Your eyes are complex organs that need many different vitamins and nutrients to function properly.
Common conditions, such as diabetic retinopathy, age-related macular degeneration, glaucoma and cataracts, can impact your eyes.
Though a variety of different factors causes these conditions, nutrition seems to have an influence on all of them — at least in part.
Here are 9 key vitamins and nutrients that help maintain eye health.
1. Vitamin A
Vitamin A plays a crucial role in vision by maintaining a clear cornea, which is the outside covering of your eye.
This vitamin is also a component of rhodopsin, a protein in your eyes that allows you to see in low light conditions.
Vitamin A deficiency is rare in developed countries, but if unaddressed can lead to a serious condition called xerophthalmia.
Xerophthalmia is a progressive eye disease which begins with night blindness. If vitamin A deficiency continues, your tear ducts and eyes can dry out. Eventually, your cornea softens, resulting in irreversible blindness.
Vitamin A may also help protect against other eye afflictions. Some studies suggest that diets high in vitamin A may be associated with a reduced risk of cataracts and age-related macular degeneration (AMD).
For general eye health, vitamin-A-rich foods are recommended over supplements. Sweet potatoes are an excellent source, as are leafy green vegetables, pumpkins and bell peppers.
2. Vitamin E
Many eye conditions are believed to be associated with oxidative stress, which is an imbalance between antioxidants and free radicals in your body.
Vitamin E is a potent antioxidant that helps protect your cells — including your eye cells — from damage by free radicals, which are harmful, unstable molecules.
One seven-year study in 3,640 people with AMD showed that taking 400 IU of vitamin E and several other nutrients in a daily supplement called AREDS reduced the risk of progressing to advanced stages by 25%.
In addition, some studies suggest that diets high in vitamin E may help prevent age-related cataracts. However, more research is needed as some studies show no association between vitamin E and this condition.
Nonetheless, a diet that includes adequate vitamin E is recommended to maintain proper eye health. Some vitamin-E-rich options include nuts, seeds and cooking oils. Salmon, avocado and leafy green vegetables are also good sources.
3. Vitamin C
Like vitamin E, vitamin C is a powerful antioxidant that may protect your eyes against damaging free radicals.
Vitamin C and several other nutrients are used in the supplement AREDS, which may benefit those with AMD. When taken daily, one study suggests that AREDS may reduce the risk of this condition progressing by 25%.
In addition, vitamin C is required to make collagen, a protein that provides structure to your eye, particularly in the cornea and sclera.
Several observational studies suggest that vitamin C may help lower your risk of developing cataracts, a condition that causes your eye to become cloudy and impairs vision.
For example, one observational study showed a 75% reduced risk of developing cataracts when the daily vitamin C intake was above 490 mg, compared to 125 mg or less.
Another study found that regular vitamin C supplements may reduce the risk of cataracts by 45%.
Citrus and tropical fruits, bell peppers, broccoli and kale contain particularly high amounts of vitamin C, making them great options to boost your daily intake.
4. Vitamins B6, B9 and B12
Researchers have also studied several B vitamins for their impact on eye health, particularly vitamins B6, B9 and B12.
This combination of vitamins can lower levels of homocysteine, a protein in your body that may be associated with inflammation and an increased risk of developing AMD.
A clinical study in women demonstrated a 34% reduced risk of developing AMD while taking 1,000 mcg of vitamin B12 along with vitamins B6 and B9.
However, more research is needed to confirm the benefits of these supplements. In addition, it’s unclear if increasing your intake of vitamin-B-rich foods would have similar effects.
Another B vitamin studied in relation to eye health is riboflavin (vitamin B2). As an antioxidant, riboflavin has the potential to reduce oxidative stress in your body, including your eyes.
In particular, scientists are studying riboflavin’s potential to prevent cataracts, as prolonged riboflavin deficiency may lead to this condition. Interestingly, many individuals with cataracts also are deficient in this antioxidant.
One study found a 31–51% decreased risk of cataracts development when participants’ diets included 1.6–2.2 mg of riboflavin per day, compared to .08 mg per day.
