When did you last hear someone order coffee with ordinary cow’s milk? Oat, almond and other dairy-free options have become the norm rather than the exception. According to market research firm Mintel, four in 10 UK consumers now use dairy alternatives.
However, research published last week in The Lancet Planetary Health has raised concerns that replacing even part of the dairy in your diet with plant-based products could mean missing essential nutrients.
Teenage girls and young women may be particularly vulnerable. Researchers from the University of Surrey and Queen’s University Belfast calculated that replacing one-third of dairy products with plant-based alternatives could leave 65 per cent of adolescent girls short of iodine, a mineral vital for healthy thyroid function.
People aged over 65 could also face problems. Some oat milks contain 85 per cent less protein than cow’s milk, at a stage of life when adequate protein is crucial for limiting muscle loss. Reduced muscle strength is a major contributor to falls, the leading cause of accidental death among older people.
Plant-based milks may also provide insufficient amounts of two important B vitamins—B2 and B12—which occur naturally in cow’s milk.
A long-term shortage of vitamin B2 can trigger mouth ulcers and skin problems, including a red, scaly rash. Too little B12 can cause anaemia, resulting in severe tiredness and shortness of breath.
A milkman making a delivery in 1972. Today, cow’s milk is falling in popularity with four in ten UK consumers now using dairy alternatives
“Lower food intakes [of these two B vitamins] in older people can turn marginal insufficiency into deficiency,” Mike Lean, professor of human nutrition at the University of Glasgow, told Good Health.
For the study, scientists assessed the nutritional details of 289 plant-based milks, yoghurts and cheeses sold in the UK. Only 12 per cent contained added iodine, while fewer than half included vitamin B12 and just one in five contained vitamin B2.
Professor Lean attributes what he calls “the current craze for dairy avoidance” to efforts to prevent weight gain and the mistaken idea that dairy products are dangerous because they raise cholesterol.
Yet a 2018 study in The Lancet, involving more than 136,000 people, reported that those eating more than two servings of dairy each day had a 16 per cent lower risk of dying or developing serious heart disease—including heart attacks and strokes—than people who ate no dairy.
One possible explanation is that calcium in foods such as cheese binds to fat in the gut, helping it pass through the body rather than being absorbed. Professor Lean also says the non-dairy industry has promoted inaccurate claims for commercial gain.
The impact of nutrient shortfalls can be serious. Experts are especially concerned about women who are pregnant or trying to conceive, as iodine intake is often too low during pregnancy.
“Iodine is especially important before and during pregnancy,” says Sarah Bath, associate professor of public health nutrition at the University of Surrey and a co-author of the study. “It supports thyroid hormone production, growth and fetal brain development.”
The researchers estimated that if teenage girls abandoned dairy altogether, 71 per cent would consume too little calcium, potentially jeopardising bone health later in life. Most of the body’s bone mass is built during childhood and adolescence.
“Low calcium can stunt growth in younger people and worsen osteoporosis in older people,” Dr Simon Welham, a nutrition expert at the University of Nottingham, told Good Health.
And organic plant milks should not automatically be considered the healthier choice.
“Organic plant-based milks are the worst because they are prohibited [under organic food regulations] from having vitamins and minerals added,” says Tom Sanders, emeritus professor of nutrition and dietetics at King’s College London.
The popularity of these products has prompted questions about whether organic regulations should be amended. Dr Pauline Scheelbeek, associate professor at the London School of Hygiene & Tropical Medicine, says the rules could be changed to permit fortification of organic plant milks.
Some manufacturers openly acknowledge the nutritional gap. Arla’s website, for example, states: “You should not think of non-dairy milk alternatives as substitutes for cow’s nutrient-dense milk.”
The differences go beyond missing nutrients. To imitate the taste and texture of dairy, some plant-based milks contain oils, emulsifiers and stabilisers.
In 2025, the Government’s Scientific Advisory Committee on Nutrition warned that most plant-based milks would be classified as ultra-processed foods (UPFs). Broadly speaking, UPFs contain industrially processed ingredients and additives rarely used in home cooking. Diets high in UPFs have been linked to weight gain, type 2 diabetes and heart disease.
