A delicacy containing beef, coriander and limes may sound fresh and healthy, but don't let this fool you - the restaurant that serves them up cooks the meat in litres of week-old dirty animal fat and six regular customers have suffered heart attacks. 'Filth Tacos', which consist of normally unusable off-cuts, have become legendary for both their apparent delectability and life-shortening properties in Mexico City.

'I'd hate to think how many calories you'd consume in each bite', said Don Beto, who invented his Tacos Beto restaurant's signature dish more than 40 years ago.

'However a lot of our best clients have told us of massive cholesterol readings. Six of my regulars have had heart attacks in the past two years.'

Two soft corn tortillas are filled with a mulch of fatty sausage and beef and pork rinds, all fried in animal fat.

It's thought that each 50p Taco de Cochinada contains more 550 calories. And customers order five at a time.

'It's great for heart attacks,' joked one customer who was working his way through one such order. 'I'll have heartburn all weekend after these, but they're absolutely delicious.'

In addition to the refried off-cuts that make up the Filth Taco, customers often ask for the burned black bits floating in the boiling fat to be sprinkled onto their orders.

The tacos are prepared in the traditional sombrero grill, a large metal frying pan with a ring of hot oil surrounding a domed hotplate on which fillings are reheated.

The beef and pork dripping used to fry every order is a dark brown colour and completely opaque.

This is due to the fact that Tacos Beto goes weeks without changing the fat with which they cook, preferring to let it cool overnight into its solid form before reheating it to cooking temperature an hour before opening.

'We'll scrape the top off when it sets,' Don Beto told MailOnline as he sliced the fat his cooks use for frying from a side of beef, 'and our food may be greasy, but our customers don't get sick'.

'It's pure garbage,' said Milena Ramirez, who had brought her two children to Tacos Beto for a Friday night treat. 'But it's delicious and the kids are always excited to come'.

MailOnline's reporter ate two of the Filth Tacos and was subsequently very ill. Heartburn is an issue even 36 hours after consuming the speciality.

Picking the taco up, its grease content is immediately obvious by the now-transparent paper lining the plate on which it is served.

Grease drips out of both ends and upon biting into it, the mouth is immediately coated in warm oil.

This dirty fat is the overwhelming taste, while the texture is of grease-soaked meat, simultaneously soggy and crispy.

The ashy carbon flecks of burned matter added as a garnish round off what is initially tasty, but quickly leaves a putrid aftertaste.

After finishing, four paper napkins were needed to remove the grease from his fingers.

'I've been coming here for years,' said Lorena Ochoa, Mexico's most famous female golfer with 27 wins on the Ladies' PGA Tour.

'I'm not a regular and I know it's the most unhealthy thing possible,' she told MailOnline as she ordered three Filth Tacos. 'But it's a local institution. It's a fun place to come for something over the top'.

While in the past two years, six regular customers have suffered heart attacks, other clients have complained of chronic heartburn, diarrhea, acne, glandular problems and constipation after eating the tacos, which are made up of about 20% saturated fat.

'This is the worst possible thing a person can eat on a regular basis,' Mexico City physician Dr Lilia Hernandez said.

'The enormous saturated and trans fat content of these tacos raises blood lipid levels to outrageous numbers. This will end up blocking arteries, which in turn causes heart attacks and strokes.

'And when we consider that the uncured animal fat they use to cook the ingredients in is reheated and reused nightly for long periods, a consumer's risk of colon or stomach cancer can be quadrupled depending on the frequency of their visits.

'I can't think of a more unhealthy combination of factors anywhere', she said, speaking from her office at the Sanatorio Durango Hospital in Mexico City.

'People who want to remain healthy must not eat this food on a regular basis.'

Despite such professional health warnings, Tacos Beto is still filled with hungry clients nightly. The average wait time for a seat at a shared table is more than twenty minutes.

'Mexicans are keen eaters,' said Don Beto, whose grandfather first started the business in the city's Narvarte district.

'If we think something is delicious then we aren't that concerned about what goes into it.'

Mexico City-based health coach Grishka Guzman said: 'Traditional Mexican food is based on fresh vegetables and good home cooking.

'But the lifestyle change in a city of 26 million is enormous. The way people eat here is increasingly similar to what is known as the North American Diet.

'Fat-based foods which are instantly available are far more satisfying in the moment than something which takes time to prepare.

'A typical breakfast here will be a bottle of coke and a doughnut. While this is a big sugar rush to start your day in a hectic city, if you stack eating badly alongside the stress of city life you can end up with very unhealthy individuals'.

Mexico, perhaps unsurprisingly, has some of the worst health statistics in the world. High blood pressure, blood glucose and obesity rates are higher across the board than North American averages.

According to World Health Orgranisation statistics, obesity in Mexicans aged over 20 is at 38.4 per cent, nearly ten points higher than the North American average of 29.7 per cent.

More than 70 per cent of Mexican adults are considered overweight.

Cardiovascular disease and diabetes, illnesses caused directly by diet issues, are by far the most common causes of death in Mexico.

More than 6,000 years of life are lost annually due to premature mortality across the country's 122 million population.

The country's average life expectancy is 67, eight years below the 75-year regional average.

A country which also struggles with fizzy-drink related problems, Mexico is the only country in the world where three-litre bottles of Coca-Cola are still available nationwide.

A 10 per tax rise on soft drinks at the start of 2014 managed to bring sales down 6 per cent.

According to a paper published by the Food and Agriculture Organisation of the United Nations, being overweight in Mexico used to be a sign of wealth, given the country's issues with malnutrition and wealth distribution.

Yet given these warning statistics, obesity and heart disease rates in Mexico climb year on year.

Health coach Grishka said: 'Mexicans need to find a way to going back to the way their grandparents ate.

'In supplanting fizzy drinks for water, they've suffered the consequences in their health. They need to learn to think in the long term.'

Dr Hernandez added: 'It's not so much a question of education as common sense. You don't need a top class education to know that eating this sort of food is bad for you.'

'If you don't believe what you're told, then people who regularly choose to eat Filth Tacos should look first-hand at the effect it has on them.'

Read the original story on the Daily Mail