In a groundbreaking research trial, healthy food was discovered to be a powerful antidepressant, significantly improving symptoms in a group with moderate to severe depression. (R)

It's been known for some time that poor diet is associated with increased risk for depression (R), but the direction of causality has been uncertain. Of course, when we're depressed we tend to reach for lower quality comfort foods, but can reaching for lower quality comfort foods more often cause us to become depressed? And if we're depressed, can improving our diets improve our symptoms? These questions have remained largely unknown from a scientific standpoint. Until now. 

Led by Dr. Felice Jacka, the director of Deakin University's Food and Mood Center in Australia, this new trial was the first randomized control trial that explicitly sought to answer the question: If I improve my diet, will my mental health improve?

The SMILES trial

My 1-hour long interview with Dr. Felice Jacka, the lead researcher of the SMILES trial

The trial, dubbed SMILES (for Supporting the Modification of lifestyle In Lowered Emotional States), involved 67 men and women who were taking antidepressants and/or were in regular psychotherapy. All of the subjects had pretty 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 placed on the intervention diet, which was a modified Mediterranean diet (researchers called it the “ModiMed” diet—details on this in a moment) and attended regular sessions with a dietician.

The other half continued eating their usual diets, but were required to attend social support “befriending” sessions.

Before and after the 3-month study, everyone’s depression symptoms were graded. The test the research group chose to focus on was the MADRS scale (Montgomery–Åsberg Depression Rating Scale), which rates mood on a scale of 0 to 60. The higher the score, the more depressed the individual, with 60 being the most severely depressed. (The average score of study participants was 25.) 

After 3 months, people in the ModiMed diet group saw their MADRS scores improve on average by about 11 points. Thirty-two percent had MADRS scores so low that they no longer met criteria for depression! Meanwhile, people in the social support group with no dietary modification improved by only about 4 points, and only 8% achieved remission. (R)

The diet

For the ModiMedi diet, calories were not limited, as the diet did not have weight loss as a focus. The breakdown of macronutrients was as follows (R):

  • Protein: 18% of total calories (ie, 90 grams of protein in a 2000 calorie-day)
  • Fat: 40% of total calories (89 grams of fat in a 2000 calorie-day)
  • Carbohydrates: 37% of total calories (185 grams of carbs in a 2000 calorie-day)
  • Alcohol: 2% of total calories
  • Fiber/other: 3% of total calories (15 grams of fiber in a 2000 calorie-day)

Encouraged foods: whole grains, fruits, vegetables, legumes, low-fat/unsweetened dairy, raw unsalted nuts, lean red meat (note: most red meat in Australia—where the trial was performed—comes from grass-fed cows), chicken, fish, eggs, and olive oil

Discouraged foods: sweets, refined cereals, fried food, fast food, processed meat.

Beverages: maximum two sugar-sweetened beverages per week and maximum two alcoholic drinks per day, preferably red wine

This diet was a vast improvement over the subjects' previous diets. As a side note, I theorize that fewer grains (less carbs) and more fibrous vegetables (to increase fiber intake a bit) would help it to perform even better. 

$urprise—it cost less!

The number one excuse people give for not buying healthy food is that it’s expensive. However, a bonus finding of the trial was that the ModiMedi diet was actually less expensive—by about 19%!—than the unhealthy diets subjects were eating prior to the intervention. Cha-ching!

Leave a comment to let me know your thoughts on this, or if you have any questions and I'll try to get to them!