Mortality rates and co-morbidities are high in people with psychiatric disorders. These patients have unhealthy dietary habits, which include increased consumption of fast food, snacks, sweets, saturated fats, and reduced consumption of protein, fruits, vegetables, and legumes, which contributes to the risk of developing chronic diseases such as obesity, type 2 diabetes, and cardiovascular disease. Unhealthy and monotonous eating habits lead to a significant lack of nutrients such as protein, omega-3 fatty acids, B-group vitamins, and fibre. The aim of the literature review is to investigate the main diet problems of patients with psychiatric disorders and, based on the studies on the nutritional value of legumes, to evaluate their suitability for the development of new products for patients with psychiatric disorders. Studies show the beneficial effects of legumes on the regulation of rapid fluctuations in cholesterol, blood pressure, excess body weight, and glucose levels, which in general delay the formation of inflammation and reduce the risk of psychiatric disorders. The benefits of legumes are due to their high protein and fibre content, low fat content, and content of iron, copper, magnesium, zinc, and B-group vitamins. In addition, legumes contain bioactive compounds that contribute to the prevention of chronic diseases.