AUTOIMMUNE DISEASES 199heart disease have common causes because they share similar geogra-
phy and similar biochemical biomarkers (chapter four), we can also
hypothesize that MS, Type 1 diabetes, rheumatoid arthritis, lupus and
other autoimmune diseases may share a similar cause if they exhibit
similar characteristics.
First, by definition, each of these diseases involves an immune sys-
tem that has gone awry in such a way that it attacks "self' proteins that
look the same as foreign proteins.
Second, all the autoimmune diseases that have been studied have
been found to be more common at the higher geographic latitudes
where there is less constant sunshine.^9 • 10, 61
Third, some of these diseases have a tendency to afflict the same
people. MS and Type 1 diabetes, for example, have been shown to coex-
ist in the same individuals.^62 -^65 Parkinson's disease, a non-autoimmune
disease with autoimmune characteristics, is often found with MS, both
within the same geographic regions^66 and within the same individuals.^5
MS also has been associated-either geographically or within the same
individuals-with other autoimmune diseases like lupus, myasthenia
gravis, Graves' disease and eosinophilic vasculitis.^63 Juvenile rheuma-
toid arthritis, another autoimmune disease, has been shown to have an
unusually strong association with Hashimoto thyroiditis.^67
Fourth, of those diseases studied in relation to nutrition, the con-
sumption of animal-based foods-especially cow's milk-is associated
with greater disease risk.
Fifth, there is evidence that a virus (or viruses) may trigger the onset
of several of these diseases.
A sixth and most important characteristic binding together these
diseases is the evidence that their "mechanisms of action" have much
in common-jargon used to describe the "how to" of disease forma-
tion. As we consider common mechanisms of action, we might start
with sunlight exposure, because this somehow seems linked to the au-
toimmune diseases. Sunlight exposure, which decreases with increas-
ing latitude, could be important-but clearly there are other factors.
The consumption of animal-based foods, especially cow's milk, also
increases with distance from the equator. In fact, in one of the more ex-
tensive studies, cow's milk was found to be as good of a predictor of MS
as latitude (Le., sunshine)Y In Dr. Swank's studies in Norway, MS was
less common near the coastal areas of the country where fish intake was
more common. This gave rise to the idea that the omega-3 fats common