A symphony of factors, including genetics, hormones, illness, and stress, can trigger depression. Now, scientists say your daily diet may also influence your risk for this mental illness. A growing number of studies—including the first randomized controlled trial on this subject—suggest that food choices "may play a role in the treatment and prevention of brain-based disorders, particularly depression," according to a published in the World Journal of Psychology.
The new report includes a review of 34 essential nutrients, 12 of which were identified as relating to the prevention and treatment of depressive disorders: folate, iron, long-chain omega-3 fatty acids, magnesium, potassium, selenium, thiamine, vitamin A, vitamin B6, vitamin B12, vitamin C, and zinc. But rather than focus on single foods or nutrients as a panacea against depression, researchers are looking at the big picture, explains , an Australian food-and-mood researcher and president of the International Society for Nutritional Psychiatry Research.
“We eat diets that comprise countless compounds that interact in highly complex ways,” says Jacka, who published the first last year in the journal Nutritional Neuroscience. (Her work is heavily cited in the new report, as well.)
That's why the authors of the new study also examined a subset of foods rich in those 12 nutrients, ranking them by nutrient density to give them each an "Antidepressant Food Score." And as it turns out, many of the same foods recommended for physical health are also good for mental health.
We took a closer look at the foods singled out in the new report and also asked food and mood researchers for their top dietary picks. While they won't replace depression treatment–like therapy, medication, or both–these are the key elements of a healthy, mood-boosting diet.
Fat is back, and with good reason. Healthy fats like those found in nuts and fish are crucial for brain health and may play a role in fighting depression.
In a large review of studies, people eating the most fish had a than those eating the least fish. Another review found that omega-3 fish oil supplements in people with depression, compared with taking a placebo.
“Omega-3 fatty acids from seafood and monounsaturated fats from nuts, avocados, and olive oil appear to be particularly important and beneficial to our mental and brain health,” Jacka says.
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A Mediterranean-style diet
Improve your overall diet and you could reduce your depression. That’s the key takeaway from a first-of-its-kind trial examining the effects of a on major depression.
The link between diet and depression is complex, involving several biological pathways and processes, each of which is “under the influence of our gut microbiota,” says Jacka, the study’s lead author.
For the study, one group upped their intake of fresh fruit and veggies, whole grains, legumes, fish, lean red meats, olive oil, and nuts, while cutting back on sweets, refined cereals, fried food, processed meats, and sugary drinks. A control group received only social support for their depression. After three months, a third of those in the Mediterranean diet group reported significant symptom relief, compared with just 8% of the control group.
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Who would have thought a side of kimchi could be a boon to mental health?
Animal studies suggest that certain live bacteria and yeasts, known as probiotics, may be helpful in fighting depression and anxiety. Fermented foods like kimchi and kefir are chock full of healthy bacteria thought to soothe gut inflammation.
As it turns out, there’s a link between digestive and brain health. Scientists call it the “gut-brain axis.” Important brain chemicals, including the mood-boosting hormone serotonin, are produced in the gut. So, the theory goes, without a sufficient supply of healthy gut bacteria, your mood can suffer.
In the new Antidepressant Food rankings, leafy greens like watercress, spinach, mustard greens, lettuce, and swiss chard got top billing. These foods earned the highest scores out of all animal- and plant-based foods, suggesting that they're an important part of preventing or treating depressive disorders.
These veggies are rich in folate, a water-soluble B vitamin. Low folate levels have been linked to depressive symptoms and poor response to antidepressants.
Plus, the vitamin may affect mood-related chemicals in the brain. “Serotonin levels have been shown to rise with foods rich in folate,” noted , a spokesperson for the Academy of Nutrition and Dietetics. Some people with depression have reduced transmission of this important chemical messenger.
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Say yes to dark chocolate! Cocoa beans contain flavonoids, plant-based nutrients that are powerful antioxidants and can improve mood. In a large study of U.S. women without previous depression, higher flavonoid consumption was linked with a , especially among older women.
Other foods rich in these helpful plant compounds include tea, apples, citrus, blueberries, and onions.
Carrots, squash, and sweet potatoes get their orange hue from carotenoids, a type of antioxidant that may be helpful in warding off depression.
Researchers who followed a group of older men and women in Italy for six years found that were associated with depressive symptoms.
A separate study of men and women in the U.S. revealed an association between greater blood levels of . Researchers weren’t able to tease out cause and effect. But they suspect that optimistic people eat healthier diets and people in better physical health are more optimistic.
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Turkey contains tryptophan, the amino acid Thanksgiving Day revelers love to blame for inducing their post-feast slumber. While turkey probably won’t really make you sleepy, tryptophan may be helpful in treating mental health problems like depression. The reason? Your body uses tryptophan to make the mood-elevating hormone serotonin.
Other food sources of tryptophan include eggs, seeds, fish, and dairy. Taking tryptophan supplements may also benefit people with depression. However, if you’re on antidepressants, talk to a doctor before taking supplements. The combination could cause serious side effects.
Some studies suggest a link between depressed mood and low levels of tyrosine, an amino acid that produces the so-called “happy hormone” dopamine. Dopamine controls your brain’s reward and pleasure centers.
It remains unclear whether eating tyrosine-rich foods will alleviate depression, but all four basic food groups–meat, dairy, grains, and fruits and veggies–contain picks that are naturally high in the amino acid. Some of the best healthy sources include bananas, avocados, and almonds.
While studies suggest a link between low levels of vitamin D and depression, what’s unclear is whether it is a cause of depressive symptoms or a consequence of being depressed, says the Vitamin D Council. Some scientists suspect that vitamin D may play a role in converting tryptophan into the mood-elevating hormone serotonin.
Sadly, the new World Journal of Psychiatry report notes, Americans aren't eating as much of these fish—or any fish in general—as they should. "Average annual seafood intake for Americans is 14.6 pounds," the authors note, "and the USDA estimates that 80 to 90% of the population fails to meet the recommendation of two servings of seafood per week."
Be careful if you get your D from dietary supplements. It’s a fat-soluble vitamin, meaning too much is potentially toxic to the body. (The recommended dietary allowance is 600 IUs per day for adults 70 and younger and 800 IUs for older folks.)
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Oysters are an excellent source of zinc, an essential mineral for proper immune system function. And when it comes to animal sources of feel-good nutrients, these bivalves got the top score in the new Antidepressant Food rankings. Clams, mussels, and other seafood–as well as organ meat from poultry and mammals–also ranked highly.
“There’s some research that links increased zinc intake to improved mood,” Armul says. What’s not clear is whether low zinc levels lead to depression or whether depression causes zinc deficiency. Other zinc sources include beef, lobster, dark-meat chicken, oatmeal, and almonds.