In recent years, health practitioners have considered switching to a more holistic approach by changing patients’ nutrition and lifestyle behavior. This change has been influenced by surmounting research on the brain-gut axis, which has established the basis of a bidirectional communication between the gastrointestinal tract and the central nervous system, driven by neural, hormonal, metabolic, immunological, and microbial signals.1 Diseases such as gastrointestinal and extragastrointestinal disease, and several mental illnesses, such as anxiety and depression, have been linked to dysbiosis in the gut-brain-axis.2
Neal Barnard, MD, shares his perspective, as a psychiatrist, on the implications of his research regarding a plant-based nutrition program to reduce body weight and cardiovascular risk in a corporate setting3 for other physicians and psychiatrists.
Dr Barnard is the founder and president of the Physicians Committee for Responsible Medicine (PCRM), a nonprofit organization “dedicated to saving and improving human and animal lives through plant-based diets and ethical and effective scientific research.” Dr Barnard is also an adjunct professor of medicine at George Washington University, Washington, DC, and the author of multiple books, including Power Foods for the Brain.
Nutrition plays a helpful role in mood disorders, particularly depression. The mechanisms likely relate to the diet’s anti-inflammatory effect and its impact on the gut microbiome, which influences neurotransmitters.
What roles do nutrition and lifestyle play in psychiatric practice to achieve optimal patient outcomes?
Dr Barnard: Nutrition plays a helpful role in mood disorders, particularly depression.3 The mechanisms likely relate to the diet’s anti-inflammatory effect and its impact on the gut microbiome, which influences neurotransmitters.4 Researchers have also shown that physical exercise has an antidepressant effect for mild to moderate depression.5 Diet also influences the risk for dementia, particularly Alzheimer disease and vascular dementia.6 In addition, because some psychiatric medications can influence body weight, risk for diabetes, and other metabolic issues, following a low-fat vegan diet can counteract these side effects.7
Neal Barnard, MD, president of the Physicians Committee for Responsible Medicine
What have you observed regarding the impact of a whole-food plant-based diet and lifestyle changes on psychiatric conditions?
Dr Barnard: In 2013, our research team conducted a study with GEICO, the car insurance company, implementing a low-fat vegan diet for company employees across the country. We found that the diet change was associated with reduced symptoms of depression and anxiety.8 We studied data from 300 employees at 10 corporate sites for 18 weeks. The participants had a body mass index (BMI) of at least 25 and/or a previous diagnosis of type 2 diabetes (T2D) and were randomly assigned to follow a low-fat vegan diet or to make no dietary changes. The healthful vegan options, which were offered in the employee cafeteria, included vegetable-hummus sandwiches, seasonal leafy green salads, black bean chili, and a variety of fruits and vegetables. Intervention group participants attended weekly “lunch-and-learn” support groups, which discussed healthy eating and cooking. We found significantly greater improvements in body weight and plasma lipids in the intervention vs the control group, and greater glycemic control in those with T2D.
Our team also examined anxiety, depression, fatigue, work productivity, and general health (as assessed by the 36-Item Short Form Health Survey [SF-36] and the Work Productivity and Activity Impairment questionnaire [WPAI]) in participants with a BMI of 25 or greater or those who had previously been diagnosed with T2D.8 We found significantly greater improvement in the intervention group in job absenteeism, nonwork-related impairment, emotional well-being, depression, fatigue, and anxiety. Participants in the intervention group also had a weight reduction by approximately 10 pounds, lowered low-density lipoprotein (LDL) cholesterol by 13 points, and improved glycemic control if they had T2D.
The study findings indicated that an intervention of this nature, delivered in a routine workplace environment, can have an enormous impact.
Is there a role for pharmacotherapy in psychiatric conditions?
Dr Barnard: Of course. For psychoses and several mood disorders, pharmacotherapy can be life-saving. Psychiatric disorders such as schizophrenia almost always require pharmacotherapy. However, incorporation of diet changes should be considered, as well. We know that drugs such as antipsychotics can contribute to metabolic conditions.9 We also know that inflammation can interfere with antidepressant response.10 Dietary interventions to reduce inflammation might mitigate some of the metabolic effects of antipsychotics, and recommending a whole-foods, plant-based diet may be valuable.
To maximize patient adherence to new dietary patterns, providers can encourage involving families, and not just patients, in healthier eating, if possible. This may result in patients not feeling “alone” and “deprived” while making adjustments to their lifestyle.
I would like to highlight groundbreaking research on Alzheimer disease, in which there is a comparison of a comprehensive lifestyle intervention and usual care in patients with mild cognitive impairment (MCI) or early dementia due to Alzheimer disease. The intervention went beyond diet and nutrition (ie, a whole-food, plant-based diet consisting of fruits, vegetables, whole grains, legumes, soy products, and nuts, reduced saturated fat and refined carbohydrates) and included a daily supplement regimen, moderate aerobic exercise, strength training, stress management techniques, and support groups. A diet plan was provided for the individuals with dementia and their caregivers or partners.11
The results were remarkable. At 20 weeks, the intervention group showed improvement on an array of cognitive tests, compared with the control group that performed worse on all cognitive measures. The amyloid-β 42/40 ratio significantly increased in the intervention group and decreased in the control group. The gut microbiome improved in the intervention group. The team of researchers attributed the success of the program not only to the diet and exercise interventions, but also to the stress reduction and social components of the program.11