Antioxidants In Oranges

  • Maria Conte Master's degree, Human Nutrition, Università San Raffaele, Italy
  • Michika Montaldo Bachelor of Science - BS, Applied Medical Sciences,UCL, UK
  • Ellen Rogers MSc in Advanced Biological Sciences, University of Exeter

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Introduction

Oranges are one of the most famous fruits, and are a symbol of a healthy diet, vitality, and health in general. But why do oranges have so many benefits for our health? The answer can be found in their main components: antioxidants. In this article, we will explore these powerful compounds, discuss their effect on our health, and explain how they can help us avoid getting ill. So if you have ever wondered why you should eat more oranges, this may be the answer you were looking for. 

What are antioxidants and why do we need them?

As their name suggests, antioxidants act against oxidation. Within the human body, the term antioxidant refers to a substance that protects us by removing or neutralising potentially harmful oxidising agents, such as oxygen, nitrogen and lipidic radicals.1 These oxidising agents, or “free radicals”, are capable of damaging the structure of cells and the genetic material they carry. Over time, this damage can accumulate to create  “oxidative stress” and can damage cells and result in chronic diseases.2 Oxidative stress has various effects on our DNA, lipids and proteins, and has been linked to diseases such as atherosclerosis, cancer, hypertension, and diabetes.3

Unfortunately, it is impossible to completely avoid free radicals, as they are created by our bodies as byproducts of the reactions that convert food into energy and are encountered in our environment. Common environmental sources of free radicals include:4

  • Cigarette smoke
  • Air pollution
  • Certain drugs and pesticides
  • Ozone
  • Sunlight (ultraviolet radiation) 

Whilst you cannot completely avoid free radicals, you can limit your exposure and try to counteract their effects. This is when antioxidants come to the scene. 

Where to find antioxidants

Our bodies are equipped with a complex and well-organised system to fight free radicals and combat oxidative stress. This system uses both enzymatic and nonenzymatic antioxidants.3 Enzymatic antioxidants are enzymes (biological catalysts) that act as our first-line defence against the free radicals produced in the body. Nonenzymatic antioxidants also help combat oxidative stress, but are smaller compounds, such as vitamins C and E, β-carotene, and glutathione. Our diet is an essential source of these nonenzymatic antioxidants, and they are present in many fruits and vegetables - including oranges.

Types of antioxidants in oranges

Oranges contain a set of powerful antioxidants, including vitamin C, flavonoids (such as hesperetin and naringenin), and carotenoids (including carotenes, xanthophylls, cryptoxanthins).5 These antioxidants help protect your cells, boost your immune system, and support your overall health by reducing oxidative stress and inflammation. Now, let’s have a closer look at them.

Vitamin C

Vitamin C is a water-soluble vitamin with tons of beneficial roles in the body. We are unable to synthesise vitamin C ourselves, so we must obtain it from our diet - meaning it’s really important to eat plenty of fruits and vegetables.6 Vitamin C is a powerful antioxidant, and reduces oxidative stress by reacting with circulating harmful free radicals. In these reactions, it “donates” its electrons to harmful compounds to make them less reactive and harmful.7

Vitamin C’s ability to donate electrons is also responsible for its other biological effects, such as preventing infections, promoting wound healing, and producing collagen, a fibrous protein found in connective tissue. Collagen is important for the structure and stability of many of the body’s systems, including the neural network, immune system, bones, cartilage, and blood.In total, vitamin C acts as an electron donor for eight different enzymes involved in:7

  • Collagen production
  • The synthesis of carnitine, which is essential for the transport of fatty acids and energy production
  • The biosynthesis of norepinephrine, a vital hormone and neurotransmitter 

Vitamin C’s role in these reactions may explain why a deficiency of vitamin C results in a condition known as scurvy, which is characterised by severe symptoms such as bleeding gums, anaemia, loose teeth, bleeding under the skin, brittle hair, and slow wound healing. 

