(Blog originally publushed by the Quadram Institute)
Professor Pete Wilde’s group at the Quadram Institute is studying how plant-based milks are digested to help develop ways to ensure nutrients are absorbed by the human body
Plant-based alternatives to dairy milk have gained huge popularity in recent years. European plant-based “milk” sector has grown by 36% between 2018 – 2020 to €1.6bn and sales in the UK are set to double by 2025.
This growth in popularity of plant-based alternatives has been stimulated by consumers moving away from animal-derived protein to plant-derived protein. The term “milk” is legally restricted in the EU to products produced by ruminant animals, similar products from plants are referred to as dairy or milk alternatives.
Many people make this change for environmental reasons. Plant-based dairy alternatives consume much less water, require less land and produce lower greenhouse gas emissions than cow’s milk. There is no doubt that plant-based alternatives are more environmentally friendly.
Nutrients in plant-based milk alternatives compared to dairy milk
Regarding nutrition and health, some people regard plant-based milk alternatives as healthier than dairy milk, but this depends on the reasons.
Individuals who have an allergy or intolerance to dairy proteins or who are lactose intolerant benefit hugely from the existence of these plant-based products.
However, for healthy individuals, dairy products are a rich source of readily absorbed, high quality protein, containing all the essential amino acids. Dairy milk is naturally rich in a range of minerals and vitamins. Plant-based milk alternatives can contain dietary fibre, but the protein quality is generally lower than dairy milk and may have to be fortified with minerals and vitamins.
The digestion of protein in plant-based milk alternatives
Clots formed by soy milk alternative in the presence of pectin during simulated stomach digestion
Researchers at Quadram are interested in how the structure of the food we eat can affect digestion and nutritional impact.
Professor Pete Wilde explains, “We use lab-based models which simulate the conditions of human digestion to understand these mechanisms in more detail. We have been interested in the past in how dairy proteins are digested and found that they can form clot-like structures in the stomach which can control how quickly they are digested. Slower protein digestion is known to make you feel fuller for longer.”
“Therefore, we wondered if plant-based milk alternatives behaved the same way during digestion.”
The Wilde group have a collaboration with Zhejiang Gongshanga University in China, where soy-based products have been established for many years. Together they are learning more about how soy-based milks alternatives are digested.
“Interestingly we found that soy-based milk alternatives behave in a similar way to dairy milk. Soy-based milk also forms clots and helps you feel fuller for longer.”
“The soy-based products are often stabilised by natural gums. We found that the type of gum used could change the rate at which the proteins were digested. This could help in developing tailored food products as slow protein digestion can reduce appetite and slow down muscle loss in the elderly. In contrast, rapidly digested protein can aid in muscle synthesis for sports nutrition.”
The research team is exploring the digestion of other plant-based milk alternatives too. “The protein component is important, as some plant proteins are not as easily digested as dairy protein. We are investigating the mechanisms underpinning the digestibility of plant proteins to understand how products from different sources behave, such as those from oats and almond.”
Increasing absorption of nutrients in plant-based milk alternatives
Currently plant-based milk alternatives are fortified with vitamins and minerals. However, some plant-based products contain antinutrients which can stop the absorption and uptake of nutrients such as calcium into our bodies.
Microscopy image of a clot structure showing protein (green) and fat (red).
“Our research is ongoing to understand how these plant-based alternatives can provide positive health benefits akin to dairy milk. Fortification with calcium, iodine and vitamins is relatively straightforward, but we must ensure that these nutrients are absorbed by the body”, highlights Professor Wilde.
“The gums we have been studying can be used to help stabilise calcium and other minerals. We are researching how the components of plant-based alternatives can influence nutrient availability and help develop ways that ensure that the nutrients are absorbed.”
Professor Wilde concludes, “We are looking at how we can make plant-based milk alternatives more nutritious, so that they meet the nutritional needs of those wishing to adopt a more sustainable diet.”