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Andria Gutierrez was only 27 years old, but she felt more like 80: mentally fuzzy, irritable, tired all the time. And then Andria began experiencing bouts of overwhelming anxiety that became more and more frequent. Andria was diagnosed with anxiety disorder, but the medications her doctors prescribed gave her little relief, so she went looking for help elsewhere.
“I talked to a few naturopaths, and they all suggested I try changes in my diet,” Andria says. Three months later, still fighting anxiety, fatigue, and brain fog, she finally decided to make major changes to her eating habits. She dropped sugar, red meat, and refined grains and switched to a more Mediterranean style of eating focused on fruits, veggies, and fish. She started noticing improvements in a matter of weeks—and now, three years later, “I have never felt better; the anxiety and depression are completely gone,” Andria says. “I had never felt comfortable and content with my life before, and now I do.”
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Eastern-medicine practitioners and naturopaths have been prescribing dietary changes to help ease mental and physical ailments for millenia, says internist Eva Selhub, MD, a lecturer in medicine at Harvard Medical School and a clinical associate in medicine at the Benson-Henry Institute for Mind Body Medicine at Massachusetts General Hospital. Now Western science is catching on, and a growing body of research suggests that the foods we eat greatly affect our brains and mental health. In fact, so much good evidence is emerging that a brand-new focus of mental-health research and treatment has been born: nutritional psychiatry.
“For the last several decades, there was this idea in psychiatry that the mind was separate from the body—that psychiatric illnesses like depression existed in the mind alone, so what you put in your body was largely irrelevant,” says Felice Jacka, PhD, an associate professor at the Deakin University School of Medicine in Melbourne, Australia, who focuses mainly on nutritional psychiatry. “But research over the last 1o years has increasingly shown us that physical and mental health are part of the whole and can’t be separated.”
For instance, in one study of several hundred Australian women, those who ate the most whole foods like fruits, veggies, unprocessed meats, and whole grains were less likely to be diagnosed with depression, anxiety, or bipolar disorder than those who had a low intake of healthy food. Two large studies later done in Norway and another here in the United States discovered much the same thing.
While it’s true that people who are mentally ill or feeling unwell may gravitate toward less-healthy “comfort” or convenience foods, that doesn’t fully explain the connection, says Jacka. Profound changes in brain structure and behavior have been seen after manipulating diets in animal studies; researchers like Jacka are in the process of investigating how this applies to humans.
So far, the strongest correlations in nutritional psychiatry have been found in the risk of depression, but evidence also suggests that food may play a role in conditions like anxiety disorders, dementia, schizophrenia, and attention deficit disorder. “With every patient I see now, I do a complete food assessment and try to make food choices a part of their treatment plan,” says Drew Ramsey, MD, assistant clinical professor of psychiatry at Columbia University in New York City and co-author of The Happiness Diet. “One patient I remember—a young guy who was really struggling with depression and anxiety—his diet was very unstructured; he skipped meals a lot, ate a lot of white carbs and almost no vegetables.” After a year of treatment, part of which included adding lots of vegetables, seafood, and whole-food smoothies to the patient’s daily meals, “His depression was in complete remission and he was no longer on any medications,” says Ramsey. “I remember him telling me, ‘If I don’t eat right, I don’t feel right.’” (Of course, diet should be just one part of your treatment plan—never stop medication without your doctor’s guidance.)
How Food Affects Mood
Like any other body part, our brains are basically built out of the food we eat. “Emotions begin in biology, with two nerve cells rubbing together, and those nerve cells are made of nutrients in food,” explains Ramsey. Your body can’t make the mood-regulating neurotransmitter serotonin without iron and tryptophan, he points out, or produce myelin, the fatty substance that insulates your brain cells, without vitamin B12 (found in seafood, beef, and dairy).
It makes sense that giving your body higher-quality fuel makes it work better head to toe, but research suggests some other fascinating specifics about how food exerts influence over your state of mind. For example, rats fed a high-fat, refined-sugar diet show reduced amounts of growth factors called neurotrophins in the brain, and scientists suspect that something similar happens to sugar-loving humans. And that’s a problem because neurotrophins prompt the growth of new brain cells in the hippocampus, a part of the brain that’s key for memory, explains Jacka.
It’s also been noted that the hippocampus is smaller in people with depression, but it grows again when the illness is successfully treated. So it’s possible that eating a less-sugary diet could impact depression at least in part based on its effect on neurotrophins and the hippocampus.
Oxidative stress on brain cells likely plays a role, too. “Your brain is burning enormous amounts of glucose [blood sugar] for energy, and just like when you burn gas in a car and there is exhaust, when you burn fuel in the brain there’s a type of ‘exhaust’: free radicals,” says Ramsey. “Over time, those free radicals damage your cells—and that’s oxidative stress.” Build up enough damage, and it can affect emotion by interfering with the way your brain cells function. Brain cells and the signals they send to each other are part of what creates emotion and mood. So if the cells are unhealthy and damaged, the signals they send become muddled or irregular, and you end up with disorders like depression and anxiety. Antioxidants like vitamins C, E, and beta carotene, and flavonoids like quercetin and anthocyanidins (found in dark berries), have been shown to help prevent and repair oxidative stress.
The molecules in food also affect our genes through epigenetics. For instance, research suggests that flavonoid antioxidants in things like dark chocolate and certain vegetables, or zinc from oysters, or omega-3 fats actually change the way our genes behave, says Ramsey. So if you have a genetic predisposition to depression, your diet can either increase or decrease your risk of developing the illness.
