The field of serology has also provided us with some very clear evidence that such peptides, and the proteins from which they derive, can be absorbed through the intestinal mucosa, and into the circulation of a significant minority of apparently healthy members of the general population (16). Investigations of abnormal electrical activity in more than two thirds of untreated children with celiac disease has indicated that most of them normalize following dietary restriction (17, 18). These findings suggest that caseomorphin and gluten-derived exorphins are at the root of such abnormal electrical activity in the brain. Since such substances act as depressants, slowing neurotransmission, it should not be surprising if the intestinal permeability, and digestive enzyme deficiencies found in celiac disease were also found in many folks suffering depression. This is underscored by the reports that depression is a very common symptom of celiac disease (19, 20, 21, 22, 23, 24, 25, 26). More on this point can be found at: http://www.gluten-free.org/reichelt.html
Please don't misunderstand us. We do not mean to suggest that all, or even most people suffering from depression have celiac disease. Quite the contrary, we suspect that only a small minority will demonstrate celiac disease when tested (although screening this population for celiac disease makes good sense). It is my suspicion that many folks suffering from depression may have underlying intestinal permeability combined with digestive enzyme deficiencies. To have celiac disease, they would also need to have some degree of damage to, or lymphocyte infiltration of, their intestinal mucosa. So celiac disease would probably be found in a relatively small, but significant percentage, of those afflicted. The prior two conditions of enzyme deficiency and intestinal permeability are abundantly found when sought, and it is these features which, we suspect, dominate the segment of the population which is chronically depressed.
Humans have spent millions of years being naturally selected, in part, on the basis of a diet that included vegetables, seeds, fruit, insects, and subsequently, meat. Yet, at most, we have had only 12,000 years to adapt to consumption of significant quantities of problematic cereal grains, with cultivation originating in southeastern Europe, and spreading to the northwest very slowly. The Romans spread it throughout their empire, reaching far flung parts of Europe, but places they never conquered, such as Ireland, Scotland, and Finland, have been consuming significant quantities of grains for less than 2,000 years. A Danish friend told me that prior to the end of World War II, many Danes considered wheaten bread to be a special treat, because wheat does not grow well in Denmark. North American natives have had a similarly limited exposure to gluten.
Humanity has also had a relatively short time to adapt to post-infancy consumption of significant quantities of milk from other species. This dietary practice probably arose out of animal husbandry. For a more extensive discussion of this topic, go to: http://www.PaleoDiet.com and http://www.gluten-free.org/hoggan/.
Our frequent difficulty with these recent foods seems congruent with the evolutionary data. Many of us simply have not had sufficient time to adapt to these recent additions to the human food supply. We would likely fare much better on foods to which our ancestors have adapted. The dramatic increase in our consumption of these recent foods during this century may have a very ominous element. Such dietary habits may well have been paving the way for Prozac.
The treatment for many cases of depression should begin with serological testing, and be followed by approximately the same treatment as that in celiac disease and milk protein intolerance. Dietary exclusion of the offending proteins will often mean exclusion of gluten-containing grains and/or dairy proteins. Such a diet would, in some cases, result in a few days of withdrawal symptoms, followed by a substantial improvement in mood. While we only know of anecdotal reports of such improvements, we find the above data, in combination with these anecdotal reports, to be quite compelling.
For more information on changing diet see:
The Gluten-Free Page: http://www.gluten-free.org/hoggan/
The No Milk Page: http://www.NoMilk.com/
The Paleolithic Diet Page: http://www.PaleoDiet.com/
PaleoFood Recipe Collection: http://www.PaleoFood.com/