“Many people have experienced food addictions. Take chocolate, for example. To some people, chocolate is an occasional treat. But for a true chocolate addict, it is a deep-seated need.
University of Michigan researchers showed that chocolate does not merely tickle your taste buds; it actually works inside your brain in much the same way opiate drugs do. The researchers gave 26 volunteers a drug called naloxone, an opiate-blocker used in emergency rooms to stop heroin, morphine, and other narcotics from affecting the brain. It turned out that naloxone blocked much of chocolate’s appeal. When they offered volunteers a tray filled with Snicker’s bars, M & M’s, chocolate chip cookies, and Oreos, chocolate was not much more exciting than a crust of dry bread.
In other words, chocolate’s attraction does not come simply from its creamy texture or deep brown color. It appears to stimulate the same part of the brain that morphine acts on. For all intents and purposes, it is a drug—not necessarily a bad one and not a terribly strong one, but powerful enough nonetheless to keep us coming back for more.
As common as chocolate addiction may be, it is by no means the only potentially addictive food, nor is it the most dangerous. In PCRM’s research studies, when we take people off meat, dairy products, and other unhealthy fare, we often find that the desire for cheese, in particular, lingers on much more strongly than for other foods. While they might like ice cream or yogurt, they describe their feelings for cheese as a deep-seated craving. Could cheese really be addictive?
In 1981, Eli Hazum and his colleagues at Wellcome Research Laboratories in Research Triangle Park, N.C., reported a remarkable discovery. Analyzing samples of cow’s milk, they found traces of a chemical that looked very much like morphine. They put it to one chemical test after another. And, finally, they arrived at the conclusion that, in fact, it is morphine. There is not a lot of it, and not every sample had detectable levels. But there is indeed some morphine in both cow’s milk and human milk.
Morphine, of course, is an opiate and is highly addictive. So how did it get into milk? At first, the researchers theorized that it must have come from the cows’ diets. After all, morphine used in hospitals comes from poppies and is also produced naturally by a few other plants that the cows might have been eating. But it turns out that cows actually produce it within their bodies, just as poppies do. Traces of morphine, along with codeine and other opiates, are apparently produced in cows’ livers and can end up in their milk.
But that was only the beginning, as other researchers soon found. Cow’s milk—or the milk of any other species, for that matter—contains a protein called casein that breaks apart during digestion to release a whole host of opiates called casomorphins. A cup of cow’s milk contains about six grams of casein. Skim milk contains a bit more, and casein is concentrated in the production of cheese.
If you examined a casein molecule under a powerful microscope, it would look like a long chain of beads (the “beads” are amino acids—simple building blocks that combine to make up all the proteins in your body). When you drink a glass of milk or eat a slice of cheese, stomach acid and intestinal bacteria snip the casein molecular chains into casomorphins of various lengths. One of them, a short string made up of just five amino acids, has about one-tenth the pain-killing potency of morphine.
What are these opiates doing there, hidden in milk proteins? It appears that the opiates from mother’s milk produce a calming effect on the infant and, in fact, may be responsible for a good measure of the mother-infant bond. No, it’s not all lullabies and cooing. Psychological bonds always have a physical underpinning. Like it or not, mother’s milk has a drug-like effect on the baby’s brain that ensures that the baby will bond with Mom and continue to nurse and get the nutrients all babies need. Like heroin or codeine, casomorphins slow intestinal movements and have a decided antidiarrheal effect. The opiate effect may be why adults often find that cheese can be constipating, just as opiate painkillers are.
It is an open question to what extent dairy opiates enter the adult circulation. Until the 1990s, researchers thought that these protein fragments were too large to pass through the intestinal wall into the blood, except in infants, whose immature digestive tracts are not very selective about what passes through. They theorized that milk opiates mainly acted within the digestive tract and that they signaled comfort or relief to the brain indirectly, through the hormones traveling from the intestinal tract to the brain.
But French researchers fed skim milk and yogurt to volunteers and found that, sure enough, at least some casein fragments do pass into the bloodstream. They reach their peak about 40 minutes after eating. Cheese contains far more casein than other dairy products do. As milk is turned into cheese, most of its water, whey proteins, and lactose sugar are removed, leaving behind concentrated casein and fat.
Cheese holds other drug-like compounds as well. It contains an amphetamine-like chemical called phenylethylamine, or PEA, which is also found in chocolate and sausage. And there are many hormones and other compounds in cheese and other dairy products whose functions are not yet understood. In naloxone tests, the opiate-blocking drug eliminates some of cheese’s appeal, just as it does for chocolate.”
Article written by Neal Barnard MD. You can read the original article on this website: http://www.pcrm.org/search/?cid=1290
Neal Barnard MD discusses the science behind food additions. Willpower is not to blame: chocolate, cheese, meat, and sugar release opiate-like substances. Dr. Barnard also discusses how industry, aided by government, exploits these natural cravings, pushing us to eat more and more unhealthy foods. A plant-based diet is the solution to avoid many of these problems. Neal Barnard is the founder of the Physicians Committee for Responsible Medicine (PCRM).
This is Dr. Barnard’s COMPLETE presentation from the VegSource HEALTHY LIFESTYLE EXPO 2003: