Mary Knudtson DNSc, NP, FAAN
Depression and anxiety are the most common mental health conditions worldwide and a leading cause of disability. Lately, there has been a renewed interest in the effect of diet on mood. Poor nutrition is a factor in the experience of low mood, and improving diet may help protect not only physical health, but also mental health. Current research suggests that dietary interventions may be an effective adjunctive treatment for depression.
Multiple studies have found that the Mediterranean diet—defined as high consumption of fruits, vegetables, nuts, and legumes; moderate consumption of poultry, eggs, and dairy products; and only occasional consumption of red meat—is associated with a reduced risk of depression. Systematic reviews of the literature have also found that diets with a high glycemic index and load (eg, diets containing high amounts of refined carbohydrates and sugars) may have a detrimental effect on depression symptoms. This may be due to the body's inflammatory response to foods with a high glycemic index.
More recently, research has suggested that dietary patterns may affect our mental wellbeing via the gut microbiome. The gut microbiome bidirectionally interacts with the brain by means of neural, inflammatory, and hormonal signaling pathways. Available research on the relationships among inflammation, intestinal flora, and mental illnesses such as depression and anxiety suggests that use of probiotics (good bacteria) and prebiotics (food for the good bacteria) lead to improved intestinal health, which can reduce inflammation and thus result in fewer symptoms of mental illness. Therefore, foods with a pro-inflammatory effect should be avoided for both preventive and de-escalation purposes in the case of mental illness.
Based on what we now know, what can you recommend? Patients with depression may benefit from a low-inflammatory diet similar to the Mediterranean diet, consisting of vegetables, fruits, fiber, fish, nuts, whole grains, legumes, and olive oil. Patients should consider excluding or severely restricting their intake of added sugars, processed foods, juices, soft drinks, and sweets to promote mental wellbeing and prevent depression. Micronutrients are also important, and magnesium, folic acid, and various B vitamins should also be included in the optimal diet for depression prevention and management.