July 2019 Issue
Clinical Nutrition: Beyond Food and Mood
By KC Wright, MS, RDN
Vol. 21, No. 7, P. 10
The Growing Field of Nutritional Psychiatry
Nearly 1 in 5 adults—46.6 million people—in the United States live with some form of mental illness,1 defined as a health condition that changes a person’s thinking, feelings, and/or behavior, and that causes distress and difficulty in functioning.2 Many different conditions can be characterized as mental illnesses, ranging from mild to moderate to severe. Treatment presently is dominated by pharmacotherapy and psychotherapy, but such treatments avert less than one-half of mental illness cases, suggesting that additional strategies are needed to prevent and treat mental disorders.3 The burden of disease will continue to rise worldwide in the coming decades, and a shortage in the mental health workforce remains.4
Although the determinants of mental health are complex, emerging and compelling evidence suggests diet is as important to psychiatry as it is to cardiology, endocrinology, and gastroenterology.5 Nutritional psychiatry is a relatively new field—the first studies to examine and establish a link between overall diet quality and depression and anxiety were published within the last decade—but it may offer some potential in addressing the large disease burden associated with mental illness.
The brain demands a constant supply of energy—approximately 20% of our daily calorie needs. What we eat directly affects the structure and function of our brains, and, ultimately, moods, so it’s important to examine whether there are specific nutrients, from either food or dietary supplements, that may affect specific brain activity. According to a review by academic members of the International Society for Nutritional Psychiatry Research, which advocates for nutritional medicine to be considered a mainstream element of psychiatric practice, a whole-food diet consisting of higher intakes of vegetables, fruits, seafood, whole grains, lean meats, nuts, and legumes, with avoidance of processed foods, is more likely to provide the nutrients that afford resiliency against the pathogenesis of mental health disorders.5
Depression and Anxiety
The relationship between depression and diet is bidirectional; those with depression are more likely to consume poorer-quality diets than those without, and those who consume higher-quality diets are less likely to experience depression.6 Depression can increase or decrease appetite,7 and negative mood states have been shown to stimulate a preference for foods high in sugar, fat, and/or salt, resulting in lower-than-recommended intakes of brain-essential nutrients such as B vitamins, zinc, folate, and magnesium, which have been inversely associated with depressive disorders.5,8,9 Fatigue and apathy associated with depression may impede motivation to engage in healthful dietary habits, cook, or grocery shop.10
Epidemiologic studies have shown associations between healthful dietary patterns and reduced risk of depression, but these observational studies can’t determine causality.11 The SMILES trial—Supporting the Motivation of lifestyle In Lowered Emotional States—was the first randomized controlled trial designed to evaluate a dietary improvement intervention for reducing symptoms of depression. Participants with moderate to severe depression were randomized to receive either a dietary intervention of a modified Mediterranean diet or a control condition consisting of social support, each in seven individual sessions over a three-month period. The intervention diet group reported feeling better emotionally, having more clarity and energy, and feeling able to overcome barriers to healthful eating.10
Results from a prevention trial showed that dietary counseling was as effective as psychotherapy at prevention of transition to case-level depression in older adults.5 A 2017 meta-analysis found that diets high in fruits, vegetables, whole grains, fish, olive oil, low-fat dairy, and antioxidants, and low in other animal foods was associated with a decreased risk of depression.12 Meanwhile, a dietary pattern high in red and/or processed meat, refined grains, sweets, full-fat dairy, butter, and potatoes, and low in fruits and vegetables was associated with an increased risk of depression. These results confirmed a previous meta-analysis that demonstrated a reduced risk of depression in subjects who had a higher adherence to a Mediterranean diet.10
Considering the early age of onset for depression and anxiety in some people, diet—from prepregnancy to early childhood—may be an important modifiable risk factor for prevention of the initial incidence of common mental disorders. Severe macronutrient deficiencies during crucial developmental periods have long been implicated in the pathogenesis of both depressive and psychotic disorders.5 In a pilot randomized controlled trial, 76% of children with endogenous vs situational depression who received psychotherapy and omega-3 supplements achieved remission, compared with 56% of those who took a placebo. The effect of an intervention using dietary sources of omega-3s is less clear,13 although they have been inversely associated with anxiety disorders.9
Eating disorders commonly co-occur with anxiety disorders, where the development of anxiety typically occurring well before the onset of disordered eating behaviors.14 Shira Evans, MS, RD, CSSD, who counsels students with a wide variety of eating disorders at Dartmouth College, says, that avoiding essential foods, like someone on a very low-carbohydrate diet, may promote obsessive thoughts related to wanting to eat the eliminated foods. In this case, a person may be at a higher risk of binging or overeating the foods they often avoid. This also can promote social isolation as a way to avoid eating forbidden foods that could potentially increase depressive thoughts.”
