Breaking the Food Seduction
By Neal D. Barnard, M.D.
Is cheddar cheese addictive? How
about steak? Or Sugar? In Breaking the Food Seduction, PCRM president
Neal Barnard, M.D., present the evidence that these foods might
actually have brain effects that keep you coming back, despite
their health risks.
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
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?
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
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 drugeliminates some of cheese’s appeal,
just as it does for chocolate.
Cheese Heads, Meat Heads
Meat-lovers defend their food of choice with
remarkable ferocity. An April 2000 survey of 1,244 adults revealed
that about one in four Americans wouldn’t give up meat for a week
even if they were paid $1,000 to do it. People from Asian and
Hispanic backgrounds were more willing to accept the hypothetical
offer (fewer than 10 percent turned it down), presumably because
meatless choices are major parts of their traditional cuisines.
But others were more reluctant, with 24 percent of whites and 29
percent of blacks absolutely unwilling to swap meat for cash.
Cholesterol, fat, salmonella, E. coli, Mad Cow disease, and foot
and mouth disease may come and go in the public’s mind, yet
meat-eating goes on.
The reason may be physical, just as it appears
to be for chocolate or cheese. British researchers found that
opiate-blocking drugs cut the appetite for ham by ten percent,
knocked out the desire for salami by about twenty-five percent,
and cut tuna consumption by nearly half. In other words, a person
might still eat some of it to quell hunger or simply out of habit.
But blocking an opiate response knocks out the added chemical
appeal a food may have, reducing the tendency to choose it.
If you are hooked on sugar, chocolate, cheese,
or meat, what do you do about it? Actually, foods can come to your
rescue. If you start your day with a good breakfast, hunger is
less likely to fuel cravings. And if your lunch, dinner, and
snacks include foods that keep your blood sugar steady throughout
the day—beans, green vegetables, unprocessed grains, and fruits,
for example, instead of sugary foods or white bread—you’ll be less
likely to dip into unhealthy foods later on.
Be sure to eat enough food, so that your
appetite-taming hormone leptin is working right. Leptin shuts down
whenever you go on a starvation diet, leaving your appetite out of
control. Exercise, rest, and social support all help, too.
And there’s nothing like taking a three-week
break from unhealthy foods. A low-fat, vegan diet skips the worst
of the food seductions. And if, for even a few weeks, you set
aside whatever foods are leading you astray, you’ll find your
resolve is much stronger than if you had eaten them yesterday.
Cheese consumption in the U.S. rose from 15
pounds per person per year in 1975 to more than 30 pounds in
1999. And you can thank the federal government. The USDA
Report to Congress on the Dairy Promotion Programs for the
year 2000 described how the government and industry worked
with fast-food chains to make sure that cheese was prominently
displayed in menu items. One federally sanctioned program
launched Wendy’s Cheddar Lover’s Bacon Cheeseburger, which
single-handedly pushed 2.25 million pounds of cheese during
the promotion period. Another promoted Pizza Hut’s “Ultimate
Cheese Pizza”—with an entire pound of cheese per pizza—selling
five million pounds of it during a six-week promotion in 2000.
And in 1996, cheese was not a required ingredient in Subway
sandwiches. So a similar federal program helped the restaurant
chain promote cheese and include it as a required ingredient
in two new sandwiches, the Chicken Cordon Blue and Honey
Pepper Melt, anticipating the sale of an extra 70,000 pounds
At a “Cheese Forum” held on December 5,
2000, Dick Cooper, the Vice President of Cheese Marketing for
Dairy Management, Inc., showed slide after slide detailing the
industry’s plans for pushing cheese in grocery chains, food
services, and fast-food restaurants. One slide asked the
question “What do we want our marketing program to do?” and
then gave the answer: “Trigger the cheese craving.” Mr. Cooper
concluded with a cartoon of a playground slide with a large
spider web woven to trap children as they reached the bottom.
The caption had one spider saying to another, “If we pull this
off, we’ll eat like kings.”
Neal Barnard, M.D., is the president of the
Physicians Committee for Responsible Medicine.