This is what’s REALLY lurking in a carton of Oat ‘milk’

Oat ‘milk’ sales have boomed in the last decade, but with the Supreme Court now saying it cannot be classed as milk, health experts have issued their own warning over the popular beverage.

What began as a somewhat niche dairy replacement for vegans and people who are lactose intolerant, for many the drink has now become a staple. 

It was invented in the early 1990s by Swedish food scientist Rickard Öste, who went on to co-found Oatly in 1994. 

Currently in Britain, nearly one in every ten glasses of milk drunk is a plant-based alternative – just a decade ago, the figure was one in a hundred.

The oat milk industry is now worth £275million, and covers 40 per cent of all plant milk sales in the UK.  

However, experts warn that the alternative that leads the way could be the least healthy.

From being high in sugar and packed with oil, nutritionists say that there are better milk alternatives than oat if someone is trying to avoid dairy.

This comes as the Supreme Court ruled that it was unlawful for companies to brand the drink as ‘milk’, ending a long legal battle between the market leaders Oatly and the dairy industry.

Rob Hobson, a Brighton-based nutritionist, said: ‘Clearer labelling can help avoid ambiguity and keep comparisons fair.

‘Nutritionally, oat milk and dairy milk are very different products. Dairy milk is naturally rich in high-quality protein, iodine, calcium and vitamin B12. Oat milk is typically lower in protein and often relies on fortification to match calcium and B vitamin levels.

‘The drinks also have added sugars and oils, particularly in barista editions and flavoured cartons.’

This may be because so-called ‘barista editions’ of oat milk – used in many drinks bought from coffee shops – are only about 10 per cent oat.

The rest is water mixed with oils and emulsifiers that keep the ingredients blended and allow it to froth like dairy milk when heated.

And these oils can still contribute to raised cholesterol levels when consumed excessively, says Dr Oliver Guttmann, consultant cardiologist at The Wellington Hospital in London.

‘Oats, eaten in porridge for instance, can actually lower cholesterol over time as they have lots of fibre, and fibre decreases cholesterol,’ he says. 

‘But drinking the frothy kind of oat milk that has a higher fat content could cause high cholesterol if you’re drinking it in excess.’

Experts warn that the high sugar content can also be damaging to the consumer’s health.

Glucose spikes occur when there is more sugar in the bloodstream than the cells can use for energy.

These rapid increases are followed by sharp drops, and this can lead to hunger pangs. In the long term, regular glucose spikes have been linked to the development of type 2 diabetes and heart disease.

‘Whereas we always thought that saturated fats were bad for cholesterol, it’s now become increasingly recognised that sugars in the diet can also affect it,’ says nutritionist Sarah Carolides. 

‘This may well be why there are anecdotal reports of people lowering their cholesterol levels when they switch away from oat milk.’

Rather than drinking oat milk, experts say that the best alternative is soy milk.

A 2025 research paper by scientists at the University of Minnesota concluded that soya milk was the alternative that was most nutritionally similar to traditional cow’s milk.

Soy milk is low in calories and saturated fat and contains plant-based proteins, which research suggests may be beneficial to health.

It is made by soaking and grinding soya beans and can be made at home or bought commercially.

Commercial soy ‘milk’ may include added ingredients such as sweeteners and salt, and also be fortified with nutrients such as vitamins B2, B12, D, calcium and iodine.

Studies suggest that the natural compounds called isoflavones, contained in soybeans, have been linked to lowering breast cancer risk and being able to slow signs of ageing.

The same compound, which is similar to oestrogen, is why there has long been a myth that eating soy feminises men.

However, research does not support the claim. For example, a review of 38 clinical studies found no adverse effects of soy on men.

‘Soy milk has been widely drunk in Asia for centuries and is the best plant-based alternative as it is most nutritionally similar to cow’s milk,’ says Clementine Vaughan, a London-based nutritionist.

Kate Overy, Nutrition Science and Communications Lead at Oatly said: ‘Fortified plant-based drinks like Oatly are included in dietary guidelines worldwide, including the UK’s Eatwell Guide.

‘Oatly’s fortified drinks combine the natural benefits of fibrous oats with added calcium, iodine, riboflavin, and vitamins B12 and D. No sugar or sweeteners are added to unflavoured drinks.

‘For every 1 litre of our drinks, we add 1-2 tbsp of rapeseed oil to enhance nutrition and recreate the creamy texture of dairy. Rapeseed oil is widely recommended in global dietary guidelines.’

What is oat milk going to be called now?    

Manufacturers of oat milk have said that the new rule will create confusion for customers.

Following the decision, Bryan Carroll, the general manager for Oatly UK & Ireland, said the company was ‘deeply disappointed’ by the ruling, which he said ‘creates unnecessary confusion and an uneven playing field for plant-based products’.

The same regulations apply to terms that are derived from other milk-based products such as cream, butter, cheese and yoghurt.

Experts say that the ruling will bring oat milk in line with other alternative products.

‘For plant-based producers the safer course is to use clearly descriptive alternatives such as ‘oat drink’, or ‘plant-based drink’, said Richard May, a partner at law firm Osborne Clarke.