Poor nutritional quality has been independently associated with symptoms of ADHD.9 A study involving 120 children and adolescents showed a higher prevalence of ADHD with fast food, sugar, and sugar-sweetened beverage consumption and low adherence to a Mediterranean diet, even after accounting for potential confounders.15 In another study, when children with existing ADHD received an omega-3 supplement, whether on its own or in conjunction with psychotherapy, there were significant improvements in hyperactivity and impulsivity compared with those who received placebos or psychotherapy alone.16
Some research has shown that micronutrient supplementation also can help with ADHD symptom relief. Julia Rucklidge, PhD, a professor of clinical psychology at the University of Canterbury in Christchurch, New Zealand, and colleagues conducted an eight-week randomized controlled trial comparing a broad-based micronutrient formula with placebo in treating ADHD in adults. Twice as many subjects reported reduced hyperactivity and impulsivity and went into symptom remission in the micronutrient group compared with placebo, and the micronutrient group attested that ADHD symptoms interfered less with their social relationships. One year later, the micronutrient group maintained these benefits and showed further improvement, whereas those who ceased taking the micronutrients had symptoms return. It’s important to note that the micronutrient formula used in this study, consisting of 15 pills with 36 nutrients, was a dose higher than what’s available over the counter.17 An eight-week case study also demonstrated significant improvements in mood, anxiety, hyperactivity, and impulsivity with micronutrient supplementation. After one year, the subject was in remission from all mental illness.18 Although more research is needed, these results demonstrate that micronutrient supplementation can be an effective and relatively inexpensive adjunct to ADHD treatment.
The human brain operates at a very high metabolic rate and is reliant on amino acids, fats, vitamins, minerals, and trace elements. Dietary intake may have a direct impact on various biological systems and mechanisms underlying depression, including oxidative processes, immune system functioning, and levels of salient brain proteins.5 Evidence suggests that high-fat, high-sugar diets can affect proteins that are important in brain development, such as the signaling molecule brain-derived neurotrophic factor, often reduced in depression, and impact oxidative stress. Nutrients such as folate, zinc, magnesium, and omega-3s from food provide antioxidants that may have a role in mental disorders, operating with the specific support of nutrient cofactors and phytochemicals.9 Omega-3 fatty acids can provide a range of neurochemical activities via several mechanisms including neurotransmitters, anti-inflammatory effects, and the enhancement of cell-membrane fluidity.5
The gastrointestinal (GI) tract also is inextricably linked to brain health; about 95% of serotonin, the neurotransmitter that helps regulate sleep, appetite, and moods, and inhibit pain, is produced in the GI tract. In addition, the GI tract is lined with millions of neurons and is highly influenced by the microbiome. The microbiome protects the intestinal lining against toxins and bad bacteria, limits inflammation, improves bioavailability of nutrients, and activates neural pathways that travel directly between the gut and the brain, affecting mood. Studies have shown that probiotics help to reduce anxiety levels and perceptions of stress while improving mental outlook.19 More research is needed on probiotics before specific supplement recommendations can be made as therapy for mental health. Meanwhile, fermented foods containing live, active cultures, such as kimchi, miso, sauerkraut, kombucha, and yogurt, may be beneficial.
Opportunities for RDs
As research on nutritional psychiatry increasingly links diet and mental illness, RDs can work with both providers and patients to emphasize the need for more healthful dietary patterns that include more whole foods and limit inflammation-promoting foods that are highly processed and/or high in sugar. But empathy also is essential when working with clients with mental illness. Jennifer Costello, LCSW, RD, a clinical social worker and dietitian in Oak Park, Illinois, stresses the importance of listening to and “just being with” patients challenged by mental health issues: “Perhaps instead of trying to teach the patient about the inner workings of food, emphasizing self-care, which includes healthful eating,” is a better approach. “Mood is profoundly affected by how people eat and take care of their bodies,” she says.
“If we’re serious about [treating] mental health, we need to get serious about the role nutrition can play,” Rucklidge says. She acknowledges that there’s much more to learn about diet and mental illness, but insists that the approach to treatment includes lifestyle. Rucklidge says, “The message is clear: A well-nourished body and brain is better able to withstand health challenges—nutrition matters!”
— KC Wright, MS, RDN, is a research dietitian at Dartmouth-Hitchcock Medical Center and maintains a nutrition communications practice. She advocates for good food and sustainable food systems at www.wildberrycommunications.com.
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