This story is from When foods get famous, an episode of The Food Chain on BBC World Service. It was presented by Emily Thomas and produced by Emily Thomas and Simon Tulett. To listen to more episodes of The Food Chain, please click here. Adapted by Bryan Lufkin.

Avocado toast. Kale shakes. Goji berry smoothies. Quinoa bowls.

If foods were celebrities, these would be just a handful of the treats that have received the red-carpet treatment in the last few years.

But why do some fruits and vegetables become the A-listers of the food industry – highly desired produce with the ability to jump-start profits and shape the daily eating habits of billions?

Why is that kale and avocado have seen such a meteoric rise in popularity and sit centre stage basking happily in the spotlight while the humble carrot or poor old turnip remain firmly on the Z-list?

The answer is complicated and complex.

How avocados conquered the world

Let’s start with the avocado – a millennial darling that’s often found these days spread on toast at bistros for a bloated price. So famous is the avocado and so strong is its pull on hungry millennials, it’s hard to find a company that isn’t trying to cash in on the soft green fruit’s star power.

Take UK company Virgin Trains, which started a marketing campaign last year it dubbed “#Avocard”. After the company sold out of new railcards, it decided to give customers aged between 26 and 30 who showed up at a station holding an avocado a discount on train tickets. (Millennial response was mixed, with some finding the promotion patronising.)