In recent years, the health of patients exposed to the consequences of the metabolic syndrome still requires the search for new solutions, and plant nutraceuticals are currently being intensively investigated. Berberine is a plant alkaloid possessing scientifically determined mechanisms of the prevention of the development of atherosclerosis, type 2 diabetes, and obesity, as well as cardiovascular complications and cancer. It positively contributes to elevated levels of fasting, postprandial blood glucose, and glycosylated hemoglobin, while decreasing insulin resistance. It stimulates glycolysis, improving insulin secretion, and inhibits gluconeogenesis and adipogenesis in the liver; by reducing insulin resistance, berberine also improves ovulation. The anti-obesity action of berberine has been also well-documented. Berberine acts as an anti-sclerotic, lowering the LDL and testosterone levels. The alkaloid exhibits an anti-inflammatory property by stalling the expression of cyclooxygenase 2 (COX-2) and prostaglandin E2. Berberine is neuroprotective and acts as an antidepressive. However, the outcomes in psychiatric patients are nonspecific, as it has been shown that berberine improves metabolic parameters in schizophrenic patients, acting as an adjuvant during antipsychotic treatment. Berberine acts as an anticancer option by inducing apoptosis, the cell cycle arrest, influencing MAPK (mitogen-activated protein kinase), and influencing transcription regulation. The inhibition of carcinogenesis is also combined with lipid metabolism.