Context

Food systems have the potential to promote both human and planetary health but currently pose a significant threat to both^{(Reference Bryant, Szejda and Parekh1,2)} . Global population, expected to reach approximately 10 billion by 2050, longer life expectancy, increased income and urbanisation will increase demand on global resources^{(Reference García-Oliveira, Fraga-Corral and Pereira3–Reference Willett, Rockström and Loken6)}. The projected increase in demand for food (50 %) and animal-derived food (70 %) will add substantial pressure to an already failing food system while animal husbandry, it is argued, also has an overall negative impact on environmental sustainability^{(Reference Choudhury, Singh and Seah7,Reference Gastaldello, Giampieri and De Giuseppe8)} . Some estimates suggest food production is already responsible for approximately one-third of anthropogenic greenhouse gas emissions^{(Reference Culliford and Bradbury9–Reference Gibbs and Cappuccio12)}. Meat and dairy also require more land and water use than foods of plant-based origin, potentially furthering deforestation and biodiversity loss^{(Reference Fiorentini, Kinchla and Nolden13–Reference Szenderák, Fróna and Rákos16)}. Although historically considered an essential dietary component, providing vitamin B₁₂, iron and calcium, overconsumption of meat, particularly processed meat, has been associated with certain deleterious health consequences^{(Reference Rust, Ridding and Ward17–Reference Farsi, Uthumange and Munoz Munoz19)}.

International recognition of this challenge has led to global strategies to accelerate transition towards a healthier, more sustainable food system^{(Reference Sridhar, Bouhallab and Croguennec5,Reference Malek and Umberger20)} . These include the UN Sustainable Development Goals and the Paris Agreement of Climate Change^{(Reference García-Oliveira, Fraga-Corral and Pereira3,Reference Willett, Rockström and Loken6)} . However, the complexity and multi-faceted nature of this problem emphasises the need for strong multi-sectoral partnerships^{(Reference MacDiarmid21–Reference Anderson, Thorndike and Lichtenstein23)}. Extensive evidence suggests that reduced meat and increased plant-based food consumption would align with both climate change and health promotion strategies^{(Reference Willett, Rockström and Loken6,Reference Rust, Ridding and Ward17,Reference Graça, Oliveira and Calheiros24–Reference Kwasny, Dobernig and Riefler26)} .

Present animal-based protein consumption is unsustainably high^{(Reference Wellesley, Happer and Froggatt27)}. In 2021, global meat consumption was estimated to be 328 million metric tonnes and is expected to increase approximately 70 % by 2050^{(Reference Choudhury, Singh and Seah7,Reference Gastaldello, Giampieri and De Giuseppe8,28,29)} . High intake of red and processed meat have been associated with increased risk of non-communicable diseases including type 2 diabetes, colorectal cancer and reduced life expectancy^{(Reference Richi, Baumer and Conrad30–Reference González, Marquès and Nadal34)}. Indeed, the WHO classifies red meat as a group 2A carcinogen (likely cause of cancer) and processed meats as a group 1 carcinogen (known cause of cancer)^{(Reference Bouvard, Loomis and Guyton35)}, with the World Cancer Research Fund recommending restriction of red meat consumption to three or less portions weekly and avoidance or restriction of processed meat⁽³⁶⁾. However, guidance does not support the total elimination of meat as a key source of energy and nutrition^{(Reference Tso and Forde18,Reference MacDiarmid21)} . Against this backdrop, however the WHO has endorsed animal-derived foods for high-quality nutrition in children aged 6–23 months⁽³⁷⁾ and Adesogan et al.^{(Reference Adesogan, Havelaar and McKune38)} challenge the notion that one-size-fits all. In many developing countries animal-sourced protein consumption is limited and nutrient intake often suboptimal, reinforcing the need to tailor recommendations to different regions to prevent exacerbating present public health challenges. Additional benefits also warrant careful consideration: the livestock sector provides increased food and nutrition security, a living income for many, and contributes to national revenue, particularly in more deprived populations^{(Reference Szenderák, Fróna and Rákos16,Reference Adesogan, Havelaar and McKune38,Reference Jairath, Mal and Gopinath39)} . Nonetheless, estimates suggest that to sustainably feed 10 billion people, a significant reduction in meat consumption of about 50–75 %, accompanied by increased consumption of plant-based foods (see Table 1) is required^{(Reference Willett, Rockström and Loken6,Reference Gastaldello, Giampieri and De Giuseppe8,Reference Hartmann and Siegrist40)} . It is noted that replacing 3 % of daily energy intake derived from processed red meat with plant-derived sources could reduce risk of all-cause mortality by 12 %^{(Reference Song, Fung and Hu41)}. Furthermore, substituting 1 kg of beef-derived protein with kidney bean sources could offer an 18-fold reduction in land use^{(Reference Sabaté, Sranacharoenpong and Harwatt42)}. Heterogeneity in modelling methods used to estimate the required intake of plant-derived proteins remains however^{(Reference Willett, Rockström and Loken6,Reference Lonnie and Johnstone43–Reference Reynolds, Horgan and Whybrow46)} . While EAT-Lancet^{(Reference Willett, Rockström and Loken6)} recommend a daily intake of 25 g soyabeans plus 50 g of beans, lentils and peas, other suggested increases in legumes, beans, pulses, nuts and oil seeds vary between 26 and 30 g daily^{(Reference Scarborough, Kaur and Cobiac45–47)}.

