In the short term it is regulated by baroreceptors which act via the brain to influence nervous and endocrine systems. Blood pressure that is low due to a disease state is called hypotension, and pressure that is consistently high is hypertension. Both have many causes and may be of sudden onset or of long duration. Long term hypertension is a risk factor for many diseases, including heart disease, stroke and kidney failure.
Decrease your sodium intake. An excessive amount of salt in the body will absorb water and cause you to retain water. Consequently, to avoid water retention, moderate the amount of sodium you eat on a daily basis. Many processed foods are high in sodium, and will cause you to exceed your daily recommended sodium intake.
Fluid overload, which causes swollen legs like these, happens with both heart failure and kidney disease. Fluid overload is most frequently caused by heart failure. As the heart weakens, blood flow returning to the heart slows, backs up in the veins and causes fluid buildup in the tissues. Heart failure also affects the kidneys, resulting in less efficient elimination of sodium and water. The retained water increases the fluid congestion.