Bacteria in the gut play a variety of roles for keeping the brain healthy. “We have a very beautiful, wonderful ecosystem of organisms that live in the mucosal areas of the body like the lining of our stomach and intestines,” says Selhub, who studies the link between gut bacteria and mental health. One way these bacteria benefit the brain is by helping to keep intact the gut lining, which is full of nerve cells that constantly send messages to the brain. The gut lining also acts as a barrier to toxins and aids digestion so your brain is protected from bad stuff while still getting needed nutrients. But overwhelm the gut lining with the wrong foods—processed sugars, some cured meats (like deli meats), trans fats, and processed, white-flour carbohydrates—and it can become inflamed and start to break down, says Selhub, adding, “And we know that more inflammation is associated with more mood disorders, including depression.”
See also A Depression Dissolving Sequence
Another way gut bacteria seem to aid the brain is by synthesizing many neurotransmitters, such as serotonin and dopamine. A 2011 study at McMaster University in Ontario, Canada, found that changing the balance of gut bacteria in mice not only changed levels of these chemicals in their brains, but also caused obvious changes in behavior, making usually timid mice act more boldly and adventurously—suggesting a shift in anxiety levels.
Although Jacka notes that researchers don’t yet understand how gut bacteria affect neurochemicals in the human brain, what is clear is that diet is one of the keys to promoting healthy gut flora. Refined carbohydrates, sugar, and saturated fats upset the balance of bacteria. On the other hand, “prebiotic foods,” such as asparagus, Jerusalem artichokes, bananas, oatmeal, unrefined wheat, chicory root, and legumes, support gut bacteria and their functions.
The effects of food on our brain may be speedier than you’d expect—days, not years. Andria Gutierrez says she noticed a mental-health upswing after two weeks of following a healthier diet. “My mind just started to feel less cluttered. I started to wake up feeling rested and with a smile,” she says. “I can remember that first day I woke up feeling good—it still gives me the chills because it felt like a miracle, a true blessing.”
The field of nutritional psychiatry is still in its infancy, but research to date suggests that what seems to matter the most is overall diet quality. Here are five ways to improve the caliber of yours.
- Get back to basics
Diets that focus more on whole, unprocessed foods—regardless of whether they include or exclude certain grains, meats, or dairy products—tend to correspond to better mental health than typical “Western” diets full of fast and processed food, cured meats, packaged snacks, and sugary drinks. “The Mediterranean diet and Asian diets would fit that healthier description,” says Elizabeth Somer, RD, author of Eat Your Way to Happiness. In other words, what experts have been telling us for years remains true: Eat lots of colorful veggies and fruits, lean protein, and whole grains, and very little processed and fatty foods.
- Eat More Fermented Stuff
Fermented foods like kefir, kimchi (Korean fermented cabbage), sauerkraut, miso (Japanese fermented soybean paste), and kombucha (a fermented drink brewed with yeast) contain probiotic bacteria that research suggests make your gut generally healthier. Some yogurts do, too, but not all, so check labels to make sure they contain “live active cultures” and no sugar. In one 2o13 study, UCLA researchers found eating a fermented yogurt with probiotics twice a day for a month led to increased activity in areas of the brain that process emotion and sensation. (How the components of yogurt might specifically affect mood, however, is still unknown.) The scientific jury is still out on exactly which probiotic supplements may work best and which types of bacteria are most beneficial in terms of mental health. But Selhub does recommend increasing your intake of fermented food and thinks that a probiotic supplement can be a good choice for those with anxiety or depression (and she does take a probiotic supplement herself).
- Avoid Junk Food
Our harried lives lead us to eat more junk and processed convenience foods, which may make us feel even more stressed. “We don’t focus on finding outlets for our stress as a modern society, so our stress overflows and the dam breaks,” says Selhub. When there’s a drop in our levels of dopamine and serotonin—two brain chemicals that improve mood—we seek out high-carb junk foods to try to feel better. “Then the food we eat increases inflammation in our guts, leads to oxidative stress in the brain, and serotonin and dopamine drop again. It creates a vicious cycle,” Selhub says. Taking the time to cook at home even when life feels crazy, or at least selecting healthier prepared meals that are lower in fat and full of vegetables, lean protein, whole grains, and fermented foods, will pay off by breaking this damaging cycle and improving your mood.
- Eat More Seafood
Omega-3 fatty acids, specifically the DHA type found in seafood like salmon, tuna, halibut, and shrimp, seem to be helpful to people with severe depression, says Jacka. The membranes of brain cells are partially made from omega-3 fatty acids, so if levels in your diet are low, your brain cells may suffer and not signal each other properly. Exact requirements aren’t known yet, but the data suggest that we need at least 22o mg of DHA per day, the amount you’d get if you ate salmon at least twice a week, says Somer.
- Focus on Foods Full of Vitamins B and D
Depressed patients are often found to be low on vitamins B9 (folate) and B12, leading experts to conclude that these nutrients are important in brain and mental health. Low vitamin D is also linked to depression. “And almost everybody is deficient in D,” says Somer. “You need 1,ooo IU a day.” Spinach, black-eyed peas, and asparagus are packed with folate; seafood, beef, and dairy have lots of B12; and D can be found in salmon, tuna, liver, milk, and eggs.
Your Happy Diet Cheat Sheet
Wondering what to nosh on next? Use this checklist of what to eat and to avoid to keep your brain balanced and firing on all cylinders.
Fill Up On
- Oily fish rich in omega-3 fats
- High-antioxidant veggies like dark, leafy greens
- Dark, colorful berries
- Chewy whole grains like brown rice, quinoa, and whole-wheat pasta
Stay Away From
- Fried foods containing saturated and trans fats
- Processed simple carbs like white-flour breads and crackers
- Sweets and candy
- Artificial sweeteners, which some research suggests may negatively affect gut bacteria
Sunny Sea Gold is a health journalist and author of the 2011 book Food: The Good Girl’s Drug.