"Does Bovine Insulin in Milk Trigger Type 1 Diabetes?"
The tight correlation among countries between the incidence of type 1 diabetes
among children and cow milk consumption didn't account for Iceland.
So you'll see studies like this.
Cow's milk consumption in children and adolescents
was correlated with the incidence of type 1 diabetes,
but only when they excluded the Icelandic data.
Is it just genetics? Maybe yes and no.
The people of Iceland are genetically similar to other Nordic countries,
but their cows are not. Icelandic cattle have been isolated
from interbreeding with other cattle breeds for over 1,000 years.
See, there are two main types of casein protein, A1 and A2,
and Icelandic cattle are unusual in that they produce mostly A2 milk.
And that may explain the lower incidence of type 1 diabetes in Iceland.
See, A1 casein breaks down into casomorphin,
whereas A2 casein doesn't.
And casomorphin has opioid properties that may alter immune function,
perhaps increasing susceptibility to infections
that may themselves trigger type 1 diabetes.
And that's the kind of milk you get with Holstein cows,
the ones with the classic black and white pattern, which makes up about 95%
of the U.S. dairy herd and much of the global dairy herd.
It got to a point where dairy boards began taking out patents on methods
for selecting non-diabetogenic milk to avoid the triggering type 1 diabetes.
It certainly did restore that tight linear relationship between milk consumption
and type 1 diabetes, if you just looked at A1 casein consumption.
But these so-called ecological, or country-by-country studies really only serve
to suggest possibilities that then need to be put to the test.
So studies like this were designed where hundreds of siblings of type 1 diabetics
were followed for about 10 years, and those that drank a lot of milk
had about 5 times the risk of coming down with the disease, too.
By the mid-90's more than a dozen such studies were done,
and overall they found that early cow's milk exposure
appears to increase the risk of type 1 diabetes by about 50%.
That was good enough for the American Academy of Pediatrics,
who decided that cow's milk protein may indeed be an important factor
in the initiation of the process that destroys your insulin producing cells.
And so the avoidance of cow's milk protein
may reduce or delay the onset of type 1 diabetes.
Yet another reason to emphasize breast is best.
And for those at risk, they strongly encourage the avoidance
of products containing intact cow's milk protein,
as opposed to hydrolyzed formula, in which the milk proteins
are all broken up into tiny pieces, which is
used for kids with dairy allergies or could
potentially make it less risky, but you don't know until you put it to the test.
Based on the population studies and meta-analyses
of all those antibody studies, which suggested that cow's milk
may serve as a trigger of type 1 diabetes,
the next year a pilot study was initiated to see if babies at high genetic risk
would be less likely to develop antibodies that then attacked their own pancreas
if they drank casein that was chopped up first.
And here's the study.
The hydrolyzed formula did seem to reduce the appearance
of at least one of autoimmune antibody, but not two or more,
which is more predictive of the development of the disease.
But that was enough for the investigators to embark on the ambitious TRIGR study,
the Trial to Reduce Incidence of Diabetes in Genetically at Risk—
a multinational, randomized, prospective trial involving randomizing thousands
of newborns across 15 countries with expected completion in 2017.
But in 2010 we got some preliminary data suggesting it may have helped,
but didn't quite reach statistical significance, meaning basically
there was greater than a 1 in 20 chance it could have just been a fluke,
and indeed when the final autoimmune antibody results were published,
the special hydrolyzed formula didn't seem to help at all.
Now they did just look at a special group of children at high genetic risk
with diabetes running in the family, whereas the great majority of children
who get type 1 diabetes don't have any afflicted close relative.
But perhaps most importantly, as the researchers themselves emphasized,
their study wasn't designed to test whether cow's milk is or is not
a trigger for the disease,
just what effect the hydrolyzed casein formula might have.
Maybe it's not the casein. Maybe it's the bovine insulin.
Insulin autoantibodies, antibodies our body produces
to attack our own insulin, often appears as the first sign in prediabetic children.
Because cow's milk contains bovine insulin, cow insulin,
around the same time the other researchers were looking into casein,
this research team was following the development
of insulin-binding antibodies in children fed with cow's milk formula.
They found significantly more antibodies
to bovine insulin in the cow's milk formula group
compared to the exclusively breastfed group,
who may only have been exposed to a few cow proteins
through their mom's breast milk, if their mom drank the stuff.
Furthermore, the bovine antibodies cross-reacted to human insulin,
potentially being that caught-in-the-crossfire cause
that triggers at least some cases of type 1 diabetes,
but you can't know for sure until— you guessed it: you put it to the test.
Same as the other one, a randomized double blind trial,
but this time they tried a cow's milk formula
from which the bovine insulin had been removed.
And indeed without the bovine insulin exposure,
the children built up significantly fewer autoimmune antibodies.
But what we don't yet know is if this will translate into fewer cases of diabetes.
Stay tuned.