Our bodies are constantly using and changing nutrients, so it is easy to see that your body is not getting enough of some chemicals because of stress, diet or environment.
When using the Recommended Daily Allowance figures, remember that there are so many things that the body needs that the government will not be able to list them all as minimum requirements.
Natural vs. Manufactured
With natural items that include part of the natural item that they come from (called excepients), you get more of what nature intended. For instance, a recent study showed that natural vitamin E is no different than artificially produced vitamin E. Of course, there's no difference between a vitamin E molecule no matter where you get it. It's what comes with it that makes the difference. Normally, synthetic vitamin E comes in vegetable oil. Natural vitamin E will contain some mixed tocopherols and tocotrienols and will possibly include wheat germ oil instead of vegetable oil.