Fat, Food, and Mood: Beyond Omega-3s
Fat, Food, and Mood: Beyond Omega-3s
Over the past several decades, omega-3 polyunsaturated fatty acids (PUFAs) have been investigated as a potential therapy for psychiatric disorders. Supplementation has been found to ameliorate depressive symptoms, with particular advantage to those who are concurrently taking antidepressants. Benefits have also been found for bipolar depression, anxiety associated with substance dependence, ADHD symptoms, adverse effects of antipsychotics, and symptoms of schizophrenia and other neuropsychiatric disorders.1
However, clinical implementation of omega-3 recommendations has been complicated by inconclusive findings. Outcomes may be attenuated by considerable heterogeneity in research participants, study designs, and small sample sizes. While the evidence has not generated prescriptive guidelines for physicians, the potential benefits and benign safety profile indicate a promising intervention.
L is a 47-year-old divorced woman with a history of MDD who reports the recurrence of depressed mood at a follow-up visit. She is taking sertraline (200 mg daily), which led to remission of her last depressive episode a year ago. She has low energy, amotivation, and poor concentration. Her appetite is “up and down” with a 15-lb weight gain in the past year; her BMI is 32. She is currently less depressed than previously but reports low mood. She sleeps 7 to 8 hours a night but rarely feels well rested; she uses CPAP for obstructive sleep apnea as instructed. She denies recent stressors or safety concerns, and further review for psychiatric symptoms is negative.
A review of her daily activity and diet reveals that she wakes around 7:30 am and eats a sausage and egg sandwich on her way to work. She is usually hungry by 10 am and has a doughnut from the break room. She frequently eats fast food for lunch (sometimes she orders a salad) and drinks a jumbo diet soda to maintain alertness throughout the afternoon. She often picks up a pizza or a hot sandwich after work or heats up a TV dinner at home. She reports having little energy or time to exercise. She wonders if the sertraline is no longer working and whether she should change medications.
What are healthy fats and why should psychiatrists care?
Previous clinical trials have not adequately considered omega-3s as a part of the larger dietary picture. Omega-3 PUFAs, along with omega-6 PUFAs, are essential nutrients that must be consumed in the diet. Alpha-linolenic acid, found in nuts and plant oils, is the essential omega-3 that can be converted to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which have been the focus of most clinical studies in psychiatry. However, the conversion rate is low and genetically variable. Therefore, maintenance of EPA and DHA sufficiency may require direct dietary intake as supplementation (eg, fish oil) or from eating fatty cold-water fish (Figure).
EPA and DHA contribute to cardiovascular, inflammatory, and neurochemical functions and have an FDA-approved indication to lower triglycerides. Linoleic acid is the essential omega-6 and comprises approximately 8% of the caloric intake of the Western diet.2 It is converted to bioactive molecules involved in energy homeostasis, endothelial function, adaptive inflammation, and endocannabinoid neurochemistry.
The dietary balance between omega-3 and omega-6 intake is important because they have several counterbalancing physiological effects. A large epidemiological study concluded that lower intake of dietary PUFAs is significantly associated with all-cause mortality—linoleic acid showed the largest effect size.3 Clearly, omega-3s are not the whole story, and interactions with the broader dietary background must be considered to explain the equivocal nature of the literature.