A Natural History of the Senses (23 page)

There’s no question that, at least for certain nutrients, if a person is in true need, some gustatory yen or body wisdom takes over. Patients with Addison’s disease become ill because of a deficiency of the adrenal hormones. They’ve been known to crave salt with a vengeance, subconsciously medicating themselves. One way they do this is by eating large amounts of licorice, which contains glasorisic acid, a substance that causes sodium retention, and while doctors certainly don’t prescribe it, they find that Addison’s sufferers feel better if they eat a lot of licorice.

Some Quechua Indians of Peru subsist largely on potatoes, but because the growing season is so short, they’re often forced to eat only partially ripened ones. Potatoes contain solanine, a bitter toxic alkaloid, but the Quechuas find that if they smear kaolin clay on the potatoes, it masks the bitterness and they don’t get upset stomachs. The kaolin also detoxifies the alkaloids in the potatoes, making them simultaneously tastier and more nutritious.

It’s odd to think of people eating dirt. Salt is the only rock we really seem to enjoy, but that’s because we are small marine environments on the move, with salt in our blood, our urine, our flesh, our tears. However, you can still find clay for sale in some of the open-air markets in the southern United States. Pregnant women buy it. In
Africa, pregnant women occasionally eat termite mounds. It’s thought that they’re after calcium and certain other minerals missing from their diet. In Ghana, some villages support themselves by selling egg-shaped balls of clay, which are rich in potassium, magnesium, zinc, copper, calcium, iron, and other minerals. A pregnant woman’s craving for dairy products makes good nutritional sense, because if the fetus doesn’t get enough calcium, it will take it from the mother’s bones and teeth. Most cultures have taboos for pregnant women, certain fish or fungi or spices they must not eat, but these are not the same as a woman’s craving certain foods. The increased blood volume of a pregnant woman lowers her sodium level, and as a result she doesn’t taste saltiness as easily as she did when she wasn’t pregnant; she may crave really salty foods, like the legendary pickle. Among the many explanations for why pregnant women crave ice cream and other sweets, one of the most interesting modern theories is that they crave foods which produce the neurotransmitter serotonin, which they’ll need to help withstand the pain of childbirth.

Some foods may stimulate endorphins—morphinelike painkillers produced by the brain—and give us a sense of comfort and calm. This is why, even though we know that salty foods, greasy foods, and candy and other sweets aren’t good for us, we have a taste for them anyway. Neurobiologists suspect that endorphins and other neurochemicals control our hunger for certain kinds of foods. According to this thinking, when we eat sweets we flood our bodies with endorphins and feel tranquil. When people are under stress, and their need for endorphins goes up, they may crave a box of cookies. Since our hunger for fats, proteins, and carbohydrates is controlled by specific neurotransmitters, which can easily get out of balance, we need only binge to knock the neurotransmitters out of whack, which leads to further binging, further imbalances, and so on. In one experiment, depriving rats of their breakfast threw off their neurotransmitters and they gorged later in the day.

Are one’s moods linked to food? Biochemist Judith Wurtman has published highly controversial findings about how food can affect our moods. She concludes that there are “carbohydrate cravers,”
who in reality are trying to raise their level of serotonin. When these levels are increased by drugs in controlled experiments, the carbohydrate cravers lose their cravings. Some scientists at the Monell Chemical Senses Institute and elsewhere dismiss her findings as being too tidy, too simple a version of how the body works, but I think some of it is persuasive. I never drink coffee after dinner, but I discovered accidentally over a period of years that I get to sleep better if I also don’t eat protein late at night, only toast and jam or some other carbohydrates. On the other hand, around 3:30 in the afternoon, when my energies start to crash but I still have work to do, I’ll be perked up by a jolt of protein, usually some cheese. My pattern gibes with Wurtman’s experiments. The real power lunch, she suggests, revolves around an initial serving of protein, then a simple protein entreé and lightly cooked vegetables, with nothing richer than fruit for dessert, and no alcohol. Carbohydrates are sedating. When I meet someone for lunch and want to stay bright-eyed and bushy-tailed I order a high-protein appetizer like a shrimp cocktail or oysters on the half shell, or sliced mozzarella cheese with basil and tomatoes, and never nibble on the bread. A heap of pasta followed by chocolate mousse for dessert is what I’d really like, but I’ve found that it leaves me too listless to work. I disagree with Wurtman about why we crave chocolate, however—I don’t think it’s just a general cry for carbohydrate, but a craving for something more specific that chocolate provides.