Table 1. Definitions of key terminology referred to in the present review

Currently, 21 % of the UK population identify as flexitarian (12⋅5 % as meat-free) and 39 % report reducing meat intake, while consumption of plant-based products between 2008–2011 and 2017–2019 doubled^{(Reference Alae-Carew, Green and Stewart48,Reference Alcorta, Porta and Tárrega49)} . Globally, 40 % report reducing meat intake while 10 % avoid red meat although these changes may have been accelerated by the recent Covid-19 global pandemic^{(Reference Alcorta, Porta and Tárrega49,Reference Attwood and Hajat50)} . Increased consumer awareness of zoonosis, coupled with the food chain disruption during the pandemic may have facilitated a dietary shift to reduce meat consumption^{(Reference Attwood and Hajat50)}. However, to achieve the UK climate change commitments, an additional 20 % reduction in high carbon meat and dairy would be required over the next decade^{(Reference Alae-Carew, Green and Stewart48)}. Novel plant-based meat alternatives (PBMAs; see Table 1) designed to replicate the preparation methods, organoleptic and nutritional qualities of meat-based equivalents, may offer a viable avenue to help facilitate the required dietary shift^{(Reference Choudhury, Singh and Seah7,Reference Gastaldello, Giampieri and De Giuseppe8,Reference Bakhsh, Lee and Lee11,Reference MacDiarmid21,Reference Boukid51,Reference Bryant52)} . This gradual shift towards reduced meat consumption and increased engagement with plant-based foods has resulted in a reportedly thriving plant-based food industry^{(Reference Alae-Carew, Green and Stewart48)}. However, accelerating this transition requires a greater understanding of the factors influencing plant-based food choice. It should be noted that there is a lack of consensus regarding a universal definition for numerous terminologies in the present review. For clarity, the present review will use the definitions outlined in Table 1.

Traditional plant-based diets v. consumption of novel plant-based meat alternatives

Consumer enthusiasm to adopt healthier, more sustainable diets has led to an increase in plant-based dietary patterns such as vegetarianism, veganism and flexitarianism^{(Reference Alcorta, Porta and Tárrega49,Reference Boukid51)} . ‘Traditional’ plant-based diets are frequently characterised as low-energy density, nutrient dense, low in saturated fat and associated with a range of health benefits including healthier BMI and protection against CVD^{(Reference Harland and Garton53–Reference Naghshi, Sadeghi and Willett55)}. A large body of evidence also recognises the role of plant-based dietary patterns in reducing risk of all-cause mortality^{(Reference Naghshi, Sadeghi and Willett55–Reference Kim, Caulfield and Rebholz58)}. Naghshi et al.^{(Reference Naghshi, Sadeghi and Willett55)} reviewed thirty-two prospective cohort studies and reported plant-based protein consumption was significantly associated with reduced risk of all-cause mortality and CVD mortality. Furthermore, a 3 % increase in energy derived from plant proteins was associated with a 5 % reduced risk of all-cause mortality^{(Reference Naghshi, Sadeghi and Willett55)}. While the authors reported no association between plant-based protein consumption and cancer mortality, other studies have inferred that ‘traditional’ plant-based diets may protect against cancer and mortality^{(Reference Dinu, Abbate and Gensini56,Reference Tantamango-Bartley, Jaceldo-Siegl and Fan59–Reference Segovia-Siapco and Sabaté61)} .

Extensive epidemiological evidence also supports the adoption of ‘traditional’ plant-based diets to facilitate weight management^{(Reference Huang, Huang and Hu62–Reference Turner-McGrievy, Davidson and Wingard64)}. For example, Tran et al.^{(Reference Tran, Dale and Jensen65)} systematically reviewed twenty-two studies, eight of which demonstrated significantly reduced body weight and/or BMI. While most studies applied the gold-standard randomised controlled trial (RCT) study design, heterogeneity in methodology, such as restrictions on dietary fat intake, limited generalisability. Furthermore, some studies failed to consider confounding factors such as physical activity, limiting the internal validity. A more recent study, which did not emphasise restricted energy intake, involved a 6 month five-arm RCT^{(Reference Turner-McGrievy, Davidson and Wingard64)}. Participants were randomly assigned to a low fat, low glycaemic index; vegan (n 12), vegetarian (n 13), semi-vegetarian (n 13), pesco-vegetarian (n 13) or omnivorous (control, n 12) group dietary pattern. All intervention group participants attended dietitian-led group meetings for 6 months. While significant weight reduction was demonstrated across all dietary groups at 6 months, the vegan dietary group demonstrated significantly greater weight loss [−7⋅5(sem 4⋅5)%] compared to the semi-vegetarian [−3⋅2(sem 3⋅8)%], pesco-vegetarian [−3⋅2(sem 3⋅4)%] and omnivorous groups [3⋅1(sem 3⋅6)%]. However, it should be noted that no significant difference was reported between the vegan and vegetarian dietary groups.

Although present evidence demonstrates health benefits linked to ‘traditional’ plant-based consumption, much of the literature base relies on large-scale, historic, observational studies in restricted populations thus increasing risk of inherent methodological bias^{(Reference Spencer, Appleby and Davey66–Reference Orlich, Singh and Sabaté71)}. For example, Kwok et al.'s^{(Reference Kwok, Umar and Myint69)} systematic review and meta-analysis identified the positive impact of a vegetarian diet on risk of CVD mortality based on studies of Seventh Day Adventist communities. However, it should be noted that the healthy lifestyles behaviours associated with this population typically includes regular physical activity and abstinence from alcohol and tobacco. Thus, the influence of potential confounding variables on cardiovascular outcomes limits the generalisability of findings to the wider population.

The fast-paced nature of contemporary lifestyles has increased demand for convenience foods, as opposed to adoption of ‘traditional’ plant-based diets, leading to a rapid expansion of PBMAs designed to mimic sensory attributes of meat^{(Reference Weinrich72,73)} . Unlike ‘traditional’ whole-plant foods, PBMAs undergo considerable processing to effectively deliver tasty, convenient substitutes for meat and meat-products^{(Reference Bryant52,Reference Michel, Hartmann and Siegrist74,Reference Elzerman, Hoek and van Boekel75)} . Such novel products may be deemed inferior to minimally processed, ‘traditional’ plant-based foods with regards to impact on sustainability and health^{(Reference Tso and Forde18,Reference MacDiarmid21,Reference Bryant52,Reference Hoek, Luning and Weijzen76–Reference van Vliet, Kronberg and Provenza79)} . However, PBMAs are not designed to replace whole-plant foods but instead to offer a steppingstone in the transition away from meat to increased plant consumption^{(Reference Gastaldello, Giampieri and De Giuseppe8,Reference MacDiarmid21,Reference Bryant52)} . For example, meat-eaters are more likely to replace a beef burger with a plant-based equivalent as this substitute does not require substantial dietary change. Thus future investigations focusing on the perceived benefits of plant-based meat v. meat-based equivalent products are warranted in order to understand consumer demand.

