Chemical Additives and the Feingold Diet
Why is it so hard to believe?
I am currently 27 years old, and I have been on the Feingold diet for about 20 years now. It works. I have seen and experienced the proof that it works. There are countless success stories out there from people claiming that it works. Despite all this, doctors like Robert Sinaiko can lose their medical licenses for suggesting the diet as treatment for ADHD (or ADHD-like symptoms) instead of more conventional treatments with drugs like Ritalin. There seems to be a lack of willingness to believe that chemical additives like artificial colors and flavors can cause behavioral changes. My question is simply "why is this so hard to believe?"
That is the question, and that is what I am going to address here. I am not going to prove that the Feingold Diet really works. I am not going to prove it because I don't have the means. I have not commissioned a study to show the effectiveness of the diet, nor have I done any laboratory experiments to demonstrate the effects of these chemicals. My goal is that after reading this page you will believe, as I do, that it is actually much harder to believe that these chemicals do not have any effect on humans.
So what are artificial colors and flavors anyway? How are
they different from natural colors and flavors? Well, the simple answer is
that natural colors and flavors are molecules that are created and found in
nature. For example, here is the chemical structure of bixin, which is the
main molecule in annatto
color.
I will note
that the structure here, from chemfinder.com, differs from the one on Wikipedia.
Two of the methyl groups are in different spots along the chain, and the
Wikipedia molecule is not drawn with the same kinks. Instead, the Wikipedia molecule appears more linear. This is an important point, since the molecule has a lot of
conjugated double bonds, it can't rotate along any one bond, so this shape
matters.
If we could easily synthesize this molecule in the lab, there
would be no problem. Our bodies only see the molecule and can't tell where
it came from. Synthesizing annatto, however, is not easy. There are
not many functional groups to work with, and each new carbon in the main chain
would have to have the right orientation. It would be a multi-step process
and at each step you don't get 100% yield. Suffice it to say, trying to
manufacture this on a large scale would not be very efficient, certainly less so
than just harvesting the natural stuff. But this still takes some doing,
so how can we get "better" cheaper red color? Take a look at this
molecule. 
This is
Allura Red, also knows
as FD&C Red 40, or, for a mouthful "disodium
6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalene-sulfonate."
In some ways, this molecule is much more complex than annatto, there are
more functional groups, rings, an azo (N=N) bond, but for synthesis purposes,
this is easier to work with. It is smaller, for one, and the ring
structures for each side are readily available, so there are fewer steps in the
process.
So now we have a molecule that's cheaper to synthesize and provides an intense red color. Sounds good, what's the problem? Well, that intense red color is caused by the way the functional groups of the molecule pull on the electrons in the bonds. In annatto, there are basically two functional groups. On one end (the upper right in the above picture) there is a carboxylic acid group. Yep, annatto is an acid. For an educated guess based on the structure, I'd expect it to be a slightly stronger acid than vinegar. At the lower left, there is a methyl ester group. Esters are often responsible for how a molecule smells or tastes. Banana smell and wintergreen are examples of simple esters. In the Red 40 molecule, we have the azo group (the N=N double bond), a phenol group (the OH sticking off of a hexagonal ring) and two sulfophenyl groups (SO3- on a phenyl ring).
What do these do, besides make the molecule red? I have no idea, but unlike the functionally simple bixin (annatto) molecule, allura red has more complex functional groups that may interact with the human body. The human body is amazingly complex, and to determine the potential effects of a molecule by looking at its stucture is virtually impossible. Different people have different reactions to various drugs (both legal and not), allergens, and even caffeine. Why is it so difficult to believe that these chemicals might interact subtly with brain chemistry, leading to changes in behavior or learning ability? Why is it so hard to believe that this might affect some people more than others? Knowing that the systems involved are so incredibly intricate and complex, I'd actually be more surprised if these chemicals had no effect on anyone.