Diet and the eye

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Prof. Marc D. de Smet & Dr. Maria Sol Rodriguez Pena

Prof. Marc D. de Smet, Ophthalmic surgeon, specialist in the retina and inflammatory diseases of the eye Dr Maria Sol Rodriguez Pena, specialist in nutritherapy MIOS AG, Retina and Ocular Inflammation, Av du Léman, Lausanne

May 31, 2021

Our eyes are exposed to various harmful factors every single day. It can be from computer screens, artificial lights, pollutions, and more. Since a good, varied diet helps our bodies in multiple ways, it’s no wonder that it can also help prevent eye tiredness. Eye tiredness can cause burning, tearing, and even headaches. To be more precise, your diet should consist of a lot of fruits and vegetables and should be as natural as possible. You can even take supplements for your vision if your doctor deems it so. There are negative effects that can come from supplements so picking out carefully what you eat is a better way to go about this. 

In order to learn more about this, keep reading the article Prof. Marc D. de Smet & Dr. Maria Sol Rodriguez Pena.

Our eyes are exposed to artificial light, computer screens, dust, smoke, air pollution and many other external influences every day. Therefore, it is not surprising that we sometimes suffer from symptoms caused by tired eyes: Burning, tearing, headaches …

As for the rest of the body, a healthy lifestyle and diet are essential for eye health. The crucial role of nutrition for healthy eyes is often discussed, but which nutrients have a positive effect on our eyes and what do they contain? Nowadays, there are many supplements that promote eye health. But are they really necessary? And which ones should we take and when? First of all, it should be explicitly stated at this point that an overly restrictive diet is not recommended without justification, without the establishment of an appropriate biological balance (blood tests) and without medical supervision. However, with or without a diet, a balanced diet must include complex carbohydrates, fats and a small proportion (15% of the plate) of proteins. Sugar, especially glucose, is essential for energy production, while fats and proteins are essential for building and maintaining our cells. Despite the bad reputation of certain fats, a diet too low in fat is anything but healthy!

The nutrients – quantity ≠ quality

The quality of sugars, fats and proteins in our diet is as important as their quantity. However, over the last few decades, their nature and quality have been greatly altered by the food industry. For the food industry, the shelf life of products has become a priority, at the expense of nutritional values. Refined sugars reduce mineral and fibre content and promote absorption in the intestines, leading to blood sugar spikes that have devastating consequences for the organism. Even worse, the food industry mainly uses refined, hydrogenated and deodorised fats because they are less prone to going rancid and are easy to process in ready-made meals. Unfortunately, these fats have few nutritional properties, in particular they have low levels of fat-soluble vitamins (vitamin E) and omega-3 fatty acids. For proteins, the balance does not look much better. The devastating consequences of industrial animal breeding have already repeatedly made the headlines. And industrially produced meat is now our biggest source of animal protein. Vegetable (often transgenic) proteins, incidentally, also fare rather poorly from a nutritional point of view.

This leads to the conclusion that a healthy diet is a real challenge in everyday life. It must not contain too many industrial foods, especially not too many convenience foods. Although these are convenient when one lacks the time to cook, they must remain the exception and must not become the rule.

Eating right for healthy eyes

Let’s start with omega-3 fatty acids. You are probably already familiar with them. Omega-3 fatty acids help lower cholesterol, are good for the skin, the hair, the brain… and of course for the eyes! Everyone is talking about them because they are essential; however, they are only found in small quantities in the modern diet. The rods of the retina contain particularly high levels of omega-3 fatty acids. It has long been known that omega-3 fatty acids are essential for nerve transmission (including that triggered by light). They even play a role in protecting neurons and developing vision in children (Gordon 2013, Demming 2013).

What are these fatty acids in? Read the label on your rapeseed oil. It is particularly rich in omega-3 fatty acids, but pay attention to the production process: It must be a cold-pressed oil and it should be stored away from light in the refrigerator. Also, look at the labels of sunflower and olive oils. These oils contain very few omega-3 fatty acids! In practice, there is no perfect oil for health. We need to consume several oils in their raw state to get maximum health benefits. Olive oil, for example, contains no omega-3 fatty acids, but is particularly rich in antioxidants and therefore very healthy. Rapeseed oil contains many omega-3 fatty acids, but these are lost when it is heated, causing the oil to go rancid quickly. Rapeseed oil should therefore be used raw, for example in a salad dressing, or better still, in combination with olive oil, which is rich in antioxidants. Omega-3 fatty acids are also found in animal fats, provided the animals have been fed on feed that naturally contains omega-3 fatty acids, such as algae, grass or seeds like linseed, which is particularly rich in omega-3 fatty acids. Unfortunately, this feed is not used in industrial breeding because it is too expensive. Some trace elements such as zinc or selenium are particularly important for the eye. They increase the effect of protective enzymes. These important co-factors are effective even in small doses and reduce the oxidative stress caused by light. Zinc is found in many foods, for example red meat, poultry, legumes, nuts, seafood (especially oysters), whole grains and dairy products. Brazil nuts contain a lot of selenium.

