Type 1 diabetes (T1D) or insulin-dependent diabetes is a classic
example of a multifactorial disease. What this term reflects is
that many factors appear to contribute to its development. Ultimately
the insulin producing cells of the pancreas are destroyed in most
cases by the body's own immune system, but what triggers this destruction
is related more to dietary and environmental factors than genetics
Basic facts of type 1 diabetes
- The result of damage of the beta-cells of the pancreas that
produce insulin
- Dependence upon daily insulin injections to maintain blood
sugar control
- Accounts for somewhere between 5 to 10 percent of all cases
of diabetes in the United States
- Peak incidence occurs during puberty, around 10 to 12 years
of age in girls and 12 to 14 years of age in boys.
- There is a higher incidence of T1D in Caucasians than in other
racial groups.
I find it interesting that most medical texts, diabetes organizations,
and doctors tend to consider T1D primarily as a genetic disorder.
The point that I want to make is that dietary and other environmental
factors are the chief factors that ultimately determine if the disease
will develop. The entire set of genetic factors linked to T1D have
been termed 'susceptibility genes' as they are neither necessary
nor sufficient for disease to develop. Just like a parched forest
may be predisposed to a forest fire, if there is a big rain, or
no match or spark, then there is no fire. But, if there is something
that ignites the fire it may burn out of control. Here is a statistic
that is very important to consider: less than 10% of those with
increased genetic susceptibility for T1D actually develop the disease.
Additional evidence
If you are still not convinced that dietary and environmental factors
are the areas that we need to focus on with prevention, consider
the following:
- If developing T1D were governed only by genes, then every time
one identical twin developed diabetes, the other should develop
it, too. In other words, the "concordance rate" should be near
100%. However, the concordance rate for developing T1D in identical
twins is only 23% to 38%. If one twin develops T1D after age 24
years, then the concordance rates drops all the way down to 6%.
- There has been a three to tenfold increase in the number of
people with T1D throughout the world over the last 40 years or
so. Such a rise is simply cannot be explained by an increased
number of people genetically predisposed to T1D. Changes to the
human genetic code across large populations take more than one
generation.
- The rate of T1D can increase dramatically when children in
areas where T1D is relatively rare move to developed countries.
For example the rate of T1D increased by nearly 4-fold in one
ten-year period in children of Asian origin moving to Great Britain
and the rate increased over 7-fold when Polynesians migrating
to New Zealand. It is ridiculous to think that genetic factors
could explain such a rapid change.
Factors that increase the risk for
type 1 diabetes
Most of the
recent information indicates that the function of the gut immune
system is central in the development in type 1 diabetes. The lack
of breast-feeding is strongly implicated as it is a very important
factor in establishing proper gut immune function. The key dietary
factors that have received the most attention are early exposure
to cow's milk proteins and intolerance to gluten (a protein in grains).
These dietary factors can trigger the formation of antibodies that
can destroy the insulin-producing beta-cells in the pancreas.
One of the
most important determinants of gut immune function is the intestinal
microflora. In researching the scientific literature I am shocked
that I could not find a single research study that has tried to
determine the status of the intestinal microflora in type 1 diabetics.
Gut bacteria, especially the Bifidobacteria, are very important
in protecting against infections due to enterovirus, coxsackievirus,
and rotavirus - common causes of intestinal infection especially
in children. All of these viruses replicate in the gut and cause
stimulation of the gut immune system that may activate the autoimmune
process in T1D. These viruses and others are also capable of infecting
pancreatic beta cells causing the white blood cells to attack them.
Vitamin D protects against
type 1 diabetes
There is emerging evidence that vitamin D supplementation during
early childhood can prevent type 1 diabetes. One study found that
the use of cod liver oil during pregnancy significantly reduced
the frequency of type 1 diabetes in their children. In the most
extensive of studies, all pregnant women in northern Finland who
were due to give birth in 1966 were enrolled (over 12,000 women)
and their children were monitored until December 1997. Final analysis
demonstrated that children who regularly took vitamin D had an 80%
reduced risk of developing type 1 diabetes while those that had
vitamin deficiency actually had a 300% increased risk of developing
the disease.
Avoid Nitrates
Another causative factor explaining the rise in the rate of T1D
is the parallel increased levels of nitrate from dietary sources
and water. Nitrates are produced by agricultural run-off from fertilizers
as well as found in cured or smoked meats such as ham, hot dogs,
bacon, and jerky to keep the food from spoiling. Nitrates react
within the body to form compounds known as nitrosamines. Nitrates
and nitrosamines are known to cause diabetes in animals. Infants
and young children are believed to be particularly vulnerable to
the harmful effects of nitrate exposure.
One of the most alarming features of type 1 diabetes is the fact
that is becoming much more prevalent with a current growth rate
of 3% per year worldwide. Some areas are hit particularly hard,
such as Finland, Great Britain, Canada, and the United States. Increased
nitrate exposure may be a key factor as the nitrate levels in ground
and surface waters of agricultural regions have increased over the
past 40 years as a result of increases in the use of nitrogen fertilizers.
Nitrate contamination occurs in geographic patterns related to the
amount of nitrogen contributed by fertilizers, manure, and airborne
sources, such as automobile and industrial emissions
Final Comment
Although genetics plays a role in virtually all chronic diseases
like diabetes, cancer, and heart disease, they generally play second
fiddle to dietary, lifestyle, and environmental factors. Disease
and good health are not pre-ordained in most cases, but rather a
result of making the right choices.
Key References:
- Kelly MA, Mijovic CH, Barnett AH. Genetics of type 1 diabetes.
Best Pract Res Clin Endocrinol Metab 2001;15:279-91.
- Knip M, Akerblom HK. Environmental factors in the pathogenesis
of type 1 diabetes mellitus. Exp Clin Endocrinol Diabetes 1999;107(Suppl
3):S93-100.
- Redondo MJ, Yu L, Hawa M, et al. Heterogeneity of Type I diabetes:
analysis of mono-zygotic twins in Great Britain and the United
States. Diabetologia 2001;44:354-62.
- Hypponen E, Kenward MG, Virtanen SM, et al. Infant feeding,
early weight gain, and risk of type 1 diabetes. Childhood Diabetes
in Finland (DiMe) Study Group. Diabetes Care 1999;22:1961-5.
- The EURODIAB Substudy 2 Study Group. Vitamin D supplement in
early childhood and risk for Type I (insulin-dependent) diabetes
mellitus. Diabetologia 1999;42:51-54.
- Stene LC, Ulriksen J, Magnus P, Joner G. Use of cod liver oil
during pregnancy associated with lower risk of Type 1 diabetes
in the offspring. Diabetologia 2000;43:1093-1098.
Michael T. Murray, N.D., is widely regarded as one of world's leading authorities on natural medicine. A prolific author, Dr. Murray has written over 20 books on health and nutrition including the best-selling Encyclopedia of Natural Medicine and his latest book The Encyclopedia of Healing Foods. Dr. Murray is also Director of Product Development and Education for Natural Factors one of the leading manufacturers of natural products.
