Diet and myopia prevention and control: a magical relationship or a beautiful misunderstanding?

Author: Yang Weiming, attending physician, Children's Hospital Affiliated to Fudan University

Reviewer: Yang Chenhao, Chief Physician, Children's Hospital Affiliated to Fudan University

You are no doubt familiar with the topic of myopia, and you may even worry about it every day. Nowadays, the incidence of myopia among adolescents is increasing year by year, and it has become a major public health problem worldwide. Parents hope to find a way to fight myopia by getting closer to nature.

In WeChat Moments, video accounts and other media, we often see information such as "eating more blueberries, cherry tomatoes, kiwis, carrots and other foods can help protect your eyes." Therefore, in order to protect their children's eyesight, many parents will deliberately let their children eat more related foods. Imagine that you are immersed in a feast of delicious food, and the nutrients in these foods have become your secret weapon in the fight against myopia. This is a dream situation where you can win with your bare hands, which is exciting! However, can they really save our eyes?

What is the relationship between diet and myopia prevention and control? Is there any scientific basis for this? In this article, we will demystify the relationship between diet and myopia prevention and control from the perspective of professional doctors.

1. The relationship between foods containing vitamin A and myopia

Vitamin A is found in many foods, such as green leafy vegetables, orange vegetables (such as carrots, sweet potatoes and pumpkins), eggs and cantaloupe, etc. There are also many commercial vitamin A nutrients (health products) on the market.

Vitamin A plays an important role in maintaining normal growth and enhancing immunity. When the human body lacks vitamin A, it may lead to a series of health problems, such as delayed bone development in children, stunted development of enamel cells, damaged epithelial tissue structure, and low immune function, which can easily lead to various infections of the respiratory, digestive and urinary systems.

In addition, vitamin A plays a key role in the formation and maintenance of vision. The eyes need vitamin A to synthesize specific proteins (such as rhodopsin), which are essential for the eyes to perceive the full spectrum of light. Insufficient vitamin A will hinder the production of these proteins, resulting in a decrease in the dark adaptation ability of children, and in severe cases, may develop into night blindness. Vitamin A also has a nutritional effect on the cornea. It can maintain the integrity of the ocular epithelial cells and the moisture of the ocular surface. Lack of vitamin A may lead to serious corneal diseases such as keratomelacia.

However, although vitamin A is essential for the overall health of the eyes, there is currently no scientific evidence that vitamin A can prevent or control the occurrence and progression of myopia. Therefore, as long as children consume a balanced variety of foods in their daily diet and avoid partial and picky eating, they do not need additional vitamin A supplements.

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2. The relationship between lutein and myopia

Lutein, a plant lutein, is an important vitamin in the carotenoid family and a key pigment in the macula of the retina. The role of lutein in the human body is mainly reflected in its antioxidant properties, filtering out harmful blue light and maintaining visual function.

The human body cannot synthesize lutein on its own and must be taken in through diet. Lutein is found in many fruits, vegetables, flowers and some algae, especially in green leafy vegetables such as kale, spinach, leeks, etc. In addition, egg yolks and corn also contain high levels of lutein. Getting enough lutein in the diet is essential for eye health.

The protective effect of lutein on the eyes is mainly reflected in the following aspects:

① Lutein can absorb blue light. The wavelength of blue light is close to ultraviolet light, which is the most harmful part of visible light. It mainly comes from sunlight and electronic screens. Lutein forms an effective blue light filter in the retina, protecting the eyes from blue light damage. This is especially important for people who use electronic devices for a long time in modern society.

② Lutein has a strong antioxidant effect. As a natural antioxidant, lutein can effectively remove oxygen free radicals and reduce oxidative damage to eye tissues. In addition, lutein also plays a certain role in preventing and slowing down eye diseases such as age-related macular degeneration and cataracts. By supplementing lutein, the development of these diseases can be delayed to a certain extent.

However, lutein has no significant effect in preventing myopia. The causes of myopia are mainly related to long-term close-up use of the eyes, genetics and other factors, and lutein mainly acts on the lens and macula of the eye. There is currently no evidence to prove a direct link between lutein and myopia. Therefore, although lutein is beneficial to the overall health of the eyes, it is still unclear whether it is related to the occurrence and development of myopia.

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3. The relationship between blueberries and myopia

Blueberries have strong antioxidant activity and free radical scavenging ability because they are rich in anthocyanins. Anthocyanins are highly biologically active substances that have significant effects in preventing cardiovascular diseases, controlling obesity, delaying the development of diabetes, lowering blood lipids, delaying brain aging, and enhancing brain function.

Anthocyanins in blueberries also show a variety of potential benefits in the prevention and treatment of eye diseases. Its main effects include:

① Protect eyesight and relieve visual fatigue. Anthocyanins can promote microcirculation in the fundus, increase blood supply to the fundus, and help regenerate rhodopsin, thereby protecting eyesight and relieving eye fatigue. Blueberry anthocyanins have a certain relieving effect on visual fatigue caused by long-term use of the eyes.

②Prevention and treatment of diabetic cataracts: Anthocyanins may effectively delay the development of cataracts by scavenging free radicals and inhibiting oxidative damage.

③Preventing form deprivation myopia, treating retinal light damage, etc. Although the above effects have been preliminarily verified in animal experiments, it should be noted that there is currently a lack of sufficient human clinical trials to confirm its effectiveness.

Therefore, although blueberry anthocyanins have certain positive significance for eye health, especially in the potential prevention and relief of eye diseases, their specific effects on myopia prevention and control are still unclear and need to be confirmed by further clinical research. Parents should not hope to achieve the goal of controlling myopia by eating blueberries.

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In short, scientific prevention and control of myopia needs to start with good behavioral habits. Although a healthy diet is good for the overall health of the eyes, it is far from enough to rely solely on diet to control myopia. A scientific lifestyle and correct eye habits are the key to preventing and controlling myopia.