麻豆传媒

Although there is no strict definition of what it means to be vegan, the basic principle is to avoid animal-derived products. Dietary vegans mostly stick to avoiding animal-derived foods. For ethical vegans, it鈥檚 a philosophy not just a diet, which rules out traditional tattoos and silk, to name just a few. In both cases, truly steering clear of anything that is animal-derived can be much trickier than it first appears to be.

Bee slaves

Many vegans avoid eating honey because it is an animal product, but a bee鈥檚 contribution to our diet goes much further than that. Bee colonies are shipped from farm to farm to help pollinate vast quantities of fruits, vegetables and nuts, and maximise yields.

Take almonds, for instance, a prize vegan ingredient. Trees bloom over about a week, and only blossoms that are pollinated can go on to produce a nut. To get the most out of each tree, farms hire hives of honeybees that can be trucked long distances. Migratory beekeeping, as it is called, is decidedly unvegan, but it is absolutely vital if we鈥檙e going to keep these plants producing enough nuts to feed a vegan world. Onions, cucumbers and avocados are just some of the vegetables that also rely on transported bees.

Could we imagine a world in which an armada of robot pollinators release bees from the yoke? Unlikely. Bees are just too efficient and their behaviour is tricky to recreate. Although some robo-bees have been built, they鈥檙e not a practical solution on a large scale. 鈥淐an you imagine a billion robotic bees?鈥� says Chensheng Lu at Harvard University. 鈥淗ow would they not collide? How would their signals not interfere?鈥�

In your meds

Our lives literally depend on animal products. Vaccine production often involves gelatin or eggs. While it wouldn鈥檛 be advisable to refuse vaccination in an attempt to adhere to a vegan lifestyle, it could be possible one day to manufacture some vaccines without animals.

Tobacco plants have been used in experimental techniques to produce vaccines for Zika and polio. Cells from carrots, rice and maize show promise as bioreactors: cellular factories where virus-like particles can be incubated en masse. These trials are in their infancy and Stanley Plotkin, a vaccine researcher who developed the rubella vaccine used around the world, says we won鈥檛 ever be able to rely entirely on plants.

鈥淎lthough some vaccines can be made in insect cells or tobacco leaves, that is not possible for all,鈥� he says. He also says it would be impossible to make vaccines without testing them in animals, which is the next step in the development process. Animals are stand-ins for humans, and it is arguably even less ethical to jump straight to testing new medical treatments on humans than it is to first trial them on animals.

There is hope that we could replace the animals in this equation with organs on chips. The technology is nascent, but relies on human stem cells to produce organ-like systems that can then be used to test treatments and tailor medication to particular patients. Drug trials in lab mice are notoriously patchy in terms of leading to useful human medications because different species react differently to certain drugs. It is a long way off 鈥� if it is even possible 鈥� but replacing animals in drug development might result in better medicine.

What about your furry friends?

So you鈥檝e bitten the bullet and turned your back on steak, quiche and cheese, but still you find yourself buying meat-based products every week. It鈥檚 the dog food that鈥檚 getting to you.

Some pets just can鈥檛 get the nutrients they need from a vegan diet, says Cailin Heinze, a veterinary nutritionist at Tufts University in Massachusetts. Cats and ferrets top the list. 鈥淒ogs and people can eat green leafy vegetables and carrots as a source of vitamin A, and can make beta-carotene into vitamin A,鈥� she says. 鈥淐ats and ferrets don鈥檛 have enough activity of the enzyme that breaks down beta-carotene into the active vitamin A.鈥� Cats also can鈥檛 make taurine 鈥� an amino acid key to vision, digestion and heart function 鈥� and it doesn鈥檛 occur naturally in plants.

Companies could supplement cat food with the individual amino acids your pet would need, but powdered amino acid doesn鈥檛 taste particularly good, Heinze says. We could also leave our cats to fend for themselves outside, but domesticated cats can decimate wild populations of songbirds or other small animals, so forcing them to hunt doesn鈥檛 decrease the amount of animal suffering in the world.

Instead of making non-vegan animals conform to a vegan ideal, perhaps it would be a better idea to keep as pets only animals that are naturally vegan. Heinze says that while dogs can survive on a vegan diet, it would have to be designed very carefully to make sure they are getting all the nutrients they need.

Alternatively, 鈥渨e could just start having miniature horses instead of dogs and then we鈥檝e solved it鈥�, Heinze muses. Pigs, which are also quite clever, can get by on plants alone. And rabbits are as furry and cute as cats.

Cruelty-free booze

Even some wines and beers are off limits for vegans. Isinglass made of fish bladders, casein from milk protein and albumen from egg whites can all be used at the end of the brewing process. They help filter proteins or yeast out of the wine or beer and leave it clearer and, some argue, better tasting. If you have ever had a hazy home brew, you鈥檝e probably had beer that hasn鈥檛 gone through this process.

Traditional brews have used isinglass for centuries. But no need to give up your Guinness quite yet. Manufacturer Diageo announced this year that it will stop using isinglass in the filtration process for the drink. Others are going vegan too. Wine-makers and brewers alike have vegan drinks available. They range from passable to downright delicious, but then so do non-vegan drinks. There鈥檚 even vegan champagne, so you can ring in a vegan New Year in style.

This article appeared in print under the headline 鈥淟iving on the veg鈥