Is Type 1 Diabetes Triggered by the Bovine Insulin in Milk?

The tight correlation among countries between the incidence of type 1 diabetes in children and cow’s milk consumption didn’t account for Iceland. Indeed, studies correlating dairy intake in children and adolescents with the incidence of type 1 diabetes deliberately excluded the Icelandic data. Why? Is it because of genetics? Perhaps, yes and no. The people of Iceland are similar genetically to other Nordic countries, but their cows are not. As I discuss in my video Does Bovine Insulin in Milk Trigger Type 1 Diabetes?, there are two main types of the cow milk protein casein: A1 and A2. Icelandic cattle, who “have been isolated from interbreeding with other cattle breeds for over 1,100 years,” are unusual in that they produce mostly A2 milk, which may explain the lower incidence of type 1 diabetes in Iceland.

Unlike A2 casein, A1 casein breaks down into casomorphin, which has opioid properties that may alter immune function, perhaps increasing susceptibility to infections that may themselves trigger type 1 diabetes. That’s what’s in the milk from the classic black-and-white patterned Holstein cows, who make up about 95 percent of the U.S. dairy herd and much of the global herd—A1 casein. This issue has even caused dairy boards to begin taking out patents on methods for selecting “nondiabetogenic” milk to avoid triggering of Type 1 diabetes. Indeed, looking only at A1 casein consumption certainly restores that tight linear relationship between milk intake and type 1 diabetes and you can see at 1:47 in the video.

These so-called ecological, or country-by-country, studies, however, primarily serve to suggest possibilities that then need to be put to the test. For example, a study was designed where hundreds of siblings of type 1 diabetics were followed for about ten years and found that those who drank a lot of milk did have about five times the risk of coming down with the disease, too. By the mid-1990s, more than a dozen such studies were done.

Overall, researchers found that early cow’s milk exposure appears to increase the risk of type 1 diabetes by about 50 percent. Those data were enough for the American Academy of Pediatrics to decide that “cow’s milk protein may be an important factor” in the initiation of the process that destroys our insulin-producing cells. The organization went on to say that the avoidance of cow’s milk protein may reduce or delay the onset of type 1 diabetes. As such, the American Academy of Pediatrics emphasizes that breast milk is best and, for those at higher risk of the disease, strongly encourages the avoidance of products containing cow’s milk protein that is intact, as opposed to hydrolyzed formula where the milk proteins are broken up into tiny pieces.

Typically, hydrolyzed formula is given to children with dairy allergies and could potentially make it less risky, but we don’t know until we put it to the test. Based on the population studies and meta-analyses of antibody studies, which suggested that “cow’s milk may serve as a trigger of Type 1 diabetes,” a pilot study was initiated the following year. Researchers wanted to see if babies at high genetic risk for the disease would be less likely to develop antibodies that would then attack their own pancreas if they drank hydrolyzed casein—that is, casein that was chopped up. The hydrolyzed formula did seem to reduce the appearance of at least one autoimmune antibody, but not two or more, which is much more predictive of the development of the disease.

Nevertheless, that was enough for the investigators to embark on the ambitious Trial to Reduce Incidence of Diabetes in Genetically at Risk, also known as the TRIGR study. This multinational, randomized prospective trial involved randomizing thousands of newborns across 15 countries. In 2010, preliminary data suggested the hydrolyzed formula may have helped, but they didn’t quite reach statistical significance, approximately meaning there was greater than a 1 in 20 chance the findings could have just been a fluke. Indeed, when the final autoimmune antibody results were published, the special hydrolyzed formula didn’t seem to help at all.

The researchers only looked at a special group of children, though—ones who were at high genetic risk with diabetes running in the family—whereas the great majority of children who get type 1 diabetes do not have any afflicted close relative. Perhaps most importantly, however, 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. Instead, it aimed to analyze the potential effects of the hydrolyzed casein formula. Maybe it’s not the casein, though. Maybe it’s the bovine insulin.

Insulin autoantibodies—antibodies our body produces to attack our own insulin—often appear as the first sign in prediabetic children. “Because cow’s milk contains bovine insulin,” around the same time researchers were looking into casein, another team “followed 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 have only been exposed to cow proteins through their mom’s breast milk (if their mothers consumed dairy). Furthermore, the bovine antibodies cross-reacted with human insulin, potentially being that caught-in-the-crossfire cause triggering at least some cases of type 1 diabetes.

Of course, we can’t know for sure until we put it to the test. Researchers ran another randomized, double-blind trial, but, this time, 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. What we don’t know yet is whether this will translate into fewer cases of diabetes.


You may also want to check out:

For more on the concerns with cow’s milk exposure in infancy and childhood, see:

I’ve developed a six-part series on the role of gluten-free, casein-free diets in the treatment of autism:

What’s The Best Baby Formula? Breast milk!

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Milk Consumption Is Linked to Type 1 Diabetes

Type 1 diabetes, which typically strikes children and young adults, is an autoimmune disease in which our own immune system attacks and destroys the insulin-producing cells of our pancreas. Untreated it’s deadly, but even with well-managed insulin replacement, it may shorten life expectancy by a decade. “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 the hopes that we can cure or prevent the disease. Genetic susceptibility plays an important role, but the “concordance for type 1 diabetes is only about 50% among identical twins.” So, even if someone with our exact same DNA gets the disease, there’s only about a 50 percent chance we will get it, too—meaning there must be external factors as well.

