It used to be a simple choice between gold and silver top: today, a shopping catalogue wouldn't go amiss when deciding what milk to buy.
Rice, coconut, soya, almond, cashew, oat and even potatoes jostle for space on our supermarket shelves, in our fridges at home and on our cereal.
In 2019 the global market for plant-based milk was valued at $16,131 million (with soy milk and almond milk each representing 40 per cent) and is anticipated to reach $41,061 million by 2025.
As we try to work out what's best for our health, and that of the planet, many of us have been tempted away from cow's milk. This year Veganuary expects to have reached the milestone of two million participants since its launch in 2014.
It has grown in popularity partly because of health credentials and issues surrounding animal welfare but, for a growing proportion, the main reason cited for taking part is environmental concerns.
But is it really saving the planet?
This week the Advertising Standards Authority banned certain adverts by the Swedish company Oatly which it found had misled consumers over the environmental benefits of switching from dairy to plant-based milk.
The brand has seen its popularity soar alongside that of other plant-based milks, and is set to become a $10b brand. However, the ASA took issue with a number of figures used in the company's advertising, as well as the claim that cutting dairy and meat from our diets was the single biggest lifestyle change people could make to reduce their environmental impact. They ruled it was a misleading claim based on a single expert; a food sustainability researcher from the University of Oxford — who had also qualified it with the word "probably", which was omitted from the advert.
Many studies have demonstrated how meat and dairy contribute to carbon emissions – accounting for 14.5 per cent of all manmade emissions, according to the UN – but some believe cutting animal foods out and replacing them with plant-based alternatives does not have the effect some would have us believe.
"For a very long time the impact has been exaggerated," says Jayne Buxton, author of The Great Plant Based Con, published later this year, "and the nutritional costs of the diet understated or even ignored. As a result we have this overwhelmingly dominant narrative that's taken hold that most people think the best way to improve the planet and personal health is to go vegan."
While she says she is no great carnivore, Buxton's book examines the vested interests in shaping the narrative around plant-based products.
"We've heard time and again that cutting meat and dairy will have the biggest environmental impact but, if you look at the facts, the single biggest change you could make is to forego a flight. Or you can reduce the use of your car. Or you can eliminate all food waste from your home."
She refers to studies that have found that by reducing your meat and dairy consumption you can reduce our personal carbon footprint by a maximum of 2 to 6 per cent. "Which really isn't very much. There are far more impactful things you can do."
Buxton acknowledges that when it comes to climate change, many of us are trying to put our money where our mouth is by making consumer choices that we hope will make a difference, but says she would welcome a more nuanced conversation where the pros and cons are discussed without prejudice.
Almond milk, for example, is massively water-intensive in drought-hit areas, while poorly managed soy plantations contribute to deforestation. A 2020 study by Nottingham University and the Sustainable Food Trust determined that a kilogram of soya beans produces 13 pints of soy milk – but up to 150 pints of dairy milk if fed to a cow.
When it comes to the health and nutrition aspect, the plant-based milk industry has a lot of work to do.
While dairy isn't vital to good health, concerns have been raised about how switching to a plant-based diet makes it harder to reach the required levels of nutrients and vitamins.
Professor Ian Givens, director of the Institute of Food, Nutrition and Health at the University of Reading, says cow's milk is nutrient-dense and an easy source of vital vitamins. A study published last year by his colleagues, which analysed the nutritional value of milk substitutes, showed plant-based milks to have a much lower protein content. Legume substitutions such as soya had the highest protein content of the lot but, says Givens, "it was still significantly lower than cow's milk, which is not a big issue for adults but is one for young children".
Cow's milk was also richest in iodine, B12 and B2. There wasn't much difference in calcium, which Givens puts down to plant-based milks being fortified.
While vegans can have a healthy diet without dairy, he says they have to work harder to get vitamins such as B12 from synthetic sources. He flags up one worrying demographic, adolescent women, whom studies show to have very low intakes of calcium, magnesium iodine and iron, consistent with following a vegan diet.
"One of the big issues in that period of life is bone development."
Rethinking the milk industry is vital if we're to address concerns about the environment, says Patrick Holden, founder of the Sustainable Food Trust.
Putting out the silage each morning on his organic dairy farm in Wales (the longest-established in the country) he listens to the radio: "At the moment there are so many adverts for Veganuary and plant-based this and that."
As well as being big business, he believes the popularity of plant-based products is a reaction to people being "rightly upset by intensive livestock production and since they don't have the information to discriminate between the livestock products who are part of the problem and those that are part of the solution, the solution is to go vegan or vegetarian".
However, he and Buxton agree that pasture-fed dairy can not only minimise carbon emissions but can also sequester carbon.
"That's really the holy grail that we should be looking for in the future," says Buxton.
But how can milk compete while supermarkets treat it as a loss leader, setting farmers on a treadmill to intensify to lower prices, while the average plant-milk costs more than £1? (Although many coffee shops, such as Starbucks, have stopped charging extra for plant-based milks.)
My own milk-drinking journey started with me abstaining from an animal welfare perspective and has seen me go full circle from silver topper to plant-based and back again. A committed milky tea drinker, I learned to love soya and now am back on the udder. I've realised that things are rarely black and white – although I've learned to love black tea (if only to avoid the problem entirely). As a consumer though, I choose organic milk and yogurt. Holden would like us to go further.
"Organic goes a long way towards delivering a lot of the things we've identified as important to sustainability, but I'd like us to have a labelling system that enables people to know what herd their milk comes from," he says.
"I would like to see us drinking milk that's been produced kindly and lovingly towards the cows. We need to know the story behind all the food we eat. And we don't at the moment."