Other than oranges, vitamin C can be found in other fruits such as grapefruit,

honeydew, kiwis, mango, papaya, strawberries, tangerine and watermelon, and vegetables like cruciferous and bell peppers.2

Flavonoids

Flavonoids are a group of compounds widely distributed in the plant kingdom. They are divided into subclasses based on their chemical structure and metabolism. These subclasses include the chalcones, flavones, flavonols and isoflavones.

Flavonoids are responsible for the colourful pigments of fruits, vegetables, herbs and spices, and they have a variety of biological functions in plants, animals, and bacteria. These roles include helping plants attract pollinators, protection against stress, UV filtering, acting as signalling molecules and detoxifying agents, and protecting against microbes.8 In humans, flavonoids have been shown to have anti-inflammatory, antioxidant, and anti-cancer properties amongst other health benefits. They have been found to both enhance cognitive performance and lower your risk of chronic ailments like cardiovascular disease.8

All citrus fruits (such as oranges, lemons and grapes), contain flavonoids such as flavanones, hesperetin, naringenin and eriodictyol - with their peels being particularly antioxidant-rich.8 These flavonoids prevent oxidative damage by counteracting a process called lipid peroxidation, which is contributes to ageing and the development of various diseases such as atherosclerosis, diabetes, and liver toxicity and inflammation.8

Furthermore, flavonoids help to prevent cancer by protecting our DNA from oxidative damage and harmful mutations.9

Carotenoids

Carotenoids are another class of active compounds found in oranges. They are divided into two main groups: xanthophylls and carotenes.10 β-carotene, violaxanthin, antheraxanthin, mutatoxanthin, and zeaxanthin are the main carotenoids found in oranges.  Like the flavonoids, carotenoids are natural pigments responsible for the colour of fruits and vegetables and have a variety of roles including protection against sunlight, antioxidant action, attracting pollinators, and acting as precursors of plant hormones.10

Carotenoids can also be found in several of our organs, such as the liver, adrenal glands, ovaries, skin, lung, and blood. Our diets are our main source of carotenoids, and numerous studies have shown that dietary carotenoids are linked to a lowered risk of cancer and other dangerous illnesses, increased stimulation of immune systems, and better skin health.10 Some carotenoids, like β-carotene and beta-cryptoxanthin, are converted into vitamin A, which is essential for growth, immune system function, and eye health. Others, such as lutein and zeaxanthin, are not converted into vitamin A and are referred to as non-provitamin A carotenoids. Their main action is to protect the eyes from sun damage. 

Health benefits of antioxidants in oranges

So, why should you consume oranges daily? We have discussed the main benefits of antioxidants, namely their protection against oxidative stress and prevention of chronic diseases. As such, consuming antioxidant-rich fruits, vegetables, and legumes has been linked to a lower chance of developing chronic oxidative stress-related illnesses like cancer and cardiovascular disease throughout your lifetime, as well as a lowered risk of all-cause mortality.11

Due to their high antioxidant content, oranges are a perfect ally for your health. Indeed, fruit and vegetables are one of the key cornerstones of a healthy diet, and it is recommended that you eat at least five portions of fruit and vegetables each day.

Fruits and vegetables are not only a good source of vitamins and minerals, but they also provide dietary fibre, which helps to maintain a healthy gut and prevent digestive problems and constipation. 

Can I take antioxidant supplements?

Antioxidant supplements do not convey the same health benefits as antioxidant-containing foods. This may be attributed to the fact that antioxidants tend to work best in combination with other nutrients, plant chemicals, and even other antioxidants.2 Most individuals can obtain all the nutrients and antioxidants they need from a healthy and balanced diet that includes at least five pieces of fruit and vegetables each day.

FAQs

Are oranges a good source of antioxidants?

Yes. Oranges are a very good source of antioxidants as they contain phenolic compounds and vitamin C.

What antioxidants are found in oranges?

Antioxidants found in oranges include flavonoids like hesperetin and naringenin, carotenoids, and vitamin C.

Can you get enough antioxidants from oranges alone?

Oranges are a good source of antioxidants, but it's recommended to consume a variety of antioxidant-rich foods, including fruits and vegetables, to obtain a wide range of these beneficial compounds.

