How Meghan's favourite avocado snack - beloved of all millennials - is fuelling human rights abuses, drought and murder 

The Duchess of Sussex has rightly been praised for making the fusty old Royal Family more socially and ethically aware.

But that was until an old friend from her Hollywood days was invited round for a bite to eat and posted online a picture of what was widely assumed to be high tea.

Pride of place went to avocado on toast —on silver platters, no less. ‘Still being the avocado toast whisperer, YUM!’, trilled her guest, Daniel Martin. The celebrity make-up artist said it took him back to the days when he and Meghan Markle collaborated on her lifestyle blog, The Tig.

‘The consummate hostess,’ he enthused.Well, perhaps not so much.

The campaigning duchess may be passionate when it comes to racial equality and female empowerment, but for someone who wants to save the planet, she’s committed something of a faux pas with avocados.

For all their health benefits and tastiness, the fact is that rampant avocado production in the Third World has been linked with water shortages, human rights abuses, illegal deforestation, ecosystem destruction and general environmental devastation.

It has proved so lucrative in Mexico that it has been dubbed ‘green gold’ and is even filling the coffers of brutal drug cartels.

In her defence, the duchess is hardly the only celebrity who’s extolled the wonders of avocados, which are full of vitamins, proteins and healthy fats.

The lifeblood of the millennial generation — who can’t stop posting pictures of avocado on toast on Instagram — this so-called ‘super food’ has been championed by everyone from nutritionists to Hollywood stars.

The duchess revealed in her Grenfell cookbook that a green chilli and avocado dip was a favourite. Pop star Miley Cyrus went further with an avocado tattoo on her arm.

Grown in Mexico for 9,000 years, the avocado has come a long way since the 16th century, when Spanish conquistadors disparagingly called it aguacate, after ahuacatl, Aztec for testicle. Between 2000 and 2015, avocado consumption in the U.S. tripled. In the UK, the avocado market is estimated to be worth around £200 million a year.

But it has become a victim of its own popularity, prompting restaurants and cafes to remove it from menus over concerns about its environmental and social impact.

The Wild Strawberry Cafe in Bucks substituted avocados, its most popular item, with garlic-sauteed mushrooms on toast. Its owner cited the ‘demand on avocado farmers, pushing up prices to the point where there are even reports of Mexican drug cartels controlling lucrative exports’.

Tincan Coffee in Bristol has replaced ‘avo’ with pea guacamole after they were judged not to ‘fit’ with it’s ‘core beliefs’. The Wildflower Restaurant in South London followed suit, citing the violence in Mexico.

Its chef, Joseph Ryan, suggested the world may be entering a ‘post-avocado era’.

Haute cuisine has also jumped on board. In Ireland, the Michelin-starred chef JP McMahon has called them the ‘blood diamonds of Mexico’ and compared avocados to battery chickens. Where trendy restaurants and chefs go, the image-conscious supermarkets may not be far behind.

The problems that come from the West’s trendy fascination with avocados have a lot to do with geography. Some 40 per cent come from Mexico and almost all of that is grown in the rural western state of Michoacan.

The region’s fertile volcanic soil and temperate climate allow avocados to be harvested all year round (in other countries they can only be harvested in summer). The rich soil means the notoriously thirsty avocado trees need only a third as much water as they do elsewhere.

Mexico now makes more money exporting avocados than oil. Unfortunately, Michoacan is also home to some of Mexico’s most violent cartels. They include La Familia Michoacana, whose leaders once tossed five rivals’ heads on to the dance floor of a nightclub; their equally vicious rivals in the Knights Templar, a quasi-religious death cult; and Los Viagras, named for their leader’s heavily moussed, erect hair.

In Michoacan, the cartels now make more money from avocados than cannabis. Some drug criminals are becoming growers themselves, others simply terrorise the industry. Avocado farmers, who in Michoacan can easily earn more than £115,000 a year, a vast sum in Mexico, live in continual fear of kidnapping and extortion.

The Knights Templar started charging a fee for every box of avocados gathered by farmers. They also extorted money from the fertiliser and pesticide retailers. Many farmers have been forced to hand over the title deeds to their farms.

If they don’t pay protection money, growers and packers risk being raped or killed, their bodies tied to avocado trees with warning notices attached. Some kidnapped farmers have been killed even after their families paid their ransom.

A businessman whose family refused to pay up was chained to one of his trees and shot dead. Officials estimated the Knights Templar alone earn as much as £115 million a year from avocados.

The cartel’s 2014 kidnap, rape and murder of an avocado farmer’s young daughter prompted the town of Tancitaro to drive out the Knights after a bloody battle. However, the cartels remain a menacing presence.

Mexico’s avocado industry is also accused of damaging the health of locals with the chemicals sprayed on the orchards. Experts are concerned that the fumigation of the trees is behind growing breathing and stomach problems, and may be polluting water supplies.

Unscrupulous farmers are clearing land for avocado orchards, often illegally by cutting down oak and pine forests. The latter provide a crucial winter nesting ground for the imperilled Monarch butterfly.

Indeed, a Mexican government study concluded that soaring avocado production has caused a loss of biodiversity, environmental pollution and soil erosion. It has also damaged the natural water cycle and threatened the survival of animal species only found in the area. Farmers exacerbate deforestation by using trees for avocado crates.

We can’t be certain where Meghan’s avocados came from, but fashionable eaters who think they can safely switch to sourcing them from the Dominican Republic, Chile or Peru should think again.

Wherever they come from, the thousands of miles any avocado has to travel to get to Britain means they leave a heavy carbon footprint.

This is because they are perishable but cannot be frozen because it alters their texture.

They must therefore be transported either by air or in air-conditioned container ships so they ripen at just the right moment.

Their relatively heavy weight and bulky packaging to prevent bruising further ratchets up their carbon footprint. Two avocados have a footprint of 846g of CO2, compared to 160g for two bananas.

The enormous amounts of water required to grow avocados is even more of an eco-issue in countries without Mexico’s volcanic soil. It can take as much as 1,000 litres (220 gallons) to grow a single kilo (about three avocados).

The Chilean province of Petorca is suffering an acute water shortage thanks to ‘green gold’. Water has been privatised in Chile (which specialises in the Hass variety so popular in the UK), meaning that those who pay — such as deep-pocketed big avocado growers — can use as much as they want.

When activists complained after a 2012 aerial survey revealed 64 pipelines were diverting river water underground to irrigate the orchards, they received death threats. Local rivers have now dried up and supplies have to be trucked in for local people while the avocado farms rely on artificial reservoirs.

Although the avocado is essentially a jungle plant, greedy growers are determined to cultivate it in dry, perennially sunny areas such as California, where orchards sap water from a state already prone to wildfires and drought.

In Israel, avocado trees are irrigated with treated waste-water, prompting fears that harmful nano-particles are not only permanently damaging the soil but penetrating the fruit.

The Chinese are being gripped by avocado mania, too, so demand is expected to keep soaring.

But given the damaging cost of ‘avocado fever’, might it not be better to eat them more sparingly — and not, for example, serve them up on silver platters?

Since Meghan’s guest was invited to high tea, surely it should have been a case of let him eat cake.