An article on Stuff has done a good job of explaining that superfoods aren't all they're cracked up to be.

Superfoods are foods that are touted as having high levels of one or more nutrients, with claims made that these nutrients can heal the body. These superfoods, such as kale, goji berries and chia seeds, are often sold at very high prices.

However, these foods do not contain much more in the way of these key nutrients than more common, and much cheaper, fruits and vegetables. Cheaper foods may also have a more rounded mix of nutrients, making they healthier for you.

Auckland dietitian Dr Carol Wham said:

"Superfood is an invented thing. But we all like something a little fanciful, don't we? All of them are great as part of a diet, but not one is going to transform somebody's health."