A research study from the University of Copenhagen identifies a widespread issue: plant-based beverages have lower levels of protein and essential amino acids compared to cow’s milk. This is attributed to the high level of processing these drinks undergo, which leads to chemical reactions that deteriorate the protein quality and may create other concerning compounds.
In the past ten years, there has been significant growth in the global market for plant-based beverages, with oat, almond, soy, and rice options becoming favored substitutes for cow’s milk in items like coffee and oatmeal.
One reason consumers may favor plant-based drinks is their generally smaller carbon footprint compared to traditional cow’s milk. However, this perception may mislead consumers into thinking that plant-based options are healthier. This point has been emphasized by new research from the University of Copenhagen, in partnership with the University of Brescia in Italy.
Researchers investigated how the processing of ten different plant-based beverages affects their nutritional value, using cow’s milk as a baseline for comparison. The findings are clear:
“We certainly encourage a greater consumption of plant-based foods. Yet, if you’re seeking adequate nutrition and think that plant-based drinks can replace cow’s milk, you might be mistaken,” explains Professor Marianne Nissen Lund from the Department of Food Science, who led the study.
Long shelf life compromises nutritional value
Unlike cow’s milk, which comes directly from the animal, oats, rice, and almonds undergo substantial processing to become drinkable. Each of the plant-based beverages examined was also subjected to Ultra High Temperature (UHT) processing, a method commonly used worldwide for shelf-stable dairy products. In Denmark, however, cow’s milk is usually found only in refrigerators and is lightly pasteurized, receiving a much gentler heat treatment.
“Even with the rising popularity of plant-based drinks, cow’s milk sales remain higher. Consequently, plant-based drinks require more intense heating than the milk typically available in Denmark, to extend their shelf life. However, this extra heat has consequences,” notes Marianne Nissen Lund.
The UHT process triggers a “Maillard reaction,” a chemical interaction between proteins and sugars that occurs when food is cooked at high temperatures. This reaction significantly affects the nutritional quality of the proteins in the drinks.
“Most plant-based drinks already contain far less protein than cow’s milk. The protein that is present also undergoes additional changes during heat treatment, resulting in a reduction of essential amino acids, which are vital for our health. The nutritional values of plant-based drinks can vary widely, but generally, they are low in nutritional quality,” the professor elaborates.
In comparison, the UHT-treated cow’s milk analyzed in the study has 3.4 grams of protein per liter, while 8 out of the 10 plant-based drinks contained only between 0.4 and 1.1 grams of protein. Additionally, all plant-based drinks had lower concentrations of essential amino acids, and 7 out of 10 contained more sugar than cow’s milk.
Heat processing may create harmful substances
In addition to diminishing nutritional value, heat treatment generates new compounds in plant-based drinks. Researchers detected acrylamide, a known carcinogen, in four of the almond and oat-based drinks. This substance is commonly found in baked goods, coffee, and fried foods.
“We were taken aback to find acrylamide since it’s not usually present in liquid foods. Its source could be the roasted almonds used in one of the beverages. The levels found are low enough that they pose no immediate threat. However, accumulating small amounts from various food sources might lead to a health risk,” says Marianne Nissen Lund.
The researchers also found α-dicarbonyl compounds and hydroxymethylfurfural (HMF) in several of the drinks. While these substances can be hazardous in high concentrations, they were not at such levels in this study.
Professor Lars Ove Dragsted, who specializes in nutrition, is not especially alarmed by these findings, but he believes they underscore the gaps in our understanding of the compounds created through food processing:
“Compounds resulting from Maillard reactions are generally viewed as undesirable since they can contribute to inflammation in the body and are associated with higher risks of diabetes and heart disease. While our gut bacteria can break down some of these, many are still unknown or not fully studied,” states Lars Ove Dragsted from the Department of Nutrition, Exercise and Sports.
He adds: “This research highlights the importance of understanding the consequences of Maillard reactions in the development of plant-based and processed foods more broadly. The compounds identified in this study represent just a small fraction of those known to arise from these reactions.”
Prioritize Home Cooking
According to Professor Marianne Nissen Lund, the findings of this study reflect larger issues surrounding ultra-processed foods:
“In an ideal world, the shift toward greener food choices shouldn’t involve taking plant ingredients, subjecting them to ultra-processing, and then believing that results are inherently healthy. While these products aren’t necessarily dangerous or outright unhealthy, they’re often not very nutritious either.”
Her recommendation for consumers is to: “Favor minimally processed foods and drinks, and try to prepare as much of your own food as possible. If you maintain a healthy diet, integrating plant-based drinks can certainly work — just be mindful to source your nutrients from other food items as well.”
At the same time, Professor Lund urges the industry to improve their practices: “This serves as an appeal to manufacturers to innovate their offerings and re-evaluate degrees of processing. They might consider whether UHT treatment is essential or if allowing shorter shelf lives for their products could be more acceptable.”
MORE INFORMATION ON CARTONS… PLEASE
Producers must currently disclose the total nutritional content of their products, including protein, carbohydrates, and fat levels. However, this does not provide specifics on the amounts of essential amino acids present. Professor Lund believes this could be an important addition:
“If there were mandates requiring lists of essential amino acids on packaging, consumers would gain better insight into protein quality. Currently, information about saturated and unsaturated fat and the composition of carbohydrates is mandated. Many people perceive protein as a single entity, but there’s a significant difference in protein quality across products.”
KEEP IT COOL
“I’ve noted that some supermarkets store plant-based drinks in refrigerated units, which is beneficial. This practice reduces the levels of Maillard reaction products compared to those kept at room temperature. As a consumer, you can adopt the same method by refrigerating these drinks after purchase instead of storing them in a cupboard,” advises Professor Marianne Nissen Lund.
The study explored two different types of UHT-treated cow’s milk along with ten types of UHT-treated plant-based beverages available in Scandinavia from three distinct manufacturers. This included six oat drinks, one soy drink, one rice drink, one almond drink, and a mixed drink containing soy, rice, almond, and oat.