The photoreceptors in your eyes use molecules derived from vitamins to absorb the energy from light around you. The most common is derived from vitamin A for use in a proteins like rhodopsin (the main photopigment in your rods) and the three color-opsins (for the three types of cones). Another is derived from Vitamin-B2 and is used in another photopigment called cryptochrome. So, in research, sometimes people can use vitamin deprivation to shut down one pathway to determine if the phenomenon they are studying happens through the -opsin pathway or through the cryptochrome pathway.
But it's interesting because these vitamins, aside from being good at absorbing energy from light, they're also inherently good at absorbing energy from free-radicals too. This makes them very good anti-oxidants, which is the main reason why they're good for us.
For the same reason, you're supposed to eat your vegetables, because they have lots of photopigments to absorb light from the sun, and act as anti-oxidants. Carotenes, lycopene, xanthophils, chlorophylls, are all photopigments, and are also good anti-oxidants.
So everyone should take their vitamins and eat their veggies and pick the most heavily pigmented ones and also you should try to give and get eight hugs a day.