These days, many people are looking to find reasons to dislike dairy, and they’re digging deep. Both the vegan and the paleo contingents love to find reasons to support their ideological hatred of dairy. And one of the myths that has been stirred up of late is the idea that dairy causes insulin resistance and diabetes.
When I read this myth, it is never accompanied by science that shows that dairy actually causes insulin resistance, or that dairy consumption correlates positively to insulin resistance. But it is often accompanied by a theory that sounds very science-like for why the person perpetuating the myth believes that dairy ought to cause insulin resistance.
And that theory is usually founded upon an incorrect understanding of the causes of insulin resistance. Namely, many people seem to believe that insulin resistance is caused by repeated insulin spikes in the blood.
In other words, they believe that eating foods that produce a strong insulin response will eventually lead to insulin resistance – as if the insulin sensitivity simply gets blunted by insulin responses after eating. But it turns out that (as we’ve already seen earlier in this book) it doesn’t seem to work that way.
If insulin resistance was caused by repeated insulin responses, then it would be easy to believe that dairy would cause insulin resistance. That is because dairy produces an unusually large insulin response that is not explained simply by the total levels of sugar and protein it contains (carbohydrates and protein are both known to trigger insulin secretion).
Instead, it would seem that the specific quality of protein, specifically the amino acid structure of whey protein, causes the insulin response. As a result, milk produces an insulin response similar to that of white bread, despite the fact that the glycemic effects are dramatically lower.
One of the properties of insulin is that it is strongly anabolic. That means that it prevents the breakdown of protein in the body and instead favors growth. Therefore, it makes perfect sense that dairy should produce a strong insulin response, since milk is ideally suited for the needs of rapidly-growing young mammals.
Dairy is well-known among athletes and bodybuilders who want to grow muscle mass and strength as being a superior food, in part because of its anabolic effects. So the mere fact that dairy prompts an insulin response is not in and of itself problematic. In fact, it can be very good for health.
Some interesting studies show that the insulin response of dairy may actually be helpful in reducing markers of insulin resistance. For example, in one such paper the authors conclude that whey protein “contributes to blood glucose control by both insulin dependent and insulin-independent mechanisms.” (Akhavan, Luhovyy, Brown, Cho, & Anderson, 2010)
Other studies show that dairy consumption improves glucose control and insulin sensitivity. For example, the Harvard School of Public Health issued a press release in 2010 stating that trans-palmitoleic acid in milk may “substantially reduce the risk of type 2 diabetes.”
Other studies show an inverse relationship between dairy consumption and insulin resistance, meaning that those who drink a lot of milk have less insulin resistance. There are also studies showing that dairy consumption has no relationship to weight gain (strongly associated with insulin resistance).
In conclusion, while dairy does create a rise in insulin secretion, the evidence is that it lowers the risk of insulin resistance. Those who promote the idea that insulin secretion in response to dairy is a problem for most people misunderstand the role and properties of insulin, as well as the possible causes of insulin resistance.
Insulin resistance does not seem to be caused solely by eating foods that create a strong insulin response. Instead, there seem to be other more likely causes, including stress, smoking, lack of sleep, inflammation, and unnaturally high intake of free fructose, to name a few of the possible contributing factors.