Health authorities recommend consuming 1.1–1.3 mg of riboflavin per day. It’s usually easy to achieve this amount, as many foods are high in riboflavin. Some examples include oats, milk, yogurt, beef and fortified cereals.
The main function of niacin (vitamin B3) in your body is to help convert food into energy. It can also act as an antioxidant
Recently, studies have suggested that niacin may play a role in the prevention of glaucoma, a condition in which the optic nerve of your eye becomes damaged.
For example, an observational study on the nutrient consumption of Korean adults and their risk for glaucoma found an association between low dietary intake of niacin and this condition.
In addition, an animal study showed that high doses of niacin supplements were effective in preventing glaucoma.
Overall, more research on the potential link between niacin and glaucoma is needed.
Supplements should be used with caution. When consumed in high amounts of 1.5–5 grams per day, niacin may pose adverse effects to the eyes, including blurred vision, macular damage and inflammation of the cornea.
However, there is no evidence that consuming foods naturally high in niacin has any adverse effects. Some food sources include beef, poultry, fish, mushrooms, peanuts and legumes.
7. Lutein and Zeaxanthin
Lutein and zeaxanthin are part of the carotenoid family, a group of beneficial compounds synthesized by plants.
Both of these carotenoids can be found in the macula and retina of your eyes, where they help filter potentially harmful blue light, thus protecting your eyes from damage.
Several studies suggest that these plant compounds may prevent cataracts and prevent or slow the progression of AMD.
A randomized, controlled study found potential benefits of lutein for people with cataracts. Over two years, those taking supplements containing 15 mg of lutein three times per week experienced improvements in vision.
Recommended daily intakes and safe supplemental doses have not been established for these compounds. However, up to 20 mg of lutein per day for 6 months has been used in studies without adverse effects.
Nonetheless, supplements may not be necessary. As little as 6 mg of lutein and zeaxanthin may yield benefits, and a diet rich in fruits and vegetables naturally provides this amount. Cooked spinach, kale and collard greens are particularly high in these carotenoids.
8. Omega-3 Fatty Acids
Omega-3 fatty acids are a type of polyunsaturated fat. The cell membranes of your retina contain a high concentration of DHA, a particular type of omega-3.
Besides helping form the cells of your eye, omega-3 fats have anti-inflammatory properties which may play a role in the prevention of diabetic retinopathy (DR).
A review of 31 studies suggested that diets high in oily fish — such as the traditional Mediterranean diet — may protect against DR. Although these findings need to be corroborated with more research, they imply that fatty acids may be responsible.
Omega-3 fats may also benefit individuals with dry eye disease by helping them produce more tears. With this condition, a lack of tears causes dryness, discomfort and occasional blurry vision.
To increase omega-3 fatty acids in your diet, include rich sources such as fish, flaxseed, chia seeds, soy and nuts. Omega-3s can also be found in cooking oils such as canola and olive oil.
Thiamine, or vitamin B1, plays a role in proper cell function and converting food into energy
It’s possibly effective at reducing the risk of cataracts.
An observational study in 2,900 people in Australia suggests that a diet high in thiamine reduces your risk of developing cataracts by 40%. This study also indicates that protein, vitamin A, niacin and riboflavin may protect against cataracts.
What’s more, thiamine has been proposed as a potential treatment for the early stages of DR.
A clinical study found that 100 mg of thiamine taken three times daily reduced the amount of albumin in urine — an indication of DR in type 2 diabetes.
Food sources of thiamine include whole grains, meat and fish. In addition, thiamine is often added to foods like breakfast cereals, bread and pasta.
The Bottom Line
Research suggests that certain vitamins and nutrients may help prevent or slow the progression of several different eye conditions.
Supplements may be beneficial if you suspect you’re missing any of these vitamins in your diet.
However, eating a balanced diet rich in fruits, vegetables, whole grains, protein and healthy fats will provide you with all the nutrients your eyes — and the rest of your body — need for optimal health.
This post originally appeared on Healthline.