MDD, or Major Depressive Disorder, is one of the most common mental health concerns in the United States, affecting 19% of the population. This disorder is characterized by persistent feelings of sadness, emptiness, and hopelessness accompanied by a loss of interest in once enjoyable activities. MDD greatly interferes in an individual’s ability to socialize as well as perform academically and professionally; additionally, MDD costs the United States an annual $44 billion in lost productivity, disability, mortality, and morbidity. In fact, the World Health Organization estimates that by 2020, MDD will be the second largest cause of morbidity (or disability) on a global scale.
Unfortunately, only about ¼ of diagnosed individuals will have access to specialized treatment including psychotherapy and psychiatric medication. Further, it has been shown that only 60% of individuals with access to these kinds of treatment benefit from clinical improvement. This is likely due to the pervasive nature of this disorder: MDD carries a very high risk of relapse and is normally seen as a recurrent disorder rather than a mood disturbance that only occurs once in a lifetime.
Due to the low percentage of individuals who are able to obtain specialized professional help, coupled with the relatively low success rate of clinical intervention, science has recently delved into the relationship between MDD and nutrition. This research, while unable to determine a causal relationship, has demonstrated that there are several nutritional habits that appear to decrease both the likeliness of developing MDD as well as decrease symptoms in individuals with this disorder. Conversely, science has also demonstrated that certain food groups and eating habits increase both the likeliness and severity of symptoms.
Amino acids, minerals, omega 3 fatty acids, and the B vitamins are among several of the most important nutrients to include when designing a diet to combat depression. These are often found in recipes adhering to the “Mediterranean Diet”, a nutritional regime characterized by consumption of fresh fruit, whole grains, nuts, seafood, and legumes. The following table delineates which nutrients are associated with which foods.
What Nutrients Can Be Found in Your Food?
Omega 3 Fatty Acids
YES: Coldwater Fish
YES: Organ Meat [i.e. liver]
YES: Brazil Nuts
YES: Salmon, Tuna, Mackerel
Vitamins B12/B9 [folate]
Why and how do these nutrients impact the symptoms associated with depression? Let’s start with omega-3 fatty acids: it is quite possible you’ve heard of these as they’ve been at the center of a relatively recent health trend, and have been heavily advertised in various mediums and locations. Firstly, studies have demonstrated that these levels are significantly lower in patients with active depression. Additionally, two omega 3 acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been found to have antidepressant effects; it is believed that this is due to the biological conversion of EPA to DHA, which also produces neurotransmitters such as prostaglandins, thromboxanes, and leukotrienes. Further, the brain has one of the highest levels of lipids in the body; gray matter contains 50% polyunsaturated fatty acids consisting of 33% omega 3 fatty acids. As these are essential fatty acids, they cannot be produced by the body independently and therefore must be consumed through diet. Similar studies have also demonstrated depleted levels of the nutrient selenium in clinically depressed patients.
Vitamins have also been determined to play an important role in depression relief- specifically Vitamin D and Vitamins B12 and B9/folate. Low levels of vitamin D and B12 are associated with decreased mood and increased likeliness of depression; similarly, patients with depression typically exhibit blood folate levels that are 25% below the “healthy” level. Low folate levels are also linked to decreased efficacy and outcomes in patients utilizing antidepressant medication, further highlighting the importance of vitamin B9 when seeking to achieve symptom relief or remission.
Zinc is a nutrient that has similar implications as those of vitamin B in that depressed patients tend to have lower than average blood zinc levels. Interestingly, patients taking zinc supplements and eating foods rich in this nutrient have experienced higher than average rates of success when taking antidepressants; scientists, therefore, believe that zinc enhances the clinical benefit afforded by these medications .
Now, you may have heard of tryptophan; you might even have discussed it at Thanksgiving when one of the younger tablemates wonders aloud why turkey makes them so tired. Tryptophan is vital to the production of serotonin (which is a biological precursor to melatonin, or one of the naturally produced chemicals that induce tiredness). This is important in the treatment of depression; although we’re uncertain of the exact mechanisms by which serotonin impacts MDD, it has been shown to have a significant impact on relieving symptoms. Further, individuals with depression may struggle to sleep due to intrusive thoughts or restlessness; the production of serotonin, and subsequently melatonin, may help them to get a good night’s rest (adequate sleep has also been linked to improvements in depression). Lastly, St. John’s Wort, or hypericum, has been linked to managing symptoms of MDD; although most individual studies are on too small of a scale to be considered significant, a meta-analysis of 27 studies demonstrated that hypericum managed depression as well as commonly prescribed SSRI medication (selective serotonin reuptake inhibitors include Prozac, Paxil, and Zoloft).
On a final note, it is just as important to address what not to eat when managing MDD. Just as the Mediterranean Diet has been linked to the decreased likeliness of MDD and increased symptom relief, a traditional “Western Diet” has been demonstrated to do the opposite. Western diets are high in saturated fat and trans fat; a European study of 12,000 volunteers demonstrated a 48% increased risk of depression in participants with high trans fat intake. Processed and refined oils contain high levels of omega 6 acids; these have the opposite effect of omega 3s in that they promote inflammation of the brain, and that inflammation may increase depression. Further, foods with large amounts of refined sugars and carbohydrates cause a “sugar rush”, resulting in a subsequent energy crash that also lowers mood and disrupts emotional homeostasis.
Caffeine is viewed as a staple of daily American life; unfortunately, this may be problematic for individuals with MDD, particularly if it is related to anxiety. Due to being a stimulant, caffeine can disrupt sleep patterns and increase anxious tendencies (as previously noted, getting consistent, quality sleep is imperative in successfully managing MDD). Alcohol is viewed as a socially acceptable method of decreasing worry and “taking the load off”; in fact, many people have experienced encouragement from those around them to have a drink to calm down or feel better. Although the initial effects may be calming, alcohol is a depressant and as such may increase present depressive symptoms. Additionally, those with MDD have a higher likeliness of developing alcohol use disorder than the general public; the immediate disinhibiting impact of the substance can become habitual and subsequently problematic.
Depression is a complex condition that often requires a multifaceted approach to achieve symptom relief, and ultimately, remission. Although many of these steps and treatment approaches require clinical direction and supervision, lifestyle choices are at the discretion of the individual. As discussed throughout this post, nutrition is one such choice that has been proven to have a significant impact on those suffering from depression. In an upcoming blog post, we will provide examples of recipes that include many of the nutrients discussed above. In the meantime, there is no shortage of creative, tasty combinations that contain these essential ingredients. From simple snacks to gourmet dinners, changing your diet can be an important step in changing, and navigating, your experience with depression.
 Popa, T. A., & Ladea, M. (2012, December 15). Nutrition and depression at the forefront of progress. Retrieved July 12, 2019, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3539842/
 Popa (2012) (n1)
 Popa (2012) (n1)
 McQuillan, S. (n.d.). Food for Mental Health: Supplements That Fight Depression. Retrieved July 12, 2019, from https://www.psycom.net/food-supplements-fight-depression-mental-health
 Popa (2012) (n1)
 Popa (2012) (n1)
 Johnson, J. (2017, July 16). Diet and depression: Foods, nutrients, and other factors. Retrieved July 12, 2019, from https://www.medicalnewstoday.com/articles/318428.php
 Johnson (2017) (n7)
 McQuillian (n4)
 Johnson (2017) (n7)