Plant-based milk has become a household staple in recent years, extending beyond vegans and those who are lactose intolerant. The most popular varieties include oat, coconut, almond, soya, hemp, rice and hazelnut milk. People may opt for plant-based milk for a number of reasons, including health concerns, environmental sustainability, ethical considerations, dietary intolerances or simply flavour preference.
Plant-based food alternatives, not only milk, are often perceived as the ‘healthier’ option due to their association with natural and whole ingredients compared with their non-plant-based counterparts. However, is this perception true, and how does their nutritional value differ from dairy milk?
Nutritional benefits of dairy milk
Dairy milk provides essential nutrients which support a healthy balanced diet, including energy and high-quality protein, along with a range of micronutrients. In particular, dairy consumption is associated with improved bone mineral density in children, which may reflect its provision of calcium, protein, vitamin D, potassium and phosphorus (Ramsing et al., 2023), making it a valuable dietary component.
Furthermore, dairy milk contains two main types of protein: whey and casein. Combined, these animal-based proteins provide all nine essential amino acids that our body requires to support tissue repair and muscle maintenance (Gil & Ortega, 2019). Casein can also help increase mineral absorption, which increases the nutritional efficiency of dairy milk (Gil & Ortega, 2019).
Additionally, dairy consumption has been linked to a reduced risk of high blood pressure, possibly due to its calcium, potassium and magnesium content (Gil & Ortega, 2019). Overall, dairy milk provides a convenient source of essential nutrients within a balanced diet with minimal processing involved.
Nutritional benefits of plant-based milks
The main concerns people may have when switching to plant-based milk are their level of processing, additives and their potential nutritional limitations compared with cow’s milk. However, classification as an ultra-processed food does not inherently mean a detriment to nutritional quality.
Processing enables the fortification of plant-based milks with essential macro- and micronutrients to help match their nutritional content to that of dairy milk. Most commonly added nutrients include vitamin A, vitamin D, calcium and vitamin B12 (Ramsing et al., 2023). Plant-based milks can still provide beneficial nutrients, including dietary fibre, antioxidants and unsaturated fats, although their nutritional composition varies depending on the base ingredient (Aydar et al., 2020; Pérez-Rodríguez et al., 2023). As a result, the overall nutrient profile, including protein and fat content, differs considerably between products, making it difficult to generalise the nutritional value of plant-based milks as a whole (Pérez-Rodríguez et al., 2023).
Why plant-based milks aren't necessarily the ‘healthier’ option
Despite the reputation of plant-based diets for promoting health and sustainability, several factors contribute to the nutritional limitations of plant-based milks compared with dairy milk.
An important limitation is the bioavailability of vitamins and minerals. Bioavailability refers to the proportion of a nutrient that the body can absorb and utilise. Although the plant ingredients used to produce these milks are often nutrient-rich and many plant milks are fortified, the bioavailability of some of these nutrients may be compromised by antinutrients (Aydar et al., 2020). Antinutrients are naturally occurring compounds, such as phytates and oxalates, which can interfere with the absorption and utilisation of essential nutrients, including calcium, iron and zinc (Aydar et al., 2020).
Many commercial plant-based milks also contain added sugars, flavourings or additives to improve palatability, extend shelf life and mimic textures and flavours of dairy milk (Pérez-Rodríguez et al., 2023). Added sugars help to replicate the naturally occurring sweetness of dairy milk, which can raise the free sugar content of the drink.
Furthermore, many plant-based milks contain less protein than dairy milk because they are often made from ingredients which naturally contain lower levels of protein and are diluted with water during production. Additionally, processing methods such as roasting can damage protein molecules which further reduces their digestibility and nutritional value (Aydar et al., 2020). However, not all plant milks are low in protein; soya milk, for example, has a similar protein content to cow’s milk (Aydar et al., 2020).
Sustainability qualities of plant-based milk
Regardless of nutritional value, plant-based milk remains the more environmentally sustainable option compared with dairy milk.
Dairy production has a considerably greater environmental impact than plant-based milk production for two main reasons: methane emissions and land use (Carlsson Kanyama et al., 2021). Cattle produce high volumes of methane, a greenhouse gas which contributes significantly to global warming. Additionally, extensive areas of land are required for cattle grazing and feed production. This land could otherwise support trees and other ecosystems, which can act as carbon sinks by absorbing carbon dioxide from the atmosphere. Dairy milk production is also highly water-intensive, for example approximately 628 litres of water are required per litre of milk compared with approximately 48 litres for oat milk production (Poore & Nemecek, 2018).
While the cultivation of crops for plant-based milks also requires land and produces greenhouse gas emissions, it is generally more resource-efficient and has an overall lower carbon footprint across the supply chain (Carlsson Kanyama et al., 2021). Therefore, the decision to opt for plant-based milk alternatives may be driven by factors other than health benefits, such as environmental impact.
Conclusions
Neither dairy milk nor plant-based milk can be considered the ‘healthier’ option.
Dairy milk has its advantages in terms of its naturally occurring nutritional content, particularly its high-quality protein and highly bioavailable vitamins and minerals. However, contemporary fortification and processing techniques allow many plant-based alternatives to achieve a nutritional profile which more closely resembles that of dairy milk.
While dairy milk may hold certain nutritional advantages, plant-based milks generally have a substantially lower environmental impact, requiring fewer resources and emitting fewer greenhouse gases.
However, consumers opting for plant-based milks should check nutrition labels, as nutrient content can differ between products. Selecting fortified varieties and ensuring key nutrients are acquired elsewhere in the diet can help to maintain nutritional adequacy.
Ultimately, the choice between dairy and plant-based milk is not simply a question of health, but also one of personal values, dietary needs and sustainability priorities.