Is one orange a day enough vitamin C?

Eating one orange a day can provide a significant amount of vitamin C and a good contribution to your daily recommended intake.

Are there other sources of antioxidants besides oranges?

Yes, there are numerous sources of edible antioxidants including apples, grapes, berries, tea, onions, olive oil, and red wine. These all provide a variety of flavonoids and other beneficial compounds.

Summary

The vibrant and vital orange offers a multitude of health benefits, largely thanks to its rich antioxidant content. Antioxidants are crucial in the fight against oxidative stress, which if left unchecked can damage cells and contribute to chronic diseases such as atherosclerosis, cancer, hypertension, and diabetes. The main types of antioxidants in oranges are vitamin C, flavonoids, and carotenoids, each possessing unique health-boosting properties. Vitamin C acts as a powerful antioxidant by neutralising free radicals, contributing to collagen production, and supporting various biological functions; flavonoids exhibit anti-inflammatory and antioxidant effects that help prevent cardiovascular disease and cancer; and carotenoids, including β-carotene, offer protection against malignancies and support our immune system. As such, oranges are a valuable addition to a healthy diet. While the importance of antioxidants is evident, it is essential to note that antioxidant supplements may not provide the same health benefits as a balanced diet rich in fruits and vegetables, which offer a wide range of nutrients and dietary fibre and thus are great for improving your overall well-being.

References

  • ScienceDirect. Antioxidant - an overview. [Internet]. [Cited 13 October 2023]. Available at: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/antioxidant
  • Avenue 677 Huntington, Boston, Ma 02115. The Nutrition Source. 2012. Antioxidants. [Cited 13 October 2023]. Available at:  https://www.hsph.harvard.edu/nutritionsource/antioxidants/
  • Birben E, Sahiner UM, Sackesen C, Erzurum S, Kalayci O. Oxidative stress and antioxidant defense. World Allergy Organ J. 2012;5:9–19. 
  • Cleveland Clinic. 2022. What are free radicals? And why should you care?[Internet
  • ] [Cited 13 October 2023]. Available at: https://health.clevelandclinic.org/free-radicals/
  • Franke AA, Cooney RV, Henning SM, Custer LJ. Bioavailability and antioxidant effects of orange juice components in humans. J Agric Food Chem. 2005;53:5170–8.
  • Abdullah M, Jamil RT, Attia FN. Vitamin C (Ascorbic acid). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [Cited 13 October 2023]. Available at: http://www.ncbi.nlm.nih.gov/books/NBK499877/
  • Padayatty SJ, Katz A, Wang Y, Eck P, Kwon O, Lee JH, et al. Vitamin C as an antioxidant: evaluation of its role in disease prevention. J Am Coll Nutr. 2003;22:18–35.
  • Panche AN, Diwan AD, Chandra SR. Flavonoids: an overview. J. Nutr. Sci. 2016;5:e47. 
  • Addi M, Elbouzidi A, Abid M, Tungmunnithum D, Elamrani A, Hano C. An overview of bioactive flavonoids from citrus fruits. Appl. Sci. 2022;12:29. 
  • Maoka T. Carotenoids as natural functional pigments. J Nat Med. 2020;74:1–16.
  • Dagfinn A, Giovannucci E, Boffetta P, Fadnes LT, Keum N, Norat T, et al. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality—a systematic review and dose-response meta-analysis of prospective studies, Int. J. Epidemiol. 2017;46:1029-1056.

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Maria Conte

Master's degree, Human Nutrition, Università San Raffaele, Italy

Maria is a pharmacist with a long experience in pharmaceutical companies. Her expertise focuses in particular on drug safety and benefit-risk evaluation. She has also cultivated a strong interest in health, movement and nutrition, that led her first to a postgrad certification in "Stress. Sport and nutrition" and then to a full MSc in "Human Nutrition".
Maria has always had a passion for writing and she strongly believes that through effective communication we can improve patients’ lives and have a positive impact on the world.

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