Illustration by Dana Collins

AS THE OLD RUSSIAN SAYING GOES, IF YOU WAKE up and you're not in pain, it's because you are dead. Life can be tough. And judging by the statistics on depression it's getting tougher. Each year, according to the National Institute of Mental Health, 19 million Americans suffer from depression. Some 50 percent will experience symptoms at some time or another in their lives, while as many as 10 percent can expect to have a “major depressive episode.” These facts alone are enough to send one spiraling into that bottomless well where no light seems to shine.

Nowhere is the pit of depression more harrowingly evoked than in that masterpiece of pre-Freudian psychoanalytics, The Divine Comedy, where Dante paints for us a veritable landscape of despair — fittingly situated inside a hole. Though ostensibly a work of theology, Dante's journey can also be read as a chronicle of psychological torment and subsequent healing. In the opening canticle of “The Inferno,” the Pilgrim descends into the underworld — venturing, as it were, into the subterranean caves of the mind. There in the rayless gloom he encounters the various modalities of hopelessness. As he drops deeper, the despair literally congeals, and the ground turns to ice, poetically signifying the psychic freezing induced by loss of hope. Rather than fire and brimstone, at the very bottom of Dante's Hell, we find the most hopeless cases imprisoned in ice “like straws in glass,” completely immobilized.

Seven hundred years before the advent of psychopharmacology, Dante understood the stultifying effects of despair, but even he couldn't have imagined its spread. Globally, more workdays are lost today to depression than to any other illness, and it is now recognized as the world's leading cause of disability. Left unchecked, its downhill slide can lead to the ultimate immobility — recent studies suggest that between 2 and 4 percent of depressives will end their days in suicide. Manic-depression (also known as bipolar disorder) now afflicts 2.3 million of us and is the second leading killer of young women, the third of young men.

Standard explanations for depression have focused on family dysfunction, psychological malaise and aberrations in brain chemistry, but new evidence suggests that at least in part, depression may be a byproduct of diet. It may be that we are eating ourselves into a collective decline. Unlikely though it may sound, the suspected culprit is fat — polyunsaturated fatty acids of the type known as omega-6, which are particularly prevalent in soy, corn, palm and cottonseed oil. Over the past century, the amount of omega-6 fatty acids in the average Western diet has skyrocketed as we have increasingly sought convenience in fried and packaged foods.

That fat is bad is almost a truism of modern life; this oleaginous substance has been implicated in everything from heart disease to cancers. Still, the idea that fat can addle your brain sounds deeply suspect — until you learn that the organ itself is 60 percent fat. Every cell in the mammalian brain is encased in a membrane through which chemical and electrical signals must pass, and this membrane is composed almost entirely of fats. As one scientist has memorably put it, “There is no difference between your brain and a stick of butter.” After years of being told that our brains are like microchips, all crystalline circuitry and electrical synapses, there is something perversely appealing about the idea that our mental machinery essentially amounts to a medium-size tub of lard. It's as if the comic-book guy in The Simpsons had suddenly triumphed over William Gibson. But there you have it. And since our minds are mired in fat, it makes sense that what types we eat might affect our psychological state.

A critical factor appears to be the balance between our intake of omega-6 fatty acids and their cousins of the omega-3 variety, which are found in fatty fish like salmon and tuna as well as in walnuts, flax seeds and olive oil. A century ago, we'd have been eating a roughly equal amount of both; today a typical Western diet contains 16 times more omega-6 than omega-3 fatty acids. Manufacturers prefer omega-6 oils because their stability promotes long shelf life in packaged foods. In the U.S., consumption of soy oil alone has increased a thousandfold over the past century — it now accounts for more than 80 percent of total fat intake.

In a 1991 study conducted by Harvard University and Baylor Medical College, manic-depressives given a daily dose of omega-3s in the form of fish oil showed striking improvements. Results were so positive that the study was called off just four months into a projected nine-month run. Of 15 fish-oil recipients, 11 improved during the trial period, with only two experiencing relapse. Of 20 in the placebo group, only six improved, with 11 relapsing. Throughout the trial, all patients continued their regular medications, but it was clear that the fish oil had a dramatic effect. Following the success of this small study, Harvard and Baylor are now in the midst of a much larger, longer-term study, again focusing on manic-depression.

Dr. Lauren Marangell of Baylor College, one of the principal researchers behind these studies, explains that inside cells, omega-3 fatty acids function in a similar way to lithium, one of the major drugs used to combat bipolar disorder. The advantage, of course, is that omega-3s are non-toxic. In bipolar patients, Marangell tells me, “Some of the chemical pathways seem to be overactive”; omega-3 fatty acids help to bring that response back down to normal. Marangell is especially interested in the possibility of using omega-3s as a non-toxic alternative for depressed women who want to have children. All pregnant women might in fact benefit from increased omega-3s, since this group of fatty acids is essential for healthy fetal development, particularly for the growth of the brain and retina. A fetus will gobble all the omega-3s it can get from its mother, leaving many women depleted at the end of term. Studies have shown that the omega-3 fatty acid DHA can lower the incidence of postpartum depression.

WHAT ABOUT REGULAR DEPRESSIVES — THE 28 million Americans (one in 10!) — who are not manic but are now taking SSRI antidepressants, such as Prozac, Paxil and Zoloft? Joseph Hibbeln, of the National Institutes of Health, believes that the huge rise in depression in the Western world over the past half-century is a direct consequence of a dietary revolution. Thousands of years ago, our ancestors would have been eating tons of leafy greens, fish and wild game, all of which are high in omega-3s. Having studied societies around the world, Hibbeln has noted a significant correlation between consumption of omega-3s and the incidence of depression. In Japan, where fish is still one of the major food groups, the reported rate of depression is just 1 percent of the population. Hibbeln believes that low omega-3s are implicated not only in depression but also in the Western world's high rates of homicide and suicide.

Skeptics point out that such differences may be due more to cultural factors; in Asia, depression is often seen as shameful and is probably underreported. While that is no doubt true, Hibbeln points out that when other cultures switch to Western diets, they too slide quickly down depression's sickly slope. Fatty acids have been shown to affect the neurotransmitter serotonin, the target of SSRI drugs, and Hibbeln has found that people with low levels of omega-3s in their spinal fluid also have low levels of serotonin. Marangell stresses that a great deal more research is needed; yet, while she remains cautious about the power of omega-3s to cure depression, she is unequivocal when I ask if we should all be considering fish-oil capsules. Absolutely, she says, recommending a daily dose of around 500 milligrams.

No one is saying that omega-3s alone will dispel our psychic clouds. Clearly there are many reasons to be depressed (not least, the recent election results), but it is an interesting and perhaps invigorating thought — that to whatever extent chemicals are involved, the resolution may lie not in your doctor's script, but in the contents of your fridge.

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