Another researcher, one at the National Institute of Mental Health, found that people with Seasonal Affective Disorder (SAD), who become very depressed in winter, share a craving for carbohydrates at that time; this helps lift their mood. In yet another study, ex-smokers were found to crave carbohydrates. The link between carbohydrate craving, serotonin, and our drive to bring ourselves back into emotional balance seems undeniable. The brain is a chemical industry, and foods are highly complex chemicals. The extent to which eating one food or another may affect one’s mood is really what’s at issue.

Most people need about 15 percent of their food to be protein, and they automatically choose foods that will provide it, but scientists
at the University of Toronto medical school discovered how much such a need can depend on genetics when they studied identical and fraternal twins. Identical twins, even though they were raised apart since birth, ate the same proportions of protein and carbohydrates, while fraternal twins didn’t. So craving may, to some extent at least, be genetically determined. Hyperactive children often respond well to changes in their diet, as do those suffering from various disorders like Addison’s disease or diabetes. But it’s hard to say where memory stops and nutritional need or genetic fiat begins. We may crave sweets because we associate them with childhood rewards, or with being fed sweet liquids when we were babes-in-arms. Or we may crave them as a way to trigger the calm serotonin brings. Or both.

Most nutritionists, who are conservative, claim that there’s no magic bullet and we should just try to eat as varied and well-balanced a diet as possible.
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Under some circumstances, food can do more than change one’s mood: It can kill. Raw liver used to be prescribed for pregnant women or those listless from iron deficiency, but now we know that liver collects the body’s impurities and probably shouldn’t be eaten at all. Polar bear liver is so high in vitamin A that it’s toxic to humans. Alexander Pope and Henry I of England reportedly died from eating eels, which have poisonous filaments cooks might forget to remove. Balzac drank over fifty cups of coffee a day, and died from caffeine poisoning. Mushroom collectors run a steady risk of plucking the wrong fungus. Salmonella, which sounds so delicatessenlike and fresh, claims victims every year. Supposed aphrodisiacs have killed many victims, too. We don’t think of plants as aggressive, but, since they can’t run away from predators, they often devise extraordinary defense systems and potions, like strychnine, which protect them in the wild and sometimes appear on our plates.

