“Sanctimonious vegans would do well to think about their diet’s global impact,” bellowed a headline above a comment column in Monday’s edition of the “i.” It includes mention of a chef who is said to have “spiked” the meal of a party of vegans with cheese; one wonders if similar disrespect would have been shown to a party of Muslims, spiking their meal with non-Halal produce, or whether it is only gentle liberals who merit such an attitude.

It is a lazy piece, the writer does not offer any illumination that would not have seemed plainly logical to any school student of economics – an increased demand for a product pushes up its price. In the case of vegans, they are held guilty of pushing up the price of staple foodstuffs such as quinoa, lentils and chickpeas; foodstuffs important to poor people in developing countries. Finding fault with the spending patterns of vegans, the columnist avoids reflecting on the damage to the poor caused by the lifestyle choices of those of us who are omnivorous, concluding with a comment that people who want to be kind to animals should remember that humans are animals too.

As someone who will eat just about anything, tripe, horse, snails, foie gras being among the various delicacies enjoyed, I understood veganism as being about considerably more than being kind to animals. Anthropomorphism can colour attitudes toward animals and subjective attitudes can underlie arguments about meat-eating, but the case for veganism rests on much firmer scientific and objective grounds than whether or not we like animals. At its heart, my choice to eat animal products, whether dairy or meat is one that is costly both for the planet and for the poor.

Meat and dairy production demand massive inputs of resources. Huge volumes of grain are used in producing feed for cattle, it demands massive tracts of land being devoted to grain production and means intervention in international markets to ensure a stable supply; in its demand for land and its need for cattle foodstuffs, eating animal products inevitably raises the cost of food for the poor. Added to the impact on price is the impact on the environment, ploughing and planting and harvesting create a huge carbon footprint and substantial pollution, as does dairy farming with the inputs required for grass production and the large volumes of methane gas discharged by cows. These things are not subjective, they are not questions of whether one is being kind to animals, they are measurable, observable economic facts.

Perhaps vegans can sometimes seem “holier than thou,” perhaps, though, it’s more a sense on our own part that we have chosen to be unjust.