The prevalence of mental disorders is so high that it can accurately be called an epidemic. The National Institutes of Health estimates that over 25 percent of Americans ages 18 and older — about one in four adults — suffer from a diagnosable mental disorder in a given year. This translates into nearly 60 million people, probably more, as this estimate is ten years old.
Nearly half of the diagnosed mental disorders in a given year are classified as mood disorders. Things like depression, bipolar, and dysthymia. Symptoms of depression include low self-esteem, loss of interest in formerly pleasurable activities, fatigue, changes in appetite, and sleep disturbances.
For many years, the belief has been that a deficit in certain brain chemicals called neurotransmitters underlies depression, and so treatment has been aimed at restoring levels of serotonin and norepinephrine to normal with drugs like Prozac, Zoloft, and Wellbutrin. But these powerful drugs have side effects which can be worse than the symptoms they are supposed to treat. Things like suicidality, nausea, weight gain, diarrhea, erectile dysfunction, etc. which make one wonder how they could possibly be first line treatment.
Isn't there something better?
Some physicians recognize the link between mood disorders and lifestyle factors which seem to influence the level of the neurotransmitters targeted by pharmacotherapy, and for good reason. Exercise has been shown to be just as effective as drugs in relieving the symptoms of depression. And many claims have been made about particular nutrients and their impact on mood. We are told to eat more vitamin D, or up our intake of omega-3. Macronutrient - carbs, protein, and fat - have also been studied for their effects on mood. It is without question that eating a nutrient-rich diet provides physiological benefits; however, none of the studies investigating a particular nutrient's effect on mood has been conclusive.
But what about food groups? Are there food groups in the diet whose exclusion or inclusion influences mood? Scientists have recently investigated the matter and their findings are quite interesting. In a follow-up study to one which showed that vegetarians reported significantly less negative emotions than omnivores, a randomized controlled trial was conducted in which subjects were placed in one of three groups: an omnivorous group eating meat, fish, and poultry; a fish group eating fish a few times a week but no meat or poultry; and a vegetarian group avoiding meat, fish, and poultry. After the two-week dietary intervention the only group to report significant improvement in mood and stress levels was the vegetarian group. This is a ground-breaking study as it is the first to focus on the impact a plant-based diet has on mood. And hopefully not the last. Additional studies of this kind may help to bring dietary considerations to the fore where they belong in a psychiatrist's armamentarium.