Some countries have low rates of incidence, and others have high rates. Japan, for example, has type 1 diabetes rates 18 times lower than the United States. This disparity isn’t due only to genetics, however, because, when children migrate, they tend to acquire the risk of their new home, suggesting it’s got 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 rates hundreds of times higher than others, and it is on the rise. Researchers looked at 37 populations from around the world and found that the incidence has been increasing about 3 percent a year—our genes don’t change that fast. In fact, they couldn’t find a single population with decreasing incidence of type 1 diabetes.

Something is going on that started around the end of World War II. “The best evidence available suggests that childhood diabetes [also known as type 1 diabetes] showed a stable and relatively low incidence over the first half of the 20th century, followed by a clear increase that began…around…the middle of the century.” Why the increase, though? A number of factors have been postulated, including vitamin D deficiency, certain infections, or exposure to cow’s milk.

Decades ago, published cross-country comparisons showed a tight correlation between milk consumption and the incidence of  type 1 diabetes. The “analysis showed that 94% of the geographic variation in incidence might be explained by differences in milk consumption.” Investigators in Finland, the country with the highest rates of type 1 diabetes and cow’s milk consumption, led much of the research into this area.

It all started with studies like the one I feature in my video Does Casein in Milk Trigger Type 1 Diabetes?, showing that the less babies are breastfed, the higher the rates of type 1 diabetes, leading to the obvious conclusion that “[b]reast-milk protects the newborn infant.” On the other hand, if babies are not getting breast milk, they’re getting formula, which probably contains cow’s milk proteins. In the first few months of life, our gut is especially leaky to proteins. Is it possible that as our immune system attacks the foreign cow proteins, our pancreas gets caught in the crossfire? This was based on animal experiments, however. In susceptible mice, a diet containing the cow’s milk protein, casein, produced diabetes, but it did not cause diabetes in rats. So, are we more like mice or rats?

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. Their finding? Every single child with type 1 diabetes had elevated anti-bovine protein antibodies circulating in their blood compared to much lower levels in the control subjects. That seems pretty convincing, but what about Iceland? They drink more milk in Iceland than in Finland, yet Icelanders have less than half the type 1 diabetes. I explore this paradox in my follow-up video Does Bovine Insulin in Milk Trigger Type 1 Diabetes?.


The vast majority of diabetes cases are type 2, so that’s been my concentration:

I’m pleased to have been able to address type 1 diabetes. For even more on this disease, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

How Not to Die from Diabetes

We’ve known since the 1930s that type 2 diabetes can be prevented, arrested, and even reversed with a plant-based diet. Within five years of following the diet, about a quarter of the diabetic patients in that early study were able to get off insulin altogether.

Plant-based diets are relatively low in calories, though. Is it possible their diabetes just got better because they lost so much weight? To tease that out, we need a study where people are switched to a healthy diet but forced to eat so much food they don’t lose any weight. Then we could see if plant-based diets have specific benefits beyond all the easy weight loss. We had to wait 44 years for such a study, which I then discuss it in my video How Not to Die from Diabetes.

Subjects were weighed every day. If they started losing weight, they were made to eat more food—so much more food in fact that some of the participants had problems eating it all. They eventually adapted, though, so there was no significant weight change despite restricting meat, eggs, dairy, and junk.

Without any weight loss, did a plant-based diet still help? Overall insulin requirements were cut about 60 percent, and half the diabetics were able to get off their insulin altogether. How many years did that take? Not years. An average of 16 days. Only 16 days.

Let’s be clear: We’re talking about diabetics who had had diabetes as long as 20 years and injected 20 units of insulin a day. Then, as few as 13 days later, they were off their insulin altogether, thanks to less than two weeks on a plant-based diet—even with zero weight loss. It’s astonishing. Twenty years with diabetes, and then off all insulin in less than two weeks. Twenty years with diabetes because no one had told them about a plant-based diet. For decades they were just 13 days away at any time from being free.

In my video, I show data from patient #15: 32 units of insulin while on the control diet and then, 18 days later, after switching to the plant-based diet, on no insulin at all. None. Lower blood sugars on 32 units less insulin. That’s the power of plants. And that was without any weight loss. His body just started working that much better once it was provided with the right fuel.

As a bonus, their cholesterol dropped like a rock to under 150. Just as “moderate changes in diet usually result in only moderate reductions in LDL cholesterol levels,” how moderate do you want your diabetes?

“Everything in moderation” may be a truer statement than some people realize. Moderate changes in diet can leave diabetics with moderate blindness, moderate kidney failure, moderate amputations—maybe just a few toes or something. Moderation in all things is not necessarily a good thing.

Remember the study that purported to show that diets high in meat, eggs, and dairy could be as harmful to health as smoking, suggesting that people who eat lots of animal protein are four times as likely to die from cancer or diabetes? If you look at the actual study, you’ll see that’s simply not true. Those eating a lot of animal protein didn’t have just 4 times the risk of dying from diabetes, they had 73 times the risk of dying from diabetes! A 73-fold increase in risk. And those who chose moderation, only eating a “moderate” amount of animal protein, had 23 times the risk of death from diabetes.


The first time someone visits NutritionFacts.org can be overwhelming. With videos on more than 2,000 health topics, where do you even begin? Imagine stumbling onto the site not knowing what to expect and the new video-of-the-day is about how a particular spice can be effective in treating a particular form of arthritis. It would be easy to miss the forest for the trees, which is precisely why I created a series of overview videos that are essentially taken straight from my live, hour-long 2016 presentation How Not to Die: Preventing, Arresting, and Reversing Our Top 15 Killers.

The other videos in this series are:

Inspired to learn more about the role diet may play in preventing and treating diabetes? Check out some of these other popular videos on the topic:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations: