Vitamins For Eye Health

Eye diseases, especially age-related ones, are becoming more and more common in society. But what is the cause? And what can be done to avoid this vision damage? Here is a simple answer: fix your diet! Recent research has now identified a multitude of vitamins and nutrient-rich foods which can prevent and treat eye conditions, and maintain good eye health. And this article will tell you all about them. 

Introduction

Importance of eye health and vision

Over one billion people worldwide suffer from visual impairments and blindness, which can sometimes be caused by things that could have been prevented.¹ For example, facial cleanliness can help prevent trachoma, a common type of eye infection that can lead to some serious visual damage.² Additionally, vision impairment is strongly correlated with decreased quality of life, affecting a person’s physical and mental well-being.¹ Many eye diseases are age-related, with increased incidences seen in older populations. This is because the eye is especially sensitive to oxidative damage, usually a consequence of prolonged exposure to light and high oxygen consumption.³

Role of vitamins in supporting eye health

Recent research has shown that diet is a highly important factor in our overall health and can be a key factor in maintaining ocular health. Extensive research has looked into what antioxidant vitamin and mineral supplements can reduce or even prevent ocular damage due to oxidative stress.⁴

Overview of common eye conditions and their connection to nutrition

Age-related macular degeneration (AMD)

AMD is characterised by degeneration in the macula, which is the central area of the retina. As the disease progresses to an advanced stage, more and more eye damage occurs. This area plays a key role in high-resolution vision, meaning damage to the latter will cause vision loss. AMD is most common in people aged 55 years or more, and some studies have found a link between disease development and diet.⁵  

Cataract

A cataract is generally defined as a visible opacity within the crystalline lens of the eye, which is usually clear if healthy. The condition can further be subcategorised depending on the location of the opacity, for example, cortical or nuclear. Cataract is an age-related disease, but oxidative reactions are thought to be a key factor in disease development. Therefore, several antioxidant nutrients have been put forward to slow or prevent cataracts. Although results have been mixed, several studies have identified specific vitamins that reduce the risk of cataracts.⁴ 

Corneal neovascularization (CNV)

CNV is characterised by the inflammation of the cornea, causing the formation and extension of vascular capillaries within the eye, especially in the corneal regions where there would usually not be any vascularisation. This can cause pain in the eye, redness, light sensitivity and more.⁷ CNV can be caused by viral infections and autoimmune diseases but has now also been associated with vitamin deficiencies, in particular, vitamin A and riboflavin.⁸

Diabetic retinopathy (DR)

DR is a common complication of diabetes, a metabolic disease involving abnormally high blood glucose levels. DR is caused by the degeneration of neurons within the retina, as well as angiogenesis, which refers to the formation of new blood vessels within the eye. This then leads to severe vision impairment and sometimes even blindness. New studies have suggested the role of multiple nutrients in the prevention of DR development, which may allow for the development of an effective DR treatment.⁹

Vitamin A

Remember your parents always telling you that eating carrots will improve your vision? Well, they weren’t completely wrong. Vitamin A is found in many foods, including carrots, leafy greens, sweet potato, pumpkin, and more. The nutrient plays a key role in vision, as it allows for the production of certain pigments for retinal function, as well as moisture, to ensure that the eyes do not dry out. Vitamin A deficiency causes a reduced production of these pigments, leading to night blindness. This is an early symptom of vision loss, characterised by difficulties seeing in the dark. Vitamin A supplements have been shown to reverse night blindness and help moisturise the eyes again. However, overconsumption of vitamin A can cause several effects such as abdominal pain, drowsiness, headaches and more. Therefore, provitamin A carotenoid supplement, containing β-carotene, can also be used. β-carotene is an orange pigment often found in fruits and vegetables. It belongs to a class of compounds called ‘carotenoids’, and many clinical trials have suggested that β-carotene supplementation significantly reduces the risk of AMD development.¹¹ An average β-carotene consumption of 3 - 6 mg per day is recommended to maintain eye health. To put this into perspective, 78 grams of carrot contains just about 6mg of β-carotene. Although provitamin A carotenoids have little to no side effects, it is always smart to be cautious when using dietary supplements. For example, in people at risk of developing lung cancer, it was shown that over-supplementing with β-carotene would increase the risk.¹²

