The China Study by Thomas Campbell

190 THE CHINA STUDY

to genes? These days, there is a popular opinion that Type 1 diabetes is
due to genetics, an opinion often shared by doctors as well. But genetics
alone cannot account for more than a very small fraction of cases of this
disease. Genes do not act in isolation; they need a trigger for their ef-
fects to be produced. It has also been observed that after one member of
identical twin pairs gets Type 1 diabetes, there is only a 13-33% chance
of the second twin getting the disease, even though both twins have
the same genes.l3, 20, 21, 25. 26 If it were all due to genes, closer to lOO% of
the identical twins would get the disease. In addition, it is possible that
the 13-33% risk for the second twin is due to the sharing of a common
environment and diet, factors affecting both twins.
Consider, for example, the observation shown in Chart 9.3, which
highlights the link between one aspect of environment, cow's milk con-
sumption, and this disease. Cow's milk consumption by children zero
to fourteen years of age in twelve countries^27 shows an almost perfect
correlation with Type 1 diabetes.^28 The greater the consumption of
cow's milk, the greater the prevalence of Type 1 diabetes. In Finland,
Type 1 diabetes is thirty-six times more common than in Japan.^29 Large
amounts of cow's milk products are consumed in Finland but very little
is consumed in JapanY

CHART 9.3: ASSOCIATION OF COW'S MILK CONSUMPTION AND

INCIDENCE OF TYPE 1 DIABETES IN DIFFERENT COUNTRIES

40

~ (J) 30

~ o

o

8" 20

~

.s (J)

u c

~ 10

'u c

DENMARK

: NEW ZEALAND

• NETHERLANDS
  CANADA
  JAPAN •• ISRAEL
  o~.-_·~FR~A~N~CE~.-r-~.---r
  o 100 200 300
  Cow Milk Consumption (liters/person/year)