Of Food, Drugs, And Brain Chemistry

A generally accepted definition of the word “food” might be something like “plant or animal-derived matter that a person ingests for nutritional value.” But does that mean coffee isn’t a food, since many people only ingest it as a delivery vehicle for caffeine? How about something like the sugary snack Ring-Dings, which nobody could claim they eat for nutritional value?

“Your Brain on Food: How Chemicals Control Your Thoughts and Feelings,” by Gary L. Wenk, is essentially a beginner’s book on neuroscience, leading the reader through such topics as stimulants and depressants, euphoria and depression, and magic and madness. But this problem of how to define food starts at the front of the book and threads its way through to the end. Wenk never really provides one clear definition. In the introduction, he defines food as a substance that a person puts into his or her body, and he makes the argument that food and drugs really aren’t that different. He notes that, by the end of the book, he hopes to convince the reader of the same.

It’s unfortunate that the tricky word food made it onto the cover of the book. A reader picking up “Your Brain on Food” could easily be misled on what the book is about. It’s not—as one might think from both the title and the cover illustration of a head of broccoli replacing a person’s brain—about how the different types of foods we eat affect our thoughts or moods. Instead, it discusses how many drugs, and a few foods like sugar, affect our brains and subsequently, our behavior.

Wenk, a professor of psychology, neuroscience, and molecular virology, as well as immunology and medical genetics at Ohio State University, writes with a definite academic style. The voice he imparts, aimed at newcomers to the neuroscience realm, is one of a professor lecturing his class—complete with dry sentences and occasional jargon. But sporadically, as perhaps a teacher striving to keep his students’ attention with bits of humor, Wenk drops a quip so unexpected as to make the reader laugh out loud.

For example, Wenk writes, “The drug asarone, which comes from a plant, Acorus calamus (found in Asia, Europe, and North America), is chemically very similar to mescaline. The roots of this plant are chewed to produce a dose-dependent effect; about two inches [of root] produces a mild euphoria, whereas nearly 10 inches produces hallucinations. In some cultures, wives will chew on the roots and collect their expectorant throughout the day for their husbands to enjoy later. Nothing says ‘welcome home’ at the end of a hard day like a nice warm bowl of spit.”

The book continues to charm and fascinate by providing glimpses into the science behind some important historical events, such as the Salem Witch Trials of the 17th century. As Wenk describes in the book, a fungus called Claviceps purpurea—the ergot fungus known to grow on both grains and corn—can produce a toxin that mimics the action of serotonin. This neurotransmitter, which is found in blood platelets and serum, acts to constrict the blood vessels. If people eat bread from grain contaminated with the ergot fungus, they experience a burning sensation in their limbs due to the extreme constriction of the blood vessels, which can eventually lead to limb death.

Some historians think that some of the behaviors that led to the Salem Witch Trials in 1691—disorderly speech, odd postures and gestures, and convulsive fits—could have been caused by consumption of ergot-contaminated rye, Wenk states. He writes: “Although ergotism was quite familiar to medical science and to historians by the 17th century, the New England Puritans chose to see these symptoms as the work of Satan brought about by the practice of witchcraft. By September 1692, 20 men and women had been tried and executed for ‘their part’ in the practice, and two died in prison.”

Along with interesting insights into bizarre historical events, Wenk spends a lot of time in the book discussing how our brains respond to different drugs. Of particular interest to a chemistry audience is the discovery and synthesis of painkillers.

It’s fascinating to learn how many drugs that exist today were either mistakes or attempts to synthesize something else entirely than what was ultimately produced. The case of heroin, for example, is a particularly interesting mistake. Opium, the compound from which heroin is derived, is a compound that has long been used as a powerful painkiller. Its first documented use was noted on an Egyptian papyrus dating back to 1500 B.C. In 1874, chemists at Bayer Labs took the known active ingredient in opium, morphine, and attached two acetyl groups. These didn’t change the overall functionality of the drug, but instead increased its lipid solubility. This allowed the new molecule, heroin, to pass through the blood-brain barrier more easily than its nonfunctionalized counterpart, rendering it a much more potent drug.

“Heroin is, in short, just a chemical trick to get morphine into the brain faster,” Wenk writes, “but once inside the brain, heroin can do nothing on its own; first it must be converted into morphine by enzymes and remove those two additional acetyl groups. Then, as the molecule originally found in the poppy seed, it can act to produce pain relief or euphoria.”

Wenk’s kicker here was that Bayer proceeded to market this new wonder drug heroin as a nonaddicting substitute for codeine. The book is crammed full of these types of appealing accounts of drug discovery and history, and he explains them well and leaves the reader wanting more.

But with all of the book’s well-explained science and interesting stories, it does lack a bit of focus. The discussion seems to wander, jumping from one topic to another, then back again. It is more stream of consciousness than an ordered scientific outline. Wenk tries to organize it by type of drug discussed or by the effect the drug has on the brain—for example, stimulants and depressants. But he says in the preface that it’s difficult to organize the book this way, as “the brain does not always behave in such a dichotomous manner.” And although that’s understandable from a scientific point of view, to the reader new to the subject it tends to be a bit disorienting.

The lack of clear diagrams or figures in the book doesn’t relieve this slightly confused feeling. There are a few line drawings and graphs, and a picture of a mushroom or two, but on the whole these are somewhat lacking. Some color pictures, even if they were simple diagrams, would have been welcome.

These flaws add up to the point that they leave the reader wondering to whom this book is really directed. Although Wenk declares it to be for a beginner audience, he may mean beginners to neuroscience. For a lay reader, though, the book remains somewhat inaccessible. It seems to exist in a hybrid space, with the content of a popular book and the voice of a more scholarly text. It would have been a more successful book if he had chosen one style or the other.

Keeping that in mind, “Your Brain on Food” is definitely worth reading, although it’s probably best seen as a collection of facts about our brains, rather than something story-shaped. Readers won’t be disappointed in Wenk’s depth of knowledge of the field or his witty passages. But will they be convinced on the appropriate definition of food? Well, that’s food (or drugs?) for thought.