Plant-based foods are increasing in popularity as more and more people are concerned about personal and planetary health. The consumption of plant-based dairy alternatives (PBDAs) has assumed a more significant dietary role in populations shifting to more sustainable eating habits. Plant-based drinks (PBDs) made from soya and other legumes have ample protein levels. PBDs that are appropriately fortified have adequate levels of important vitamins and minerals comparable to dairy milk.
1. Introduction
Plant-based foods are increasing in popularity with concerns about personal and planetary health. Food-based dietary guidelines (FBDGs) reflect dietary patterns that are associated with a decreased risk of non-communicable diseases (NCDs) and nutrient deficiencies. They may also be associated with more sustainable dietary patterns with an emphasis on plants and plant-based foods and a relatively low contribution of meat and dairy
[1][2][3]. Sustainable Healthy Diets are dietary patterns that promote an individual’s health and wellbeing; are accessible, affordable, culturally acceptable, and equitable; have a low environmental impact; and support the preservation of planetary health and biodiversity
[4].
Unfortunately, the proportion of the world’s population that meets FBDGs is low
[5], hence NCDs make a major contribution globally to premature mortality
[6]. There is, therefore, a real need to increase the proportion of the population consuming diets that are closer to the FBDG ideal to improve health and environmental sustainability. Expecting populations to adopt wholly plant-based (vegan) diets is unrealistic and this is reflected in current sustainable dietary recommendations, where the focus is on increasing healthy plant foods, especially plant sources of protein, whilst reducing, rather than avoiding, the consumption of animal-derived protein
[2][7][8]. Plant foods such as nuts, legumes and pulses, and cereals, as well as alternative proteins and PBDAs used to produce products that mimic their animal-based counterparts, are one of the fastest-growing sectors within the food industry
[9]. This growth is expected to continue to meet increasing demand from meat and dairy consumers who wish to improve the healthfulness and sustainability of their diets
[10].
2. Plant-Based Dairy Alternatives
2.1. Environmental Footprint
The environmental impact of dairy milk varies across different practices and depends on the life span of the cow, the milk yield, and the feed, among other factors
[11]. An efficient dairy system where milk yield is maximized and feed optimized will result in a lower impact. On average, European milk is responsible for 2.2 kg CO2e/L from farm to retail which is one of the lowest impacts globally
[12]. Most of the emissions (>70%) occur at the farm with enteric fermentation, representing 45% of the total, being the greatest contributor. In comparison, PBDs have a lower carbon footprint compared to dairy milk by 59%, 62%, and 71% for rice, soya, and oat drinks, respectively
[13].
European dairy milk has the highest impact compared to European PBDs across all environmental indicators except for water use in the production of rice drinks. This situation exists even though European dairy milk is based on a highly efficient production system. The contrast between environmental indicators for dairy milk and PBDs is more pronounced on the global scene, since the global dairy industry has a much higher impact due to inefficient feeding, low milk yield, and other issues. In the case of water use, European dairy milk requires considerably more water than oat and soya drinks (72-fold and 200-fold, respectively), while European rice drinks require substantially more water (58%) than dairy milk. This is due to the need in Europe for irrigation water rather than the rainwater used in Asia during the rainy season, which allows Asia to irrigate using less water at higher rice yields.
European oat drink generates the lowest emissions, followed by soya drink, while rice drink emits the highest GHGs among the dairy-free options. The rice drink is lowest in the eutrophication impact and occupies the least land but has significantly higher water use. In conclusion, the environmental performance varies for PBDs across different indicators. However, the ecological footprint of dairy milk is the highest for all impacts except for water use, where the water usage for growing rice is more than double the dairy usage
[13].
The environmental impact of the fortification stage has been commonly overlooked. Since the fortification of PBDs adds nutritional value, the environmental implications should also be considered. Typically, the fortification stage will account for 14–18% of the total emissions for PBDs. Considering the agricultural, processing and fortification stages, the impact contribution is still lower than the burden of the farming stage of dairy milk. The overall emissions of 1 L of a fortified PBD are still lower by at least 23–39% when considering the fortification stage within the analysis. Moreover, energy use is the main contributor to the fortification processing’s impact, and the decarbonization of energy will reduce these impacts further. Whereas, in the case of dairy milk, the biggest contributor is the methane emissions from the animal’s enteric fermentation
[12], and while there are efforts to reduce these emissions, it remains a challenge to lower them significantly.
