We are often presented with information on food choices that seem contradictory. Years ago fat was bad for you, what was presented to you is that there are different types of fat (Good & Bad). With the media campaign of always presenting the message that all fat, most people followed that in the food choices they made. Another example would be that milk is a good source of calcium that the body needs. A great source of calcium are leafy greens that not only provide calcium but additional nutrients that help the body absorb the calcium efficiently. One last one, orange juice is a good source of Vitamin C, sense the juice is separated from the pulp of the orange this causes the sugar content to be introduced much more quickly (spiking the blood sugar level) than would be eating a orange whole.
So what are we talking about wholesome food or processed food like substances. This my friend is where your stomach comes into play. We have good bacteria and bad bacteria in our gut. These aren't just for the digesting of foods but also for the communication process of minerals, vitamins and possibly antioxidants which effect not only our physical well being but also our mental well being specifically how and what we think. The "Glycemic Index Foundation" has a brief article that can explain this in detail here.
"As Always, From Me to You in Health & Happiness"