Consumer perceptions influencing plant-based food choice

There are a wide range of complex interacting factors that influence an individual's food-related behaviours^{(Reference Onwezen, Bouwman and Reinders80,Reference Szejda, Urbanovich and Wilks81)} . Taste, cost and convenience have all been reported as primary drivers underpinning general and plant-based food choice^{(Reference Bryant52,Reference Szejda, Urbanovich and Wilks81)} . Increased awareness of animal welfare, environmental sustainability and individual health has increased demand for plant-based foods more aligned with aspirational factors^{(Reference McClements and Grossmann14,Reference Singh, Trivedi and Enamala15,Reference Tso and Forde18,Reference Bryant52)} (Fig. 1).

Fig. 1. Key factors influencing individual plant-based food choice adapted from Szejda and Parry^{(Reference Szejda and Parry188)}.

Primary drivers

Aspirational drivers

While primary drivers of cost, taste and convenience are important, animal welfare, environmental impact and health have a significant influence on food choice^{(Reference Szejda, Urbanovich and Wilks81)}.

Novel plant-based meat alternatives: health considerations

Despite the paucity in evidence regarding the impact of novel PBMAs on health, a limited number of published studies have indicated their adoption may be associated with a range of health benefits. Notably, a systematic review and meta-analysis of RCTs investigating the impact of plant-protein consumption on lipaemia proposed that protein itself may be responsible for the health-associated benefits^{(Reference Li, Mejia and Lytvyn134)}. Hence, processing whole-plant foods into protein isolates may not necessarily compromise their health value. An RCT^{(Reference Crimarco, Springfield and Petlura135)} comparing the impact of PBMAs with animal-derived meat across a range of health risk factors in thirty-six healthy omnivorous adults randomised participants to either plant–animal or animal–plant sequence and instructed them to consume ≥2 servings of the intervention meat product daily while ensuring consumption of other (non-study) foods was comparable in each phase (8 weeks each). PBMA consumption was associated with cardioprotective changes including significantly lower trimethylamine-N-oxide concentrations [PBMA mean = 2⋅7(sem 0⋅3) μm v. meat mean = 4⋅7(sem 0⋅9) μm; mean difference = −2⋅0 [95 % CI −3⋅6, −0⋅3]], LDL-cholesterol concentrations [PBMA mean = 109⋅9(sem 4⋅5) mg/dl v. meat mean = 120⋅7(sem 4⋅5) mg/dl; mean difference = −10⋅8 [95 % CI −17⋅3, −4⋅3]] and weight [PBMA mean = 78⋅7(sem 3⋅0) kg v. meat mean = 79⋅6(sem 3⋅0) kg; mean difference = −1⋅0 [95 % CI −1⋅5, −0⋅5]] compared to meat consumption. It should be noted that the level of dietary control was limited as participants were able to consume chicken or fish in the plant-arm and self-selected all other dietary components. However, this in turn increases the generalisability and external validity of the study findings. A recent RCT^{(Reference Toribio-Mateas, Bester and Klimenko136)} also demonstrated positive changes in the gut microbiome when substituting several meat-based meals weekly for PBMA meals, resulting in a significant increase in butyrate-production pathways and significant decrease in the Tenericutes phylum; attributes associated with a healthy gut microbiome. Zhou et al.^{(Reference Zhou, Hu and Tan137)} also reported higher levels of dietary fibre from the digestion of PBMAs compared to meat that may increase satiation after consumption of the PBMA.