2.2. What Is the Nutritional and Environmental Impact of Introducing PBDs to the EAT Planetary Health Diet
According to the EAT Lancet Planetary Health Diet (EAT PHD), the daily 250 mL full-cream dairy milk allowance accounts for 6% of the calorie and 9% of the protein consumption but contributes 39% to calcium and 48% to vitamin B12 intake
[8]. Despite the low calorie and protein contribution, dairy makes up 16% of the total dietary carbon footprint
[8]. Replacing dairy milk with PBDs may therefore reduce the overall environmental impact of the diet.
Consuming soya or oat drink instead of one serving of dairy milk reduces dietary greenhouse gas emissions by 9% and 12%, respectively. The total calcium for the replacement with PBDs is comparable to dairy whilst vitamin D almost doubles, iodine increases by 31%, and vitamin B2 intake modestly increases by 5%. With current vitamin B12 fortification and following the EU EAT PHD with few animal products, this vitamin intake will drop by 5%. However, a higher fortification product or using a vitamin B12 supplement is a good way to avoid low vitamin B12 intake. Protein intake is marginally reduced by 1% and 7%, respectively, when soya or oat drink is substituted. Nevertheless, the diet will still substantially exceed the European dietary reference value for protein by 43–52%. Incorporating PBDs into the diet will not only have benefits for the environment but also will not compromise the nutritional profile of the total diet.
2.3. Environmental and Nutritional Indices
Several proposed initiatives aimed to develop an index that combines the environmental impact with the nutritional value of foods. A common limitation of these integrative indices is that they tend to focus on a limited number of factors within the nutritional and environmental domains
[14][15][16]. Also, the choice of functional unit (mass, energy, serving size, nutrient density, protein, etc.) to express the result can strongly influence the interpretation and comparability of different foods
[17]. Furthermore, the nutrient density, as well as the climate impact of foods, has to be considered with respect to the total diet.
The usefulness of nutrient density scores, in combination with environmental parameters, is limited by the lack of harmonization
[18]. There is significant heterogeneity between different nutrient density scores; for example, the choice of nutrients, the number of nutrients included, and the weight attributed to each in the index (nutrients that should be encouraged and/or nutrients to limit), and no or little adaptation to specific population needs or taking into consideration the current level of intakes compared to dietary reference values. Additionally, how these are integrated with environmental assessments highly impacts the interpretation and recommendations of which foods are best to consume
[19][20][21][22][23][24][25][26]. The combined indices can be very misleading in the broader context of dietary advice.
2.4. Nutrient Adequacy
2.4.1. Protein
While plant foods contain all the essential amino acids, their amino acid profile varies from one protein to another. When a variety of plant foods are eaten and energy needs are met, the various proteins complement each other
[27]. Legumes are a rich source of protein, with soya having a high-quality protein (i.e., quantity, amino acid composition, and bioavailability) equivalent to animal protein
[28]. Among the PBDs, those based on pea protein or soya beans have a protein content comparable to dairy milk
[29]. Both pea and soya proteins are rated as good-quality proteins by standard methods
[30].
PBDs made from grains or nuts have considerably lower levels of protein unless they have added soya or pea protein
[29]. However, the replacement of dairy milk in European populations with PBDs containing lower protein levels will not compromise one’s protein status since the overall protein intake typically greatly exceeds the requirements
[31][32][33][34].
From survey data, it observes that Europeans may consume more than double the protein Population Reference Intake (PRI) for the general population
[32]. National dietary surveys of 12 European countries reveal that protein intakes range from 62 to 111 g for adult men and 70 to 130 g for women. This exceeds the PRI of 58 g protein per day for a reference body weight in Europe of 70 kg
[35][36]. Replacing two 250 mL servings of milk (containing 8 g protein/serving) with a plant-based drink containing 1 to 3 g of protein/serving would reduce overall protein intake by 10–14 g. Therefore, a daily protein intake of 100 g/d containing two servings of milk would be reduced to an intake of 86–90 g/d by this substitution, which is still above the recommended intake.