What food do you crave? Ask the question with enough smoldering emphasis on the last word, and the answer is bound to be chocolate. It was first used by the Indians of Central and South America. The Aztecs called it
xocoatl
(“chocolate”), declared it a gift from their white-bearded god of wisdom and knowledge, Quetzalcoatl, and served it as a drink to members of the court—only rulers and soldiers could be trusted with the power it conveyed. The Toltecs honored the divine drink by staging rituals in which they sacrificed chocolate-colored dogs. Itzá human-sacrifice victims were sometimes given a mug of chocolate to sanctify their journey. What Hernán Cortés found surrounding Montezuma was a society of chocolate worshipers who liked to perk up their drink with chili peppers, pimiento, vanilla beans, or spices, and serve it frothing and honey-thick in gold cups. To cure dysentery, they added the ground-up bones of their ancestors. Montezuma’s court drank two thousand pitchers of chocolate each day, and he himself enjoyed a chocolate ice made by pouring the drink over snow brought to him by runners from the mountains. Impressed by the opulence and restorative powers of chocolate, Cortés introduced it to Spain in the sixteenth century. It hit the consciousness of Europe like a drug cult. Charles V decided to mix it with sugar, and those who could afford it drank it thick and cold; they, too, occasionally added orange, vanilla, or various spices. Brillat-Savarin reports that “The Spanish ladies of the New World are madly addicted to chocolate, to such a point that, not content to drink it several times each day, they even have it served to them in church.” Today, chocolate-zombies haunt the streets of every city, dreaming all day of that small plunge of chocolate waiting for them on the way home from work. In Vienna, the richest chocolate cakes are decorated with edible gold leaf. More than once, I’ve been seriously tempted to fly to Paris for the afternoon, just to go to Angelina, a restaurant on the rue de Rivoli where they melt a whole chocolate bar into each cup of hot chocolate. How many candy bars
don’t
contain chocolate? Chocolate, which began as an upper-class
drink, has become déclassé, trendy, cloaked in a tackiness it doesn’t deserve. For example, an ad in
Chocolatier Magazine
offers a one-quarter-pound chocolate “replica of a 5¼
-inch
floppy disk.” In fact, the company can provide an entire “computer work-station comprised of a chocolate terminal, chocolate computer keyboard, chocolate chip and chocolate byte.” Their slogan is “Boots up into your mouth, not in your disk drive.” One September weekend in 1984, the Fontainebleau Hotel in Miami offered a Chocolate Festival Weekend, with special rates, menus, and events. People could fingerpaint in chocolate syrup, attend lectures on chocolate, sample chocolates from an array of companies, learn cooking techniques, or watch a TV actor be dunked in six hundred gallons of chocolate syrup. Five thousand people attended. Chocolate festivals rage in cities all across America, and there are highly popular chocolate tours of Europe. In Manhattan last month I heard one woman, borrowing the jargon of junkies, say to another, “Want to do some chocolate?”

Because chocolate is such an emotional food, one we eat when we’re blue, jilted, premenstrual, or generally in need of TLC, scientists have been studying its chemistry. In 1982, two psychopharmacologists, Dr. Michael Liebowitz and Dr. Donald Klein, proposed an explanation for why lovesick people pig out on chocolate. In the course of their work with intense, thrill-seeking women who go into post-thrill depressions, they discovered that they all had something remarkable in common—in their depressed phase, virtually all of them ate large amounts of chocolate. They speculated that the phenomenon might well be related to the brain chemical phenylethylamine (PEA), which makes us feel the roller coaster of passion we associate with falling in love, an amphetaminelike rush. But when the rush of love ends, and the brain stops producing PEA, we continue to crave its natural high, its emotional speed. Where can one find lots of this luscious, love-arousing PEA? In chocolate. So it’s possible that some people eat chocolate because it reproduces the sense of well-being we enjoy when we’re in love. A sly beau once arrived at my apartment with three Droste chocolate apples, and every wedge I ate over the next two weeks, melting lusciously in my mouth, filled me with amorous thoughts of him.

Not everyone agrees with the PEA hypothesis. The Chocolate Manufacturer’s Association argues that:

And Dr. Liebowitz himself, in
The Chemistry of Love
, later asked of chocolate craving:

As a thoroughgoing chocoholic, I should say that I do indeed eat a lot of cheese. Smoked salami is too unhealthy for me even to consider; the Cancer Society has suggested that people should not eat foods that are smoked or contain nitrites. So, it’s entirely possible that cheese fills some of my PEA need. What else do chocoholics eat? In other words, what is the total consumption of PEA from all sources? Chocolate may be a more appealing, even if smaller, source of PEA because of its other associations with luxury and reward. The NIMH study tested average people, but suppose people who crave chocolate aren’t average? Isn’t that the idea? Liebowitz now says that PEA may break down too fast to affect the brain. We still know very little about the arcane ways in which some drugs do this, not enough to completely dismiss chocolate’s link with PEA.