From the Boston Globe:
If you love cheese so much and joke that you think you might be addicted -- well, you probably are. Dr. Neal Barnard, founder and president of the Physicians Committee for Responsible Medicine, didn’t famously call cheese “dairy crack” for no reason. But if you’re looking for someone to blame for your new-found addiction, head to the barnyard: It’s all the cows’ fault.
The primary protein in milk is casein. When the human body digests casein, it produces casomorphins, which have an opiate-like effect on humans. Because cheese is denser than, for example, milk, the casein is more heavily concentrated, meaning that eating cheese produces a larger amount of casomorphins in the body compared to eating other dairy products.
Cheese-related research going as far back as the ‘80s has also confirmed that cheese contains small amounts of morphine. Scientists postulate that cows produce morphine in their milk because it helps calm their calves, making sure the young cows bond with their mothers and come back for more (does this make cows the dairy farm equivalent of drug dealers?)
.If science isn’t enough to get you to “hold the cheese” more often, consider this nutrition fact: One four-ounce piece of cheddar has over 450 calories and a whopping 37 grams of fat.
All of this research, however, isn’t to say that cheese doesn’t have its benefits, too. The delicious dairy product contains plenty of calcium, a necessity for strong bones and teeth, and is definitely part of a healthy, balanced diet.