There is conflicting evidence regarding the impact of plant-based foods upon appetite^{(Reference Kristensen, Bendsen and Christensen138–Reference Kahleova, Tintera and Thieme140)}. Williamson et al.^{(Reference Williamson, Geiselman and Lovejoy141)} conducted a three-way crossover study in overweight subjects (n 42) investigating the satiating efficacy of a mycoprotein pasta preload and a tofu pasta preload compared to an isoenergetic chicken pasta preload, closely matched for protein and organoleptic characteristics. The authors concluded pre-loading with mycoprotein and tofu led to significantly lower food intake compared to chicken preloading (138⋅7, 135⋅2 and 158⋅3 g, respectively). A similar study^{(Reference Kristensen, Bendsen and Christensen138)} reported plant-based protein (beans/peas) to be significantly more effective than energy and protein matched animal-based protein (veal/pork) on subjective markers of appetite in a healthy cohort of male participants (n 43). In contrast, no differences were found between plant-based (fava beans/split peas) and meat-derived (veal/pork) protein meals, matched for energy, macronutrient and fibre, in a single-blinded RCT^{(Reference Nielsen, Kristensen and Klingenberg139)}. Similarly, a recent double-blind RCT^{(Reference Pham, Knowles and Bermingham142)} also reported no significant differences regarding markers of appetite between a lamb burrito and a plant-based meat burrito meal. However, it should be noted that the study meals were not matched for protein which may have influenced the results. In addition, Neacsu et al.^{(Reference Neacsu, Fyfe and Horgan143)} suggested plant-based and meat-based high-protein diets had a similar impact on gut-peptide hormones and subjective appetite responses. However, a randomised crossover study demonstrated increased peptide YY, glucagon-like peptide 1, amylin and thalamus perfusion following consumption of a plant-based meal compared to an energy- and macronutrient-matched meat-based meal^{(Reference Kahleova, Tintera and Thieme140,Reference Klementova, Thieme and Haluzik144)} . Proposed satiating mechanisms include high dietary fibre content (promoting SCFA production) in addition to modification of gastric hormone secretion and gastric emptying related to appetite suppression^{(Reference Salleh, Fairus and Zahary145,Reference Sánchez, Miguel and Aleixandre146)} . Grundy et al.^{(Reference Grundy, Edwards and Mackie147)} also described how dietary fibre encapsulates macronutrients to regulate digestion, while soluble dietary fibre increases viscosity in the gastrointestinal tract which in turn may slow macronutrient digestion. However, extensive processing is associated with nutrient loss and UPFs are noted to be limited in appetite-regulating nutrients such as dietary fibre and protein^{(Reference Fardet and Rock148,Reference Sha and Xiong149)} . Thus, the influence of processing on the capacity of commercial PBMAs to elicit fullness needs further investigation. Furthermore, while the RCT study design is considered the gold-standard method, there is an urgent need for longitudinal data to evaluate the long-term consequences of habitual consumption of PBMAs on appetite and health.

Nutritional profile of novel plant-based meat alternatives

Limited published scientific evidence is inconclusive regarding the health value of novel PBMAs and their capacity to replicate the nutritional profile of meat-equivalents. Curtain and Grafenauer^{(Reference Curtain and Grafenauer160)} reported that most PBMAs demonstrated a healthier nutrient profile than meat-based equivalents in their audit of Australian supermarkets. For example, PBMAs were significantly lower in energy density, total fat, saturated fat and significantly higher in dietary fibre. However, the sodium content of PBMAs was particularly high, with only 4 % of products classified as ‘low in sodium’. In fact, plant-based mince had 6-fold higher sodium content than the meat-based equivalent while meat sausages had significantly greater sodium than PBMAs. A similar study in the UK^{(Reference Alessandrini, Brown and Pombo-Rodrigues161)} also reported significantly higher sodium levels in all categories except for sausages and reinforced concerns by identifying approximately three-quarters of products having salt content greater than their maximum salt reduction target. The authors also reported significantly lower protein content in four out of six PBMA categories. However, although the study targeted fourteen UK retailers for PBMAs, Covid-19 restrictions meant that only one supermarket was targeted for meat-equivalent products. Consistency in search method for both product types would increase rigour in future research.

