Nutritional Psychiatry: From Concept to the Clinic.

The field of 'nutritional psychiatry' has evolved with rapidity over the past several years, with an increasing amount of dietary or nutrient-based (nutraceutical) intervention studies being initiated, and more preclinical and epidemiological data being available. This emergent paradigm involves the clinical consideration (where appropriate) of prescriptive dietary modification/improvement, and/or the select judicious use of nutrient-based supplementation to prevent or manage psychiatric disorders. In the last several years, significant links have increasingly been established between dietary quality and mental health (although not all data are supportive). Maternal and early-life nutrition may also affect the mental health outcomes in offspring. In respect to nutraceutical research, like with many recent conventional drug studies, results are fairly mixed across the board, and in many cases there is not emphatic evidence to support the use of nutraceuticals in various psychiatric disorders. This may in part be due to a preponderance of recent studies within the field revealing marked placebo effects. Due to current indicators pointing towards mental disorders having an increasing burden of disease, bold and innovative approaches on a societal level are now required. In light of the widespread use of nutrient supplements by those with and without mental disorders, it is also critical that scientifically rigorous methodologies be brought to bear on the assessment of the efficacy of these supplements, and to determine if, or what dose of, a nutrient supplement is required, for whom, and when, and under what circumstances. More simple studies of additional isolated nutrients are not of great benefit to the field (unless studied in supra-dosage in an individualised, biomarker-guided manner), nor, based on recent data, is the research of 'shotgun' formulations of nutraceuticals. The next critical step for the field is to design psychiatric interventional studies for both dietary modification and nutraceuticals, based on more of a personalised medicine approach, using biomarkers (e.g. nutrient deficiencies, inflammatory cytokine levels, genomic assessment, microbiome analysis) and a person's dietary patterns and individual macro/micronutrient requirements.