Although plant milks typically have a smaller environmental footprint than dairy, Professor Lean says their green credentials are not entirely simple.
“Manufacturing, packaging and transport can all add to greenhouse gas emissions,” he says.
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Sugar presents another issue. Some plant-based drinks are sweetened, and a study published in the British Journal of Nutrition earlier this year found that almost three in 10 plant milks sold in the UK were sweetened, compared with fewer than one in four in 2020.
The quantities can be unexpectedly high—even in products labelled “no added sugar”. One organic rice milk carrying that claim contains almost 18g of sugar in a 250ml glass, equivalent to eight McVitie’s digestive biscuits.
Research has warned that swapping cow’s milk, cheese or yoghurt in your diet for plant-based alternatives could leave you missing out on vital nutrients
Sweetened varieties can contain as much as 25g—more than twice the amount found in cow’s milk.
Oat milk contains maltose, a sugar created as oats are broken down during production. As a result, a drink can contain sugar even when its label says no sugar has been added.
Mouth bacteria feed on these sugars and release acids that erode tooth enamel.
The lactose in cow’s milk is less likely to cause decay because it produces less acid. Milk also contains calcium and proteins that help protect teeth, explains Bridget Benelam, a nutrition scientist at the British Nutrition Foundation.
The Government’s Scientific Advisory Committee on Nutrition has warned that replacing dairy with plant-based milk could raise sugar intake across every age group. It advised against using sweetened plant milks as a cow’s milk replacement for children aged one to five.
“It’s best to choose unsweetened plant-based drinks fortified with micronutrients including calcium, iodine and B12,” says Bridget Benelam.
The nutritional concerns extend to plant-based cheeses and yoghurts. Products made with vegetable oils, starch, soya and coconut are increasingly common, but many contain far less protein, calcium and other nutrients than consumers might expect.
The Coconut Collab’s natural coconut yoghurt contains only 1.2g of protein per 100g, compared with about 4g in standard natural dairy yoghurt.
It also contains 9g of saturated fat per 100g, versus approximately 2.6g in full-fat natural dairy yoghurt. Its nutritional information lists no added calcium or iodine.
“Plant alternatives are not nutritionally equivalent,” Professor Sanders warns.
Fortification could help replace the nutrients that are missing. In July last year, the Government’s scientific advisers recommended that plant-based drinks should contain iodine, calcium and vitamins B2 and B12 at levels comparable with semi-skimmed cow’s milk.
However, not every product is fortified. “Some are, others are not,” says Gunter Kuhnle, professor of nutrition and food science at the University of Reading. “That makes it confusing for a consumer who does not want to spend ages reading food labels.”
Professor Lean believes the health risks of dairy have been overstated. “Humans have used dairy products throughout most of our civilisations, across most cultures, for more than 9,000 years,” he says.
So what’s really in oat milk?
A bottle of M&S Barista Oat Drink, which due to the additives it contains, counts as an ultra-processed food
Cow’s milk contains one ingredient: milk. Some oat drinks, by contrast, include a much longer list.
M&S Barista Oat Drink, priced at £2.20 for one litre, contains 14 ingredients: water, oats, sunflower oil, chicory fibre, broad bean protein, coconut oil, calcium phosphates, E340 (an acidity regulator), sea salt, E471 (an emulsifier), E418 (a stabiliser), iodine, and vitamins B12 and D.
Because of its additives, including added fibre, the drink technically qualifies as an ultra-processed food.
“Current advice is that these additives have been extensively tested toxicologically and are safe for human consumption,” says Jules Griffin, professor of nutrition and metabolism at the University of Aberdeen.
However, he notes that research has associated ultra-processed foods with poor health in ways that cannot be explained solely by their salt, sugar and saturated-fat content. Additives are believed to play a role. Homemade oat milk is another option and is simple and inexpensive to make, although it contains little protein and no calcium, iodine or vitamins B2 and B12.
How to make it
Blend 100g of porridge oats with one litre of very cold water for 30 seconds. Blending for longer can make the mixture unpleasantly slimy.
Strain the liquid through a fine sieve lined with muslin or a clean tea towel. Transfer it to a clean bottle and refrigerate for up to three days, shaking well before drinking.