Green lentils reproduce the shape of an ECG trace (electrocardiogram) on a background of red lentils. ECG's provide a record of the heart's electrical activity and are used in the diagnosis of various heart disorders. Lentils are pulses (the seeds of a leguminous plant), and as such are a valuable supplement to a healthy diet. They can be a useful alternative to meat because they provide a good source of protein while being free from the saturated fats associated with animal products. A study of the frequency of coronary heart disease in different countries has shown it to be linked to the the amount of animal fats in the diet.