Tonheim et al.^{(Reference Tonheim, Austad and Torheim162)} recently conducted a similar survey investigating PBMAs available on the Norwegian market. Again the Covid-19 pandemic restricted the range of suppliers and data collection was undertaken in two phases. The authors compared PBMAs to their meat-based equivalents in two categories: ‘regular’ meat and ‘healthy’ meat (identified with a keyhole symbol, a labelling scheme identifying healthier food products)⁽¹⁶³⁾. These ‘healthy’ meats were typically reduced fat alternatives to ‘regular’ meats. PBMAs were typically lower in energy content compared to ‘regular’ meat, though they contained more energy than their ‘healthy’ meat comparator. PBMAs were generally lower in saturated fat and higher in dietary fibre than either category of meat comparator. There was also between product variation in salt content. While salt content was more favourable in the plant-based meatballs v. both meat-equivalents, it was greater than both meat-equivalents in other product categories with plant-based mince demonstrating a 10-fold greater salt content than the ‘healthy’ meat comparator. In contrast, Boukid and Castellari^{(Reference Boukid and Castellari164)} reported no significant difference in sodium content between the four burger products (vegetarian, red meat, fish and poultry-based) in their survey of the EU burger market.

Heterogeneity both within and between product categories was also demonstrated in other similar studies^{(Reference Curtain and Grafenauer160,Reference Pocklington, Hackett and Lamkin165–Reference SafeFood167)} . Fresán et al.^{(Reference Fresán, Mejia and Craig10)} reviewed fifty-six PBMAs according to their protein source and concluded that despite some between product variation, the nutritional profile demonstrated no substantial differences. Meanwhile, Bohrer^{(Reference Bohrer166)} reported the nutritional composition of a plant-based burger to be similar to that of a McDonald's^® beef patty but found differences in meatballs where the plant-based version was lower in energy, saturated fat and higher in dietary fibre compared to the meat-based equivalent. In addition, safefood^{(Reference SafeFood167)} identified chicken alternatives to be less favourable on a number of nutritional components including energy density, protein, saturated fat, sugar and salt in their audit of PBMAs in Irish supermarkets. However, the method of product categorisation may have influenced the findings^{(Reference SafeFood167)}. For example, while other studies^{(Reference Curtain and Grafenauer160–Reference Tonheim, Austad and Torheim162,Reference Bryngelsson, Moshtaghian and Bianchi168)} typically selected an equivalent meat-based product as a comparator, the authors^{(Reference SafeFood167)} compared all chicken alternatives, including breaded, battered and plain alternative products, to a skinless, grilled chicken breast. Similarly, while other studies^{(Reference Curtain and Grafenauer160,Reference Alessandrini, Brown and Pombo-Rodrigues161,Reference Bryngelsson, Moshtaghian and Bianchi168)} compared plant-based mince to beef mince, the authors^{(Reference SafeFood167)} compared plant-based alternative steaks, mince, meatballs and Bolognese to beef mincemeat. This method of categorisation limits the reliability of study findings as the selected meat product does not reflect a suitable comparator. This highlights a substantial challenge for research conducted within this area. For example, a robust feeding trial would require an appropriate comparator arm which includes an element of blinding across a range of factors including sensory attributes, cooking technique and nutritional profiling. However, a major limitation in the afore-mentioned studies is the omission of micronutrient analysis. As meat is considered a valuable vehicle of vital micronutrients such as vitamin B₁₂, zinc, iron and calcium, vitamin and mineral content should be considered when evaluating nutritional value of PBMAs^{(Reference Rust, Ridding and Ward17,Reference Tso and Forde18,Reference Curtain and Grafenauer160)} .

More recent studies have considered micronutrient alongside macronutrient composition in their evaluation of PBMAs^{(Reference Bryngelsson, Moshtaghian and Bianchi168–Reference Cole, Goeler-Slough and Cox170)}. These studies used similar methods, identifying PBMAs via a search of defined supermarkets and extracting nutritional information from product packaging, front of pack information and both supermarket and manufacturer websites. While there was substantial between product variation, the studies generally reported PBMAs to be lower in saturated fat, richer in dietary fibre and substantially higher in sodium than their meat-based comparator. However, despite reporting an intention to analyse micronutrient content of PBMAs, D'Alessandro et al.^{(Reference D'Alessandro, Pezzica and Bolli169)} failed to present data for these variables. While Bryngelsson et al.^{(Reference Bryngelsson, Moshtaghian and Bianchi168)} reported that a large proportion of PBMAs lacked micronutrient information, the limited data highlighted a wide variation between product categories. For example, while PBMAs were typically richer in iron and folate compared to their meat-equivalent, vitamin B₁₂ was noted to be higher in plant-based sausages, lower in bacon and similar within the nugget product range. However, these data were derived from a very limited number of products as information for iron, folate and vitamin B₁₂ were provided on 13, 6 and 6 % of products, respectively.

