The most common reason someone might want to slow their heart rate down is because they are suffering from palpitations or a racing heart. When a heartbeat becomes more than 100 beats per minute, it is called tachycardia and indicates problems. Ventricular tachycardia can be fatal if not treated by medical personnel, so palpitations and or tachycardia should be diagnosed by a doctor before trying home remedies.
If your heart just started racing, this is your body's way of telling you it's time to slow down. Stop what you're doing, sit down, take deep breaths, visualize something calm and serene, and do what you can to bring your heart rate down. Often just taking a break and taking a breath is all that is needed to correct the problem.
In nature, sea mammals such as seals, dive into icy cold water which causes their heart rates to automatically slow down. This is mother nature's way of helping to preserve the brain and the heart. To take advantage of this, fill a basin with icy water and then hold your breath and put your face in the icy water. Sometimes this will automatically slow your heart rate down just as it does with the sea mammals.
Eliminate Stimulants in Your Diet
Stimulants such as coffee, tea, cola, and even chocolate can cause your heart to race because of the caffeine content. Eliminating these and other stimulants from your diet will ensure that your heart beat will not race due stimulant consumption.
Magnesium and Potassium
Magnesium helps the heart create rhythmic contraction and relaxation, making it ideal for helping to keep the heart muscle from getting irritated. Foods that include magnesium are nuts, bran, beans and soybeans.
Potassium is another mineral that can actually slow down the heart rate and keep the muscle fibers from becoming irritated. Foods that include potassium are fruits and vegetables--bananas in particular are a good source. Two important facts to keep in mind is that people with high sodium diets, or overuse laxatives are going to be potassium deficient.
People who are fit tend to have lower resting heart rates than people that are not fit. This is because people that are fit get their heart rate up regularly and because of this, the heart rate naturally goes down to a lower resting rate. So, someone that exercises on a regular basis, and gets their heart rate up is going to have less problems with their heart racing, and it's going to be easier for them to get their heart rate down when it does begin racing.