Let’s move on to antioxidants. Unlike many animals, which can produce antioxidants in large quantities themselves, humans are unable to do so. His only source of antioxidants is diet. Antioxidants include the vitamins (A, C and E), but not only …The cones and rods of the retina need vitamin A to turn light into a nerve signal. A vitamin A deficiency is the cause of poor vision, especially poor night vision. This vitamin is found in the form of a precursor (beta-carotene) in carrots, but also in all other orange-coloured fruits and vegetables: sweet potato, pumpkin, mango and apricot. Vitamin A is found in many animal products such as liver, fish liver oils, butter, fatty dairy products and egg yolks. Vitamin C is a water-soluble vitamin that is found in high concentrations in the lens, cornea and the fluid inside the eye. Vitamin C is mainly found in fresh fruits and vegetables. Vitamin E helps fight the effects of ageing thanks to its antioxidant properties. This vitamin is not present in excess in our diet. Nuts (almonds, hazelnuts) and unrefined vegetable oils are the most important sources of vitamin E. It complements the action of vitamin C and carotenoids and helps protect lipids (fats) in cell membranes by scavenging free radicals. Light generates many free radicals on the retina. If the radicals are not captured by antioxidants, they denature the fats and over time initiate a process that leads to age-related macular degeneration.

Carotenoids are pigments that are normally present in the retina. They are produced solely by photosynthetic microorganisms and by plants. The latter use them to protect themselves against the harmful effects of intense light and oxygen. Carotenoids include carotenes (abundant in carrots and tomatoes), zeaxanthin (abundant in yellow foods such as corn, but also in eggs if the hen has been fed a diet high in zeaxanthin) and lutein (abundant in green leafy vegetables). Carotenoids are responsible for the yellowish colour of the macula (yellow spot). These powerful antioxidants also filter out blue light, which is particularly damaging to the retina. These two effects help protect the retina from degeneration. Their presence in the retina decreases with age. To improve vision and minimise the risk of disease, a balanced and nutrient-rich diet with foods that are as unprocessed as possible is best. You could even say a diet with regional products. This will ensure that you are eating whole foods rich in zeaxanthin, lutein, antioxidant vitamins and minerals, and a balance of omega-3 fatty acids.

What should the diet specifically look like?

Specifically, your diet should be as natural as possible and rich in fruits and vegetables. Food should be freshly prepared. It must contain enough complex carbohydrates (starch and fibre); simple and refined sugars such as fructose, table sugar and sucrose should be avoided. High-quality fats and proteins and a sufficient amount of water are important components. Fruits and vegetables contain many vitamins, minerals and antioxidant molecules that are valuable for the eye. Vitamins C and E and the carotenoids from fruit and vegetables enable the neutralisation of free radicals. High-quality proteins and fats are found in fish, meat, eggs, milk, etc. When buying meat and fish, make sure that the animals have been fed with natural feed. If you are on a vegetarian diet, you already know that a combination of cereals and pulses will also give you very high quality protein. The quality of fat in our food is very important for our health in general and that of our eyes. And yet, fat is the nutritional ingredient that has been most altered in convenience foods. The valuable omega-3 fatty acids are mainly found in fatty fish (sardines, herring, mackerel, salmon) or in meat from animals that have been fed grass or grains with omega-3 content, for example linseed, linseed yolk or rapeseed. Be especially careful when preparing food with oils containing omega-3 fatty acids and store them properly, because these fatty acids are very sensitive to heat. Deep-frying and other cooking methods with temperatures above 100ºC destroy the omega-3 fatty acids and char the proteins in the meat, leading to the formation of radicals that are harmful to the organism. Despite the bad reputation of saturated fats, they are also important for our health. Trans fats, however, are to be avoided. They are found in almost all industrial foods and sometimes even in dishes we prepare at home in the kitchen! Trans fats can be caused by incorrect heating of oils, especially vegetable oils (rapeseed, sunflower, nut, olive oil)!

Your doctor may recommend that you take supplements for your vision if necessary. However, taking high-dose supplements can have undesirable side effects. For example, taking vitamin E or omega-3 fatty acids in the wrong way without medical supervision can increase the effect of anticoagulants (medicines that make the blood fluid) and thus increase the risk of bleeding. High-dose beta-carotene (in the form of supplements) increases the risk of lung cancer in smokers. However, there are no known side effects for a balanced diet rich in antioxidants. So eat healthy and with pleasure! Change your diet! You no longer have an excuse! There is plenty of room on your plate for plenty of vegetables. And how about a dessert with red fruits (berries, raspberries, strawberries) or another fruit!

Health goes through the stomach! In some cases, your doctor may refer you to a nutritionist or nutritherapy specialist if you wish. The latter can give you precise recommendations tailored to your individual case. During a check-up with one of these experts, specific nutrient deficiencies can be detected with a targeted blood test. However, it should also be noted at this point that most Swiss health insurance companies do not cover the costs of a consultation with nutrition specialists or specialists in nutritherapy.

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