REN and cardiovascular disorder: Ghrelin, known as the “hunger hormone”, is a 28-amino-acid peptide predominantly secreted in the stomach, and it is associated with the control of food intake and energy metabolism on the central and peripheral levels, influencing lipogenesis and insulin sensitivity, possessing anti-inflammatory properties, blocking the renin–angiotensin system, reducing sympathetic activity, affecting blood pressure and heart rate, and ultimately being involved in the development of cardiovascular disease (with low values being associated with an increased risk of cardiovascular disease worldwide) [84,85].