The combination of avocado with tuna in this salad is a healthy one. Tuna is a very healthy and lean protein, an oily fish that we should all be including in our diets. It is packed full of A and B vitamins, along with iron, magnesium, potassium and zinc. It is also a great source of omega-3 fatty acids. The creamy element for this salad comes from avocado, rather than mayonnaise. Avocado is a great source of vitamin E, folate and fibre as well as copper, iron and potassium.