Everyone wants to know how to get the colorful green, yellow and red bell peppers. I truly believe that we have all heard the answer but choose to believe that there just might be an easier way. Sorry there is not...patience is how we get the different colors. In other words, bell peppers start out green, then if left alone they will turn yellow but if they are allowed to ripen even more, they then turn red. This is why the red ones cost the most in the grocery stores; it takes them longer to mature.
Now I have seen the labels that say Yellow Bell and Red Bell but I think they were created simply to appease those folks who do not believe in the waiting process. Orange peppers are the ones turning from green to red. Sometimes the red ones (if allowed to stay on the vine longer) can turn a darker, more purplish color. By the way, there is a variety of "Green" bell peppers that is green, even at maturity. For the record, California Bell peppers are not green at maturity, but red. They do indeed change their color with time. And one more fact; California Bell peppers are heirloom peppers.
The most nutritious and the sweetest peppers are the more mature red peppers. They contain the same ingredients as the green bell peppers however at a more concentrated rate. They have more lycopene that helps prevent Prostate and breast cancers. Also found in the red peppers are lutein and zeaxanthin, which aid in the prevention of macular degeneration and cataracts.