.
• Plants are one of the active sources of antioxidants.
• Plants supply human bodies with several valuable bioactive compounds.
• The use of synthetic antioxidants should be restrained as they cause several potential health risks.

Previous Years’ Questions

1. Oxidative rancidity of oils can be prevented by adding… (COMEDK UGET - 2011)
2. Which one of the following is correctly matched… (NEET - 2001)
3. An example of anthraquinone dye is… (Haryana PMT - 1999)
4. Among the following, the narrow spectrum… (NEET - 2019)
5. Which one of the following is employed as a tranquilizer drug… (NEET - 2010)
6. The artificial sweetener containing chlorine that has the appearance… (KEAM)
7. Arsenic containing medicine used for the treatment… (KEAM)
8. ...................is a potent vasodilator… (KEAM)
9. The drug chloramphenicol is an/a… (JIPMER - 2016)
10. Which of the following pairs give positive Tollen's test… (JEE Advanced - 2004)