Have you sworn off meat this year? According to the latest estimates around a third of us are looking to eat less of the stuff. And it’s not just millennials: a recent YouGov poll showed that over-55s were the age group keenest to reduce their meat consumption.

Some are going the whole hog: this year, the numbers participating in ‘Veganuary’ — forsaking all animal products for one month — exceeded the combined total for the previous four years. Whether it’s environmental guilt or the much-discussed health benefits, veganism, which was once the preserve of animal rights hardliners, has gone mainstream. Which begs one question: what does it mean for the markets?

Just like the old joke about how to identify a vegan (answer: they’ll tell you), vegan investment enthusiasts aren’t a quiet bunch. Witness the hype around Beyond Meat, the American start-up which claims to be able to replicate the taste and texture of chicken, pork and beef with its protein-based burgers. In the summer, it made headlines as the year’s most successful IPO on US markets, spiking some 700 per cent above its initial public offering price. Then came the slump: last month, the company lost 40 per cent of its total value, with around one fifth of that drop occurring within a single day’s trading. Analysts believe its fundamentals are still strong, and that October’s performance marked a correction after speculators’ over-excitement.

Closer to home, shares in Greggs, the discount bakery, have rocketed more than 50 per cent this year on the back of its decision to stock a vegan sausage roll. Since the meat-free snack hit the shelves, the company has increased its profit forecasts four times. Now it’s planning a vegan version of its famous steak bake.

The rise of alternative — and artificial — meat has been an obsession for big investors for a while now. A report by Barclays private banking division estimates the market will grow tenfold in the next decade (rising from $14 billion to $140 billion). Investors get particularly excited by stem-cell technologies that grow ‘real’ meat. Some, though, have spotted a less futuristic opportunity: they’re betting that the race to find mass-market meat substitutes will breathe new life into old-fashioned food-processing companies, many of which have fallen from fashion.

Not everyone is convinced. Investment firm Charles Stanley warned this summer that faux meat was beginning to resemble a classic market bubble. It is, though, highlighting more specialist companies that might benefit from the veganisation of the economy. Its analysts recently picked Senzagen, a Swedish firm developing cruelty-free allergenic tests for the cosmetic and pharmaceutical industries, and Simris, which produces vegan-friendly omega-3 supplements from algae, as ones to watch.

But might there be another, and more cautious, way to see the rise of veganism? If eating meat grows more taboo, perhaps becoming as unpopular as fossil fuels or selling arms, might we see the rise of similar boycotts and divestment campaigns?

The animal rights lobby has a track record of successful customer boycotts. For years, People for the Ethical Treatment of Animals (Peta) has railed against high-end fashion houses for their use of fur, persuading the majority to abandon the practice. It also publishes a database of companies that engage in animal-testing.

The food industry seems to have picked up on the change, hence companies from Marks & Spencer to Ben & Jerry’s rushing to proclaim their vegan-friendly credentials. Even KFC has begun experimenting with plant-based options, trialling a new ‘Imposter’ chicken burger. Although others have found it isn’t that easy: when Tesco unveiled its new vegan-friendly advertising campaign last month, in which a young girl tells her dad she won’t eat animals anymore, the National Farmers’ Union responded with its own proposed boycott, slamming the supermarket for ‘demonising meat’ and putting farmers’ livelihoods at risk.

Earlier this year, Beyond Investing launched the first climate-friendly, all-vegan exchange-traded fund for US investors (trading as ‘VEGN’). Although sceptics pointed out that while many of its investments might not be endangering animals, they weren’t exactly at the forefront of social justice either (Apple, Microsoft and Facebook being three of its biggest holdings). Meanwhile, Maryland-based investment house Karner Blue Capital, which has long used its muscle to improve animal welfare standards, has begun naming and shaming offenders. Last month it slammed the pharmaceutical giant Pfizer for its treatment of horses in making the estrogen-replacement drug Premarin.

The Mayfair-based Fairr Initiative (Farm Animal Investment Risk and Return) pursues a similar strategy. With some £2 trillion of cash within its orbit (largely from pension funds and other institutional investors) it shuns companies with unethical farming practices in their supply chains. It has also threatened to boycott big food manufacturers unless they invest in plant-based foods. It seems to be working: last year, Unilever, one of the companies named, announced it was rejigging its portfolio towards vegan products and had bought a Dutch meat-substitute producer.

For investors enthusiastic about meat-free investments, however, there is a reason to be sceptical about how deeply vegan products can penetrate the food market: their cost. Beyond Meat’s burgers currently cost around three times more to manufacture than high-end beef burgers. And anyone who’s bought vegan chocolates, cheese and ice creams in supermarkets can’t have failed to notice the hefty price tags. Is that because the brands are aimed at the well-heeled middle class — or is it an inevitable cost of going vegan?

Either way, veganism is on the march. Whether or not you’ll be joining in, it might be worth keeping an eye on the numbers who do: sooner or later your portfolio, if not your food bills, might well feel the effect.