Clearly, dairy milk is not essential to ensure an adequate protein intake in European adult populations. The replacement of dairy milk with a plant-based drink with a lower protein content seems very unlikely to result in an inadequate protein intake given the high overall protein consumption of adults and the fact that there are plenty of other protein-rich foods available. Even for European school-aged children, the protein intake has been reported
[37][38] to be more than adequate.
2.4.2. Calcium
While dairy products are an important contributor of calcium to diets in many European populations, the intake of dairy foods varies widely across Europe, with per capita consumption being as low as 1.3 L/week (less than 200 mL/day) in some countries
[39]. The prevalence of lactose malabsorption is high in some European populations, especially in Eastern Europe
[40]. People also avoid dairy products for other health, ethical, or environmental reasons.
Most European countries have recommendations within their food-based dietary guidelines (FBDG) for the inclusion of dairy products, while some also include fortified plant-based alternatives in the guidelines. However, dairy is not a unique source of calcium
[41]. Other calcium-rich plant foods consumed by Europeans include tofu, legumes, nuts and seeds, vegetables, and various calcium-fortified foods. The recommendations emphasize the importance of consuming fruits and vegetables in the diet, and some of these foods do contribute significantly to calcium intake (such as cruciferous and other leafy, green vegetables low in oxalates) and other nutrients (such as vitamin K, Mg, and K) and phytonutrients (such as flavonoids) that are essential to supporting bone health
[42][43][44][45][46][47][48].
Calcium intake is of particular concern during adolescence and early adulthood when bone mass is accumulating. Given the sometimes poor quality of diets in adolescence, the availability of varied calcium sources, including fortified PBDs, may provide useful opportunities for improving the quality of the diet during this stage of growth.
2.4.3. Vitamin B12
Animal-based foods and B12-fortified plant foods are the only reliable sources of dietary vitamin B12
[49]. It is imperative that those who consume only plant-based diets consume fortified plant foods to obtain adequate vitamin B12. Otherwise, they will need to rely upon a regular dietary B12 supplement to avoid a B12 deficiency. Vitamin B12 deficiency is a common cause of macrocytic anaemia and has been implicated in a spectrum of neuropsychiatric disorders
[50][51]. The deficiency can have serious long-term consequences.
For individuals who avoid animal foods altogether and who prefer not to take a B12 supplement, it is imperative that they consume two to three servings a day of foods fortified with vitamin B12 such as meat or dairy alternatives, yeast extracts, nutritional yeast flakes, and breakfast cereals
[52]. Food manufacturers should provide such fortified foods readily available to the public. Supplementing foods with vitamin B12 may be vital to avoid vitamin B12 deficiencies, especially among those following a vegan diet. Non-dairy alternatives that are labelled as organic are not fortified in Europe, so it is important to advise individuals to select non-organic varieties fortified with vitamin B12.
Vitamin B12 added to fortified foods does not require digestion before its absorption, since it is already in a free form. Vitamin B12 status is better maintained when consuming fortified foods or a B12 supplement than from meat, fish and other animal-based foods
[53].
Experts recommend that a mother following a 100% plant-based diet consume B12-fortified foods and ideally take a vitamin B12 supplement before and during pregnancy and during lactation. Low B12 intake and status during pregnancy or lactation have been linked to adverse maternal and perinatal health outcomes
[54]. Vitamin B12-deficient pregnant women can lead to deficiency in the infant during the first few months of life
[54][55].
2.4.4. Vitamin D
Although vitamin D can be produced endogenously when skin is exposed to sunlight, many factors influence vitamin D status. Endogenous production can only occur at certain times of the year at certain latitudes and does not occur during autumn or winter months in high latitudes and consumers must become reliant on dietary sources and perhaps take supplements. The EFSA has established an adequate intake (AI) for vitamin D of 15 µg/day for children and adults based on an assumption of minimal endogenous synthesis
[56].