Vitamin C

Vitamin C plays a key role in collagen synthesis, which is an important substance for the structure of blood vessels, ligaments and bone. Additionally, it is an extremely effective antioxidant, meaning it is good at protecting important molecules in the body from damage by reactive oxygen species or free radicals. The latter are generated during normal metabolism, and due to the eyes having an especially high metabolism, they need good antioxidant protection. In addition to being an antioxidant itself, vitamin C may also help regenerate other antioxidants, further protecting the eye from oxidative damage.³

Vitamin C is found in a high number of foods, including broccoli, oranges, blueberries and more. The recommended serving size of vitamin C is both age- and gender-dependent, with men over 19 years old requiring about 90 mg per day, but women the same age only 75 mg per day, for example. Over-consumption is unlikely to be harmful but can lead to some side effects such as diarrhoea, nausea and vomiting.¹³

Vitamin E

Vitamin E is a family of 8 fat-soluble antioxidants. α-Tocopherol is the type of vitamin E often used as a supplement, as it is naturally present in the human body and plays a big antioxidative role. Fats play an important part in cell membrane construction and maintenance but are sensitive to oxidative damage. The retina contains a very high concentration of fatty acids, making it very vulnerable. However, retinal damage can be prevented by α-Tocopherol, which attacks free radicals and avoids oxidative stress. Vitamin E, therefore, plays an important role in maintaining eye health and preventing damage. One downfall of α-Tocopherol molecules is that, once it has attacked a free radical, they lose their antioxidant abilities. However, other antioxidants such as vitamin C can help them regenerate this capacity.¹³ Studies have also shown vitamin E to play an important role in the prevention and treatment of AMD, cataracts and other eye disorders. For example, it was shown that people with relatively high daily vitamin E intakes, about 20 mg a day, showed an average 20% less risk of developing AMD compared to those with low intake (less than 10 mg a day).¹⁴ Additionally, early AMD patients were found to reduce their risk of development to an advanced stage by 25% when taking a daily multivitamin supplement, which contained vitamin E.¹⁵ It is recommended for both men and women over the age of 19 years to consume about 15 mg of vitamin E a day. Foods high in vitamin E include almonds, sunflower seeds, peanuts and more.³

Vitamin D

Vitamin D is most well known as the ‘sun vitamin’, as sunlight can trigger vitamin D synthesis in the blood when it comes in contact with the skin. However, vitamin D is also found in various food sources, including fatty fish such as salmon or tuna, as well as fish liver oils, beef liver, egg yolks and cheese.¹⁶ Recent studies have found an important link between vitamin D and a variety of eye disorders, including AMD and DR. For example, vitamin D can protect cells, reduce oxidative stress, and have an anti-inflammatory role. Additionally, it can stop angiogenesis and play a role in the prevention or slowing down of AMD. Concerning DR, vitamin D is thought to inhibit neovascularization; however, research results are mixed. Lastly, vitamin D is proposed to play a role in the development of myopia, a common visual impairment causing blurriness of objects farther away. Spending time outside has been shown to prevent this condition, and researchers suggest that this is due to vitamin D. However, although myopia seems to be inversely associated with vitamin D levels, the latter is unlikely to play a direct role in disease prevention.¹⁷

Vitamin B complex (B6, B9 and B12)

The vitamin B complex includes a variety of B vitamins which play an important role in our health, with deficiencies possibly leading to cardiovascular and cognitive disorders. Regarding eye health, vitamins B6, B9 and B12 seem to be especially important. Recent studies found that higher consumption of vitamins B6, B8 and B12 could significantly reduce the risk of AMD progression to an advanced stage. It is believed that this is due to the role of these vitamins in homocysteine level regulation, which is a risk of AMD when overproduced.¹⁸

Aside from food supplements, vitamin B consumption can be increased by eating more chickpeas, tuna, beef liver, salmon, spinach, white rice and many more foods.¹⁹

Vitamin K

Vitamin K is mostly known for playing a role in blood clotting and supporting the mechanism which heals wounds. Additionally, the nutrient has been found to influence bone metabolism and other physiological functions.²⁰ The adequate intakes of vitamin K depend on age and gender, with 19+ year-old assigned females at birth only needing 90 micrograms, whereas males the same age need about 120 micrograms. Several food sources contain vitamin K, such as collards, turnip greens, spinach and more. However, the body's absorption rates of the nutrients from these foods can vary.

