People who wish to protect the health of their eyes should try to include sufficient amounts of the following vitamins in their diet.

1. Vitamin A and beta carotene

Vitamin A is essential for good vision. It is a component of the protein rhodopsin, which allows the eye to see in low-light conditions. According to the American Academy of Ophthalmology, a deficiency in vitamin A can lead to night blindness.

Vitamin A also supports the function of the cornea, which is the protective outer layer of the eye. A person who is deficient in vitamin A may find that their eyes produce too little moisture to stay lubricated.

Beta carotene is the primary source of vitamin A in the human diet. Beta carotene is a type of plant pigment called a carotenoid that exists in many colorful fruits and vegetables. When a person consumes carotenoids, their body converts the pigments into vitamin A.

2. Vitamin E

Alpha tocopherol is a form of vitamin E that has particularly powerful antioxidant properties.

Antioxidants help fight free radicals, which damage tissues throughout the body. Sometimes, free radicals may damage proteins within the eye. This damage can result in the development of cloudy areas called cataracts on the lens of the eye.

A 2014 review looked at studies linking vitamin E to the prevention of cataracts. Some of the research found that lens clarity was better in people who took vitamin E supplements.

However, the authors note that a separate study showed that vitamin E supplements had no effect on the progression of cataracts. They conclude that further research is necessary to determine the effectiveness of vitamin E supplements in preventing and slowing cataract development.

3. Vitamin C

Vitamin C is another powerful antioxidant that helps protect against oxidative damage.

Oxidative damage is a key factor in two of the most common age-related cataracts: cortical and nuclear cataracts. Cortical cataracts develop on the edges of the lens, while nuclear cataracts occur deep in its center or "nucleus."

A 2016 longitudinal study investigated different factors that may help prevent nuclear cataract development. The study involved more than 1,000 pairs of female twins.

At the start of the study, the researchers measured the participants' cataracts. They then tracked each participant's intake of vitamin C and other nutrients over 10 years.

At the end of the study period, the researchers remeasured the cataracts in 324 pairs of twins. The participants who reported consuming more vitamin C showed a 33% reduction in the risk of cataract progression. They also had clearer lenses overall.

4. B vitamins

A 2009 study suggests that daily supplementation with a combination of vitamins B-6, B-9, and B-12 may reduce the risk of AMD. AMD is a degenerative eye disease that affects the vision.

However, this particular study only included women. Further research is, therefore, necessary to support the use of B-vitamins in preventing AMD in both women and men.

An older study looked at nutrient intake and eye health in 2,900 people between the ages of 49 and 97 years. The findings revealed that higher intakes of protein, vitamin A, and the B-vitamins riboflavin, thiamine, and niacin had an association with a lower rate of nuclear cataracts.

A 2018 nationwide study in South Korea found a link between a reduced intake of vitamin B-3, or niacin, and glaucoma. In people with glaucoma, a buildup of fluid within the eye puts pressure on the optic nerve. Over time, this can damage the nerve, resulting in vision loss.

Research suggests that the following nutrients are also beneficial for the eyes.

1. Lutein and zeaxanthin

Lutein and zeaxanthin are carotenoids that exist in high quantities in green leafy vegetables. They are also present in the lens and retina of the eye.

As antioxidants, lutein and zeaxanthin may help reduce oxidative damage in the retina. Some research suggests that taking approximately 6 milligrams (mg) a day of lutein and zeaxanthin may lower a person's risk of developing AMD.

2. Zinc

Zinc is a mineral that helps maintain the health of the retina, cell membranes, and protein structure of the eye.

Zinc allows vitamin A to travel from the liver to the retina to produce melanin. Melanin is a pigment that protects the eyes from ultraviolet (UV) light.

According to the American Optometric Association, zinc supplementation may help people who have AMD or are at risk of developing the condition. Taking 40–80 mg of zinc each day, alongside certain antioxidants, could slow the progression of advanced AMD by 25%. It could also reduce visual acuity loss by 19%.

3. Omega-3 fatty acids

The retina of the eye contains a particularly high concentration of omega-3 fatty acids (omega-3s). These fatty acids help protect the retina from damage and degeneration.

Specifically, omega-3s reduce the buildup of fatty deposits in the blood vessels, including those that supply blood to the retina. Some scientists believe that fatty deposits in these blood vessels could contribute to AMD.

Additionally, a small amount of research suggests that increasing the intake of omega-3s may lower the risk of dry eye syndrome. A person with dry eye syndrome does not produce enough tears to keep the eyes lubricated. However, research in this area is limited, and further studies are necessary to support this claim.

A balanced, healthful diet containing a range of the following foods should provide enough vitamins and nutrients to promote good eye health. Research suggests that these nutrients work together to protect the eye, so eating a wide variety of healthful foods is the best approach.

People who take medications or have an existing health condition should check with their doctor before taking dietary supplements. In some cases, certain supplements may be harmful to health. For example, high dosages of zinc can affect how the body absorbs copper.

Additionally, it seems that very high dosages of beta carotene can increase the risk of lung cancer in people who smoke.

Below, we list the dietary sources of the vitamins that we mention in this article.

Vitamin A and beta carotene:

Vitamin E:

Vitamin C:

Vitamin B-1, or thiamine:

• beans
• lentils
• pork
• fish
• green peas
• yogurt

Vitamin B-2, or riboflavin:

Vitamin B-3, or niacin:

Vitamin B-6, or pyridoxine:

• chickpeas
• dark leafy greens
• poultry
• beef liver
• salmon and tuna

Vitamin B-9, or folic acid:

• dark leafy greens
• peanuts
• beans
• seafood
• sunflower seeds
• eggs

Vitamin B-12, or cobalamin:

People can only get vitamin B-12 from animal sources. As such, people who do not consume animal products will need to take vitamin B-12 supplements or consume products that manufacturers have fortified with vitamin B-12.

Lutein and zeaxanthin:

Zinc:

• seafood, such as oysters, crab, and lobster
• turkey
• beans
• chickpeas
• nuts
• pumpkin seeds
• whole grains
• milk
• fortified cereals

Vegetarians may need to double their intake of zinc-rich foods because a vegetarian diet provides less zinc than an omnivorous diet.

Omega-3 fatty acids:

Specific vitamins and nutrients are essential for maintaining good eye health. Some may even help prevent certain eye diseases from developing or progressing.

A balanced, healthful diet will provide people with the necessary range of nutrients. The diet should include whole grains, legumes, and plenty of colorful fruits and vegetables.