Awareness of the importance of maintaining physical health for patients with severe mental illnesses has recently been on the increase. Although there are several elements contributing to poor physical health among these patients as compared with the general population, risk factors for cardiovascular disease such as smoking, diabetes mellitus, hypertension, dyslipidemia, metabolic syndrome, and obesity are of particular significance due to their relationship with mortality and morbidity. These patients present higher vulnerability to cardiovascular risk factors based on several issues, such as genetic predisposition to certain pathologies, poor eating habits and sedentary lifestyles, high proportions of smokers and drug abusers, less access to regular health care services, and potential adverse events during pharmacological treatment. Nevertheless, there is ample scientific evidence supporting the benefits of lifestyle interventions based on diet and exercise designed to minimize and reduce the negative impact of these risk factors on the physical health of patients with severe mental illnesses.

The gut microbiota is a complex and dynamic ecosystem essential for the proper functioning of the organism, affecting the health and disease status of the individuals. There is continuous and bidirectional communication between gut microbiota and the host, conforming to a unique entity known as “holobiont”. Among these crosstalk mechanisms, the gut microbiota synthesizes a broad spectrum of bioactive compounds or metabolites which exert pleiotropic effects on the human organism. Many of these microbial metabolites can cross the blood–brain barrier (BBB) or have significant effects on the brain, playing a key role in the so-called microbiota-gut-brain axis. An altered Microbiota-Gut-Brain (MGB) axis is a major characteristic of many neuropsychiatric disorders, including major depressive disorder (MDD). Significative differences between gut eubiosis and dysbiosis in mental disorders like MDD with their different metabolite composition and concentrations are being discussed. In the present review, the main microbial metabolites (short-chain fatty acids -SCFAs-, bile acids, amino acids, tryptophan -trp- derivatives, and more), their signaling pathways and functions will be summarized to explain part of MDD pathophysiology. Conclusions from promising translational approaches related to microbial metabolome will be addressed in more depth to discuss their possible clinical value in the management of MDD patients.

Major depressive disorder (MDD) is a complex and common disorder, with many factors involved in its onset and development. The clinical management of this condition is frequently based on the use of some pharmacological antidepressant agents, together with psychotherapy and other alternatives in most severe cases. However, an important percentage of depressed patients fail to respond to the use of conventional therapies. This has created the urgency of finding novel approaches to help in the clinical management of those individuals. Nutraceuticals are natural compounds contained in food with proven benefits either in health promotion or disease prevention and therapy. A growing interest and economical sources are being placed in the development and understanding of multiple nutraceutical products. Here, we summarize some of the most relevant nutraceutical agents evaluated in preclinical and clinical models of depression. In addition, we will also explore less frequent but interest nutraceutical products which are starting to be tested, also evaluating future roads to cover in order to maximize the benefits of nutraceuticals in MDD.