How your next meal could help fight depression, stress

(CNN) - Do you find that food deeply affects your mood? Science is beginning to back up such gut feelings.

The link between poor diet and mood disorders has been long known, but what has been less clear is the direction of causality. When we're depressed, we tend to reach for lower-quality comfort foods, but can more comfort foods contribute to depression? And if we're depressed, can improving our diets improve our symptoms?

New research is helping to pave the way toward greater clarity. One small but important trial was recently published from Deakin University's Food and Mood Centre (the center's very name a testament this burgeoning line of research). It involved men and women who were taking antidepressants and/or were in regular psychotherapy.

All of the 67 subjects had unhealthy diets at the start, with low intakes of fruits and vegetables, little daily dietary fiber and lots of sweets, processed meats and salty snacks. Half of the subjects were then placed on a healthy diet focusing on extra-virgin olive oil, nuts, seeds, eggs, fruits, vegetables, fatty fish and grass-fed beef. The other half continued eating their usual diets and were required to attend social support sessions.

Before and after the three-month study, the subjects' symptoms were graded on a common depression scale. After three months of healthier eating, those in the intervention group saw their scores improve on average by about 11 points. Thirty-two percent had achieved scores so low that they no longer met criteria for depression. Meanwhile, people in the social support group with no dietary intervention improved by only about 4 points; only 8% achieved remission.

What this early research demonstrates is that even for patients with major depression, food may be a powerful antidepressant. And with no negative side effects.

One way a healthier diet may improve one's mood is through our bodies' immune systems. The same process by which we respond to acute injuries or threats also puts out fires initiated by our diets and lifestyles. That's why poor diet can lead to chronic low-grade inflammation, a risk factor for noncommunicable diseases such as Type 2 diabetes and even Alzheimer's disease. These sorts of illnesses now account for 60% of deaths worldwide, according to the World Health Organization.

Though the mechanisms linking inflammation to depression are just beginning to be understood, other studies involving compounds with a known anti-inflammatory effect, such as curcumin (a component of the spice turmeric), have also demonstrated some efficacy in reducing symptoms. Though the studies are small and warrant further research, they strengthen the notion that depression may be the brain's response to inflammation in the body, at least for some.

Whole, healthy foods also provide micronutrients that help the brain better cope with daily stress. Today, with 90% of Americans deficient in at least one vitamin or mineral, it has left our brains weaponless as it attempts to repair from the damage. Case in point: Nearly 50% of Americans don't consume enough magnesium, a mineral involved in DNA repair. And yet it is easily found in foods such as almonds, spinach and avocado.

Some of the most nutrient-dense foods include dark leafy greens, cruciferous vegetables, eggs and even properly raised red meat. A large study found that women who consumed less than three to four servings of red meat per week were twice as likely to have a diagnosed depressive or anxiety disorder. The study was performed in Australia, where more of their meat comes from grass-fed cows, a caveat the researchers call out as noteworthy.

What foods should we avoid consuming to maintain a healthy, balanced mood? Sugar and highly refined, processed oils, which include canola, corn and soybean oil (the use of which has skyrocketed up to 1,000% over the past century). These foods have been linked to mental health issues including depression, and both now saturate our food supply, constituting in large part the ultra-processed foods that now make up 60% of our caloric intake. These foods, when consumed chronically, drive inflammation and deplete our bodies' protective resources, compounding the damage done.

Although the science regarding diet and mood has a long way to go before being settled, there's little reason to wait given that switching to a healthier diet may help and is definitively better for your overall health. Research suggests that a better diet may even be easier on your wallet.