Basic Facts On Vision Vitamins

By Nita McKinney


Apart from improving eyesight, vision vitamins also play a very vital role in the prevention of certain eye diseases such as macular degeneration and cataracts. Of all the nutrients that are known to have these benefits, vitamin A is undoubtedly the most published. It will be worth noting that there are many other nutritional elements that are equally as helpful. These include, for example, vitamin C and b6 and elements such as selenium, magnesium and zinc. Such nutrients will be found in great quantities in foods such as oranges, leafy vegetables and pumpkins.

We will look at vitamin A in detail and understand what it is that it does at cellular level. Research has revealed to us that this vitamin is very important in the synthesis of a pigment known as rhodopsin. This pigment is found in high amounts on the retina which acts as a screen on which images from the environment are formed. Adequate levels of rhodopsin are needed to help one see better in dim light.

It should be understood that vitamin A is not a single unit. Rather, it is made of several non-saturated hydrocarbons. These hydrocarbons include retinoic acid, retinol, retinal and other precursors known as carotenoids. Beta carotene is the most important of these carotenes. The retinal hydrocarbon reacts with a protein known as opsin to form rhodopsin. The resultant molecule helps in the achievement of scotopic (low light) and colour vision.

Deficiency of vitamin A results in a number of eye conditions that vary in severity depending on the extent of involvement. It often occurs when there is reduced intake of provitamin A carotenoid containing foods such as vegetables, dairy and animals products and fruits. This is the commonest scenario and is also referred to as primary vitamin A deficiency.

Secondary deficiency may be seen in a number of circumstances. For instance, it is seen when there is malabsorption of the vitamin. This frequently occurs when there is decreased uptake of lipids and reduced release of bile. The vitamin requires fat to dissolve and a deficiency of the fats will therefore result in decreased absorption. Other risk factors for the same include prolonged smoking and alcohol intake.

One of the most initial manifestations of vitamin A deficiency is night blindness. This refers to impaired scotopic vision. With time, the condition may worsen and changes such as drying of the conjunctiva may occur. This happens because the normal tear secreting system is replaced by keratinisation. This is accompanied by formation of keratin plaques in the cornea which eventually gets eroded as more keratinisation leading to complete blindness.

The antioxidant properties of vitamin C help protect the eye from damage due to radiation. This nutrient also helps in maintaining normal pressure, collagen and capillary integrity. Vitamin B6 helps maintain the structure and function of red blood cells found within the retina. A trace element such as zinc plays a key role in ensuring good vision. It is responsible for converting beta carotene to vitamin A.

While it may not be practical to take all vision vitamins every day, it is advisable to take food supplements that contain the maximum number of essential vitamins in them. The amount of intake is also limited by factors such as age, sex, pregnancy and lactation. It is important to ensure that one takes just the right amount of nutrients to avoid toxicity and related complications.




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