Fancy a nice juicy steak? Most of us do from time to time, and we don’t trouble our consciences too much with the rights and wrongs of eating meat. Others, while vaguely aware that we ought to go vegan, just can’t face the rest of our lives denying ourselves bacon, beef, butter etc. But once we start looking into the arguments for veganism (and it has to be full-blown veganism, because eggs and dairy are all part of the animal food production line), it becomes difficult to justify the omnivore diet. Take the environment for starters. As polemical author and commentator George Monbiot argued in this debate, livestock farming has a massive impact on the planet, producing around 14% of carbon dioxide equivalent emissions according to the UN. That’s roughly the same as the total amount of global transport emissions. Animals are extremely inefficient processors of the maize and soya that farmers grow to feed them. If we ate those crops ourselves instead of feeding them to livestock, we could free up hundreds of millions of hectares of rainforests, savannahs and wetlands where wild animals could flourish instead. And then there are the arguments about animal welfare. Recent scientific research indicates what many of us feel we already know – that animals have complex emotional lives not dissimilar to our own. Intensive farming – the kind that confines hens, pigs and cattle to squalid indoor pens – thwarts their instincts to move around freely and build social bonds with their group. Tens of billions of animals exist in this way, and that’s before their short lives are ended in the horror house of the abattoir. As for those who say a vegan diet isn’t healthy, elite athletes who have made the switch, including world tennis No 1 Novak Djokovic, prove you don’t need animal protein to excel at the highest levels in sport.

On the other side of the argument, making the case for the meat munchers, was sharp-tongued Sunday Times food critic AA Gill. The fact is, he will say, we developed as omnivores and every human culture has its culinary traditions, based on the taste and aesthetics of meat and dairy. Do we really want to live in a world where there is no beef Wellington or cheese soufflé? As for the environmentalist arguments, omnivores now have some serious eco-credentials behind them. A study at Cornell University shows that a diet that includes a few small portions of grass-fed meat a week may actually be greener than eating no animal products at all. And when it comes to animal welfare, rather than abandoning animal products altogether, couldn’t we do more good by pressing for genuinely transparent labelling of our meat and dairy? If consumers really know what they are getting, fewer people might be willing to buy the £3 chicken produced in the barbaric conditions of the agricultural industry. As for a vegan diet being healthier, we should stop giving airtime to self-appointed health experts and lifestyle bloggers. Some dieticians argue that there are nutrients we need that we just can’t get from plants alone. Yes, we can get calcium from kale and iron from beans, but the quantity, quality and bio-availability of such elements are far better when we get them from animal rather than plant sources.

How do we pick our way through these thorny arguments?