The term antioxidants is widely coined by the media, food, and nutrition industries all over the world. They are widely considered cures for a wide variety of diseases. How true is this idea, and how valuable are these antioxidants for the body? Let’s dive deep into the concept of antioxidants, how they act, their health benefits, health hazards, and their sources.
The Action of Antioxidants
Free Radicals and Oxidative Stress
Whenever we eat something or some toxic chemical goes into the body, the body tends to fight it back. It does so by either making the foreign particles react with chemicals, which renders them useless, or by the help of phages, which release ROS (reactive oxygen species), the free radicals which kill the bacteria or fungi that enter the body. The amount of these ROS can increase in the body in certain conditions, which is called Oxidative Stress.
ROS are maintained at low levels in the body by various enzyme-driven homeostasis processes. Thus, oxidative stress can also be considered an imbalance between the pro-oxidants (free radicals) and antioxidants in the body.
The buildup of oxidative stress can lead to cancer, arthritis, heart disease, lung problems, liver disease, Parkinson’s disease, and Alzheimer’s.
Antioxidants are molecules or chemicals that work against these ROS, or free radicals. Free radicals, or ROS, damage the body by taking the electrons away from the molecules that make up the human body. These ROS can:
- Can damage the DNA. This changes the information in the genes, i.e., a cancerous mutation.
- It also traps the bad cholesterol in the arteries, increasing the risk of heart attacks.
- It can alter the cell membrane lipids. This can completely change the regular flow of chemicals in and out of the cell, leading to diseases like cognitive decline, Parkinson’s, and dementia.
- Damage to heart muscles leads to the formation of infarcts in healthy tissue.
How do Antioxidants Work against ROS?
As free radicals take electrons away from biomolecules, antioxidants can donate their electrons to free radicals. This neutralizes the effect of these excess free radicals in the body—the quenching process. Thus preventing the accumulation of oxidative stress in the body. (1)
They can also act by chelating the metal ions, which leads to the formation of free radicals. They are described in sections coming later on.
What are the different antioxidants?
A huge number of antioxidants have already been discovered, and many more are discovered now and then. Following is a list of antioxidants and their sources.
1. Vitamins
- Vitamin A: liver, sweet potatoes, carrots, milk, and egg yolks
- Ascorbic Acid/Vitamin C: oranges, blackcurrants, kiwifruit, mangoes, broccoli, spinach, passion fruit, capsicum and strawberries
- Vitamin E: vegetable oils (such as wheatgerm oil), avocados, nuts, seeds like papaya seeds and whole grains
2. Minerals
- Copper: seafood, lean meat, milk and nuts
- Manganese: seafood, lean meat, milk and nuts
- Zinc: seafood, lean meat, milk and nuts
- Selenium: seafood, lean meat, offal, and whole grains
3. Phytonutrients
These nutrients are found in different plants, in their seeds, fruits, leaves, roots and stems.
Phenolic compounds
- Flavonoids (e.g., Quercetin): tea, green tea, citrus fruits, red wine, onion and apples
- Lignans: bran, sesame seeds, whole grains and vegetables
- Anthocyanins: eggplant, grapes and berries
- Isoflavonoids: soybeans, tofu, lentils, peas and milk
- Resveratrol: Resveratrol is a compound found in grapes, red wine, and chocolate.
- Curcumin: Turmeric
- Catechins: red wine and tea
- Ellagic acid: Berries, pomegranates, and walnuts
- Piceatannol and Scirpusin B: Passion fruit (Maracuya)
Others
These include pigments, pro-vitamins, and other phytonutrients.
- Beta-carotene: mangoes, apricots, pumpkin, carrots, spinach and parsley
- Lutein: corn and green, leafy vegetables like spinach
- Non- Phenolic Allium sulfur compounds (e.g., Allicin, diallyl sulfide, and diallyl disulfide): leeks, onions, and garlic
- Cryptoxanthins: red capsicum, pumpkin and mangoes
- Indoles: cruciferous vegetables such as cabbage, broccoli, and cauliflower
- Lycopene: tomatoes, apricots, pink grapefruit and watermelon
- Glucosinolate metabolites: broccoli, cabbage, cauliflower, kale, and Brussels sprout, radishes, mustard, radishes.
