Both mutton and chicken are sources of protein, but they have different nutritional profiles. Chicken is generally considered to be a leaner protein source than mutton.

Chicken breast is leaner than other cuts of chicken and is a good source of protein, B vitamins, and minerals such as phosphorus, selenium and niacin. It is also lower in saturated fat than mutton.

Mutton on the other hand, is a good source of protein, B vitamins and minerals like zinc and iron. However, it is higher in saturated fat than chicken. Saturated fat intake, particularly in large amounts, can raise the total cholesterol levels in your blood and it is associated with an increased risk of heart disease.

When it comes to heart health, it's important to pay attention to not just the protein source but also the preparation method as well. Poultry meat can be healthy if it's grilled or baked and not fried, and the same goes with mutton. So it's important to be mindful of cooking methods too.

It's also worth noting that a diet rich in fish, whole grains, fruits, vegetables, and legumes is typically recommended to promote heart health.