Cole et al.^{(Reference Cole, Goeler-Slough and Cox170)} restricted their analysis to burger categories (imitation burger, vegetarian burger and conventional beef burgers) and highlighted variation in vitamin and mineral content. For example, although the imitation burger demonstrated comparable levels of iron, it was significantly richer in vitamins A, C and D, potassium and calcium compared to the meat-based equivalent. However, the authors were unable to obtain information regarding a range of vitamins and minerals that are key components of beef, including zinc, vitamin B₁₂, phosphorus and magnesium. This may reflect that in the EU labelling of vitamin and mineral information on packaged food labelling is at the discretion of the manufacturer and highlights a limitation of evaluating micronutrient value through nutrition facts labelling⁽¹⁷¹⁾. Meanwhile, Harnack et al.^{(Reference Harnack, Mork and Valluri172)} used food ingredient information alongside nutrition facts labelling to develop recipes and estimate nutritional value of selected beef alternative products in contrast to meat counterparts. They reported plant-based ground beef to be a rich source of dietary fibre with comparable levels of iron compared to ground beef but highlighted a shortfall in protein, zinc and vitamin B₁₂ alongside substantially higher sodium content. Again, the authors acknowledged that inaccurate labelling and limitations in the Food and Nutrition Database used to develop recipes increased the risk of inaccurate calculations of nutritional value.

Two studies^{(Reference Swing, Thompson and Guimaraes173,Reference De Marchi, Costa and Pozza174)} have investigated nutritional composition using laboratory analysis techniques. Although it was not reported, it could be inferred that the associated time and cost-burden may have resulted in restricted focus of these studies^{(Reference Swing, Thompson and Guimaraes173,Reference De Marchi, Costa and Pozza174)} to single-product categories (burger products). Both studies^{(Reference Swing, Thompson and Guimaraes173,Reference De Marchi, Costa and Pozza174)} concluded that the plant-based burger products were able to demonstrate a comparable nutritional profile and richer content of certain minerals although there was again variability between products. However, in contrast to other studies where PBMAs were reported to be lower in saturated fat content but contain substantially more sodium, De Marchi and colleagues^{(Reference De Marchi, Costa and Pozza174)} reported no significant difference in sodium or saturated fat content between plant-based and meat-based burgers. However, the comparable levels of saturated fat may be attributed to use of particular ingredients in the selected products such as coconut oil in the plant-based burgers^{(Reference Kołodziejczak, Onopiuk and Szpicer175)}.