Vitamin D has a limited distribution in foods and is found primarily as vitamin D3 (cholecalciferol) in fish oils, the flesh of fatty fish, and eggs from hens fed vitamin D
[57]. Some wild mushrooms are a source of vitamin D2 (ergocalciferol)
[58]. A vegan source of vitamin D3, isolated from lichen, is now available
[59]. The intake of vitamin D from food alone varies among countries but is generally well below the AI in European populations. The mean intake of vitamin D was found to range from 1.1 μg/day in women in Spain to 8.2 μg/day in men in Finland
[60].
Certain population groups have been identified as having a high risk for vitamin D deficiency and care should be taken to ensure adequate intakes, which may involve taking supplements. Such groups include the elderly (in which endogenous synthesis is reduced), institutionalized individuals who have little skin exposure to sunlight, pregnant women, and those living in countries at high latitudes.
Concerns about inadequate vitamin D status in some European populations have led to calls for the fortification of a range of foods including not just dairy milk but country-specific staple foods, thereby ensuring adequate intakes and dietary diversity
[61]. The practice of food fortification is a common and efficient approach to increasing daily nutrient intake and avoiding deficiencies. For example, the fortification of salt with iodine, and the fortification of flour with B vitamins and iron have done much to improve the nutritional status of populations
[62][63].
PBDs fortified with vitamin D2 are currently available in most European countries, with over three-quarters being fortified with vitamin D2
[64], while about one-half of PBAY are fortified
[65].
2.4.5. Iodine
The World Health Organization promotes salt iodization as an effective means of ensuring adequate iodine intake
[66]. As countries have adopted this policy, people see fewer populations encountering iodine deficiency
[67][68][69]. However, in some countries in Europe, iodized salt is not widely used or the level of fortification is low
[69], so suboptimal iodine status exists. There is a real need for implementing a standardized programme for the fortification of salt or other commonly consumed food product across Europe
[70]. Aligned with this is the need to avoid excessive salt consumption and run counter to public health messaging to reduce salt intake for improved cardiovascular outcomes
[71].
The iodine content of food varies widely depending on the soil levels and food processing. Dairy milk can significantly contribute to dietary iodine due to the cattle being fed iodine-supplemented feed and the milking sanitation procedures used on farms and in milk processing plants
[72][73]. In countries where iodine-based disinfectants are not used, the iodine content of milk is much lower
[74]. Iodine content is typically lower in organic milk
[75][76] and in milk produced during the summer
[77].
2.4.6. Riboflavin
Estimates of dietary intake of riboflavin in Europe, based upon surveys in nine countries
[78], suggest that mean riboflavin intakes meet the recommendations established by the European Food Safety Authority (EFSA)
[79] and exceed those established by both the Institute of Medicine (IOM)
[80] and the WHO
[81].
The main contributors of riboflavin to the diets of European populations are dairy products, grains and grain-based products, and meat products
[79]. The enrichment of grains with B vitamins is less common in Europe than in the US, but even so, the riboflavin intake among European vegans appears to be adequate
[82][83][84][85]. The riboflavin content of PBDs varies. Some PBDs are good sources, while other PBDs may provide much less riboflavin than dairy milk unless they are fortified
[86][87].
2.5. Ultra-Processed Food Classification
In recent years, a new approach to food classification has been developed, which is based on the degree of processing rather than on nutrient composition. The most common classification system used is NOVA. This assigns foods into one of four categories: category 1 is minimally/unprocessed foods (e.g., milk, plain yoghurt); category 2 includes processed culinary ingredients (e.g., butter, oils, sugar); category 3 includes processed foods (e.g., canned vegetables, cured meats); and category 4 includes ultra-processed foods (UPFs) which are defined as “ready-to-eat, industrially formulated foods” and include chocolate, ice cream, biscuits, and fruit yoghurts
[88]. The foods in category 4 are often characterized as having high energy density, high glycaemic index, and low satiety
[89][90].
