- Olga Khazan<\/li><\/ul>\n\n\n\n
Read when you\u2019ve got time to spare.
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<\/p>\n\n\n\nPhoto by Beawiharta Beawiharta \/ Reuters<\/em><\/p>\n\n\n\n
At the turn of the 20th century, prominent physicians who were trying to understand where mental illness comes from seized on a new theory: autointoxication. Intestinal microbes, these doctors suggested, are actually dangerous to their human hosts. They have a way of inducing<\/a> \u201cfatigue, melancholia, and the neuroses,\u201d as a historical article in the journal Gut Pathogens<\/em> recounts.<\/p>\n\n\n\n
\u201cThe control of man\u2019s diet is readily accomplished, but mastery over his intestinal bacterial flora is not,\u201d wrote<\/a> a doctor named Bond Stow in the Medical Record Journal of Medicine and Surgery<\/em> in 1914. \u201cThe innumerable examples of autointoxication that one sees in his daily walks in life is proof thereof … malaise, total lack of ambition so that every effort in life is a burden, mental depression often bordering upon melancholia.\u201d<\/p>\n\n\n\n
Stow went on to say that \u201ca battle royal must be fought\u201d with these intestinal germs.<\/p>\n\n\n\n
Another physician, Daniel R. Brower of Rush Medical College, suspected that the increasing rates of melancholia\u2014depression\u2014in Western society might be the result of changing dietary habits and the resulting toxins dwelling in the gut.<\/p>\n\n\n\n
Of course, like most medical ideas at the time, this one was not quite right. (And the proposed cures\u2014removing part of the colon or eating rotten meat\u2014seem worse than the disease.) Your gut doesn\u2019t contain \u201ctoxins\u201d that are poisonous so much as it hosts a diverse colony of bacteria called the \u201cmicrobiome.\u201d But these doctors were right about one thing: What we eat does affect how we feel, and gut microbes likely play a role.<\/p>\n\n\n\n
A poor diet is a leading risk factor<\/a> for early death, responsible for one in five deaths globally. Depression, meanwhile, is the leading cause <\/a>of disability worldwide. A relatively new line of research suggests the two might be related: An unhealthy diet might make us depressed, and depression, in turn, makes us feel even sicker.<\/p>\n\n\n\n
In a one abstract,<\/a> researchers studying 964 elderly participants over six and a half years found those who followed the DASH diet, which emphasizes whole grains, fruits, and vegetables, had lower rates of depression, while those who ate a traditional Western diet were more prone to depression. The participants were asked how often they ate various foods, and they were screened for depression annually using a questionnaire.<\/p>\n\n\n\n
\u201cI think we need to view food as medicine,\u201d Laurel J. Cherian, an assistant professor of vascular neurology at Rush University Medical Center in Chicago and the study\u2019s lead author, told me. \u201cMedications to treat depression are wonderful, but for many people, it\u2019s going to be a combination of things.\u201d<\/p>\n\n\n\n
The research will be presented at the upcoming meeting of the American Academy of Neurology. The study has not been published yet in a peer-reviewed journal, but other researchers have found similar antidepression benefits from the DASH diet<\/a>, which was developed by the U.S. National Heart, Lung, and Blood Institute.<\/p>\n\n\n\n
Past research has found that following the DASH diet was associated with reduced depression in adolescent girls<\/a> and with less physician-diagnosed depression among thousands of Spaniards<\/a>. The results in teens suggest that diet could be a way to stave off some mental disorders entirely, since half of all mental illnesses <\/a>start in the teen years.<\/p>\n\n\n\n
John Cryan, an expert in the gut-brain connection at University College Cork in Ireland, said he\u2019s enthusiastic about this field, but there are a few cautionary notes about this study in particular. It\u2019s an observational study, for example, and it studied a very old population. \u201cGeriatric depression is a different beast,\u201d he says.<\/p>\n\n\n\n
Of course, rich people tend to be happier<\/a> and can afford to eat better. Cherian\u2019s study did not control for socioeconomic status. But overall, the evidence suggests diet improves depression symptoms even when controlling for factors like income or education, says Felice Jacka, a professor of nutritional psychiatry at Australia\u2019s Deakin University.<\/p>\n\n\n\n
Jacka found in 2010 <\/a>that women who ate a diet high in produce, meat, fish, and whole grains had lower odds of major depression and anxiety than others. Since then, a meta-analysis of 21 studies<\/a> found that \u201ca dietary pattern characterized by high intakes of fruit, vegetables, whole grain, fish, olive oil, low-fat dairy and antioxidants and low intakes of animal foods was apparently associated with a decreased risk of depression.\u201d<\/p>\n\n\n\n
In fact, Jacka told me that at this point, the connection between diet and depression is so well-established that more studies like Cherian\u2019s aren\u2019t really necessary. \u201cGiven how many observational studies there are already published, the field does not really need more of these,\u201d she said. \u201cWhat it needs now are interventions that show that if you improve diet, you also improve depression.\u201d Jacka found in a small study<\/a> last year that depressed people were more likely to see improvements in their mood if they were given dietary advice over a three-month period, rather than just social support. She says such interventions are cost-effective, to boot.<\/p>\n\n\n\n
The DASH diet itself is nothing revolutionary\u2014a typical dinner <\/a>consists of a lean meat, baked potato, and lots of vegetables. Researchers are still figuring out why it\u2019s so beneficial, but a major pathway might be through the gut-brain connection. When people eat a plant-heavy diet, the fiber from the plant matter ferments in the gut and creates short-chain fatty acids, which, in turn, regulate the immune system and influence gene expression in the brain and elsewhere. People who eat fiber have more diverse gut bacteria<\/a>, and these bacteria make various chemicals that influence our mood.<\/p>\n\n\n\n
Inflammatory molecules, called cytokines, that are produced by body fat can spark inflammation elsewhere in the body. Inflammation increases the risk of depression and other diseases by harming the lining of the blood vessels. Meanwhile, healthy fats increase the production of proteins called neurotrophins, which \u201cact like manure to the brain as they promote the growth of new brain cells in the hippocampus,\u201d Jacka says. \u201cThere is a strong link between the quality of people\u2019s diets and the size of their hippocampus.\u201d<\/p>\n\n\n\n
Cryan says these studies point to the growing recognition of the importance of diet\u2014along with the other old standbys, exercise and sleep\u2014in regulating mood. In fact, despite feeling cautious about the early nature of this line of research, he says he would recommend depressed people try eating better to see if it helps.<\/p>\n\n\n\n
Indeed, the real connection between diet and mental health might be closer to the work of a different 19th-century figure: The French lawyer Jean Anthelme Brillat-Savarin, who wrote, in 1825, \u201cDis-<\/em>moi<\/em> ce<\/em> que<\/em> tu<\/em> manges<\/em>, <\/em>je te<\/em> dirai<\/em> ce<\/em> que<\/em> tu<\/em> es.<\/em>\u201d<\/p>\n\n\n\n
Translation: Tell me what you eat, and I will tell you what you are. Olga Khazan<\/a> is a staff writer at The Atlantic.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
Several studies show that healthy eating is connected with better mood. The Atlantic Olga Khazan Read when you\u2019ve got time to spare. Photo by Beawiharta Beawiharta \/ Reuters At the turn of the 20th century, prominent physicians who were trying to understand where mental illness comes from seized on a new theory: autointoxication. Intestinal microbes,<\/p>\n