As a kid my Mother always insisted that eating carrots would improve my eyesight. I was disappointed to discover that no matter how many carrots I ate, my near sightedness got worse. But there was some basis for my mother’s advice. Carrots are high in Vitamin A, and a deficiency in this nutrient can cause some difficulty seeing in dim light.
Vitamin A is essential for the formation of the chemical retinal, whose presence in the retina is necessary for vision. Our eyes have two kinds of light sensitive cells: the rods and the cones. The rods are the cells we rely on to see in dim light. They are sensitive to Vitamin A deficiency, because it can cause a shortage of retinal.
When light strikes the retinal molecule, it changes its shape. This activates a cascade of chemical reactions that informs the brain that light has entered the eye. When the levels of light sensitive molecules are low, due to Vitamin A deficiency, there will not be enough retinal to detect the light at night. During the day there is enough light to produce vision, despite low levels of retinal. So it’s only night vision that can be improved by eating carrots.
Since most of us get enough Vitamin A in our diet to produce sufficient retinal, eating more carrots won’t have a noticeable effect on our eyesight.
So next time, follow Mum’s advice and eat those carrots, even if they don’t improve your vision, you’ll certainly keep her happy.