A number of epidemiological studies have reported associations between the consumption of UPFs and the risk of obesity, metabolic syndrome, colon cancer, and mortality
[91][92][93], but the use of this system in nutritional epidemiology studies has been challenged. Reports of contradictory findings have led to some questioning the validity of NOVA
[94][95][96]. A healthy eating pattern is defined by NOVA in terms of the degree of food processing rather than by the nutritional content of the food
[96].
The definitions of UPFs are inconsistent between various classification systems
[96] and, furthermore, criticism has been expressed about the difficulty of distinguishing between ultra-processed products with differing nutritional qualities
[97][98]. This is particularly relevant for fortified PBDAs, which are usually classified as UPFs because of added ingredients including additives such as stabilizers and emulsifiers and micronutrients, whereas their dairy counterparts (including milk and plain yoghurts) are considered unprocessed or minimally processed
[99][100]. Despite this, recent studies demonstrate that PBDAs may exhibit similar or better nutritional quality than their dairy counterparts. For example, the energy density of soya-based drinks is lower than that of dairy milk, both whole and low fat, and they are lower in saturated fat and similar in protein content
[101].
Food processing plays an important role in food security and safety, but some processes can also lead to products high in salt, sugars, and saturated fats
[102]. However, it is clear that classifying PBDAs as UPFs, with the implied adverse nutritional and health associations, is inconsistent with current findings regarding the nutritional quality of such products and may discourage people from transitioning to a plant-based diet with all its health and environmental advantages.
2.6. Factors Influencing Change towards Plant-Based Dairy Alternatives
Taste, cost, health, availability, convenience, and ethical and environmental concerns are important influences on food choices as consumers search for healthier and more sustainable diets
[103][104][105][106]. These motivations must be addressed to enhance the popularity of PBDAs. Because these PBDAs are designed to mimic milk-based products, they can conveniently be substituted without the consumer needing to change their habitual eating patterns. For example, the British Dietetic Association’s One Blue Dot
® resource on meal swaps includes making breakfast more sustainable by using a fortified PBD rather than milk with breakfast cereal
[7].
The increased availability of PBDAs on supermarket shelves, usually alongside the dairy version, indicates that PBDAs are no longer considered a niche market
[9]. Not only does this location of PBDAs make their purchase more convenient for would-be consumers, but the location could also subconsciously increase purchasing by “nudging” consumers at the point of choice by acting as a cue, reducing the effort required and changing the perception of social norms
[107].
The sensory properties (especially taste) of foods and drinks are one of the most important motivations for food choice
[108]. Those who are already consumers of PBDAs appraise the sensory properties of the products positively
[109][110]; however, taste and taste perception remains one of the biggest hurdles to overcome for non-consumers. Familiarity with foods is an important positive influence on food preferences and food choices across the lifespan
[111]. Food neophobia (avoidance of the ingestion of novel foods) can be reduced through repeated tasting (exposure) of the novel food, which in turn increases the consumption of the food
[111].
Although the higher cost of PBDAs
[112] could be a barrier to consumption
[113][114][115], the continued growth in the market and the development of new PBDAs driven by increasing demand from consumers suggests that increasing the consumption of PBDAs is a potential driver for shifting population intakes towards more healthy and sustainable plant-based diets
[116].
3. Conclusions
PBDs have a substantially lower environmental footprint than dairy milk. The production of plant-based dairy alternatives uses markedly fewer natural resources, such as land and water, and greenhouse gas emissions are considerably lower in their production. With present concerns about climate change, planetary health, and the need to consume a more sustainable diet, PBDAs will continue to be popular among environmentally minded consumers in addition to those who are dairy intolerant.
PBDs made from soya and pea have ample protein with regard to both quantity and quality. Fortified non-organic varieties, provide levels of calcium and vitamin D comparable to dairy milk. The consumption of PBDAs fortified with nutrients such as calcium, and for some countries iodine and vitamins B2 and B12, would ensure nutritional adequacy among healthy European populations transitioning to a more plant-based sustainable eating