If you want to protect your eyes, forget carrots -- there's another "C" that plays a much more important role in how you see: Vitamin C.

Two new studies show how C can keep your peepers performing at their peak -- including one that finds that certain retina cells literally shut down when they run out of C.

The researchers wrote in the Journal of Neuroscience that their finding suggests a diet rich in vitamin C may protect against glaucoma -- but more importantly, they say the retinal cells used in the study are closely related to similar cells in the brain.

And if low C can cause those cells in the eye to go dark, just imagine how it can dim your mind.

But let's get back to your eyes here, because another new study -- this one out of India -- finds that people with the highest dietary intake of C have a 39 percent lower risk of cataracts than those with the lowest C levels.

That study was based on a questionnaire over dietary habits, so I'm not going to waste your time with the details -- but it's worth mentioning because plenty of other studies have also made a much more direct link between low C and cataract risk.

I remember one a few decades back that found every 1 mg/dl increase in blood levels of vitamin C led to a 26 percent decrease in cataract risk.

Along with vision, vitamin C also appears to have a direct impact on hearing: When I say "vitamin C," most people just hear "orange juice" -- and that's the last place you should be looking for this nutrient.

OJ is pure sugar with some vitamin C swimming around in it. You may as well put vitamin C in your Coke.

The best natural sources of C are actually peppers -- bell and chili -- along with broccoli, kale and papaya. But to get what you really need, you'll probably want a supplement.

I suggest at least 1,200 mg a day, or roughly 15 times what the U.S. government recommends.