Antioxidants, also referred to as 'free radical scavengers,' are compounds or nutrients that inhibit oxidation (a chemical reaction that creates free radicals). Free radicals or reactive oxygen species are unstable molecules (waste substances) produced in the body during processes such as digestion and response to environmental and other stresses. 

When the body can't process and dispose of the free radicals effectively, oxidative stress, which is harmful to body and cell functions, occurs. Oxidative stress has been associated with loss of vision, immune deficiency, respiratory diseases, heart disease, arthritis, stroke, cancer, Parkinson's disease, emphysema, and other inflammatory conditions.

Antioxidants can protect the eyes and other body parts from oxidative damage and inflammation. They help to neutralize free radicals and boost a person's overall health. Antioxidants may prevent cataract formation, lower the risk of age-related macular degeneration (AMD), and protect the eyes from the harmful blue light.

Antioxidants include phytonutrients, anthocyanins, resveratrol, isoflavones, lycopene, lutein, , vitamin C, vitamin A and beta-carotene, B vitamins, vitamin E, manganese, zinc, selenium, zeaxanthin, and omega 3-fatty acids. Antioxidants are obtained from the diet. A healthy, balanced diet that includes cereals, legumes, nuts, eggs, meat, fish, dairy products, tubers, fruits, and vegetables should provide enough antioxidants to promote good eye health. Studies suggest that antioxidants work together to promote health and protect the eyes, so eating a wide variety of healthy foods is the best approach.

Antioxidants are also available as multivitamin supplements.
 

Types

  • Tablets 
  • Serums
  • Creams
  • Capsules
  • Eye drops, e.g., N-acetylcysteine amide (NACA) 

 

Uses

Multivitamin supplements are used to prevent or treat certain illnesses, vitamin deficiencies because of poor diet, or during pregnancy. They can also help keep one in good health.

Antioxidant eye drops may help to promote healthy vision. They are used in the treatment and prevention of vision disorders from primary open-angle glaucoma, diabetic retinopathy, cataracts, age-related macular degeneration and aging. 

High doses of antioxidants might help lower the risk of loss of vision for patients with intermediate age-related macular degeneration and advanced AMD in a single eye.

Eye creams and serums might help to decrease the appearance of wrinkles, fine lines, dark circles and puffiness. It may also provide some protection against environmental factors and free radical damage.
 

Dosage

It is healthy to have a high intake of fresh plant-based produce. A balanced, healthy diet is the best source of antioxidants.

Antioxidants supplements come in many forms and dosages. One should seek advice from a doctor before taking any supplements, including the multivitamin supplements. It is mainly the case for pregnant or breastfeeding women and patients on other medications.

The recommended dosage per day or dietary allowance (RDA) is:

Vitamin C  

  • Breast-feeding women -120 mg
  • Pregnant women - 85 mg 
  • Women - 70 mg 
  • Men - 90 mg 

 

Vitamin E 

  • Breastfeeding women -19 mg
  • Pregnant women -15 mg
  • Adults and teens - 15 mg 

 

Zinc 

  • Breast-feeding women -12 mg
  • Pregnant women - 11 mg 
  • Women - 8 mg
  • Men - 11 mg 

 

Folic acid 

  • Breast-feeding women - 500 mcg
  • Pregnant women - 600 mcg  
  • Adults - 400 mcg 

 

Thiamin 

  • Breast-feeding women - 1.4 mg
  • Pregnant women - 1.4 mg 
  • Women – 1.1 mg
  • Men – 1.2 mg 

 

Selenium 

  • Breast-feeding women - 70 mg
  • Pregnant women - 60 mg 
  • Adults and teens - 55 mg

 

Potential Side Effects

Some patients experience temporary side effects such as an upset stomach, constipation and diarrhoea. 

In rare cases, there is a severe allergic reaction which may include:

  • Hives
     
  • Wheezing
     
  • Severe dizziness
     
  • Severe diarrhea
     
  • Muscle weakness
     
  • Trouble breathing
     
  • Severe constipation
     
  • Tingling and numbness
     
  • Tightness in the chest or throat
     
  • Agitated stomach or throwing up
     
  • Swelling of the throat, mouth, tongue, lips, or face
     

If one experiences any of these effects, they should call the doctor or seek urgent medical attention.

High-dose antioxidant supplements might be linked to health risks in some cases. Some studies indicate that using a high-dose of vitamin E can heighten the chances of prostate cancer and hemorrhagic stroke.   Huge doses of beta-carotene can raise the risk of lung cancer in smokers. Some antioxidant supplements have been associated with a higher risk of tumor growth.
 

Interactions

Interactions with drugs can change how antioxidant supplements work or increase the risk of side effects. Patients should inform the doctor and pharmacist about any medications they may be taking, including prescription and OTC medication and herbal products. Some of the antioxidants, like vitamin C and Vitamin E, may react with certain medications, including warfarin, anticoagulants or blood thinners, ferrous gluconate and some birth control pills. Moreover, some multivitamin supplements, especially those containing iron, may react with antacids, levodopa, bisphosphonates, thyroid medications, and antibiotics. 

Therefore, a patient should seek the doctor's approval before starting, changing, or stopping the dosage of any medicines. The patient should also ask the doctor or pharmacist for assistance in getting a dosing schedule that works with all their medications.

Alcohol consumption may also decrease many nutrients in the body, including antioxidants. Alcohol could also make it difficult for the body to absorb some of the essential nutrients.
 

Symptoms of Overdose 

Overdose sign and symptoms may include:

  • Stomach pain
  • Diarrhea
  • Vomiting
  • Nausea

 

If a patient has had an overdose and has severe symptoms, such as trouble breathing or passing out, they should call a poison control center immediately or call 911.