Oranges For Eye Health

Why eye health is just as important as our brain health?

The health of our eyes is often overlooked, even though they play a vital role in our daily lives. It is important to know by looking after our eyes we are indirectly helping our brain to remain healthy also. This inevitably leads to improving our overall quality of life. By having good vision quality, we will have great memories to create and remember. But this is only one small benefit of looking after our eyes.

It is extremely important to maintain our eye health so we can prevent vision deterioration as we age, as well as the progression of eye-related diseases. An eye health exam can detect a range of indicators of our general health, including diabetes, stroke, arthritis, and even cancer. Worldwide, approximately over 200 million people have issues with progressively worsened vision with prevalent causes including cataracts.¹⁰ As a common explanation that our vision decreases with age, scientists have not pinpointed the exact causation with a multitude of factors that have to be considered. A notable contribution to vision loss is associated with circulating oxidative stress in the body as a cause, which the eye is extremely sensitive to.¹⁰ Accordingly, the contribution of our diet remains of promising avenue of interest. As oranges present antioxidant properties, it remains a promising and beneficial factor in promoting eye health. 

So how do we promote eye health?

Nutrition and diet have a central role in facilitating our health. Likely beneficial effects in promoting eye health reside in the consumption of antioxidant vitamins to prevent further oxidative stress. Nutrition therefore can contribute as an effective strategy in preventing the development of eye diseases. Studies have associated the intake of a diet full of vitamin C, lutein, zeaxanthin, and catechins with facilitating eye health.¹¹ Furthermore, a large summation of research emphasises the importance of contributing antioxidants in our diets to prevent the chances of chronic diseases. 

A research study by Westmead Institute for Medical Research in 2018 found a direct association between consuming oranges and preventing macular degeneration. Macular degeneration is a condition which directly affects the retina and continues to deteriorate it with time. It results in reduced central vision and can eventually lead to blindness.¹⁵ The study revealed that individuals who consumed just one orange a day had decreased their risk by over half of developing macular degeneration for up to fifteen years (Westmead Institute for Medical Research, 2018). 

What is so beneficial about oranges?

The citrus fruit contains an array of beneficial nutrients ranging from elevated levels of fibre, vitamin C, and flavonoids. Each has a beneficial factor on our health. For example, consuming an individual unit of orange relates to the regular required amount of vitamin C at 60mg.⁹ Vitamin C is renowned for protecting against infections circulating in the body and also has notable antioxidant effects. It works to destroy the presence of circulating harmful free radicals in the body. The phrase ‘An apple a day keeps the doctor away’ may not be so literal as to achieve the same amount of vitamin C from one orange you would have to eat fifteen apples! So oranges are really nutritionally beneficial. 

Oranges contain a large volume of antioxidants loaded with vitamin C and flavonoids. One flavonoid of particular importance is Hesperidin found in elevated levels in orange juice.⁸ This makes the consumption of oranges extremely beneficial as Hesperidin is found in citrus sources but not all foods.¹² Notably more recent research by Maekawa, S et al. has highlighted the neuroprotective effects of this polyphenol. The research has explored Hesperidin as a potential target for effect in retina damage and injury. The association led to findings such as the positive action of Hesperidin in reducing free radicals and suppressing oxidative stress linked to retina cell death.⁷ The findings are suggestive of the potential of Hesperidin as a potential supplement in the future. Hesperidin is present in large amounts particularly in orange juice, with 100 containing between 20-60mg and up to 45mg in oranges.⁸ This is double the concentration compared to that found in a grapefruit!

