Avocado.

The avocado has quite a fatty flesh – which is perfect for smoothies. However, it will thicken the mixture quite a lot – so has to be offset with liquids of some sort, or you’ll end up with something with the consistency of yogurt!

It’s also high in calories – so it’s not something that you’ll want to use if you’re trying to lose weight.

The taste is subtle and will normally be overridden by the other ingredients. However, it’s a great source of nutrients and gives a smoothie quite a unique texture.