Whatever health benefits may come from not eating meat, milk, fish or eggs, veganism is still a minority pursuit, which means that vegans looking for vegan dates sometimes have a hard time.
Publisher Alex Bourke is a strict vegan. He does not eat any animal products. His last two girlfriends were vegans. Currently, he is single.
He is looking for vegan love.
"I have dated meat-eaters in the past and I have dated vegetarians and vegans. It is just so much easier when I can eat their food and they can eat mine," says Bourke.
But it is not just convenience that drives him to seek someone with a similar diet. It is also a question of ethics. For Bourke, eating meat is morally wrong.
"I cannot condone non-veggies any more than I can condone people who beat their children.
"I do not want any part of the cruelty involved, not just in factory farming, but in any kind of animal farming.
"I did break up with someone over cheese," he says.
"Every week I go for restaurant meals and I meet dozens of friends, some of whom are very attractive, and sometimes things happen," says Bourke. "If I kiss someone I just do not want the hassle of wondering, what is stuck between her teeth?"
Looking for a vegan mate, however, is like looking for a needle in a haystack.
The British Vegan Society estimates that there are only some 150,000 vegans in the UK, out of 65 million people - that is about 1 in 400.
In the US the odds are a little better. The Vegetarian Resource Group estimates that there are some two million, out of a total population of 313 million - roughly one in 150. A Gallup poll published two weeks ago, on the other hand, suggests that as many as 2% of Americans are vegan.
Like Bourke, Robb Masters, another Londoner, also finds it hard to imagine dating a non-vegan. In 16 years of veganism the diet has become part of his identity, he says.
He reckons there are 20,000 vegans in London.
"It may sound like a lot but it is less than a quarter of 1% of the population. You are unlikely to meet a vegan by chance."
He therefore organizes the London Vegan Meetup group, a chance for vegans to "meet without meat".
According to Masters, the numbers ought to favour heterosexual men, as vegan women outnumber them by about three to one. But in practice it doesn't work out like that, he says. Vegan women, it seems, are more willing to tolerate a non-vegan partner.
"When I get together with my male vegan friends, we do sometimes grumble a bit about all the vegan women with non-vegan men," he says.
One example is New Yorker Arden Levine. When she met her husband she had been a vegetarian for some time but had recently become a vegan. "On our second date he told me he had gone out and bought two vegan cook books. I was very touched by his openness," she says.
Although Levine won't cook meat, she's happy to have it in her fridge. Her father-in-law is a keen hunter and from time to time sends the couple venison.
"I do not restrict what my husband eats," she says, adding that she refuses to become a sanctimonious "vegangelist".
Of course, there are men, too, who are prepared to be flexible - or maybe have little choice.
Gary MacIndoe became a vegan at the age of 12, while growing up in Aberdeen in the north of Scotland, where there was not much hope of going out with a vegan girl.
"They are hard to come by in Aberdeen," he says.
His girlfriend used to offer him some of her meat pie on the way home.
"I would have to remind her that I could not eat it," he says.
But he accepts his girlfriend's diet. "There are relationships in which, though the people are completely different they support each other's beliefs - and it works," he says.
However difficult it may be vegans to date one another today, it used to be harder, says Bourke.
For one thing, vegetarianism is more mainstream.
"It is not the case any longer that vegans are socially clumsy, gormless loners living in a caravan and growing vegetables," he says.
Former US President Bill Clinton now eschews animal products, he points out.
The internet has also made life easier, with numerous vegetarian dating websites such as veggieromance.com and veggievisiondating.com offering "veggie dates and love".
Masters says that his vegan get-togethers include a broad mix of people. "A slightly younger crowd and more professional but a good slice of the population," as he puts it.
But in the end hunting, or gathering, outside the group may become unavoidable.
Although Masters is not going to change what he eats, with the passage of time he sees that he may need to date a non-vegan if he is to find his life partner.
"I would definitely prefer to go out with a vegetarian or a vegan but you cannot choose who you fall in love with."