‘Eating carrots allows you to see in the dark`

This phrase has circulated the world, and isn't far wrong that carrots can help with our vision! This is because it contains carotenoid pigment which is beneficial for our eyes. Importantly this is found in abundance in oranges. In orange juice levels of lutein are around 50%.¹³ The flavanoid appears as a bright colour in fruit usually yellow but turns orange in high concentrations. Lutein is found predominantly in the macula and retina of the eye. It is also thought to have a protective mechanism for tissue in the eyes by preventing the entry of ultraviolet rays from the sun.¹¹ This prevents phototoxic damage. Essentially, it acts as a filter for blue rays. Furthermore, it is also found to enhance eye health alongside preventing disease progression of macular degeneration which leads to blindness.¹¹ This is because research has hypothesised a correlation between the intake of lutein and the density of the macular pigment in the eye.⁴ Macular pigment density in the eye is important for preventing the progression of diseases such as age-related macular degeneration. Therefore intake of the caratoinid can a larger consumption of lutein can help stop ARMD (Sommerburg O., 1998). The key message here is that we can only receive lutein from our food so it is important to eat your oranges.

Where does vitamin C come into the bigger picture?

Vitamin C is found in between the retina and lens of our eye in a region called the vitreous humour. For context the area of the eye that appears as a gel-filled liquid. The elevated levels of this vitamin and its properties of UV absorption have presented it as a biological sunscreen.⁵ This in itself is a beneficial property in protecting our eyes and vision from phototoxic damage like lutein. Therefore, its role includes absorbing as much UV light so that it does not enter the tissue behind the retina and lead to damage. Research experiments on rats have shown that vitamin C acts to shield against oxidative stress caused by exposure to harmful UVs.⁵ To assess these findings further research involved similar criteria to the human eye by testing guinea pigs. This is because they need supplemented vitamin C alike humans.⁵ It was found that in comparison to guinea pigs with a lack of vitamin C, they were much more shielded from UV-B rays and damage to the layers of the cornea.⁵ Summed together, these findings propose that vitamin C levels are extremely important for protecting against DNA damage to the eye specifically the epithelium lens which is exposed to direct light. Therefore having just one orange a day is close to the daily requirement amount of vitamin C needed.

One of the top leading eye conditions in the world is cataracts. They are caused due to the gradual decay of proteins in the eye; leading to a cloudy appearance that is experienced.³ Cataracts over time can be damaging to an individual's quality of life as vision becomes limited. A new association between vitamin C and reduced cataract risk has been explored. A study was partaken amongst the Mediterranean population assessing the consumption of vitamin C on cataract progression. The Mediterranean diet is high in consumption of citrus fruits such as oranges which contain high levels of flavanoids and vitamin C. Findings displayed that the protective properties of vitamin C were seen in abundance amongst the population having reduced likelihood of developing cataracts due to higher consumption of vitamin C.⁶ 

Collagen for Youth

Vitamin C in oranges is rich in promoting the production of collagen in our body, specifically the eyes. As we age collagen depletesand so it is essential to build the levels of collagen in our eyes now whilst we can. Vitamin C works to build collagen which provides the shape of our eyes.² It is found specifically in the sclera and cornea of the eye, and so vitamin C is vital for stimulating collagen production.¹

Not to forget Vitamin A

Oranges contain levels of beta carotene which are beneficial to consume as the human body converts this into vitamin A which is vital for eye health. Vitamin A has two central components which work to enhance eye health, as it prevents night blindness and assists retinal function.¹⁴ As night blindness is sometimes caused by a deficiency in the vitamin, supplements are needed to alleviate this condition. It is also essential for the systematic functioning of our eyes, and a lack of this source can lead to eye conditions such as hypovitaminosis which is vision dysfunction.¹⁴ However this is possible to treat with vitamin A intake. It emphasises the importance of vitamin A which we can retrieve from oranges for our health. It is important to note that of course vitamin A is good for assisting our eye health in moderation, however intake outside of this range can be harmful and individuals should be aware.

Summary 

Oranges must be considered a plentiful nutritious citrus fruit with a range of benefits particularly to our eye health and beyond. This is because it consists of a range of enhancing supplements which aid our immune system and provide anti-oxidant effects. For example, the large quantities of vitamin C present in oranges prevent the retina from oxidative stress and damage to the eye. It contains the precursor of vitamin A which is essential for promoting good eye health and prevents the development of night blindness. The benefits of oranges extend beyond eye health to helping us develop particular diseases associated with the eyes including macular degeneration and cataracts. It is important to incorporate oranges into one of your five a day, as an orange a day may help keep the optician away!