Vitamin A From Meat & Two Veg.

I have this rather unusual hypothesis that if you eat right for your eyes, your body will take care of itself. With that in mind, we are talking about vitamin A (aka Retinol). Today’s tip is…

One certain thing, however, is the importance of vitamin A for the whole body and especially for the eyes. Today, I’m going to attempt to make a complex biological explanation easy to understand and apply for the benefit of your eyes.

You see, vitamin A in our foods has 2 major important roles that I can think of in the eye. The main one is to allow your eyes to make the visual pigment called rhodopsin, which allows your eyes the ability to adapt to dark and light conditions and do so in a replenishing cycle.

Vitamin A also helps the transparent membrane of the eyes called the cornea and conjunctiva to function well and prevent a range of extreme dryness signs and symptoms associated with the condition called xerophthalmia.

We can get vitamin A directly from certain foods, but some other foods provide vitamin A only in a form called beta-carotene, which needs to be converted first to vitamin A before rhodopsin can be produced for the eye. It therefore requires more steps and energy for the body to produce rhodopsin from beta-carotene.

Food sources of vitamin A

There are two different ways we can get it from our diet.

• Meat sources - The first is by consuming animal foods that contain retinol, sometimes known as “preformed vitamin A.” Retinol is a highly bioavailable form of vitamin A that the human body can use in its current form.

• Plant sources - Many plant foods contain carotenoids, which are sometimes called “provitamin A carotenoids.” The best sources of carotenoids are foods such as carrots and sweet potatoes. However, the human body needs to convert carotenoids into retinol before it can use them as vitamin A.

Preformed Vitamin A (Retinol) vs. Provitamin A (Carotenoids)

While carotenoids can be converted to form rhodopsin to benefit the retina, the conversion rate of carotenoids to retinol from plants can be low and variable in humans. As a result, plant foods do not offer the same biological availability as animal food sources of vitamin A.

Plant sources of vitamin A (Carotenoids): There are about 50 plants that provide Retinol. Here are some of the highest sources…

• Carrot juice

• Pumpkin

• Spinach

• Sweet potato

• Butternut squash

• Broccoli

The highest animal sources of Vitamin A (Retinol) include…

• Beef liver

• Herring fish

• Cod liver oil

• Egg yolks

• Chicken liver

• Dairy products like whole yoghurt

Hopefully, this makes clear the benefit of vitamin A for the eyes. Use the tips here as a basis to do more research.

Until the next issue,

Martin Oguzie | Optometrist