4. Zoochemicals:
Then these are extracted from the animals. These are phytochemical counterparts.
- Conjugated linoleic acid (CLA): Found in beef, dairy products, and lamb
- Lutein: found in egg yolks
- Omega-3 fatty acids: found in fatty fish, such as salmon, tuna, and mackerel
- Zeaxanthin: found in egg yolks
5. Synthetic Antioxidants:
- Butylated hydroxyanisole (BHA)
- Butylated hydroxytoluene (BHT)
- Propyl gallate
- Ethoxyquin
- Tertiary butylhydroquinone (TBHQ)
These are widely used in cosmetics and pharmaceutical industries. They might be advised for consumption in moderation in certain diseases.
How do Antioxidants classify?
They classify on various criteria
By their source:
- Natural antioxidants: These are found in plants and animals, such as vitamins C and E, carotenoids, and flavonoids.
- Synthetic antioxidants: These are man-made antioxidants, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT).
By their mechanism of action:
- Primary/Direct antioxidants: They directly neutralize free radicals. Examples of primary antioxidants include vitamin C, vitamin E, and glutathione.
- Secondary/Indirect antioxidants: They work indirectly to protect against free radical damage, such as by chelating metal ions or repairing damaged cells. Examples of indirect antioxidants include carotenoids, flavonoids, and selenium.
By their solubility:
- Water-soluble antioxidants: These antioxidants dissolve in water and are found in the cytoplasm of cells. Examples include vitamin C and glutathione.
- Fat-soluble antioxidants: They dissolve in fat and are found in the cell membrane and other lipid-rich tissues. Examples include vitamin E and carotenoids.
By their enzymatic activity:
- Enzymatic antioxidants: These antioxidants are enzymes that catalyze reactions that detoxify free radicals and other reactive oxygen species (ROS). Examples include superoxide dismutase and catalase.
- Non-enzymatic antioxidants: They are not enzymes and work directly to neutralize free radicals and other ROS. Examples include vitamin C and vitamin E.
By their chemical structure:
- Phenolic antioxidants: These antioxidants contain a phenol group, which is a hydroxyl group attached to an aromatic ring. Examples include vitamin C, flavonoids, and polyphenols.
- Carotenoid antioxidants: These are derived from carotenoids, which are plant pigments that give fruits and vegetables their orange, red, and yellow colors. Examples include beta-carotene and lycopene.
- Vitamin antioxidants: They are vitamins, such as vitamins C and E.
It is important to note that antioxidants often work together to provide the best protection against free radical damage. For example, vitamin C can regenerate vitamin E from its oxidized form, and vitamin E can protect vitamin C from oxidation.
The Health Benefits of Antioxidants
- Heart Health: Antioxidants like vitamin C and E can help reduce the risk of cardiovascular diseases by preventing the oxidation of LDL cholesterol and reducing inflammation in blood vessels.
- Cancer Prevention: Some antioxidants, such as resveratrol (found in red grapes) and lycopene (found in tomatoes), are linked to a lower risk of certain cancers i.e., Prostate Cancer due to their ability to combat DNA damage.
- Skin Health: Vitamin C can protect the skin from UV damage, reduce the signs of aging, and promote collagen production for healthier, more youthful skin.
- Blood Pressure management: Scipusin B and Piceatannol are two strong vasorelaxants. They dilate the blood vessels, increase the blood flow, and reduce the blood pressure. Several other antioxidants are also helpful in this regard.
- Eye Protection: Nutrients like lutein and zeaxanthin help protect the eyes from age-related macular degeneration and cataracts by shielding them from oxidative damage.
- Immune System Support: They also boost the immune system by reducing oxidative stress and inflammation, helping the body fend off infections and illnesses. Vit C, Vit A, Scirpusin B and many other polyphenols are responsible for boosting immunity.