There is not a lot of research on the role of vitamin K in eye health. However, some studies suggest that its link to a special protein, the matrix Gla protein (MGP), makes it beneficial. The nutrient is believed to improve circulation in the eyes. Additionally, MGP, and thus vitamin K deficiencies, have been linked to glaucoma, cataracts and other ocular disorders. Studies have found this to be due to vitamin K’s anti-inflammatory and antioxidative effects, as well as its important role in the blood system.²¹

Lutein and zeaxanthin

Lutein and zeaxanthin are carotenoids, which, unlike β-carotene, do not contain any vitamin A. Additionally, they are the only carotenoids in the human body that can be found in the lens and retina of the eye. The nutrients are specifically located within the macula and are also called macular pigment. They are antioxidants, so play a protective role against oxidative stress. On top of this, lutein and zeaxanthin are thought to absorb blue light, which has previously been linked to AMD, and get rid of reactive oxygen species. This further suggests their importance in maintaining eye health and avoiding oxidative damage to the retina. Lutein and zeaxanthin can usually be found in the same foods, mainly in broccoli, kale, spinach and other green leafy vegetables.³

Omega-3 fatty acids

Omega-3 fatty acids, commonly found in salmon and other kinds of cold-water fatty fish, have been linked to eye health. They play roles in the modulation of oxidative stress, inflammation, and vascularization and are, therefore, key factors in eye and retina protection. Omega-3 fatty acids have been particularly linked to AMD, with people consuming higher amounts of dietary omega-3s showing a significantly lower risk of developing the disease.²² However, further studies did not find a positive effect of increasing Omega-3 consumption on disease progression.²³ In addition to AMD, omega-3s are thought to reduce the risk of dry eye disease, a chronic condition characterised by eye inflammation and damage due to decreased tear quality and volume. This can then lead to pain, discomfort and vision loss. On top of reducing the risk of developing the disease, some studies claim to have found beneficial effects of omega-3 supplementation on the symptoms of dry eye disease patients. However, more research is needed to help understand the exact link.²³ 

Zinc

Zinc is a key factor in the metabolism of the eye and, therefore, plays an important role in maintaining retina health. The nutrient plays both an antioxidant and immune function in the eye but is also involved in membrane and protein structure. Therefore, a lack of zinc in a membrane can increase their sensitivity to oxidative stress and their risk of oxidative damage. Research has also shown that zinc supplements can aid in delaying the progression of AMD and vision loss, and this is theorised to be by preventing damage in the retina.²⁴ The recommended daily intake is between 9 - 11 mg/day, depending on age and gender. Turkey (dark meat), oysters, crab and cashews are among the food sources that are rich in Zinc.³

Incorporating eye-healthy vitamins into the diet

Due to the inconsistency in recommended serving sizes of nutrients from different studies, it is difficult to create a ‘one size fits all’ rule. In addition, it is believed that individual nutrients do not provide protection, but they need to work together to be most efficient. Therefore, before jumping immediately to dietary pills, it may be better to simply focus on incorporating more vitamin-rich foods into your day-to-day diet. Several food sources were mentioned in this article, but the key thing to remember is to eat a varied diet with a variety of fruits, vegetables, nuts, legumes, lean meats, dairy and fish. This will ensure that you’re consuming a healthy diet that is antioxidant-rich and protects your eye health. Dietary supplements have mostly been proven useful in the case of eye diseases, such as AMD or cataracts. Here, the incorporation of eye-healthy vitamins has been shown to slow down disease progression, sometimes even preventing the development of the condition altogether.³ 

Conclusion

Many vitamins are involved in eye health due to their antioxidant, anti-inflammatory and repairing properties. These include Vitamin A, C, E, D, K and B, as well as zinc, lutein, zeaxanthin and omega-3 fatty acids. The important takeaway is that an overall balanced and healthy diet will help avoid any vitamin deficiencies, and supplementation is not always needed. However, in case of disease or symptoms related to decreased eye health, it may be beneficial to consult a doctor and possibly use specific vitamin supplements to treat the condition.