A more recent study conducted a comprehensive nutritional analysis of a large range of PBMAs (hot and cold categories) v. their meat-based counterparts using four national nutrient databases and laboratory analyses^{(Reference Pointke and Pawelzik176)}. The authors support previous study findings^{(Reference Curtain and Grafenauer160,Reference Alessandrini, Brown and Pombo-Rodrigues161,Reference Bryngelsson, Moshtaghian and Bianchi168,Reference Cole, Goeler-Slough and Cox170)} where despite substantial variation between PBMA product ranges, PBMAs were demonstrated to have lower energy density, total and saturated fat but considerably higher sugar and sodium levels compared to their meat-equivalents. In addition, analysis of micronutrients demonstrated similarities to other reports where PBMAs were notably higher in calcium, phosphorus and iron^{(Reference Bryngelsson, Moshtaghian and Bianchi168,Reference Cole, Goeler-Slough and Cox170)} . In contrast to other studies, the authors analysed a greater range of micronutrients and highlighted substantial between product heterogeneity. For example, while levels of micronutrients, such as folate, vitamins B₆, E and K, were either comparable or superior to their meat-based comparator, others demonstrated a significant shortfall, in particularly vitamin B₁₂ and zinc. Similarly, the study was unable to detect vitamin D within PBMAs; highlighting the need for manufacturers to consider fortification of certain products to ensure sufficient nutrient content. This supports previous studies that have raised concern regarding the level of and/or bioavailability of nutrients such as vitamin B₁₂, zinc and iron in plant-based diets and the need to consider meal plans and supplementation to avoid nutrient deficiency^{(Reference Harnack, Mork and Valluri172,Reference Rizzo, Laganà and Rapisarda177–Reference Craig, Mangels and Fresán179)} . For example, plant-based foods are a primary source of non-haem iron, which has much lower bioavailability compared to haem iron, the predominant form present in animal-derived foods; reinforcing the need for PBMA fortification^{(Reference van Vliet, Kronberg and Provenza79,Reference Kołodziejczak, Onopiuk and Szpicer175,Reference Rizzo, Laganà and Rapisarda177,Reference Harnack, Reese and Johnson180)} . However, fortification of PBMAs with vitamin B₁₂, iron and zinc is inconsistent with under a quarter of products fortified with these nutrients^{(Reference Curtain and Grafenauer160,Reference Bryngelsson, Moshtaghian and Bianchi168,Reference Harnack, Reese and Johnson180)} . Tso and Forde^{(Reference Tso and Forde18)} recently compared a model omnivorous reference diet to model diets replacing animal-derived products for either ‘traditional’ plant-based foods or novel plant-based products (e.g. PBMAs). Acknowledging the variability in fortification of plant-based products, the authors excluded fortified products from their reference diets. The findings highlighted that novel plant-based products were unable to meet dietary requirements for a range of nutrients including zinc and vitamin B₁₂ in contrast to the omnivorous reference diet. While this study was a hypothetical comparison, it yet again reinforces the need to consider fortification methods to protect against deficiency for diets incorporating PBMAs.

Ultimately, these findings demonstrate the inconsistent nutrient profile of PBMAs and highlight the challenge of successful replication of meat-equivalents. There are multiple confounding variables that may have influenced the heterogeneity of the reported findings including geographical location, product search methods and measurement tools used. For example, despite being deemed a reliable tool, questions have been raised regarding the ability of the UK Nutrient Profiling Index to reflect present consumption behaviour and recent revisions have been made to the model to address such limitations⁽¹⁸¹⁾. Furthermore, while the healthy star rating system has been praised for inclusivity and understandability, it is contextualised to Australia and New Zealand^{(Reference Jones, Thow and Ni Mhurchu182)}. However, a key limitation of these tools is that they fail to consider the potential impact of degree of processing on the nutritional and mechanistic quality of food products and there is a need for greater understanding of the possible impact of this on the health benefits associated with particular ingredients. For example, processing can increase or decrease the bioavailability, digestibility, nutritional and functional characteristics of particular foods and ingredients^{(Reference Aguilera183)}. Furthermore, the potential impact of antinutrients commonly present in PBMAs, such as phytate and tannins, requires further understanding, particularly regarding possible positive or negative interactions within the food matrix in addition to their potential inhibition of the absorption of other key vitamins and minerals^{(Reference Aguilera183)}. In addition, despite some inconsistency, the majority of studies highlighted considerably higher levels of sodium in PBMAs and some authors attributed this to ultra-processing^{(Reference Gehring, Touvier and Baudry96,Reference Wickramasinghe, Breda and Berdzuli131)} . This is concerning given the association between high sodium intake and increased risk of non-communicable disease such as CVD^{(Reference Lane, Davis and Beattie184,Reference Mozaffarian, Fahimi and Singh185)} .

Thus, without further clarification on the impact of processing, categorising UPFs as ‘healthy’ may inflate the so-called ‘health halo’ surrounding PBMAs^{(Reference Wickramasinghe, Breda and Berdzuli131)}. Present paucity in knowledge, coupled with the rapid expansion of the PBMA market means there is a growing urgency for more scientific evidence to address this ambiguity and a strong rationale to improve consumer literacy of PBMAs^{(Reference Estell, Hughes and Grafenauer110,Reference Wickramasinghe, Breda and Berdzuli131)} .