- Anti-Inflammatory Effects: Antioxidants can reduce inflammation in the body, which is linked to various chronic diseases, including arthritis, asthma, and inflammatory bowel disease. Reducing chronic inflammation can also help reduce the occurrence of cancer.
- Neurological Health: Antioxidants like vitamin E and flavonoids may help protect brain cells from oxidative damage and reduce the risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
- Protect Preterm Infant Deaths: During pregnancy, preterm infants are at high risk for morbidities including eye diseases, hemorrhages, and lung diseases. This is likely to be related to their exposure to reactive oxygen and nitrogen species early in life. Adding selenium to the diet has potential benefits for protecting the babies against these radicals. (2)
- Diabetes Management: Some antioxidants, like alpha-lipoic acid, may help improve insulin sensitivity and lower blood sugar levels, making them beneficial for those with diabetes.
- Liver Health: Antioxidants like glutathione help detoxify the liver and protect it from damage caused by toxins, alcohol, and certain medications.
- Respiratory Health: They can support lung health by reducing inflammation and protecting against conditions like asthma and chronic obstructive pulmonary disease (COPD).
- Gut Health: They can promote a healthy gut by reducing inflammation and supporting the growth of beneficial gut bacteria. This may help with digestion and overall gastrointestinal well-being.
- Allergy Relief: Quercetin, a type of flavonoid, has been linked to reducing allergic reactions by stabilizing mast cells and decreasing the release of histamines.
- Wound Healing: Vitamin C can play a role in collagen formation, which is essential for wound healing and tissue repair. Zinc and Vitamin E can also assist in the healing procedure.
- Weight Management: Some antioxidants, like green tea extract and resveratrol, have been associated with weight management and may help with controlling body weight.
- Protection from Environmental Toxins: They can also help the body detoxify and protect itself from the harmful effects of environmental toxins and pollutants, such as heavy metals and chemicals.
- Menstrual Health: Antioxidants like vitamin E may alleviate symptoms of premenstrual syndrome (PMS) and dysmenorrhea (painful periods) by reducing inflammation and oxidative stress.
- Fertility Support: They may enhance reproductive health by protecting sperm and eggs from oxidative damage and improving overall fertility.
- Anti-Aging: The ability of antioxidants to reduce oxidative stress and protect against DNA damage contributes to their potential for slowing down the aging process and promoting longevity.
Health Hazards of Antioxidants
- Antioxidant minerals or vitamins can damage the body and become “pro-oxidants” when they are consumed above the recommended amounts for dietary intake. These can have the effects of the free radicals themselves i.e., cancer, heart disease, etc., leading to a variety of diseases caused by them. (1)
This is why it is advised to choose a healthy, balanced, and varied diet containing all the necessary antioxidants in your diet to provide thorough protection against free radicals.
- Some studies have indicated that taking high doses of vitamin E supplements can increase the risk of heart-related diseases in some people. Vitamin E has also been found to increase the risk of prostate cancer. (3)
- Drug interactions of antioxidants are very common. Some of these can interact with certain medications, such as blood thinners and chemotherapy drugs like cisplatin. (3)
- Antioxidants can interfere with the body’s natural defense mechanisms. Antioxidants can neutralize free radicals, but they can also quell other important molecules like nitric oxide. Nitric oxide is a signaling molecule that plays a role in many important bodily functions, including blood vessel dilation and immune function.
Antioxidants in Supplements
Research shows that using vitamin supplements can increase the risk of cancer. For example, vitamin A has been linked with a reduced risk of certain diseases, like skin cancer, but it can also lead to severity in other cancer types, such as lung cancer in smokers. (4)
The supplements do not show any health benefits because antioxidants tend to work best in combination with other nutrients, phytochemicals, and even other antioxidants.
Try to consume a serving of fruit and vegetables daily for a better antioxidant combination. Serving sizes can vary depending on gender, age, and lifestyle, but generally, a medium-sized piece of fruit or a half-cup of cooked vegetables is considered the right amount.
Myths regarding Antioxidants
1. Cooking reduces antioxidants
Cooking can either increase or decrease the antioxidant levels of certain foods.
