In a statement, the consumer protection organisation mentions having analysed the vegan, ovo-lactovegetarian, Mediterranean and planetary regimes (“developed based on scientific evidence, combining diet, health and protection of the planet”) and concluded that the first “is the most expensive, requiring more than €7,000 euros a year”, while “the planetary diet, which costs around less than €1,000, does not have the same environmental benefits”.

“All the values presented are based on a balanced meal plan for four people (two adults, one child and one teenager)”.

In terms of reducing the environmental footprint, the best advice is to follow a vegan diet, which does not include the consumption of animal protein. But even in this case, DECO points out that “exchanging the almond drink for an oat drink reduces water consumption by 20%.

“In one week, more than 1,500 litres of water and two kilos of CO2 equivalent are saved. That is, it cuts the warming potential by 10%.”

For those who consider it too difficult to follow a vegan diet, the organisation states that “a diet tending to be more vegetable, seasoned with enough animal protein, also has environmental benefits, when compared to Mediterranean and planetary diets”.

Lacto-ovo vegetarians can replace cow's milk with a soy drink, reducing “5% CO2 emissions, 6% water consumption and 1% land use”.

And even those who follow the Mediterranean diet manage to reduce their global warming potential and water consumption by 5% if they switch from beef (which requires more resources) to chicken.

Cheapest diet

In terms of cost, the cheapest is the planetary diet, based on vegetables, whole grains, legumes and oilseeds and in which dairy products and red meat are reduced to extras.

The weekly basket for this diet totals 120 euros, the Mediterranean 127 euros, the lacto-ovo vegetarian 131 euros and the vegan 142 euros, according to the study.

Vegans spend 45% of their weekly global expenditure on dairy equivalents (given the absence of any food of animal origin) and vegetables and fungi (such as mushrooms), while 44% of ovo-lactovegetarians' expenditures are due to vegetables and fruits .

Vegetables, cereals and tubers and fruits represent 59% of the total expenditure of those who follow a Mediterranean diet, with moderate consumption of dairy products and red meat, while those who opt for a planetary diet spend 65% of the weekly amount on “vegetables, cereals and tubers, meat, fish and eggs”.