Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Type 1 diabetes is an autoimmune disease that typically strikes children and young adults, in which your own immune system attacks and destroys the insulin-producing cells of your pancreas. If untreated, it’s deadly. But, “even with well-managed insulin replacement,” it could cut a decade off your life. “Families are devastated when a child receives a diagnosis of type 1 diabetes.” Thus, one of modern medicine’s “holy grails” is to understand what causes the body to attack itself, in hopes that we can prevent and cure it.

Genetic susceptibility plays an important role, but the concordance for type 1 diabetes is only about 50% among identical twins—meaning even if someone with the same DNA as you gets the disease, there’s only about a 50% chance you’ll get it too, meaning there must be external factors, as well.

Some countries have low rates; some have high rates. Japan, for example, has type 1 diabetes rates 18 times lower than the United States. And, that’s not just genetics, since when children migrate, they tend to acquire the risk of their new home—suggesting it’s got to have something to do with the environment, diet, or lifestyle.

In fact, the incidence rates vary more than 350-fold around the world. Some countries have hundreds of times higher rates than others, and it’s on the rise. Researchers looked at 37 populations from around the world, and the incidence is going up about 3% a year. In fact, they couldn’t find a single population going the other direction. 3% higher every year; our genes don’t change that fast. Something is going on, starting right around World War 2. “The best evidence available suggests that [type 1] diabetes showed a stable and relatively low incidence over the first half of the 20th century, followed by a clear increase [around] the middle of the century.”

And, the question is, why? A number of factors have been postulated for tipping children over into diabetes, including vitamin D deficiency, certain infections, or exposure to cow’s milk.

Decades ago, cross-country comparisons like this were published, showing a tight correlation between milk consumption and the incidence of type 1 diabetes—insulin-dependent, childhood-onset diabetes—showing as much as “94% of the geographic variation in incidence might be explained by differences in milk consumption [alone].” This country, with the highest rates at the top—Finland—led much of the research into this area.

It all started with studies like this, showing the less babies are breastfed, the higher the rate of type 1 diabetes—leading to the obvious conclusion: breast milk protects newborn infants. On the other hand, if they’re not getting breast milk, they’re getting formula, which contains cow’s milk proteins. In the first few months of life, the gut is especially leaky to proteins. And, so, maybe, as our immune system attacks the foreign cow proteins, our pancreas gets caught in the crossfire. But, this was based on animal experiments. In susceptible mice, “a diet containing [the cow’s milk protein] casein produced diabetes.” But, it doesn’t cause diabetes in rats. So, are we more like mice, or rats?

So, researchers drew blood from children with type 1 diabetes to see if they had elevated levels of antibodies that attack bovine proteins, compared to controls. And, every single one of the affected kids had elevated anti-bovine protein antibodies circulating in their blood, compared to much lower levels in the control subjects.

Okay, that seems pretty convincing, but what about Iceland? They drink more milk than Finland, yet have less than half the type 1 diabetes. We’ll cover the Icelandic paradox, next.

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