Lycopene is the antioxidant that gives tomatoes their rich red color. When tomatoes are cooked, the lycopene in them becomes more readily available for our bodies to process and use. (5)
However, several studies have also shown that cauliflower, peas, and zucchini lose much of their antioxidant activity in the cooking process.
This is why keeping a variety in diet can ensure a better antioxidant supply, whether cooked or raw.
2. Antioxidants can be a cure for all sorts of diseases
While they play a role in preventing and reducing the risk of certain health conditions, they are not some magical cure. They can help the body heal faster, manage healthy tissue, and improve health. Their effects can vary based on the specific disease, individual factors, and the overall health of a person.
3. A high antioxidant dose has more health benefits
Taking heavy quantities of antioxidants can be seriously harmful. Recent researches have suggested that taking too many these can actually increase the risk of certain diseases, such as cancer and heart disease.
One reason for this is that they can interfere with the body’s natural defense mechanisms.
No two antioxidants suffice the requirements of each other
In previous sections it’s been already mentioned how every antioxidant differ from each other. The different natures and modes of action can give one antioxidant edge over the other one.
They have varied roles and effectiveness in the body. Consuming a wide variety is important because it allows you to get the full range of health benefits that each antioxidant compound has to offer
How do I know if I have enough antioxidants in my diet?
A balanced diet rich in fruits and vegetables typically provides sufficient antioxidants. Try adding more colorful items to your diet, and use whole foods instead of processed foods.
Consider factors that increase your need for antioxidants, such as smoking, exposure to pollution, or engaging in intense physical activity. These factors can increase your oxidative stress and may require additional antioxidant support.
Takeaway
Antioxidants are like the superheroes of our body, helping to keep us healthy and protect us from harm. The healthy balanced and varied can rich in these nutrients can provide us with numerous health benefits. However, too much of a good thing can have drawbacks, so it’s important to strike a balance. As science continues to explore the secrets of antioxidants we can safely consider that they are an essential part of our journey towards a healthier lifestyle in future
References
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- Rahal A, Kumar A, Singh V, Yadav B, Tiwari R, Chakraborty S, Dhama K. Oxidative stress, prooxidants, and antioxidants: the interplay. Biomed Res Int. 2014;2014:761264. doi: 10.1155/2014/761264. Epub 2014 Jan 23. PMID: 24587990; PMCID: PMC3920909. https://pubmed.ncbi.nlm.nih.gov/24587990/
- He L, He T, Farrar S, Ji L, Liu T, Ma X. Antioxidants Maintain Cellular Redox Homeostasis by Elimination of Reactive Oxygen Species. Cell Physiol Biochem. 2017;44(2):532-553. doi: 10.1159/000485089. Epub 2017 Nov 17. PMID: 29145191. https://pubmed.ncbi.nlm.nih.gov/29145191/
- Deepika, Maurya PK. Health Benefits of Quercetin in Age-Related Diseases. Molecules. 2022 Apr 13;27(8):2498. doi: 10.3390/molecules27082498. PMID: 35458696; PMCID: PMC9032170. https://pubmed.ncbi.nlm.nih.gov/35458696/
- Tindell R, Tipple T. Selenium: implications for outcomes in extremely preterm infants. J Perinatol. 2018 Mar;38(3):197-202. doi: 10.1038/s41372-017-0033-3. Epub 2018 Jan 3. PMID: 29298985; PMCID: PMC5967885. https://pubmed.ncbi.nlm.nih.gov/29298985/
- Khan UM, Sevindik M, Zarrabi A, Nami M, Ozdemir B, Kaplan DN, Selamoglu Z, Hasan M, Kumar M, Alshehri MM, Sharifi-Rad J. Lycopene: Food Sources, Biological Activities, and Human Health Benefits. Oxid Med Cell Longev. 2021 Nov 19;2021:2713511. doi: 10.1155/2021/2713511. PMID: 34840666; PMCID: PMC8626194. https://pubmed.ncbi.nlm.nih.gov/34840666/