It is well known that the natural pigments in the fresh foods that we eat (the reds, yellows, and greens) have many health benefits, and a diet rich in these foods is important for achieving optimal health, but did you know that Carotenes (the most widespread group of these naturally occurring pigments) may actually be the key to longevity.
In the world of nutrition Carotenes are best known for their capacity for conversion into Vitamin A, but unlike a vitamin A supplement which can be toxic in excess, the body stores unconverted carotenes in fat cells, epithelial cells, and other organs; there is no know toxicity to carotene.
It's this storing of carotene in the cells that makes this pigment so extraordinary. Studies have shown that there is a strong correlation between carotene intake and various cancers involving epithelial tissues... the higher the carotene intake, the lower the risk for cancer. So what does this mean?
Since cancer and aging share a number of characteristics (i.e an association with free-radical damage)
it leads to the idea that preventing cancer should promote longevity, and there is great evidence supporting this because it appears that there is a better correlation with the maximal life-span of mammals and tissue carotene levels than with other factors. And since tissue carotenes appear to be the most significant factor in determining a species' maximal life-span potential, it only makes sense that those within a species that have the highest carotene levels in their tissues have the greatest chance of living the longest.
Below are carotene levels (in um) in common foods
Apples (unpeeled)--> 5,500 to 12,600
Butternut Squash--> 17,700
Beet Greens--------> 10,000
Collard Greens-----> 20,000
...and yes increased carotene consumption can cause the appearance of slightly yellow-to-orange tinted skin, it's called carotenodermia and it is not harmful; in fact it simply indicates that the body has a good supply of carotenes.
"The Healing Power of Foods" by Michael T. Murray N.D.