Food-Derived Peptides: Neuropeptides and the Diet–Microbiome–Brain Axis

Food-derived peptides are short chains of amino acids encrypted in the proteins of several plant sources. Several functions of food-derived peptides, or bioactive peptides (BPs), such as antioxidant, antihypertensive, antidiabetic, antiobesity, and antimicrobial, have been well studied. However, at the beginning of the twenty-first century, due to stressful situations such as prolonged aging and pandemic diseases, the study of BPs with the potential to mitigate the impact of anxiety, cognitive impairment, and the progression of neurodegenerative diseases has received increased attention. Classical processes such as enzymatic hydrolysis, fermentation, the use of probiotics, and the simulation of gastrointestinal digestion are used to release BPs. Heating, high pressure, and in silico design are methods proposed to obtain novel peptides. In addition, gut microbiota play a key role in the metabolism of dietary proteins; therefore, through cross-kingdom communication, the diet-gut-brain axis is a fundamental mechanism in maintaining health status that is only just beginning to be understood. Furthermore, attention is being paid to small peptides, or noncoding peptides, which can be found in dietary foods, as new players capable of modulating the diet-gut-brain axis.