Challenge with diet and food supplements

It is nice to understand the potential activity or mechanism of action of food supplements and act on it. Example: "Vitamin C: MedlinePlus Medical Encyclopedia

www.nlm.nih.gov/medlineplus/ency/article/002404.htm

Function. Vitamin C is needed for the growth and repair of tissues in all parts of your body. It is used to: Form an important protein used to make skin, tendons, ..."

That knowledge empowers you and helps you take action.  You run to the store and buy a good supply of vitamin C and take it for now and the future.  What the information can not tell you is just as important.  How much Vitamin C you need to actually have the benefit described? How long you should be doing this?  Is your body just getting rid of the extra or all of it?  Based on your chromosome heterogeneity, was it safe for you to have done it?  Are you missing a critical enzyme to process the vitamin?
The NIH is finding out that things that are promised by food supplements, when put to the test and scientific scrutiny, do not deliver a clearly evident output.  "Taking an apple a day" (low methionine food item) will prolong your life.  While the scientific evidence as to how this is possible is established:  Does it really happen? No.  Why? Because what is left out is even more important.  How many apples  a day should you eat, what type of apple, what else should accompany this practice to make this goal achievable (low calory diet)? And so on and so forth. We all know that food supplements can impact some of the signal transduction pathways in our cells and, as a result, they could potentially impact our lives in some beneficial ways.  But is it safe to constantly be bothering our signal transduction pathways?  Do you believe it is right to do so constantly?  Who said this pathway needs to be switched on all the time?  What guarantees you that the body will not respond and shut it off anyway as it always reacts to action that we deliberately impose upon it!
Keeping a pathway on all the time may impact another pathway all the time, and if you just happen to have the wrong gene for this particular game, you may start on some road you should not be on!  So please, just because it may make sense, it does not yet mean that it is true and relevant for YOU!